SS 607-2015

Licensed by SPRING Singapore to JEROME CHAN KUAN HOE/MR, LR2J CONSULTING ENGINEERS Singapore Standards eShop Or der No: 6800034411/Downloaded 6800034411/Downloaded:2015-11-23 :2015-11-23 Single user licence only, copying and networking prohibited

SS 607 : 2015 (ICS 13.340.60)

SINGAPORE STANDARD

Specification for design of active fall-protection systems

Published by


SS 607 : 2015 (ICS 13.340.60)

SINGAPORE STANDARD


All rights r ights reser reserved. ved. Unless otherw otherwise ise specifi s pecified, ed, no part pa rt of this Singapore Singap ore Standard may be reproduced or utilised in any form or by any means, electronic or mechanical, including photocopying and microfilming, without permission in writing from SPRING Singapore at the address below:

SPRING Singapore 1 Fusionopolis Walk #01-02 South Tower, Solaris Singapore 138628 Email : : [email protected]

ISBN 978-981-4726-07-8


SS 607 : 2015 (ICS 13.340.60)

SINGAPORE STANDARD


All rights r ights reser reserved. ved. Unless otherw otherwise ise specifi s pecified, ed, no part pa rt of this Singapore Singap ore Standard may be reproduced or utilised in any form or by any means, electronic or mechanical, including photocopying and microfilming, without permission in writing from SPRING Singapore at the address below:

SPRING Singapore 1 Fusionopolis Walk #01-02 South Tower, Solaris Singapore 138628 Email : : [email protected]

ISBN 978-981-4726-07-8


SS 607 : 2015

This Singapore Standard was approved by the General Engineering and Safety Standards Committee on behalf of the Singapore Standards Council on 1 October 2015. First published, 2015

The General Engineering and Safety Standards Committee, appointed by the Standards Council, consists of the following members: Name

Capacity

Chairman Deputy Chairman

:

Mr Chan Yew Kwong

Member, Standards Council

:

Mr Seet Choh San

Singapore Institution of Safety Officers

Secretary

:

Ms Kong Wai Yee

Singapore Manufacturing Federation – Standards Development Organisation

Members

:

Ms Barbara Bok

SPRING Singapore Housing and Development Board Building and Construction Authority Nanyang Technological University Association of Small and Medium Medium Enterprises Land Transport Authority Singapore Contractors Association Limited Association of Singapore Marine Marine Industries Packaging Council of Singapore Institution of Engineers, Singapore National Environment Agency Society of Loss Prevention in the Process Industries Access and Scaffold Industry Association Singapore Manufacturing Federation JTC Corporation Ministry of Manpower Singapore Welding Society

Er. Goh Keng Cheong Er. Hashim Bin Mansoor Assoc Prof Hoon Kay Hiang Mr Koh Yeong Kheng Mr Liu Png Hock Mr Ng Yek Meng Mr Derek Sim Ms Annabelle Tan Mr Tan Kai Hong Mr Tan Kee Pin Mr Tay Cheng Pheng Mr Jonathan Wan Mr Wong Choon Kin Mr Wong Siu Tee Mr Winston Yew Dr Zhou Wei

The Technical Committee on Personal Safety and Health, appointed by the General Engineering and Safety Standards Committee and responsible for the preparation of this standard, consists of representatives from the following organisations:

CoChairmen

:

Name

Capacity

Assoc Prof Chew Chye Heng

National University of Singapore Member, General Engineering and Safety Standards Committee

Mr Winston Yew Secretary

:

Ms Julia Yeo

Singapore Manufacturing Federation – Standards Development Organisation

Members

:

Mr Bhupendra Singh Baliyan

Institution of Engineers, Singapore Singapore Contractors Association Limited Ministry of Manpower

Mr Thomas Fong Mr Fung Chan Hua

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SS 607 : 2015

Members

:

Singapore Association of Occupational Therapists Ministry of Manpower TÜV SÜD PSB Pte Ltd Singapore Institution of Safety Officers Association of Singapore Marine Marine Industries Human Factors and Ergonomics Society of Singapore SETSCO Services Pte Ltd

Mr Patrick Ker Mr Lim Cheong Mr Seah Chong An Mr Seah Liang Bing Mr Derek Sim Mr Edwin Yap Mr Yusoof Aynuddin

The Working Group, appointed by the Technical Committee to assist in the preparation of this standard, comprises the following experts who contribute in their individual capacity : Name Convenor

:

Dr Goh Yang Miang

Members

:

Ms Azzalina Zainuddin Mr Han Kin Sew Mr Hoe Yee Pin Er. Louis Hwang Mr Koh Keok Chuah Mr Sean Leo Er. Liau Wai Kun Mr Ong Ho Peng Mr Derek Sim Mr Bernard Soh Mr Sunny Teo Er. Raymond Tsui Er. Joanne Wong

The organisations in which the experts of the Working Group are involved are:

AECOM Singapore Pte Ltd Association of Consulting Engineers Engineers Singapore Association of Singapore Marine Marine Industries Engineers 9000 Pte Ltd Housing and Development Board Institution of Engineers, Singapore Keon Consult Pte Ltd Land Transport Authority Ministry of Manpower National University of Singapore PDS International Pte Ltd Singapore Institution of Safety Officers TRACTEL Singapore Pte Ltd Workplace Safety and Health Council

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Licensed by SPRING Singapore to JEROME CHAN KUAN HOE/MR, LR2J CONSULTING ENGINEERS Singapore Standards eShop Or der No: 6800034411/Downloaded:2015-11-23 Single user licence only, copying and networking prohibited

SS 607 : 2015

Contents Page National Foreword

6

Preface

7

1

Scope

8

2

Reference publications

8

3

Definitions

9

4

Drawings and specifications

19

5

Materials, equipment, and other design requirements

20

6

Safety criteria

24

7

Fall-protection system loads and forces

28

8

Clearances for fall-arrest systems

32

9

Design assumptions and analytical methods

35

Annexes ZA

Technical deviations and their explanations

44

A

Commentary

48

B

Bibliography

55

7.1

Lumping factor, M , for rigid anchorage systems

31

7.2

Lumping factor, M , for flexible anchorage systems

31

1

Free fall resulting from lanyard lifeline slack

38

2

Free fall on vertical lifelines resulting from lanyard slack and movement of the fall arrester

39

3

Horizontal lifeline sags and forces

40

4

Stretch out

41

5

Swings falls

42

6

Clearances (excluding swing-fall distance)

43

Tables

Figures

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National Foreword This Singapore Standard was prepared by the Working Group appointed by the Technical Committee on Personal Safety and Health under the direction of the General Engineering and Safety Standards Committee. This Singapore Standard is a modified adoption of CSA Z259.16-04(R2014) – ‘Design of active fall-protection systems’, published by the Canadian Standards Association. The modifications are given in Annex ZA which contains the technical deviations and their explanations to suit the local requirements and the needs of the industry. The changes in the main text are indicated with lines along the margins. In preparing this standard, reference was also made to the following publications: 1.

ANSI/ASSE Z359.6

Specifications and design requirements for active fall protection systems

2.

SS 528

Specification for personal fall-arrest systems. Part 1: Full body harnesses Part 2: Lanyards and energy absorbers Part 3: Self-retracting lifelines Part 4: Vertical rails and vertical lifelines incorporating a sliding-type fall arrester Part 5: Connectors with self-closing and self-locking gates Part 6: System performance tests

3.

SS 541

Specification for restraint belts

4.

SS 570

Specification for personal protective equipment for protection against falls from a height. Single point anchor devices and flexible horizontal lifeline systems

5.

Workplace Safety and Health (Work at Heights) Regulations

Acknowledgement is made for the use of information from the above publications. Attention is drawn to the possibility that some of the elements of this Singapore Standard may be the subject of patent rights. SPRING Singapore shall not be held responsible for identifying any or all of such patent rights.

NOTE

1.

Singapore Standards are subject to periodic review to keep abreast of technological changes and new technical developments. The changes in Singapore Standards are documented through the issue of either amendments or revisions.

2.

Compliance with a Singapore Standard does not exempt users from legal obligations.

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Preface This is the first edition of CSA Z259.16, Design of active fall-protection systems. It is part of the Z259 series of Standards for components of personal fall-arrest systems. The purpose of this standard is to specify requirements for the design and performance of complete active fall-protection systems, including travel-restraint and vertical and horizontal fall-arrest systems. This Standard was prepared by the Technical Committee on Fall Protection, under the jurisdiction of the Strategic Steering Committee on Occupational Health and Safety, and has been formally approved by the Technical Committee. It will be submitted to the Standards Council of Canada for approval as a National Standard for Canada.

February 2004 NOTES:

(1)

Use of the singular does not exclude the plural (and vice versa) when the sense allows.

(2)

Although the intended primary application of this Standard is stated in its Scope, it important to note that it remains the responsibility of the users of the Standard to judge its suitability for their particular purpose.

(3)

This publication was developed by consensus, which is defined by CSA Policy governing standardization – Code of good practice for st andardization as “substantial agreement. Consensus implies much more than a simple majority, but not necessary unanimity”. It is consistent with this

definition that a member may be included in the Technical Committee list and yet not be in full agreement with all clauses of this publication. (4)

CSA Standards are subject to periodic review, and suggestions for their improvement will be referred to the appropriate committee.

(5)

All enquiries regarding this Standard, including requests for interpretation, should be addressed to Canadian Standards Association, 5060 Spectrum Way, Suite 100, Mississauga, Ontario, Canada L4W 5N6.

Requests for interpretation should (a)

define the problem, making reference to the specific clause, and, where appropriate, include an illustrative sketch;

(b)

provide an explanation of circumstances surrounding the actual field condition; and

(c)

be phrased where possible to permit a specific “yes” or “no” answer.

Committee interpretations are processed in accordance with the CSA Directives and guidelines governing standardization and are published in CSA’s periodical Info Update, which is available on the CSA Web site at www.csa.ca.

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Specification for design of active fall-protection systems 1

Scope

1.1

This Standard is intended for professional engineers with expertise in designing fall-protection systems. It specifies requirements for the design and performance of complete active fall-protection systems, including travel-restraint and vertical and horizontal fall-arrest systems.

1.2

This Standard is not intended as a substitute for testing and certification of individual components of fall-protection equipment in accordance with applicable CSA Z259 equipment Standards.

1.3

This Standard does not cover the design of passive fall-protection systems such as guardrails and nets, except where such passive systems are also designed to serve as anchorage and/or anchorage connector subsystems for active fall-protection systems covered by this Standard.

1.4

This Standard does not cover the design of positioning systems.

1.5

This Standard does not cover the determination of structural strength and behaviour of components or anchorages of active fall-protection systems. It does, however, establish the safety criteria once the strengths and behaviours are known. Such strengths and behaviours are determined by analytical testing or engineering methods and by CSA or other design Standards for the materials and structural systems being used.

1.6

This Standard does not specify design or performance requirements for fall-arrest equipment or systems that have been manufactured and successfully tested in accordance with the requirements of another CSA Z259 Standard.

1.7

This Standard does not supersede the requirements of applicable occupational safety and health regulations. Where the requirements in this Standard differ from legislated requirements, the most conservative requirement is followed.

1.8

In CSA Standards, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the standard. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Legends to equations and figures are considered requirements.

2

Reference publications

This Standard refers to the following publications, and where such reference is made, it shall be to the edition listed below, including all amendments published thereto. CSA (Canadian Standards Association) A23.3-94 (R2000)

Design of Concrete Structures

CAN/CSA-C225-00

Vehicle-Mounted Aerial Devices

G4-00

Steel Wire Rope for General Purpose and for Mine Hoisting and Mine Haulage 8 COPYRIGHT


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G40.20-04/G40.21-04

General requirements for rolled or welded structural quality steel/Structural quality steel

PLUS 1156

Fall-Arrest Systems – Practical Essentials, by Andrew C. Sulowski

CAN/CSA-S16-01

Limit States Design of Steel Structures

CAN/CSA-Z91-02

Health and Safety Code for Suspended Equipment Operations

Z259 series of Standards: CAN/CSA-Z259.1-95 (R1999)

Safety Belts and Lanyards

CAN/CSA-Z259.2.1-98 (R2004)

Fall Arresters, Vertical Lifelines, and Rails

CAN/CSA-Z259.2.2-98 (R2004)

Self-Retracting Devices for Personal Fall-Arrest Systems

Z259.2.3-99

Descent Control Devices

CAN/CSA-Z259.10-M90 (R2003)

Full Body Harnesses

CAN/CSA-Z259.11-M92 (R2003)

Shock Absorbers for Personal Fall Arrest Systems

CAN/CSA-Z259.12-01

Connecting Components for Personal Fall Arrest Systems (PFAS)

Z259.13-04

Flexible horizontal lifeline systems

Z259.15 (under development)

Anchorage connectors

CAN/CSA-Z271-98 (R2003)

Safety Code for Suspended Elevating Platforms

ANSI (American National Standards Institute) Z359.1-1992 (R1999)

Safety Requirements for Personal Fall Arrest Systems, Subsystems and Components

National Research Council Canada

National Building Code of Canada, 1995 Other publications Arteau, J. (2003). “Protection contre les chutes de hauteur : absorbeur d’energie, distance de freinage, grande hauteur de chute et grande masse (Protection against falls from height: energy absorber, e deceleration distance, large free fall distance and large mass) ”. Actes du 25 congrès de l’ AQHSST, Trois-Rivières, 7-9 May, 2003, pp. 249-260 Sulowski, A. C. Evaluation of Fall Arresting Systems (Ontario Hydo Research Report 78-98-H). Toronto, 1978

3

Definitions

The following definitions apply in this Standard: Activation distance The distance that a fall arrester travels, or an SRL pays out, from the moment that the falling mass is released until the arresting force is initially applied to the mass. Active fall-protection system A means of providing fall protection that requires workers to take specific actions, including wearing (and otherwise using) personal fall-protection equipment and following prescribed procedures. Examples include travel restraint and fall-arrest systems. 9 COPYRIGHT


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Anchorage A secure connecting point capable of safely withstanding the impact forces applied by a fall-protection system or anchorage subsystem. NOTE 1 – A fall-arrest or restraint anchorage is independent of any anchorage used to support or suspend workers or work platforms. NOTE 2 – An anchorage is generally a structural member such as a beam, girder, column, floor, or wall.

