Pipe Support

DESIGN GUIDE FOR PIPE SUPPORT

DESIGN GUIDE FOR PIPE SUPPORT CONTENTS

1.0

2.0

OBJECTIVE

3

1.1

Design Objective as a Civil/Structural Engineer

3

1.2

PIPE SUPPORT OBJ ECTIVE

3

CODES, STANDARDS AND REFERENCE BOOKS, DOCUMENTS IN THIS GUIDE

4

3.0

ABBREVIA TION

4

4.0

PIPE SUPPORTS’ DUTY

5

5.0

PIPE SUPPORTS’ LOCATION

5

6.0

TYPES OF PIPE SUPPORTS

5

6.1

Rigid Support

5

6.2

Spring sup port (BY PIPING)

9

6.3

Snubber /shoc k absorb er (BY PIPING)

10

6.4

SUPPLEMENTARY STEEL

10

7.0

RESPONSIBILITY

11

7.1

BY PIPING

11

7.2

BY CIVIL

11

7.3

PIPE SUPPORT ON PIPERACK

11

8.0

SUPPORTS (RESTRAINT)

12

9.0

INPUT PIPING DESIGN LOADS TO STAAD-PRO

12

9.1

LOADS ON PIPE SUPPORT MODEL

12

9.2

HYDROSTATIC TEST LOAD

12

9.3

SUSTAINED LOAD

12

9.4

OPERATION LOAD

13

9.5

OPERATION AND WIND LOAD

13

9.6

FRICTION LOAD

13

10.0

TYPES OF SUPPORTS (IMAGE)

15

11.0

AXIS OF DIFFERENT BETWEEN PIPING & CIVIL (STAA D-PRO)

17

12.0

INPUT AND OUTPUT ± SIGN

18

13.0

DESIGN PARA RMETER

18

14.0

CLIPS LOA DING TO VENDOR

19

14.1

CONSTRUCTABILITY EXAMPLE

19

15.0

SCOPE OF WORKING RESPONSIBIL ITY

19

16.0

CONNECTION OF PIPE SUPPORT

19


1.0

OBJECTIVE The design guide for pipe support is to provide the Civil Engineer to consider the design and construction of the design processes. (The specification mainly describ ed as on pipe rack and attached on the vessel)*

1.1

Design Objectiv e as a Civil /Struct ural Engineer Civil/Structural Engineers need to know how difficult to design pipe support with a safe & economical design to support the piping loads, especially when final piping drawings are not available. Civil/Structural Engineers are last to get all the information but the first group required to produce construction drawings to meet the specifications and schedules.

1.2

PIPE SUPPORT OBJECTIVE The layout and design of piping and its supporting elements shall be directed toward preventing the following: a) piping stresses in excess of those permitted in this Code b) leakage at joints c) excessive thrusts and moments on connected equipment (such as pumps and turbines) d) excessive stresses in the supporting (or restraining) elements e) resonance with imposed or fluid-induced vibrations f)

excessive interference with thermal expansion and contraction in piping which is otherwise adequately flexible

g) unintentional disengagement of piping from its supports h) excessive piping sag in piping requiring drainage slope i)

excessive distortion or sag of piping (e.g., thermoplastics) subject to creep under conditions of repeated thermal cycling

j)

excessive heat flow, exposing supporting elements to temperature extremes outside their design limits


2.0

CODES, STANDA RDS AND REFERENCE BOOKS, DOCUMENTS IN THIS GUIDE ASME 31.1 & 31.3 Power Piping & Process Piping MSS SP-58 Pipe Hangers and Supports - Materials, Design, and Manufacture MSS SP-69 ANSI/MSS Edition Pipe Hangers and Supports - Selection and Application MSS SP-77 Guidelines for Pipe Support Contractual Relationships MSS SP-89 Pipe Hangers and Supports -Fabrication and Installation Practices MSS SP-90 Guidelines on Terminology for Pipe Hangers and Supports PIPING AND PIPE SUPPORT SYSTEMS (Paul R.Smith, P.E & Thomas J. Van Lann, P.E)

3.0

ABBREVIATION SPS

-

Special Pipe Support

HYD

-

Hydro test

SUS

-

Suspension

OPE

-

Operation

OPE+Wind

-

Operation with Wind

FRIC

-

Friction

SW

-

Self-Weight

DL

-

Dead Load

LL

-

Live Load

VDB

-

Vendor Data Base

VDBC

-

Vendor Data Base Comment

IDC

-

Internal Discipline Check

IFR

-

Issued For Review

IFC

-

Issued For Construction


4.0

5.0

6.0

PIPE SUPPORTS’ DUTY 

Support piping system loads



Restrain or guide piping system elements



Permit movement of our piping system



Transmit pipe loads to structural members



Prevent heat transfer to the surrounding structure



To carry load



To ensure that material is not stressed beyond a safe limit



Holdup of liquid can occurred due to pipe sagging (allow draining)



To permit thermal expansion



To withstand and dampen vibrational forces applied to the piping

PIPE SUPPORTS’ LOCATION 

(On pip e racks & vessel)*



Near grade on sleeper



In trench



Near steelwork or equipment

TYPES OF PIPE SUPPORTS 1. 2. 3. 4.