Anchorage connector A component or subsystem for coupling a personal fall-arrest system to an anchorage. Anchorage subsystem A subsystem of a complete active fall-protection system to which workers connect their personal equipment. NOTE – Examples of anchorage subsystems include fixed-anchor points, VLLs, HLLs, rigid rails, and ladderclimbing systems. An anchorage subsystem may allow one or more workers to be attached to it, depending on its design. Anchorage subsystems are separated into two classes in this Standard: flexible and rigid.

Flexible anchorage subsystem An anchorage system, such as a VLL or an HLL, that appreciably deflects, deforms, or stretches when a fall-arrest impact occurs. For the purposes of this Standard, a flexible anchorage subsystem is one where the deflection or stretch exceeds 100 mm when the peak impact force from the worst-case fall arrest or travel restraint loading is applied to the subsystem. Rigid anchorage subsystem An anchorage system, such as a rigid rail system or a single point of attachment, that does not appreciably deflect, deform, or stretch when a fall-arrest impact occurs. For the purposes of this Standard, a rigid anchorage subsystem is one where the deflection or stretch is not more than 100 mm when the peak impact force from the worst-case fall-arrest or travel-restraint loading is applied to the subsystem. Ballasted anchor An anchorage that rests on, but is not mechanically connected to, an underlying structure. NOTE – A ballasted anchor uses its own weight and/or the lateral friction it develops with the underlying structure to resist the imposed forces.

Boatswain’s chair A simple body-support device used in a positioning system, typically incorporating a rigid seat and a suspension bridle, and suspended from a higher anchorage. NOTE – Workers typically sit on the boatswain’s chair for transport or work, and are protected from falling by an independent fall-arrest system.

Body-holding device A manufactured system of straps that encircles the wearer ’s body and provides a safe means for connecting to an active fall protection system. NOTE – The most common body-holding device in active fall-protection systems is a full-body harness.

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Certified Meeting the requirements of a Standard, as attested by a certification organization accredited by the Standards Council of Canada or the Occupational Safety and Health Administration. Clearance The distance from a specified reference point, such as the working platform or anchorage of a fall-arrest system, to the highest obstruction that a worker might encounter during a fall (see Figure 6). Clutching self-retracting lanyard (SRL) A type of SRL that uses a clutch or other mechanism to dissipate fall energy by deploying additional lifeline at a relatively constant force after the device has locked off (see Clause 5.4.4.2.4). Compatible connection A connection that uses only compatible hardware between the components of a fall-protection system to prevent roll-out (see Clause 5.4.2). Connecting means A lanyard, SRL, or other device used to connect a body holding device to an anchorage or anchorage subsystem, to provide protected mobility for an elevated work task. Cusp sag The sag that an HLL attains before it begins to provide significant deceleration force to stop a fall. NOTE – Cusp sag is the state where the initial length of cable, at essentially its pre-tension force, has been pulled into two essentially straight lines extending from one anchorage, to the point of fall-arrest load application, to the next adjacent anchorage. During the arrest of a fall, there is no appreciable deceleration force on the falling worker, nor is there an appreciable increase in HLL cable tension until the sag exceeds the cusp sag (see Figure 3).

Deceleration distance The distance fallen during the period from engagement of a fall-arrest system to the moment of fall arrest. NOTE – The deceleration distance is determined by the response and interaction of all of the components of the fall-arrest system (including deployment of PEAs, stretching of lanyards and lifelines, sagging of HLLs, etc.) (see Figure 6).

Descent controller A device designed to be used by one worker for personal decent or to lower another worker from an elevation. NOTE – A descent controller may be used for egress, work positioning, or both.

D-ring A connector used integrally in a harness as an attachment element or fall-arrest attachment, and in lanyards, energy absorbers, lifelines, and anchorage connectors as an integral connector.

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Dynamic analysis A method for predicting the performance of an active fall-protection system by calculating the velocity of a moving or falling body at selected time or distance intervals. The method takes into consideration both the arresting force from the system and the gravitational pull on the falling body to determine how much the body speeds up or slows down over the selected interval. Energy absorber Any device that dissipates kinetic energy and does not return it to the system or into the human body. NOTE – Elastic devices such as springs are not classified as energy absorbers under this Standard because they temporarily store the energy and return it to the system when the applied forces are reduced. Examples of energy absorbers include PEAs, clutching SRLs, and HLLEAs.

Energy-absorbing lanyard A lanyard that includes an integral PEA. Energy analysis A method for predicting the performance of an active-fall protection system by calculating the energy produced by a moving or falling body and determining how this energy is absorbed or dissipated by the components of the fall-protection system. Fall arrest Stopping a fall. NOTE – For the purposes of this Standard, fall arrest is the instant when a falling body is first stopped. Fall arrest coincides with the greatest forces and deflections of the fall-arrest system.

Fall arrester A device that locks onto a lifeline, cable, or rigid track to arrest a fall. It travels vertically on the lifeline, cable, or rigid track and follows either manually or automatically the vertical movements of the worker. Fall-arrest system An assembly of components that will arrest a worker ’s fall when properly assembled and used together and when connected to a suitable anchorage. Fall-protection system Any secondary system that prevents workers from falling or, if a fall occurs, arrests the fall. Examples include guardrail, travel-restraint, safety net, and fall-arrest systems. Force factor The ratio of peak arresting force of a rigid mass to a human body of the same weight, both falling under identical conditions. Free-fall distance (FFD) The vertical distance from the onset of a fall to the point where the fall-arrest system begins to apply force to arrest the fall. NOTE – Free fall is often measured by following the D-ring of the full-body harness (see Figure 6).

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Full-body harness A body-holding device, similar to a parachute harness, designed to transfer suspension forces or impacts during a fall arrest to the worker ’s pelvis and skeleton. Harness See Full-body harness. Horizontal lifeline (HLL) A component of an HLL system that extends horizontally from one end anchorage to another and consists of a flexible line made from wire, fibre rope, wire rope, or rod, complete with end terminations. NOTE – Intermediate anchorages may be used on long HLL systems to reduce sags.

Horizontal lifeline energy absorber (HLLEA) An energy absorber, in line with an HLL, that is used to reduce the MAL imparted to the end anchorages of the HLL during a fall. Horizontal lifeline system A fall-protection system that uses an HLL to which one or more workers may attach their personal fall-arrest systems using a suitable connecting means. NOTE – An HLL may be used as part of a travel-restraint system but more commonly is part of a fall-arrest system. An HLL allows horizontal movement parallel to the HLL but may also allow protected vertical movement below the HLL if an SRL is used as the connecting means.

Horizontal track system A form of rigid rail system that typically encloses a trolley inside a formed channel or track. NOTE – Horizontal track systems are usually mounted overhead in fall-arrest systems but may be mounted at lower heights as anchorages for travel-restraint systems.

Initial sag The initial mid-span deflection of an HLL due to static equilibrium between gravitational forces and pretension (see Figure 3). Inspection A thorough examination of equipment or systems, including but not limited to verification of general conformance to required standards. Lanyard A flexible line or strap used to secure a full-body harness to an energy absorber, a fall arrester, lifeline, or anchorage. Lifeline A component consisting of (a)

a flexible line for connection to an anchorage or anchorage connector at one end to enable the line to hang vertically (a VLL); or 13 COPYRIGHT


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(b)

a flexible line for connection to anchorages or anchorage connectors at both ends to enable the line to span horizontally (an HLL).

Manual fall arrester A fall arrester that will remain locked where it has been positioned on a VLL until deliberately repositioned by a worker. Manual rope grab See Manual fall arrester . Maximum anchorage system deflection (MASD) The dynamic displacement of the anchorage system to the position at fall arrest after all slack has been removed. NOTE – In HLLs, the maximum anchorage system deflection is the change in sag from the cusp sag to the peak sag at fall arrest. In VLLs, it is the stretch of the lifeline (see Figure 3 and 6).

Maximum arrest force (MAF) The peak force exerted on a worker or test weight when a fall-arrest system stops a fall (see Figure 3). Maximum arrest load (MAL) The peak force applied to an anchorage by an active fall-protection system when arresting a fall. NOTE – The MAL is a force vector that is co-linear with the cable in an HLL (see Figure 3). The MAL equals MAF in a vertical system.

Maximum sag The peak sag of an HLL at the instant of fall arrest (see Figure 3). Passive fall-protection system A means of providing fall protection that does not require workers to wear or otherwise use fall-protection equipment or to have any special knowledge or skills related to this system. Examples include guardrail systems and nets. Personal energy absorber (PEA) A lanyard component that sacrificially elongates to dissipate energy generated during a fall. NOTE – A PEA reduces the MAF experienced by the worker but increases the fall-arrest distance.

Personal fall-arrest system A fall-arrest system, other than a safety net system, designed to safely stop a worker from reaching a lower level or obstructions if a fall occurs. Personal shock absorber See Personal energy absorber .

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Positioning lanyard A lanyard used to connect a worker to an anchorage or anchorage subsystem for the purpose of holding or suspending the worker at the desired location. NOTE – Positioning lanyards may be fixed length or adjustable and are part of a positioning system.

Positioning system A system of components, including suspension lines, boatswain’s chairs, descent controllers, and/or positioning lanyards, used to support or suspend a worker at a working point. Positioning systems are primary systems and are not fall-protection systems. Pre-tension The initial force (tension) in an HLL cable immediately before a fall occurs. Pre-tension of the HLL balances the weight of the cable, holding it to its initial sag. Primary system In fall-protection terminology, the main mechanism that allows a worker to maintain his or her desired position. NOTE – Primary systems are typically considered to comprise the worker ’s balance, his or her climbing skills, and the safety of the platform, surface, or structure that supports him or her. Fall protection is a secondary form of protection in case the primary system fails.

Professional engineer A person who holds an engineering licence or temporary engineering licence in the province or other jurisdiction in which he or she is applying this Standard. Proof test A test to prove the structural integrity of a component or system. Required clearance below the anchorage The minimum distance between the anchorage of a fall-arrest system and the highest obstruction a worker might encounter during a fall (see Figure 6). Required clearance below the platform The minimum distance between the working platform and the highest obstruction a worker might encounter during a fall (see Figure 6). Rescue The process of evacuating a worker after a fall to a safe location where he or she can receive medical attention. Restraint anchorage An anchorage used in a travel-restraint system.

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Restraint lanyard A lanyard that has been manufactured or adjusted to a specific length, such that when coupled between a restraint anchorage and a worker ’s body-holding device, the worker cannot reach an unprotected edge or unprotected opening. Restraint system See Travel-restraint system. Rigid rail system A fall-protection system that uses one or more trolleys on a horizontal track (often an I-beam or slotted tube). NOTE – In a rigid rail system, a connecting means is attached between the worker ’s full-body harness and the trolley. Rigid rail systems allow horizontal movement parallel to the rigid rail but may also allow vertical movement if an SRL is used as the connecting means.

Roll-out Unintended disconnection of connection hardware. Rope grab See Fall arrester . Safety margin A clearance factor of safety defined as the distance between the lowest extremity of the worker ’s body at fall arrest and the highest obstruction the worker might otherwise make contact with during a fall (see Figure 6). Safety net system A fall-arrest system that uses nets to stop falling workers before they make contact with a lower level of obstruction. Secondary system In fall-protection terminology, the back-up mechanism that protects a worker if the primary system fails. NOTE – Secondary systems include guardrail, travel-restraint, and fall-arrest systems.

Self-retracting lanyard (SRL) A connecting means that automatically adjusts its length under light tension as the worker moves toward or away from the anchorage. It stops a fall. NOTE – The SRL housing typically contains a spring-loaded drum on which a line (made of rope, wire rope, or webbing) is wound and unwound. The device has a mechanism to lock the drum if the worker falls by pulling cable out of the device at a speed greater than the device’s lock-off speed.