6.1

Rigid Support Spring Support Snubber /shock absorber Supplementary steel

Rigid Suppor t Rigid supports are used to restrict pipe in certain direction(s) without any flexibility (in that direction). Main function of a rigid s upport can be Anch or, Rest , Gui de or bot h Res t & Guide. For supporting elements shall be based on the loadings: including the weight of the fluid transported or the fluid used for testing, whichever is heavier. Exceptions may be made in the case of supporting elements for large size gas or air piping, exhaust steam, relief or safety valve relief piping, but only under the conditions where the possibility of the line becoming full of water or other liquid is very remote.

DESIGN GUIDE FOR PIPE SUPPORT Stanchion/Pipe Shoe Rigid support can be provided either from bottom or top. In case of bottom supports generally a stanchion or Pipe Clamp Base is used. It can be simply kept on steel structure for only rest type supports. To simultaneously restrict in another direction separate plate or Lift up Lug can be used. A pipe anchor is a rigid support that restricts movement in all three orthogonal directions and all three rotational directions, i.e. restricting all the 6 degrees of freedom . This usually is a welded stanchion that is welded or bolted to steel or concrete. (In case of anchor which is bolted to concrete, a special type of bolt is required called Anch or Bo lt , which is used to hold the support with concrete.) Resting 

To support the pipe weight & is generally used where littl e or no pipe movement is anticipated.

Guides 

Pipe lines containing expansion joints or other where lateral pipe mov ement needs to be controll ed.



Permits movement along pipe axis

Prevents lateral movement





May permit pipe rotation



Where guides are provided to restrain, direct, or absorb piping movements, their design shall take into account the f orces and moments at these elements caused by internal pressure and thermal expansion.


Stopper For pressure testing and stopping all pip ework.



Anch or 

Full fixation



Permits very limited (if any) translation or rotation



Where anchors are provided to restrain, direct, or absorb piping movements, their design shall take into account the forces and moments at these elements caused by internal pressure and thermal expansion.


Other types of support

DESIGN GUIDE FOR PIPE SUPPORT Rod Hanger(By Piping) It is a static restraint i.e. it is designed to withstand tensile load only (no compression load should be exerted on it; in such case buckling may take place). It is rigid vertical type support provide from top only . As it comes with hinge and clamp, no substantial frictional force comes into play.

Rigid Strut(By Piping) It is a dynamic component i.e. is designed to withstand both tensile and compression load. Strut can be providing in vertical as well as horizontal direction . V-type Strut can be used to restrict 2 degrees of freedom. It consists of stiff clamp, rigid strut, welding clevis. Selection depends on pipe size, load, temperature, insulation, assembly length. As it comes with hinge and clamp, no substantial frictional force comes into play.

6.2

Sprin g supp ort (BY PIPING) 1. Variable Spring Hanger or Variable Effort Support. 2. Constant Spring Hanger or Constant Effort Support. Load calculations for variable and constant supports, such as springs or counterweights, shall be based on the design operating conditions of the piping. They shall not include the weight of the hydrostatic test fluid. However, the support

DESIGN GUIDE FOR PIPE SUPPORT shall be capable of carrying the total load under test conditions, unless additional support is provided during the test period.

6.3

Snubber /shoc k absor ber (BY PIPING) Dynamic

restraint:

earthquake,

fluid,

certain

system

functions,

environmental

influences.

6.4

SUPPLEMENTARY STEEL Where it is necessary to frame structural members between existing steel members, such supplementary steel shall be designed in accordance with AISC specifications, or similar recognized structural design standards. Increases of allowable stress values shall be in accordance with the structural design standard being used. Additional increases of allowable stress values, such as allowed stress values are not permitted.

DESIGN GUIDE FOR PIPE SUPPORT 7.0

RESPONSIBILITY

7.1

BY PIPING Anchors, guide and restraints shall be designed for imposed loading as determined by the Piping Design Engineer. For guided systems, in the absence of specified lateral loads, the guide shall be designed for 20% of the dead weight load based on the spans, with a design load of 50lbs (0.22 kN) as a minimum. For pressure piping with joints not having a restraining design, other positive restraining such as clamps, rods and/or thrust blocking shall be used to maintain the integrity of the joints. The necessity for, and the location of, shock suppressors and seismic control devices shall be as determined by th e Piping Design Engineer’s scope.