Self-retracting lifeline See Self-retracting lanyard.

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Sequential fall A multiple-worker fall where the impacts from each worker occur at different times, in a cascading manner. Shock absorber See Personal energy absorber . Shock-absorbing lanyard See Energy-absorbing lanyard. Simultaneous fall A multiple-worker fall where the impacts from each worker occur at the same instant. Snap hook A hook with a spring-loaded gate that, when open, allows objects to pass into and out of the interior of the hook. NOTE – A snap hook is mechanically spliced as the end termination of a lanyard or lifeline and may be used, as appropriate, to connect to anchorages, D-rings, and other components of a fall-protection system.

Span The portion of the system between any pair of adjacent supports on fall-protection systems such as rigid rails and HLLs. NOTE – The number of spans in a system is typically one less than the number of supports.

Static analysis A method to predict the performance of an active fall-protection system based on applying static loadings specified by this Standard. Stretch out The change in distance between the worker ’s D-ring and toes during a fall arrest. (see Figure 6). NOTE – Stretch out accounts for stretching of the body-holding device, sliding of the D-ring, and the reaction of the worker ’s body to the deceleration forces, sometimes including lengthening of the body if starting from a kneeling or lying position.

Suspended equipment Machines, platforms, or other equipment suspended by support lines. Swing-drop distance The vertical drop in height experienced by the worker using a fall-arrest system from the onset of the swinging motion to the point where the user can initially make contact with a structure. NOTE – Swing-drop distance is measured by following the D-ring of the harness (see Figure 5).

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Swing fall A pendular motion experienced by the worker using a fall-arrest system, resulting from the anchorage not being directly above the user at the onset of a fall. Swing-fall distance The vertical drop in height experienced by the worker using a fall-arrest system from the onset of the swinging motion to the lowest point reached during the swing. NOTE – Swing-fall distance is measured by following the D-ring of the harness (see Figure 5).

Synthetic For the purposes of this Standard, items manufactured from non-organic plastic fibres. include synthetic ropes and webbing.

Examples

Testing and interpolation analysis A method for determining the performance of an active fall-protection system through direct testing of the system and mathematical interpolation of test results for similar systems. Total-fall distance (TFD) The maximum distance fallen by worker using a fall-arrest system between the onset of a fall and the instant when the worker first achieves zero vertical velocity. NOTE – Total-fall distance is often determined as the displacement of the dorsal D-ring on the full-body harness and is the sum of the free fall and the deceleration distance. It also includes any applicable swing-fall distance (see Figures 5 and 6).

Travel-restraint system A system that prevents one or more workers from reaching an unprotected edge or opening. NOTE – An active fall-protection system couples the workers’ body-holding device(s) to an anchorage using a suitable means, such as restraint lanyards. A guardrail is a passive travel-restraint system.

Trolley A mobile anchorage device that travels along a track (horizontal track system), structural beam (rigid rail system), or cable (HLL system). Vertical lifeline (VLL) A length of rope with a manufactured termination at the top end. It may or may not include a means to tension the line, such as a small weight at the bottom end. Vertical lifeline system A fall-arrest system that uses a VLL, fall arrester, connecting means, and body-holding device. Worker For the purposes of this Standard, any person who is protected from falling by an active fall-protection system, or in the case of a fall-arrest system, any person who might fall while attached to the system.

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4

Drawings and specifications

4.1

General

A fall-protection system meeting the requirements of this Standard shall have drawings and/or specifications prepared by or under the direction of a professional engineer.

4.2

Sealing by professional engineer

The professional engineer who designs the system shall affix his or her professional seal to each drawing and specification issued.

4.3

Required information

Drawings, specifications, and instructions provided by the professional engineer shall include (a)

a statement defining the type of system (fall arrest, travel restrain, etc.) and indicating that the design is in accordance with the requirements of this Standard;

(b)

a drawing showing the layout of the system, including where it is located and the complete assembly of all components. In the case of relocatable systems, the layout shall depict the professional engineer ’s expected typical installation;

(c)

a specification of the number, location, and qualifications (including minimum and maximum weights and training) of workers using the system;

(d)

specifications for all components, including sizes and minimum required breaking strengths. The specifications shall reference applicable Standards and/or fully specify the makes and models of the components. Where substitute materials are allowed, the specifications shall adequately describe the acceptable substitutions;

(e)

a description of any proof testing required before the system may be put into use;

(f)

a specification of any environmental limitations on the use of the fall-protection system, such as chemical, temperature, radiation, or weather factors that may temporarily or permanently render the system unsafe to use;

(g)

information on the expected performance of the system, including the maximum arrest load (MAL), maximum loadings of all components, sags and deflections, deployment of energy absorbers, and the maximum arrest force (MAF). Where system performance may be affected by variable environmental conditions such as temperature, performance in worst-case conditions shall be described; NOTE – In horizontal lifelines (HLLs), the greatest deflections occur at the highest temperature and the greatest forces occur at the lowest temperature.

(h)

a description of the greatest required clearances for all permitted worker locations, connecting means, and full-body harness combinations. Where a required clearance varies with environmental conditions, the worst-case value shall be specified;

(i)

instructions for assembly and installation. In the case of generic or relocatable systems, the instructions shall specify (i)

the minimum required strength of the anchorages;

(ii)

the clearances required below the working platform or anchorages; and

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(iii)

any safety precautions that shall be followed during the erection and dismantling of the system

(j)

instructions for inspection, maintenance, and retirement of the system and all of its components, including how often inspection and maintenance are to be performed and a description of the qualifications required for persons performing these tasks;

(k)

instructions for safe access to, egress from, and use of the system;

(l)

for fall-arrest systems, a rescue plan or directions to the owner of the system or the employer of the workers using the system to develop and implement a rescue plan before the system is used. The professional engineer shall indicate the appropriate uses of the system or its anchorages during a rescue;

(m)

a statement specifying (i)

that the professional engineer who designed the system shall be consulted before modifying the design; and

(ii)

whether the system is intended to be generic or relocatable, i.e., so that it may be used at multiple locations; and

(n)

for permanent systems, “as-constructed” drawings sealed by the professional engineer. The professional engineer shall certify that the installation is in accordance with the as-constructed drawings and specifications.

5

Materials, equipment, and other design requirements

5.1

Composition of materials

Load-bearing components of active fall-protection systems shall be composed of synthetic or metallic materials. Organic fibres and materials may be used only for non-load-bearing components.

5.2

Ductility of materials

Metallic or synthetic materials (with the exception of composite plastics such as fibreglass) shall have at least 10% elongation prior to failure in the environments to which they will be exposed.

5.3

Environmental considerations

All components of an active fall-protection system shall be selected to provide safe and durable service in the environment(s) where the system may be used. Environmental considerations include, but are not limited to, corrosion, chemical attack, weather, abrasion, and ultraviolet exposure.

5.4

Equipment

5.4.1

General

Fall-arrest equipment components used in systems designed in accordance with the requirements of this Standard shall be certified by a certification organization accredited by the Standards Council of Canada. The certification organization shall certify that the component or components in question meet the requirements of the applicable CSA Z259 Standard (CAN/CSA-Z259.1, CAN/CSA-Z259.2.1, CAN/CSAZ259.2.2, CSA Z259.2.3, CAN/CSA-Z259.10, CAN/CSA-Z259.11, CAN/CSA-Z259.12, Z259.13, or Z259.15). Where a CSA Z259 Standard does not exist for a particular component, suitable specifications for manufacturing or purchasing the component shall be provided by the professional engineer.

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5.4.2

Compatibility

Equipment and hardware for all components of an active fall-protection system shall be selected to provide compatible connections. Combinations of equipment from different manufacturers shall be permitted if the professional engineer is satisfied that the connections are compatible and that there is no dangerous interactions between them, e.g., loading of carabiner or snap hook gates to allow roll-out. 5.4.3

Energy absorbers

5.4.3.1 General Energy absorbers, including personal energy absorbers (PEAs), clutching self-retracting lanyards (SRLs), and horizontal lifeline energy absorbers (HLLEAs), shall sacrificially dissipate the energy from a fall. They shall not release the energy that they have absorbed back to the system or worker. Springs, bungees, and other elastic devices shall not be considered energy absorbers under this Standard. Elastic mechanisms within energy absorbers may be used to buffer, without permanent elongation, thermal shrinkage or travel-restraint forces. 5.4.3.2 Selection of personal energy absorbers NOTE – See Annex A.

When selecting personal energy absorbers, (a)

when the free-fall distance allowed by the system is 1.4 m or less and worker mass is 140 kg or less, energy absorbers and energy-absorbing lanyards, where used, shall meet the requirements of CAN/CSA-Z259.11; or

(b)

the professional engineer shall (i)

use dynamic analysis, energy analysis, or testing and interpolation analysis to ensure that the impact forces on the worker ’s body do not exceed 6 kN; or

(ii)

ensure that the maximum free fall allowed by the system does not exceed hMax in the following formula:

hMax

 1000F Avg  mg   XMax mg  

= 

where

hMax

= maximum free fall permitted by the system, m

F Avg

= average deployable force of the PEA or clutching SRL, kN, in accordance with Clause 7.3.3.2 or 7.3.4.2, as applicable

m

= the falling mass, kg, in accordance with Clause 7.3.2

g

= 9.81 m/s (acceleration due to gravity)

X Max

= maximum rated extension of the PEA, m

2

Specialized energy absorbers and energy-absorbing lanyards may be used to control the impact forces when devices meeting the requirements of CAN/CSA-Z259.11 do not provide adequate protection.

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Specialized energy-absorbing lanyards meeting the requirements of ANSI Z359.1 are manufactured for larger free falls and workers whose mass exceeds 140 kg. These devices typically deploy at forces greater than those permitted by CAN/CSA-Z259.11 but should be used to control impact forces for more severe falls or to stop the fall sooner where clearances are inadequate. When used, these devices shall keep the impact forces below 6 kN for the maximum worker mass and free fall allowed by the system. 5.4.3.3 Low-temperature performance of energy absorbers Particular attention shall be paid to the performance of all types of energy absorbers in low-temperature conditions. Low-temperature embrittlement of metallic energy absorbers shall be prevented by selecting materials that remain adequately ductile throughout the temperature range within which the system may be used. Structural steels that have the Category 4 impact properties specified in Clause 6.2, Table 9A, and Table 9B of CSA G40.21 shall be acceptable for the Canadian outdoor environment. PEAs meeting the requirements of CAN/CSA-Z259.11 shall be acceptable for the Canadian outdoor environment. Professional engineers shall note that CAN/CSA-Z259.11 PEAs under normal temperature and dry conditions limit the MAF to 4 kN but may generate an MAF as high as 6 kN when wet and frozen. 5.4.4

Self-retracting lanyards

5.4.4.1 Travel-restraint systems SRLs shall not be used in travel-restraint systems unless the length of the lifeline on the drum of the SRL will not permit the worker to reach the hazard even when fully deployed. If the SRL is a clutching SRL, the professional engineer shall determine whether the restraint force could cause the reserve lifeline to deploy and shall ensure that such deployment will not permit the worker to reach the fall hazard. 5.4.4.2 Fall-arrest systems NOTE – See Annex A.

5.4.4.2.1 Flexible anchorage systems When an SRL is used in a flexible anchorage system such as an HLL, the professional engineer shall specify that the device is equipped with an anti-ratchet mechanism, or that the dynamic interaction between the locking mechanism and the natural frequency of the flexible anchorage system does not cause the SRL to unlock during the rebound of the system after fall arrest or, in a system used by multiple workers simultaneously, as a result of subsequent falls. 5.4.4.2.2 Systems where free fall is limited to the self-retracting lanyard ’s activation distance When the fall-arrest system anchors the SRL sufficiently above the worker ’s dorsal D-ring so that the free fall allowed by the system equals the SRL ’s activation distance, all SRL types meeting the requirements of CAN/CSA-Z259.2.2 may be used. 5.4.4.2.3 Systems where free fall exceeds the self-retracting lanyard’s activation distance Where the conditions of Clause 5.4.4.2.2 cannot be met, only clutching SRLs or SRLs with integral PEAs may be used.

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5.4.4.2.4 Clutching self-retracting lanyards To meet the requirements of Clause 5.4.4.2.3, clutching SRLs shall be (a)

CAN/CSA-Z259.2.2 Type 2 or Type 3 SRLs; and

(b)

warranted by their manufacturer

5.4.5

(i)

to have a minimum of 1.0 m of available deployment over the entire range of operation of the SRL;

(ii)

that they will deploy at a peak force, F Max , specified by the manufacturer, which shall be less than 6 kN; and

(iii)

that they will deploy at a relatively constant force, F Avg , preferably specified by the manufacturer but not less than 0.65 F Max , in accordance with Clause 7.3.4.2.

Lanyards

5.4.5.1 Lanyards in travel-restraint systems PEAs may be used in lanyards in travel-restraint systems, provided that the professional engineer has determined whether the restraint force could cause the PEA to deploy and, if so, that such deployment will not permit the user to reach the fall hazard. 5.4.5.2 Lanyards in fall-arrest systems Except as allowed by Clause 5.4.3.2 or 6.4.2, lanyards in fall-arrest systems shall meet the requirements of CAN/CSA-Z259.11. 5.4.6

Full-body harnesses

Full-body harnesses shall meet the requirements of CAN/CSA-Z259.10. Stretch out used in clearance calculations in Clause 8.2.4 of this Standard shall account for stretching of the type(s) of full-body harnesses permitted for use with the fall-arrest system. 5.4.7

Fall arresters

Fall arresters used on vertical lifelines (VLLs) and ladder-climbing systems shall meet the requirements of CAN/CSA-Z259.2.1. 5.4.8

Horizontal lifeline energy absorbers

5.4.8.1 Travel-restraint systems HLLEAs may be used in travel-restraint systems, provided that the professional engineer has determined whether the restraint forces will cause the HLLEAs to deploy and, if so, ensures that the deflection of the cable caused by the HLLEA deployment, in combination with other deformations of the restraint system, will not permit the worker(s) to reach the fall hazard. The restraint system shall meet the requirements of Clause 5.4.8.2. 5.4.8.2 Fall-arrest systems NOTE – See Annex A.

HLLEAs may be used only to control or reduce the MAL, and only if the professional engineer has ensured that the increased clearance requirements can be met.

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The maximum span in any HLL where HLLEAs are used shall be not greater than LMax in the following equation: 2

LMax

 1000T Avg    4 = 1.4 16  Mm g 

where

LMax

= maximum span, m

T Avg

= average deployment force of the HLLEA, kN, in accordance with Clause 7.3.6.3

M

= “lumping factor” for the maximum number of workers that may attach themselves to one span of the HLL at any one time, as specified in Clause 7.3.7.2

m

= the mass of one worker, kg, in accordance with Clause 7.3.2

g


5.5

Other design requirements for travel-restraint systems

2

In addition to ensuring compliance with the applicable safety criteria in Clause 6, the professional engineer shall ensure that the worker cannot reach and fall into any open hole or off the edge of the working platform. Special attention shall be paid to the use of flexible anchorage systems, such as HLLs, that may influence how short the lanyard or lifeline needs to be to meet this requirement.

5.6

Other design requirements for fall-arrest systems

5.6.1

General

In addition to the applicable safety criteria outlined in Clause 6, the requirements in Clauses 5.6.2 and 5.6.3 shall apply. 5.6.2

Rescue

To satisfy the requirements of Clause 4.3.1 (l), the design shall take into consideration the potential uses of and loads on the fall-arrest system, in order to facilitate the prompt rescue of workers who may fall while attached to the system. 5.6.3

Anchorage for suspended equipment operations

The fall-arrest anchorage requirements for individuals working from suspended equipment shall be as specified in CAN/CSA-Z91 and CAN/CSA-Z271.

6

Safety criteria

6.1

Specified loads

The load effects on each component of an active fall-protection system shall be determined for the following loads: NOTE – The symbols identified below appear in Clause 6.2.3.

(a)

D – dead loads from the static weight of materials used in the system and, as applicable, from the structure to which it is attached.

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(b)

A – fall-arrest or travel-restraint loads applied to the system determined in accordance with Clause 7. The applied loadings from energy absorbers shall be determined in accordance with Clauses 7.3.3.1, 7.3.4.1, 7.3.5, and 7.3.6.2, as applicable.

(c)

L – live loads, including loads due to intended use of the active fall-protection system or intended use and occupancy of the structure to which it is attached. Live loads shall be as specified in the

National Building Code of Canada (d)

Q – wind, earthquake, or other loads that may be applied to the active fall-protection system or the structure to which it is attached. These loads shall be as specified in the National Building Code of Canada.

(e)

T – influences resulting from temperature changes, shrinkage or creep of component materials, or differential statement. Temperature changes shall be as specified in the National Building Code of Canada. Shrinkage or creep shall be in accordance with the applicable design code for the materials used in the construction of the active fall-protection system or the structure to which it is attached.

6.2

Strength

6.2.1

General

All components and subsystems of an active fall-protection system, and the structure to which it is attached, shall have sufficient strength and stability such that

R ≥ F * where

R

= the factored resistance of the component or subsystem

F *

= the worst-case factored effect of the applied loads on the component or subsystem

6.2.2

Determination of factored resistance

6.2.2.1 General Factored resistance shall be determined as follows:

R

= ØU

where

Ø

= the capacity-reduction factor

U

= the ultimate strength of the component or subsystem

6.2.2.2 Factored resistance for common construction materials

R , Ø, and U for common construction materials used in the construction of the active fall-protection system or the structure to which it is attached shall be determined in accordance with the requirements of the applicable CSA design code(s) in Clause 2. 6.2.2.3 Factored resistance for materials not covered by a CSA limit states design code Where a CSA limit states design code does not exist for a material used in the construction of a fallarrest system, (a)

the ultimate strength, U , of a component shall be based on testing of the component or calculation of the strength of the component using the known strength of the material; and 25 COPYRIGHT


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(b)

6.2.3

the capacity-reduction factor, Ø, shall be as follows: (i)

for brittle materials such as fiberglass, 0.3;

(ii)

for synthetic ropes and webbing, 0.5;

(iii)

for materials that exhibit at least 10% elongation prior to failure at a yield stress that is between 60 and 80% of the ultimate stress, 0.6; and

(iv)

for wire ropes meeting the requirements of CSA G4, 0.75 (applied to the terminated strength of the wire rope.)

Determination of factored load effects

NOTE – See Annex A.

The factored load for each component of an active fall-protection system shall be the worst-case force effect, F *, using the following formula for all possible combinations of applied loading:

F * = α DD* + Ψ (α A A* + α LL* + α QQ* + α TT *) where

D*, A*, L*, Q*, and T *

= the forces carried by each component due to the applied loads D, A, L, Q, and T described in Clause 6.1

α

= the load factor for the specific type of loading, as follows: α D = 1.25 or, when the dead load opposes the effect of A, 0.85 α = 1.5 A α L = 1.5 or, when the live load opposes the effect of A, 0 α Q = 1.5 α T = 1.25 or, when thermal stresses change the HLL pre-tension, 1.5

Ψ

= the load combination factor, as follows: Ψ = 1, where only A is applied Ψ = 0.7, if A acts in combination with either L or Q Ψ = 0.6, if A acts in combination with both L and Q

NOTE 1 – Unlike the limit states design methods described in the National Building Code of Canada, the load factors in this clause are applied to the forces carried by each component, rather than to the load resisted by the system. This is necessary to ensure a consistent safety factor throughout the system. For example, in an HLL system, the tension in the HLL increases in much lower proportion to the increase in applied loading, and where HLL energy absorbers are employed, there may be no increase in lifeline tension due to factoring the applied load. NOTE 2 – In systems where the majority of the load effect is due to the fall-arrest or travel-restraint force, A, professional engineers may choose to simplify their determination of F * by using α D = α A = α L = α Q = α T = 1.5, which is often only slightly conservative.

6.3

Swing falls


In fall-arrest systems, anchorages shall be located directly above the worker(s) to eliminate swing falls, wherever it is reasonably practical to do so. Where it is not reasonably practical to prevent swing falls, the swing-drop distance shall not exceed 1.2 m (see Figure 5).

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6.4

Forces on the worker ’s body

6.4.1

Travel-restraint systems

Where a worker is using a safety belt (see CAN/CSA-Z259.1) in a travel-restraint system, the force on the worker ’s body shall not exceed 1.8 kN. Where a worker is wearing a full-body harness and is connected to the system at the dorsal D-ring, the force shall not exceed 6 kN. 6.4.2

Fall-arrest systems

6.4.2.1 Attachment to the full-body harness In a fall-arrest system, a worker shall wear a full-body harness and be attached to the system at the dorsal D-ring. The only permitted exception shall be for ladder-climbing systems, which may be used with a sternal attachment when the free-fall distance is limited to 0.2 m or less. 6.4.2.2 Maximum arrest force NOTE – See Annex A.

The MAF experienced by each worker using a fall-arrest system shall not exceed 6 kN, except that when PEAs or clutching SRLs are omitted in accordance with Clause 6.4.2.3, the MAF shall not exceed 8 kN. 6.4.2.3 Use of personal energy absorbers or clutching self-retracting lanyards Fall-arrest systems shall use PEAs meeting the requirements of Clause 5.4.3.2 or clutching SRLs meeting the requirements of Clause 5.4.4.2.3 except (a)

in accordance with Clause 5.4.4.2.2;

(b)

for ladder-climbing systems where the free fall is limited to 0.6 m or less; or

(c)

when elimination of energy absorbers is required to stop a fall within very limited available clearances.

NOTE – PEAs are often incorporated into lanyards but may also be located elsewhere in the fall-arrest system, e.g., as part of an anchorage connector or permanently attached to the full-body harnesses.

6.5

Clearance

6.5.1


In travel-restraint systems, consideration of clearance is not required. 6.5.2

Fall-arrest systems

In fall-arrest systems, the required clearance, calculated in accordance with Clause 8.2, shall be less than or equal to the available clearance for the system. For the purposes of clearance calculations, the applied loadings from energy absorbers shall, as indicated in Clauses 7.3.3.2, 7.3.4.2, and 7.3.6.3, be applicable.

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6.6

Stability of free-standing systems

6.6.1

General

Free-standing systems may only be used on surfaces with a downward slope of less than 5° toward any side or opening where a worker could fall. Ballast materials, providing mass for the counterbalance or sliding resistance, shall be rigid and positively connected to the fall-arrest structure. Liquids, sand, gravel, or other spillable materials shall not be used as ballast. 6.6.2

Overturning of counterbalanced systems

Where an active fall-protection system is free-standing or counterbalanced and is not anchored to a solid support, the system shall have a factor of safety against overturning to resist the worst-case combination of fall-arrest loading and configuration of the system as follows: (a)

not less than 4.0;

(b)

not less than 2.0 where the design makes it impossible to change the counterbalance mass or move the fulcrum point; or

(c)

not less than 1.5 where

6.6.3

(i)

the design makes it impossible to change the counterbalance mass or move the fulcrum point; and

(ii)

there is a minimum 4.0 factor of safety when the energy required to bring the system to incipient tipping is compared to the total energy generated by the worst-case fall(s) that could occur.

Sliding of ballasted systems

Where an active fall-protection system relies on friction between a ballasted anchor and its supporting surface, instead of being anchored to a solid support, the ballasted anchor shall have a factor of safety against sliding of not less than 3.0 to resist the worst-case combination of fall-arrest loading and configuration of the system. The following requirements shall also apply: (a)

the coefficient of kinetic friction used in calculating the resistance to sliding shall be determined by field testing in the direction(s) of potential loading at the site where the ballasted anchor will be used and shall simulate the worst-case weather conditions that may affect the coefficient of friction; and

(b)

unless any applicable stops or parapet walls are analyzed or tested to prove that they are strong enough to prevent the ballasted anchor from sliding to an edge and falling, the ballasted anchor shall be installed a minimum of 2.5 m from any edge of the surface it might fall from if it were to slide while resisting the fall-arrest loading.

7

Fall-protection system loads and forces

7.1

General

The force, A, applied to an active fall-protection system to stop or prevent falls shall be determined in accordance with Clauses 7.2 and 7.3.

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7.2


7.2.1

Maximum arrest force and maximum arrest load

The loads and forces in all components of a travel-restraint system due to the worst-case impact from worker(s) being stopped short of the fall hazard shall be determined in accordance with Clauses 7.2.2 and 7.2.3. 7.2.2

Level surfaces

For surfaces that slope less than 5%, (a)

temporary-restraint anchorages shall be designed using static analysis with A = 1.8 kN per worker attached to the anchorage; and

(b)

permanent-restraint anchorages shall be designed for fall arrest, determined in accordance with Clause 7.3.

NOTE – Designers should be aware that fall arrest can result if workers have an improperly adjusted lifeline, lanyard, or SRL that is long enough to allow a fall to occur.

7.2.3

Sloping surfaces

Temporary- or permanent-restraint anchorages intended to prevent workers from falling off the bottom edge of a downward sloping surface shall be designed for the force required to stop the worst-case slides down the slope. Forces may be determined using one of the methods outlined in Clauses 9.3.2 to 9.3.6, but shall be not less than what is required by Clause 7.2.2.

7.3

Fall-arrest systems

7.3.1

Maximum arrest force and maximum arrest load

The loads and forces in all components of a fall-arrest system shall be determined, for the worst-case fall, by one of the methods outlined in Clauses 9.3.2 to 9.3.6. 7.3.2

Design mass of workers


For an analysis in accordance with Clauses 7.2 and 7.3, the design mass, m, shall be the mass of the heaviest worker permitted on the system, including all tools and equipment, but not less than 140 kg. 7.3.3

Deployment force of personal energy absorbers and energy-absorbing lanyards

7.3.3.1 F Max (for strength calculations) PEAs and energy-absorbing lanyards meeting the requirements of CAN/CSA-Z259.11 shall be assumed to deploy at a force of F Max = 4 kN, or, in environments where they may become wet and frozen, at a force of F Max = 6 kN. Where a specialized PEA is required by the design, as permitted by Clause 5.4.3.2, the device shall be assumed to deploy at the maximum force specified by its manufacturer, but not less than 4 kN. 7.3.3.2 F Av g (for clearance calculations) PEAs and energy-absorbing lanyards shall be assumed to deploy at the minimum average force specified by their manufacturers. In the absence of information from the manufacturer, PEAs meeting the requirements of CAN/CSA-Z259.11 may be assumed to deploy at F Avg = 0.8 x F Max . 29 COPYRIGHT


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7.3.4

Deployment force of clutching self-retracting lanyards

7.3.4.1 F Max (for strength calculations) Clutching SRLs meeting the requirements of CAN/CSA-Z259.2.2 shall be assumed to deploy at the maximum rated deployment force specified by their manufacturer, but not less than 4 kN. 7.3.4.2 F Av g (for clearance calculations) Clutching SRLs shall be assumed to deploy at the minimum average force specified by their manufacturers. In the absence of information from the manufacturer, clutching SRLs meeting the requirements of CAN/CSA-Z259.2.2 shall be assumed to deploy at a minimum force of F Avg = 0.65 x F Max . 7.3.5

Impact force of non-clutching self-retracting lanyards

7.3.5.1 General Non-clutching SRLs may be used only in accordance with Clause 5.4.4.2.2. The maximum impact force shall be determined using one of the methods in Clauses 7.3.5.2 to 7.3.5.4. 7.3.5.2 Dynamic analysis and energy analysis When a fall-arrest system is analyzed in accordance with Clause 9.3.2 or 9.3.3, the MAF shall be calculated using the assumption that the device does not stretch and does not dissipate any energy after it has locked off. 7.3.5.3 Static analysis When a free-arrest system is analyzed in accordance with Clause 9.3.4, the MAF shall be the maximum impact force specified by the manufacturer for the free fall permitted by the system. 7.3.5.4 Testing and interpolation analysis The MAF shall be the measured force(s) when a fall-arrest system is tested in accordance with Clause 9.3.5. 7.3.6

Deployment force of horizontal lifeline energy absorbers

7.3.6.1 General When HLLEAs are used, the deployment forces to be used in strength and clearance calculations shall be as specified in Clauses 7.3.6.2 and 7.3.6.3. 7.3.6.2 T Max (for strength calculations) HLLEAs shall be assumed to deploy at the maximum force specified by their manufacturer. 7.3.6.3 T Av g (for clearance calculations) HLLEAs shall be assumed to deploy at the minimum average force specified by their manufacturer, or, when the total energy consumed by an HLLEA at full deployment is specified by the manufacturer, as follows:

T Avg

= U Max / X HEAMax

where

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T Avg

= average deployment force, kN

U Max

= total energy absorbed by the HLLEA at full deployment, kN•m

X HEAMax = maximum available deployment of the HLLEA, m 7.3.7

Multiple-worker falls

7.3.7.1 General For systems that may allow more than one worker to be attached to an anchorage, anchorage connector or anchorage subsystem, the effect of possible simultaneous or sequential impacts shall be accounted for in determining the MAF, MAL, and clearances. In HLLs, unless the design of the system or control of the work procedures reliably precludes the gathering of workers at a single point, all workers allowed within a single span shall be assumed to fall at the same point on the system. In multiple-span HLLs, the simultaneous falling of workers on different spans is considered highly improbable. It shall not be necessary to consider the possibility of simultaneous falls unless there is some unusual circumstance, such as a multiple-span HLL above a single-span work surface that, in the event of a collapse, would result in impacts on more than one span within a very short time. 7.3.7.2 Equivalent lumped mass NOTE – See Annex A.

In the absence of more rigorous analytical methods, the effect of multiple-worker falls may be modelled by (a)

lumping the masses of the falling workers into a single mass that is the product of the mass of the design worker, m, defined in Clause 7.3.2, times the lumping factor, M , given in Table 7.1 or 7.2, in accordance with the rigidity of the anchorage system; and

(b)

lumping PEAs or clutching SRLs, where used, in parallel into a single device that deploys at a force which is the product of the design deployment force of a single unit ( F Max or F Avg as applicable) defined in Clause 7.3.3 or 7.3.4 times the lumping factor, M , given in Table 7.1 or 7.2, in accordance with the rigidity of the anchorage. Table 7.1 – Lumping factor, M , for rigid anchorage systems (See Clauses 7.3.7.2 and A.8.) Number of workers falling 2 3 4

Systems using PEAs or clutching SRLs 2.00 3.00 4.00

Table 7.2 – Lumping factor, M , for flexible anchorage systems (See Clauses 7.3.7.2, A.8, and A.12.) Number of workers falling 2 3 4

Systems using PEAs or clutching SRLs 1.75 2.25 2.75

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7.3.7.3 Sequential falls on horizontal lifeline systems On HLLs only, the load effect, A, for multiple-worker falls may be determined by loading the HLL, pre-sagged by the deployment of any applicable HLLEA due to the earlier falls, with the dead weight of all prior fallen workers, in accordance with Clause 7.3.2, plus the fall-arrest impact from the last worker. The free fall of and clearance required for the last worker will be greater than for the prior workers because the HLL has been pulled downward by the prior falls and permanent HLL sag due to deployment of an HLLEA. 7.3.8

Horizontal systems

The professional engineer shall determine worker locations where falls would result in the least difference between required and available clearances and cause the maximum forces in the system components. Professional engineers shall, at a minimum, determine the performance of the system when a fall occurs on the shortest span and the longest span in the system. Professional engineers shall also determine the variation in system performance due to temperature or other environmental variations, if applicable. NOTE – Professional engineers may assume that for HLLs (a)

the maximum transverse forces on system anchorages occur when workers fall while immediately adjacent to end or intermediate anchorages; and

(b)

the greatest HLL tension and total-fall distance for each span of the system will occur when a fall occurs midway between supports.

8

Clearances for fall-arrest systems

8.1

Clearance reference

Clearances shall be referenced to the working platform ( C p), except when it may be necessary for portable or temporary systems to reference clearances to the anchorage ( C A) (see Figure 6).

8.2

Required clearance

8.2.1

General

Clearance requirements shall account for the worst-case total of free-fall distance, deceleration distance, stretch out, applicable swing-drop distance, and the safety margin specified in Clauses 8.2.2 to 8.2.6 (see Figures 4, 5, and 6). In multiple-worker systems that are analyzed in accordance with Clause 7.3.7.2, the required clearance shall be adjusted in accordance with Clause 8.2.6. 8.2.2

Free-fall distance

8.2.2.1 General Free fall is the unimpeded fall distance of the worker. Free fall ends when all slack has been taken out of the fall-arrest system so that further displacement of the worker will be resisted by forces developed in the system. Free fall will include any applicable lanyard or HLL or VLL slack, or activation distance (see Figures 1, 2, and 6).

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8.2.2.2 Lanyard or lifeline slack The lanyard or lifeline slack shall be taken as the height of the worker ’s D-ring above the opposite end of the lanyard or lifeline, plus the length of the lanyard or lifeline. Where the worker ’s D-ring is below the opposite end of the lifeline or lanyard, the difference in height shall be negative (see Figures 1 and 2). 8.2.2.3 Activation distance The activation or lock-off distance of a fall arrester or SRL shall be included in the free-fall distance (see Figure 2). 8.2.2.4 Horizontal lifeline slack In HLL systems, the change in sag between the initial sag and the cusp sag shall be included in the freefall distance (see Figure 3). 8.2.3

Deceleration distance

8.2.3.1 General Deceleration distance is the distance over which a fall-arrest system reacts to bring a falling worker to a complete stop. Deceleration distance shall include any applicable stretch of lifelines and lanyards, the maximum anchorage system deflection, and deployment of PEAs and clutching of SRLs (see Figure 6). 8.2.3.2 Stretch of lanyards Significant dynamic stretch of SRLs and conventional lanyards shall be included in the deceleration distance. Where the stretch is known to be less than 50 mm, it may be ignored (see Figure 6). 8.2.3.3 Maximum anchorage system deflection (MASD) The dynamic displacement of the anchorage, dynamic stretch of a vertical lifeline, or dynamic sag of an HLL shall be included in the deceleration distance (see Figures 3 and 6). 8.2.3.4 Deployment of personal energy absorbers and clutching self-retracting lanyards NOTE – See Annex A.

In fall-arrest systems that use PEAs or clutching SRLs, the deceleration distance shall include the deployment distance of these devices (see Figure 6), as follows: (a)

PEAs may be assumed to fully deploy;

(b)

deployment of PEAs or clutching SRLs may be accurately determined using dynamic analysis, energy analysis, or testing and interpolation analysis in accordance with Clause 9.3.2, 9.3.3, or 9.3.5, respectively; or

(c)

if static analysis is used (as allowed by Clause 9.3.4), deployment of PEAs or clutching SRLs may be estimated using the following formula:

X PEA

=

mg h 1000F Avg  mg

where

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X PEA

= deployment of PEA or clutching SRL, m

m

= the falling mass, kg, in accordance with Clause 7.3.2

g


h

= the free fall, m

F Avg

= average deployment force of the PEA or clutching SRL, kN, in accordance with Clause 7.3.3.2 or 7.3.4.2, as applicable

2

The professional engineer shall review the manufacturer ’s literature to determine the maximum deployment of the PEA that he or she has specified for the fall-arrest system or shall otherwise assume 1.2 m worst-case deployment. NOTE – PEAs meeting the requirements of CAN/CSA-Z259.11 are permitted by that Standard to deploy a maximum of 1.2 m (4.0 ft). Most manufacturers offer PEAs that also meet the requirements of ANSI Z359.1 for the American market, in which case the maximum deployment is only 1.07 m (3.5 ft).

8.2.4

Stretch out


The required clearance shall include allowance for stretch out, including harness stretch, and reaction of the worker ’s body to the deceleration forces, including applicable lengthening of the worker ’s body if falling from a kneeling or lying position (see Figure 4). The type of full-body harness being worn by the workers is a major component of stretch out. Harness stretch data shall be obtained from the harness manufacturer or shall be determined by testing harness performance at the MAF allowed by the fall-arrest system. If the professional engineer is unable to obtain harness stretch information or does not otherwise specify and control the type(s) of full-body harnesses being used, a minimum of 750 mm (2.5 ft) shall be assumed for the harness contribution to stretch out. 8.2.5

Swing-fall distance

The required clearance shall include an allowance for any applicable swing-fall distance (see Figure 5). 8.2.6

Safety margin

8.2.6.1 Rigid anchorage systems The safety margin, E , for rigid anchorage systems (see Figure 6) shall be not less than 0.6 m. 8.2.6.2 Flexible anchorage systems NOTE – See Annex A.

The safety margin, E , for flexible anchorage systems (see Figure 6) shall be not less than the value given by the following formula:

E = 0.6 + C MASD x MASD (m) where

C MASD depends on the method used to determine the maximum anchorage system deflection (MASD), as follows:

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C MASD = 0.10 for dynamic analysis or energy analysis in accordance with Clause 9.3.2 or 9.3.3 C MASD = 0.05 for testing and interpolation analysis in accordance with Clause 9.3.5 8.2.7

Clearance for equivalent lumped-mass simulation of multiple-worker falls


Where a flexible anchorage system providing protection for multiple workers has been analyzed using an equivalent lumped mass as defined in Clause 7.3.7.2, the required clearance calculated for the equivalent lumped mass shall be increased to account for the increased total of free fall and deceleration distance seen by the last worker to fall. In the absence of other proven methods, the following formula may be used to calculate the required clearance:

C = 1.6C LM – 0.6C 1 where

C

= clearance for the last worker to fall

C LM

= required clearance for the equivalent lumped-mass fall

C 1

= required clearance for a single-worker fall

NOTE – C, C LM , and C 1 are the applicable C P or C A values, depending on whether the clearance is specified below the platform or below the anchorage.

9

Design assumptions and analytical methods

9.1

Elasticity of ropes

9.1.1

Wire ropes

Wire ropes may be assumed to behave in a linear elastic manner, using the elastic modulus recommended by the manufacturer and in accordance with the grade and construction of the wire rope. 9.1.2

Synthetic ropes

Synthetic ropes may be assumed to behave in a linear elastic manner. In the absence of more accurate analytical methods, the professional engineer shall use an elastic modulus that gives the correct stretch (± 5%) at the greatest MAF or MAL to which the rope will be subjected. The stretch properties of the rope shall be determined by testing or shall be detailed in information supplied by the manufacturer.

9.2

Horizontal lifelines sags

HLL sags due to pre-tension may be determined using catenary or parabolic equations. NOTE – For all sags greater than or equal to the cusp sag (SC ), the HLL may be idealized as straight-line chords, ignoring the slight sags that occur because of its self-weight (see Figure 3).

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9.3

Analytical methods

9.3.1

General

The analytical methods described in Clauses 9.3.2 to 9.3.6 may be used to determine the performance of active fall-protection systems. 9.3.2

Dynamic analysis

Dynamic analysis may be used on all active fall-protection systems. 9.3.3

Energy analysis

Energy analysis may be used on all active fall-protection systems. 9.3.4

Static analysis

9.3.4.1 General Static analysis may be used only on active fall-protection systems where the requirements of Clause 9.3.4.2 or 9.3.4.3 are met, i.e., so that the MAF or restraint force applied to the system is known. 9.3.4.2 Travel-restraint systems In travel-restraint systems, static analysis may be used only if the requirements of Clause 7.2.2 are met, i.e., so that the force specified in that clause is applicable. 9.3.4.3 Fall-arrest systems NOTE – See Annex A.

In fall-arrest systems, static analysis may be used only when all of the following conditions can be met: (a)

PEAs or clutching SRLs are used to control the MAF;

(b)

the free-fall distance for any worker attached to the system is less than hMax as calculated in Clause 5.4.3.2; and NOTE – In systems used by multiple workers simultaneously, the free fall of the last worker to fall in a sequential fall is used for comparison to the allowable hMax . In the absence of more rigorous methods, the free fall of the last worker may be taken as the free fall of the first worker plus the maximum anchorage system displacement to arrest a lumped-mass fall of all workers prior to the last worker.

(c)

in HLL systems that incorporate HLLEAs, the total available deployment of all HLLEAs used in the system is greater than X HEAMin as defined below:

    1   X HEAMin = 1.5  1 L ( 2) MF Avg   1         2T Avg  where

X HEAMin = the minimum required total deployment of all HLLEAs used in the system, m

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9.3.5

M

= the “lumping factor ” for the maximum number of workers that may attach to one span of the HLL at any one time, in accordance with Clause 7.3.7.2

F Avg

= the average deployment force of the PEA or clutching SRL, kN, in accordance with Clause 7.3.4.2

T Avg

= the average deployment force of the HLLEA, kN, in accordance with Clause 7.3.6.3

L

= the maximum span of the HLL, m

Testing and interpolation analysis

Forces and clearance requirements for active fall-protection systems may be based on tests of a prototype of the actual system or interpolation of test results for similar systems that bracket the system being designed. Where interpolation of test data is required, an adequate range of configurations shall be tested, but not fewer than four tests for each parameter that is being varied, to permit interpolation to an accuracy of ±5 %. Rigid test weight(s) or articulating mannequins shall have a mass as specified in Clause 7.3.2. For multiple-worker systems, a lumped mass in accordance with Clause 7.3.7.2 may be used. The test(s) shall use the actual equipment specified for use in the active fall-protection system. Full-body harnesses may be omitted, provided that clearances are increased to account for stretch out of both the worker and the harness. PEAs may be substituted for clutching SRLs in the tests, provided that testing has proved that the average deployment force of the chosen lanyard is within ±5% of the average deployment force of the clutching SRL. 9.3.6

Other acceptable methods

Other analytical methods, based on proven scientific principles, shall be acceptable if they can be shown to accurately predict the performance of active fall-protection systems.

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Legend:

FF

= free fal = FF L = HD A + LY

FF L

= free fall resulting from lanyard/lifeline slack = HD A + LY

H DA

= vertical distance from the D-ring to the anchorage system end of the lanyard (H DA is negative if the D-ring is initially below the anchorage)

LY

= length of lanyard

Figure 1 – Free fall resulting from lanyard lifeline slack (See Clauses 8.2.2.1 and 8.2.2.2 and Figure 6.)

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SS 607 : 2015

Legend:

FF

= free fall

FF A

= free fall due to the activation distance of the fall arrester (to lock onto the vertical lifeline)

FF L

= free fall resulting from lanyard slack = HD A + LY

H DA

= vertical distance from the D-ring to where the lanyard connects to the anchorage connector (H DA is negative if the D-ring is initially below the fall arrester)

LY

= length of lanyard

Figure 2 – Free fall on vertical lifelines resulting from lanyard slack and movement of the fall arrester (See Clauses 8.2.2.1 – 8.2.2.3 and Figure 6.)

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Legend:

F C

= force required to pull slack out of adjacent spans and hold the initial length of cable into approximate straight-line cords (because this force is low, there is negligible worker deceleration prior to achieving cusp sag)

FF C

= free-fall distance due to slack in the horizontal lifeline cable

MAF

= maximum arrest force

MAL

= maximum arrest load (a force vector co-linear with the cable)

MASD = maximum anchorage system deflection = SMax - SC

SC

= cusp sag of the horizontal lifeline (due to all slack being pulled out of adjacent spans and to the initial length of cable being pulled into approximate straight-line cords)

SI

= initial sag of the horizontal lifeline (due to self-weight being balanced by the pre-tension force)

SMax

= maximum sag of the horizontal lifeline at fall arrest (due to the applied MAF)

Figure 3 – Horizontal lifeline sags and forces (See Clauses 3, 8.2.2.4, 8.2.3.3, and 9.2 and Figure 6.)

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Legend:

H F

= final height of D-ring (above the worker ’s toes) at fall arrest

H I

= initial height of D-ring (above the working surface) at start of fall

X W

= stretch out (due to D-ring flip and slide, harness stretch, and straightening of the worker ’s body)

Figure 4 – Stretch out (See Clauses 8.2.1 and 8.2.4.)

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Legend: SDD

= swing-drop distance (drop in height of D-ring from the onset of the swing to the point where the worker may impact any structure)

SFD

= swing-fall distance (drop in height of D-ring from the onset of the swing to the lowest point it reaches during the swing)

NOTE – SDD and SFD are calculated assuming a circular (pendular) motion of the worker ’s D-ring on a fixed and taut length of lifeline. They do not include a drop in height due to free fall or deceleration distance.

Figure 5 – Swing falls (See Clauses 3, 6.3, 8.2.1, and 8.2.4.)

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Legend: C A = required clearance below the anchorage = FF – H DA + DD + H F + E

C P

= required clearance below the platform = FF + DD + X W + E H = C A A

DD

= deceleration distance = MASD + X L + X PEA

E FF

= safety margin = free fall = FF Figures 1, 2, and 3) A + FF L + FF C (see

H A H DA

= height of anchorage above the working platform

H F H I

= final height of D-ring (above the worker ’s toes) at fall arrest

= height of D-ring above the anchorage (H DA is negative if the D-ring is initially below the anchorage) = initial height of D-ring (above the working surface) at start of fall

MASD = maximum anchorage system displacement (dynamic deflection of horizontal lifelines, flexible anchorages, vertical lifelines, etc.) TFD

= total fall distance (of the worker ’s dorsal D-ring) = FF + DD

X L X PEA X W

= stretch of the lanyard = deployment of the personal energy absorber or clutching self-retracting lanyard = stretch out (due to D-ring flip and slide, harness stretch, and straightening of the worker ’s body) Figure 6 – Clearances (excluding swing-fall distance) (See Clauses 3, 8.1, 8.2.1, 8.2.2.1, 8.2.3, and 8.2.6.) 43 COPYRIGHT


SS 607 : 2015

Annex ZA (normative)

Technical deviations and their explanations Annex ZA contains the list of modifications and their explanations. Clause

Modifications

Explanations

Preface

Delete the Preface.

It is the Preface of the Canadian Standard and not the Singapore Standard. See the National Foreword for the local context.

1.2

Replace “CSA Z259” with “SS 528” where

To align with SS 528.

appropriate. 1.4

Replace the clause with the following: This Standard does not cover the design of work positioning systems, e.g. rope access systems, per se . Nevertheless, this Standard covers fall arrest or backup sub-system of an industrial rope access system.

1.7

Replace “occupational safety and health regulations” with “workplace health regulations”.

1.8

safety

This is to clarify that even though rope access systems are generally classified as work positioning systems, the backup line is essentially a fall arrest system. Thus, the standard covers the design of the back-up line. To align with local terminology.

and

Replace “CSA Standards” with “Singapore

To align with local standards.

Standards” where appropriate. 3 Definitions – Anchorage connector

Replace “a personal fall-arrest system” with Active fall protection systems also cover “an active fall protection system”.

travel restraint systems.

3 Definitions – Anchorage subsystem

Replace “personal equipment” with “personal

For clarity.

3 Definitions – Boatswain’s chair

Also known as bosun’s chair or work Add “

3 Definitions – Certified

Replace the definition with “Meeting the

3 Definitions – Compatible connection

Replace “roll-out” with “roll-out and other

3 Definitions – Deceleration distance

Replace “moment of fall arrest” with “first moment the velocity of the user becomes zero”.

It is possible to have several instances of when the velocity becomes zero. Thus, it is important to clarify that the definition refers to the first moment.

3 Definitions – Energy absorber

Replace “into the human body” with “to the

To align with the SS 528 : Part 2.

protective equipment”. To align with local terminology.

seat.” to the definition at the end of the sentence. To align with local context.

requirements of a recognised Standard as attested by a certification organization accredited by the Singapore Accreditation Council.” incompatibility issues”.

user ”.

Add “The device shall limit the arresting forces applied to the fall arrest system and user .” to the definition after the sentence.

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Besides roll-out, there are also other types of incompatibility issues.


SS 607 : 2015

Clause

Modifications

3 Definition – Professional engineer

Replace

Explanations

“Professional engineer ” “Qualified engineer ” wherever the appears in the standard.

with term

Replace the definition with “ A person who holds a civil or mechanical engineering degree, or qualification listed in the Professional Engineers (Approved Qualifications) Notification, has completed relevant training(s) in design of fall protection systems and has the relevant experience in fall protection systems.” 3 Definition – Snap hook

A connector with Replace the definition with “

Even though Professional Engineers (PEs) in Singapore may have the necessary technical background to understand the content of this standard, the Work Group agrees that fall protection engineering is a specialized field, thus, the standard emphasizes a suitably qualified engineer instead of a PE. In this standard, “qualified” refers to the successful completion of a suitable fall protection engineer course and having the relevant experience. “Connector” is a more generic term.

a spring-loaded gate that, when open, allows objects to pass into and out of the interior of the connector ”. (The Note remains unchanged.)

3 Definition – Vertical lifeline

Replace “length of rope” with “flexible line”.

To align with local terminology.

4.2

Replace header with “Endorsement by

Due to the change from “professional engineer ” to “qualified engineer ”.

qualified engineer ”.

Replace the clause with “The qualified engineer who designs the system shall endorse drawings, calculations and specification(s) issued.” 4.3 (b)

4.3 i(iii)

Add “The layout should highlight the usable anchors and any unsafe locations should not be accessible by the design of the system”.

To indicate usable and unusable anchorage locations clearly and to reduce the accidental usage of unsafe anchors.

Add “Reference can be made to SS 570


Clause 12.5”. 5.1



Clauses 12.2 and 12.5”. nd

5.3

Replace

the 2 sentence with “Environmental considerations include, but are not limited to elevated temperature, corrosion, chemical attack, weather, abrasion, and ultraviolet exposure.”

Elevated temperature Singapore.

5.4.1

Delete “accredited by the Standards Council

To align with local standards.

of Canada”.

Replace “CSA Z259 Standard (CAN/CSAZ259.1, CAN/CSA-Z259.2.1, CAN/CSAZ259.2.2, CSA Z259.2.3, CAN/CSA-Z259.10, CAN/CSA-Z259.11, CAN/CSA-Z259.12, Z259.13, or Z259.15)” with “Singapore Standards (SS 541, SS 528 series, SS 570) or equivalent”.

Replace

“CSA Z259 Standard” with “Singapore Standard” where appropriate.

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is

a

concern

in


SS 607 : 2015

Clause 5.4.2

Modifications

Explanations

Add “Qualified engineer should consider manufacturer’s instructions, and implications such as warranty and conformance to standards.” at the end of the clause.

5.4.3.2 a)

Replace the clause with “the free fall distance and total mass shall conform to the requirements stipulated in SS 528 : Part 2, or ”.

To emphasize the need to consider manufacturer’s instructions, and implications such as warranty and conformance to standards. To align with SS 528 : Part 2 which specifies type 1 and type 2 PEAs.

5.4.3.2 b)

Replace “ANSI Z359.1” with “SS 528 : Part 2”.

To align with SS 528 : Part 2.

5.4.3.3

Delete clause.

Not relevant in the local context.

5.4.4.1

Add “Reference can be made to SS 528 :


Part 3”. 5.4.4.2.2

Delete “types” from “SRL types”.


Replace “CAN/CSA-Z259.2.2” with “SS 528 : Part 3”. 5.4.4.2.4 (a)

Replace “CAN/CSA-Z259.2.2 Type 2 or Type


3” with “SS 528 : Part 3”. 5.4.5.2

Replace “CAN/CSA-Z259.11” with “SS 528 :


Part 2”. 5.4.6

Replace “CAN/CSA-Z259.10” with “SS 528 :


Part 1”. 5.4.7

Replace “CAN/CSA-Z259.2.1” with “SS 528 :


Part 4”. 5.6.3

Replace “CAN/CSA-Z91 and CAN/CSA-Z271”


with “SS 570”. 6.1 (c), (d), (e)

Replace “National Building Code of Canada”

To align with local context.

with “relevant prescribed building codes in Singapore”. 6.2.2.2

Delete “CSA”.

6.2.2.3

Replace “CSA limit states design code” with


“relevant prescribed Singapore”. 6.2.2.3 (b) (iv)

Replace

“CSA standard(s)”.

building

G4”

with

code


in

“relevant


CSA G4 is not commonly used in Si ngapore.


Clause 6.2.1” 6.2.3



with “relevant prescribed building codes in Singapore”. 6.4.1

Replace “safety belt” with “restraint belt”.


Replace “CAN/CSA Z259.1” with “SS 541”. 6.4.2.1

Replace the clause with “In a fall-arrest system, a user shall wear a full-body harness and be attached to the system at the manufacturer designated attachment point for fall arrest.”

6.6.1 and 6.6.3

Add “Reference can be made to SS 570 Clause 12.7”.

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To align with local context whereby the attachment point could be at either the dorsal or sternal positions.



SS 607 : 2015

Clause

Modifications

Explanations

7.3.2

Replace “140 kg” with “100 kg”.

In accordance with A.7, a force factor of 1.0 is adopted. Since SS 528 requires test mass of 100 kg, the design mass should be 100 kg.

7.3.3.1

Replace the clause with “PEAs and energy-

To align with SS 528 : Part 2 which specifies type 1 and type 2 PEAs.

absorbing lanyards meeting the requirements of SS 528 : Part 2 shall be assumed to deploy at a force of F Max = 4 kN for type 1 and F Max = 6 kN for type 2 . Where a specialized PEA is required by the design, as permitted by Clause 5.4.3.2, the device shall be assumed to deploy at the maximum force specified by its manufacturer, but not less than 4 kN. For PEAs and energy absorbing lanyards that have been tested for wet and cold conditions in accordance with SS 528 Part 2, it shall be assumed that FMax = 6 kN when used in wet and cold conditions.” 7.3.3.2

Replace “F Avg = 0.8 x F Max ” with “F Avg = 2.45 kN for SS528 : Part 2 Type 1 personal energy absorbers and F Avg = 3.2 kN for SS 528 Part 2 Type 2 personal energy absorbers”.

8.2.3.4 (c)

Replace “1.2 m worst-case deployment” with

This is based on the testing of 31 PEAs in the publication Goh, Y. M. (2015). “An Empirical Investigation of the Average Deployment Force of Personal Fall Arrest Energy Absorbers.” J. Constr. Eng. and Manage. – Am. Soc. Of Civ. Eng. , 141(1). The information supplied by CSA Z259.16 Working Group also supports this amendment. To align with SS 528 : Part 2.

“1.75 m worst-case deployment”. 8.2.3.4 (c) NOTE

Replace the note with “PEAs meeting the

Annex A

Delete “NOTE 3”.

Not applicable in the local context.

A.4




requirements of SS 528 : Part 2 are permitted by that Standard to deploy a maximum of 1.75 m for Type 2 PEAs and 1.2 m for Type 1 PEAs. Some manufacturers offer PEAs that also meet the requirements of ANSI Z359.1 in which case the maximum deployment is only 1.07 m (3.5 ft).”

with “relevant prescribed building codes in Singapore”.

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SS 607 : 2015

Annex A (informative)

Commentary NOTE 1 – This Annex is not a mandatory part of this Standard. NOTE 2 – This commentary provides additional information on selected clauses in this Standard. It was developed, at the request of legislative bodies from across Canada, by a Working Group of specialists in fall-protection engineering. Fall-protection engineering is a relatively new specialization, and for this reason the Standard has adopted a fairly conservative approach to fall protection. NOTE 3 – The authors of this Standard expect that some clauses will be refined as time and further research allow. Users of this Standard who believe that it can be improved are invited to submit proposed changes, supported by research and sound reasoning, to the Technical Committee on Fall Protection.

A.1

Selection of personal energy absorbers (see Clause 5.4.3.2)

Clause 5.4.3.2 limits the assumption of a 4 kN peak impact force for CAN/CSA-Z259.2.11 shock absorbers to situations where the free fall is 1.4 m or less and worker mass is 140 kg or less. The purpose of this limitation is to prevent the shock absorber from bottoming out. When either of the above restrictions cannot be met, the formula provided in Clause 5.4.3.2 allows one to calculate the maximum allowable free fall needed to ensure that the personal energy absorber (PEA) does not bottom out. It is based on all of the energy from the fall being consumed by the PEA. The 1.4 m limit is less than is currently allowed by some provincial regulators and was determined as follows: (a)

CAN/CSA-Z259.2.11 establishes a test for PEAs that involves dropping a 100 kg mass 1.8 m. The PEA is permitted to deploy up to 1.2 m, with a peak force of up to 4 kN.

(b)

Most PEAs sold in Canada are manufactured for both the U.S. and Canadian markets (and therefore limit their maximum deployment to 3.5 ft (1.07 m) to meet the ANSI Z359.1 (and CSA) requirement.

(c)

Most PEAs deploy at an average force of 2.8 to 3.6 kN.

(d)

Given the commentary in Clause A.7, the Technical Committee on Fall Protection has concluded that a 140 kg mass should be used to simulate the effect from a 140 kg worker. This is a departure from the previously accepted assumption that a 100 kg test mass would properly represent a 140 kg worker.

(e)

The formula in Clause 5.4.3.2 yields a maximum allowable free fall of 1.4 m, based on F Avg = 3.2 kN, X Max = 1.07 m, and m = 140 kg.

A.2

Self-retracting lanyards used in fall-arrest systems (see Clause 5.4.4.2)

Clause 5.4.4.2 restricts the use of self-retracting lanyards (SRLs) that meet the requirements of CAN/CSA-Z259.2.2 but do not have a clutching mechanism to control the maximum impact force. These SRLs are restricted to fall-arrest systems where the SRL is anchored above the worker (such that the free fall is the lock-off distance of the SRL). 48 COPYRIGHT


SS 607 : 2015

The reasoning behind this requirement is as follows: (a)

The testing method in CAN/CSA-Z259.2.2 subjects Type 1 SRLs to a free fall of only 1.0 m plus the lock-off of the SRL. The maximum arrest force (MAF) is not measured (which would determine the MAF seen by the worker). Most of these devices include a label stating that the impact force to the worker ’s body is kept below 4 kN, but only if the device is anchored above the worker prior to the drop, so that the free fall is limited to the lock-off distance of the SRL.

(b)

When used in the United States in accordance with Occupational Safety and Health Administration (OSHA) regulations, most of the SRLs that meet only the Type 1 requirements of CAN/CSA-Z259.2.2 (i.e., do not meet the requirements of Types 2 or 3) are restricted to free falls of 2 ft (0.6 m) or less.

(c)

The testing method in CAN/CSA-Z259.2.2 subjects Type 2 or 3 SRLs to a free fall of only 0.6 m plus the lock-off distance of the SRL. The maximum impact force seen by the test weight may be as much as 8 kN, which exceeds the maximum force normally permitted by Clause 6.4.2.2. Most of these devices include a label stating that the impact force to the worker ’s body is kept below 4 kN, but only if the device is anchored above the worker prior to the drop, so that the free fall is limited to the lock-off distance of the SRL.

(d)

Many, but not all, SRLs carrying the CAN/CSA-Z259.2.2 Type 2 or 3 certification include a clutching mechanism intended to limit the MAF to 4 kN (which is not currently called for in CAN/CSA-Z259.2.2). To meet the intent of Clause 6.4.2.2, it is necessary to restrict SRL usage to clutching devices.

A.3

Horizontal lifeline energy absorbers used in fall-arrest systems (see Clause 5.4.8.2)

Clause 5.4.8.2 provides the following formula for limiting the maximum span of horizontal lifelines (HLLs) when horizontal lifeline energy absorbers (HLLEAs) are used: 2

 1000T Avg  Lmax = 1.4 16   4  Mng  where

Lmax

= maximum span, m

T Avg

= average deployment force of the HLLEA, kN, in accordance with Clause 7.3.6.3

M

= the “lumping factor ” for the maximum number of workers that may be attached to one span of the HLL at any one time, in accordance with Clause 7.3.7.2

m

= the mass of one worker, kg, in accordance with Clause 7.3.2

g


2

Some members of the Technical Committee have tested HLLEAs on long spans where, due to the properties of the energy absorber, the system has become unstable beyond certain span lengths and sagged well past a simple balance of forces between the PEA and HLLEA.

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The above formula was derived using the following progression of theoretical arguments: (a)

A body being accelerated by gravity will continue to accelerate downward until acted on by an upward force that is greater than the weight of the falling body.

(b)

Because there is always elasticity in actual fall-arrest anchorage systems, the force applied to arrest the falling body is related to the deflection of the system.

(c)

In the case of HLLs, and particularly HLLs with HLLEAs, significant sag is required before the system reacts with a force greater than or equal to the weight of the falling body (the sag beyond which the falling body begins to slow).

(d)

The worst case is a mid-span fall.

(e)

The cable will deflect into a V shape of two straight lines.

(f)

The average cable tension is equal to the average deployment force of the HLLEA (usually less than the nominal [peak] deployment force).

(g)

The average vertical arresting force applied to arrest the falling body is equal to the sum of the vertical components of the average cable tension.

(h)

The sag at which the system begins to slow the falling mass is the sag where the average vertical arresting force applied by the cable equals the weight of the falling mass.

HLLs meeting the requirements of this formula will begin to slow the falling worker(s) within the first 1.4 m of sag. The 1.4 m value was selected to ensure that the PEA does not bottom out in a fall with a 1.8 m lanyard connected to an HLL at waist height. With a few exceptions, HLLEAs on the market are already limited by their manufacturers to spans shorter than those permitted by this formula. Readers should note that the final sag of the HLL at fall arrest is typically two to four times the sag where the system begins to slow the falling body.

A.4

Determination of factored load effects (see Clause 6.2.3)

Because fall-arrest systems are subjected to dynamic rather than static forces, and because of the use of PEAs and HLLEAs to limit the forces in fall-arrest systems, it was necessary to apply the load factors to the load effects rather than to the loads themselves. This is contrary to the limit states design methodology in the National Building Code of Canada, where the load factor is applied to the weight of the falling mass. (If this approach were used in a system that includes a PEA, the maximum impact force could be identical to that calculated for the unfactored weight, resulting in no factor of safety for the strength of the system.) The overall factor of safety for the strength of the system is equal to the ratio of the load factor, α , divided by the capacity-reduction factor, Ø. The load factor applied to the load effect, α A, was chosen to be 1.5 for consistency with load factors used in other Canadian design codes. It was not developed based on a statistical review of the variability of loadings. The authors of this Standard believe that the capacity-reduction factors used in CAN/CSA-S16 and A23.3 generally maintain an overall factor of safety greater than or equal to 2 between the applied loading and the ultimate strength of the supporting system, which agrees with the fall-protection regulations in most jurisdictions where the factor of safety has been specified, e.g., British Columbia (Workers’ Compensation Board), Ontario, and the United States (OSHA).

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Clause 6.2.3 specifies capacity-reduction factors for materials not covered by Canadian design codes. These factors were selected with a view to maintaining a consistent factor of safety of at least 2, in accordance with the factors of safety that have been used for other materials. Applicable references are as follows: (a)

Clause 4.3(b) of CAN/CSA-C225 for vehicle-mounted aerial devices specifies a structural factor of safety of at least 5 for fibreglass. This Standard therefore uses a capacity-reduction factor of 0.3, which, in combination with the load factor of 1.5, matches the factor of safety of 5 in CAN/CSA-C225.

(b)

CSA Z259.13 requires a factor of safety of 3 for synthetic rope. A capacity-reduction factor of 0.5 was therefore selected, in order to be consistent with CSA Z259.13.

(c)

A capacity-reduction factor of 0.6 was selected for other ductile materials not covered by Canadian design codes to provide an overall factor of safety of 2.5.

(d)

Although CSA A23.3 suggests a capacity-reduction factor of 0.9 against the ultimate strength of pre-stressing strands, a value of 0.75 was selected for all wire rope cables to maintain a minimum factor of safety of 2.

A.5

Swing falls (see Clause 6.3)

The “swing velocity” of a worker is created by the potential energy gained by the worker ’s drop in elevation during the swing. The swing velocity is therefore identical to the velocity attained in a vertical fall for the same drop in elevation. The important difference with swing falls is that the impact will always be perpendicular to the main axis of the body, whereas in vertical falls the orientation of the body on impact may be random but can be affected by the twisting and tumbling of the falling workers as he or she attempts to land in the strongest possible orientation (feet first). The Working Group therefore believed that a conservative limit on the maximum permissible elevation drop during a swing fall was warranted, but also needed to allow a reasonable amount of lateral movement from an overhead anchorage. A maximum swing drop distance of 1.2 m was chosen. NOTE – Canadian legislative bodies require fall protection above threshold heights that are typically between 1.2 and 3.5 m.

A.6

Maximum arrest force (see Clause 6.4.2.2)

Sulowski (1978) and other sources have recommended that the maximum impact to a worker wearing a properly fitted full-body harness should not exceed 9 g . The current maximum force accepted virtually everywhere in North America is 8 kN, which ensures that no more than 9 g is felt by the worker so long as his or her body mass is at least 91 kg (200 lb). There is certainly a significant proportion of the working population that weighs less than this. In early 2002, the Technical Committee on Fall Protection voted to move toward a maximum impact force of 6 kN in all Standards, thus protecting workers down to body weights of 67 kg (150 lb). The figure of 6 kN coincides with the maximum impact permitted elsewhere, including Europe. For most clutching SRLs, and all shock absorbers meeting CAN/CSA-Z259.11 requirements, the maximum impact force that a worker should experience with a dry energy absorber at room temperature is 4 kN, thus keeping impacts below 9 g for body masses down to 45 kg (100 lb).

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For large workers or long free falls where sufficient clearance exists, two or more energy absorbers meeting the requirements of CAN/CSA-Z259.11 could be used in series. This should be done only under the direction of a professional engineer. See Arteau (2003) and CSA PLUS 1156.

A.7

Design mass of workers (see Clause 7.3.2)

This Standard radically departs from other testing and design Standards in that the mass employed to represent a 140 kg worker is 140 kg. ANSI Z359.1 and Standards in the CSA Z259 series published before 2003 provide for the dropping of 100 kg rigid test masses to simulate the effect from a 140 kg worker (the heaviest worker that these Standards are designed to protect). The 100 kg test mass is based on a commonly accepted principle that a human body will stretch and absorb energy, so that the impact forces from a person should be less than those from a rigid test mass of the same weight. The rule adopted by testing standards and some OSHA regulations specifies a relationship of 1.4 between the impact forces generated by a test mass and those generated by a person of the same weight. This factor, established several decades ago, was based on dynamic testing using non-shock-absorbing lanyards. It has been assumed that the force relationship also translates into a mass relationship of 1.4 (e.g., a 100 kg mass will have the same effect on a fall-arrest system as a 140 kg worker). One member of the Technical Committee stated that he had done some very limited testing comparing the deployment of shock absorbers using rigid test torsos and human subjects and found virtually no difference between the two. A preliminary examination of the historical basis of the 1.4 factor revealed a tremendous variation in the test data, and showed that 1.4 was more a consensus value picked by regulators than a number clearly proved by testing. (Testing of rope lanyards at the time the 1.4 factor was chosen showed a variation of 1.1 to 1.8.) The Working Group decided to look at his data and re-examine the 1.4 assumption. There was an initial review of a mathematical study prepared by one of the members, comparing the force factor to the mass for various types of 1.8 m non-shock-absorbing lanyards. The study proved that for a force ratio of 1.4 (between the impact force generated by a rigid mass and a worker of the same weight) there was an equivalent mass factor (which would generate the same impact) of 1.7 to 1.9 (depending on the elasticity of the lanyard). It was conclude that if the force factor is exactly 1.4 where non-shock-absorbing lanyards are being used, testers should be using a rigid drop test mass that is 140 kg ÷ (1.9 to 1.7), i.e., 74 to 82 kg, to generate the same impact force as a 140 kg person. Therefore, the current CSA test weight of 100 kg is conservative if the force factor actually exists. Because this Standard makes PEA use mandatory (unless Clause 6.4.2.3 applies), the discussion moved on to consider the fact that the 1.4 factor was developed by testing non-shock-absorbing lanyards, whereas most systems today use shock absorbers that will result in no differences in the forces as long as the shock absorber partially deploys, so the force factor should be 1.0. Therefore, it was concluded that a person might absorb some of the fall energy, resulting in lower shock absorber deployment, whereas a rigid test weight would not. The Technical Committee concluded that whereas one would expect a human body to absorb some fall energy because of its internal elasticity, shock absorber deployments might not reflect this, for two reasons: (a)

The drop tests led to the 1.4 factor probably produced greater impact forces on the human body (perhaps up to 8 kN or more), in which case the influence of the elasticity of the human body would be stronger. With the lesser forces of a shock absorber (nom inally 4 kN, and likely closer to 2.8 to 3.6 kN), it is possible that the force takes up all of the initial slack in the human body, all of which lowers the body’s centre of mass, generating some fall energy (which may be of the same magnitude as the energy the body absorbed as it flexed). It is only at higher forces that tendons and joints bottom out, leading to increased compression or crushing of cartilage, 52 COPYRIGHT


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stretching of tendons, and stretching of muscles beyond their range of easy movement. Thus where the forces are greater, the body may absorb or dissipate fall energy at a greater rate than is produced by the additional lowering of the centre of gravity (leading to development of the 1.4 factor). (b)

When a person wears a full-body harness with a sliding D-ring, the harness stretches and the Dring slides, lowering the body by perhaps 15 to 61 cm (6 to 24 in), depending on the stretchiness of the harness. This flex of the harness and sliding of the D-ring occurs at relatively low forces and therefore does not absorb as much energy as is gained by the additional lowering of the person’s centre of mass.

After further discussion, it was agreed that this Standard should not rely on the 1.4 factor for forces or for equivalency of test (or design calculation) masses, particularly since shock absorbers are now mandatory and the basis of the 1.4 factor was testing with non-shock-absorbing lanyards. In the face of the test data, and with plausible explanations why a person in a harness should cause the same deployment of a shock absorber as a rigid test mass, the consensus vote of the Working Group was to eliminate the 1.4 factor from this Standard and require the designer to analyze the system for a rigid mass equal to the maximum human mass permitted on the system. The Technical Committee sought additional test data for human falls using shock absorbers, and the results are pending.

A.8

Equivalent lumped mass (see Clause 7.3.7.2)

For multiple-worker falls, a common approach is to lump the masses of workers together into a single mass that may then be analyzed using techniques for a single-worker fall. Early research on multiple-worker falls not involving a PEA showed that it was virtually impossible to have a simultaneous peak impact involving multiple workers. Most recent research, with PEAs, has shown that simultaneous impacts are now possible because of the longer duration of the fall arrest. In developing Table 7.1, the Working Group decided to conservatively assume that all impacts occur simultaneously. It was believed that this requirement would not be overly onerous in the design of most rigid anchorage systems. In developing Table 7.2, the Working Group used computer software to analyze a wide variety of HLL systems. This involved comparing a lumped-mass analysis to a sequential fall in which the computer simulation hung the masses of the previously fallen workers from the HLL as the next worker impacted the system. In most cases that were analyzed, the chosen lumping factors gave reasonable or conservative results. It should be noted that the recommended lumping factors that have been provided by other sources are lower than those required by this Standard. Many of the earlier lumping formulas, however, were developed before the common use of PEAs (which reduce the ratio between the peak impact force and the dead weight of the worker) and were developed using drop masses of 100 kg, whereas this Standard requires drop masses of 140 kg, as explained in Clause 7.3.2.

A.9

Deployment of personal energy absorbers and clutching self-retracting lanyards (see Clause 8.2.3.4)

If the designer of a fall-arrest system has met the requirements of Clause 5.4.3.2, the PEA will not fully deploy, and for this reason the designer may conservatively assume full deployment in calculating clearance requirements.

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If the designer is using energy analysis, dynamic analysis, or testing and interpolation analysis, the amount of deployment of the shock absorber can be accurately calculated. Static analysis, however, will not enable the designer to determine the amount of fall energy absorbed by other components of the fall-arrest system (meaning that the designer cannot accurately calculate the deployment of the shock absorber). The equation in Clause 8.2.3.4 is another version of the equation in Clause 5.4.3.2(b)(ii), algebraically manipulated to solve for PEA deployment rather than free-fall height.

A.10 Stretch out (see Clause 8.2.4) The stretch out of the worker and harness was kept as a separate factor so that designers account for (a)

situations where a worker using an SRL anchored overhead might fall from a kneeling or lying position. These situations require more clearance below the working platform than situations where the worker falls from a standing position; and

(b)

the stretch of a full-body harness, which can vary tremendously (typically from 150 to 750 mm) depending on the harness design and the elasticity of the webbing.

A.11 Safety margin for flexible anchorage systems (see Clause 8.2.6.2) The safety margins for flexible anchorage systems are adjusted to account for the anticipated worst-case inaccuracies expected for the various analytical methods. The C MASD factors in this Standard reflect the consensus of the Working Group and do not have a rational or scientific basis. They were chosen as a starting point for this edition of the Standard, because of their use by some Working Group members. They may be subject to refinement in future editions if research into this topic is undertaken by interested parties and submitted to the Technical Committee.

A.12 Clearance for equivalent lumped-mass simulation of multiple-worker falls (see Clause 8.2.7) In a sequential fall on a flexible anchorage system, the last worker falling will have the greatest free fall because the anchorage system (such as HLL) will have been moved by the preceding falls. The equation in Clause 8.2.7 was derived in conjunction with the development of Table 7.2. The Working Group used computer software to analyze a wide variety of HLL systems. This involved comparing a lumped-mass analysis to a sequential fall in which the computer simulation hung the masses of the previously fallen workers from the HLL as the next worker impacted the system. The chosen equation gave reasonable or conservative results in most cases that were analyzed.

A.13 Condition required for static analysis of fall-arrest systems (see Clause 9.3.4.3(c)) The equation in Clause 9.3.4.3(c) was developed to ensure that an HLLEA will not deploy more than twothirds of its maximum available deployment in a worst-case fall. This requirement permits users of static analysis to safely assume that the maximum tension in the HLL will be T Max (See Clause 7.3.6.2). Should the HLLEA bottom out, static analysis no longer applies. In that case, the designer would use energy, dynamic, or testing and interpolation analytical methods to accurately determine the peak forces in the HLL, which will be greater than the deployment force of the HLLEA.

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Annex B (informative)

Bibliography NOTE – This Annex is not a mandatory part of this Standard.

Riches, D. (2002) “ Analysis and evaluation of different types of test surrogate employed in the dynamic performance testing of fall-arrest equipment”. Health & Safety Executive HSE (United Kingdom), Research Report CRR 411/2002. Sulowski, A.C., and Amphoux, M. (eds). “Fundamentals of Fall Protection”. International Society for Fall Protection, Toronto, June 1991.

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ABOUT SPRING SINGAPORE SPRING Singapore is an agency under the Ministry of Trade and Industry responsible for helping Singapore enterprises grow and building trust in Singapore products and services. As the national standards and accreditation body, SPRING develops and promotes an internationally-recognised standards and quality assurance infrastructure. SPRING also oversees the safety of general consumer goods in Singapore. As the enterprise development agency, SPRING works with partners to help enterprises in financing, capability and management development, technology and innovation, and access to markets. SPRING Singapore 1 Fusionopolis Walk #01-02 South Tower, Solaris Singapore 138628 Tel: 6278 6666 Fax: 6278 6667 E-mail: [email protected] Website: http://www.spring.gov.sg

ABOUT THE NATIONAL STANDARDISATION PROGRAMME Under the national standardisation programme, SPRING Singapore helps companies and industry to meet international standards and conformity requirements by creating awareness of the importance of standardisation to enhance competitiveness and improve productivity, co-ordinating the development and use of Singapore Standards and setting up an information infrastructure to educate companies and industry on the latest developments. SPRING Singapore is vested with the authority to appoint a Standards Council to advise on the preparation, publication and promulgation of Singapore Standards and Technical References and their implementation. Singapore Standards are in the form of specifications for materials and products, codes of practice, methods of test, nomenclature, services, etc. The respective committee or working group will draw up the standards before seeking final approval from the Standards Council or the relevant Standards Committee. To ensure adequate representation of all viewpoints in the preparation of Singapore Standards, all committees appointed consist of representatives from various interest groups which include government agencies, professional bodies, tertiary institutions and consumer, trade and manufacturing organisations. Technical References are transition documents developed to help meet urgent industry demand for specifications or requirements on a particular product, process or service in an area where there is an absence of reference standards. Unlike Singapore Standards, they are issued for comments over a period of two years before assessment on their suitability for approval as Singapore Standards. All comments are considered when a technical reference is reviewed at the end of two years to determine the feasibility of its transition to a Singapore Standard. Technical References can therefore become Singapore Standards after two years, continue as Technical References for further comments or be withdrawn. In the international arena, SPRING Singapore represents Singapore in the International Organization of Standardixation (ISO), the Asia-Pacific Economic Co-operation (APEC) Sub-committee for Standards and Conformance (SCSC) and in the ASEAN Consultative Committee on Standards and Quality (ACCSQ). The Singapore National Committee of the International Electrotechnical Commission which is supported by SPRING Singapore, represents Singapore in the IEC.

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