7.2

BY CIVIL Pipe support is classified as a special pipe support and under the civils’ responsibility to design the pipe support when one or more of following criteria are met. Total vertical load transmitting by piping ≥ 3.0MT. Total lateral load transmitting by piping

≥ 1.0MT.

Height of support

≥ 3.0M.

All reactions applied to SPS will be provided as a sketch by the Pipe Stress Engineer. 7.3

PIPE SUPPORT ON PIPERACK A pipe may be supported to resist gravity only, or may have varying degrees of restraint from guided in a single direction to fully anchored supports. Pipe stress analysis can be completed for all the pipes located in the pipe rack. This stress analysis takes into account the support type and location for each support and provides individual design forces for each pipe at that specific location. These resultant pipe loads can be used for design. However, application of loads in this manner does not include additional loads for futures expansion. Therefore, a uniform load at each level of the rack is typically applied in lieu of actual pipe forces. Local support condition should also be verified where large anchor forces are present.


SUPPORTS (RESTRAINT) Vertical (gravity direction) Axial (parallel to pipe run (longitudinal axis) Lateral (perpendicular to both the vertical & the axial axes(transverse axis)

  

9.0

INPUT PIPING DESIGN LOADS TO STAAD-PRO

9.1

LOADS ON PIPE SUPPORT MODEL Dead load (Structure dead load (self-weight) Live Load (Usually no Live Load on pipe support) Piping HYD Hydro test load







9.2

SUS

-

Suspension

OPE

-

Operation

OPE +Wind

-

Operation with Wind

HYDROSTATIC TEST LOAD The sustained load due to the weight of water required for hydrostatic testing (especially on large diameter pipes) shall be accounted for in the pipe support and structural steel designs. Hydrostatic test loads and stresses are considered short term design conditions. An extended allowable test stress is permissible unless otherwise noted.

9.3

SUSTAINED LOAD Sustained load is caused by mechanical forces which are present throughout the abnormal operation of the piping system. Include both weight & pressure loadings. (All piping systems must be designed for weight loading) Many piping systems are under internal pressure loadings from the fluid they transport. Calculated stresses are due to sustained load by (a) Internal Pressure Stresses. (b) External Pressure Stresses. (c) External Loading Stresses.


9.4

OPERATION LOAD The sum of the stresses produced by internal and external pressure, live and dead loads during operation.

9.5

OPERATION AND WIND LOAD The sum of the stresses produced by internal and external pressure, live and dead loads during operation and wind.

9.6

FRICTION LOAD Caused by hot lines sliding across the pipe support are assumed to be partially resisted by nearby cold lines. Friction forces can be estimated based on the coefficient of friction between the pipe shoe and support beam. Friction loads are cause by expansion and contraction of pipes. Based on the expansion and contraction of pipes, friction loads are typically seen in the longitudinal direction of the pipe support. (When a pipe expands due to increase in temperature from the installed condition, some friction forces will be transferred to the line-stops and rest supports tending to move them in the same or opposite direction of the thermal expansion. It is advisable that the pipe stress analyst do not list the friction forces in the load table on the stress isometric. The reason is that this has led to that the friction load has been misunderstood by the pipe supporter or structural department, and hence a line-stop has been installed where the pipes were to move freely in the axial direction . Guidance should be given to the pipe support department on how to handle friction forces not listed on the stress isometric. Typical is to add an axial fric tion l oad of 1/3 of the reported vertical loads .)1 Note1

RECOMMENDED PRACTICE DET NORSKE VERITAS DNV-RP-D101 STRUCTURAL ANALYSIS OF PIPING SYSTEMS

So, we have to consider additional friction load which is need to consider for local strength check and this load is acting along longitudinal axis of the pipe. Friction load need to consider when pipe support is rest, or guide or rest +guide. Friction load is calculated as: Friction Load (FRIC) = Static Friction Coefficient x Operating Load (OPE)

DESIGN GUIDE FOR PIPE SUPPORT Where static friction coefficient between steel to steel

=

0.3 and

Operating

load

actin g

vertically (gravity directi on).

Friction has been described from each. “Detailed Engineering Design Data for Civil and Structure" Project specification


10.0

TYPES OF SUPPORTS (IMAGE)



AXIS OF DIFFERENT BETWEEN PIPING & CIVIL (STAAD-PRO)

Axis from Pipe Stress Engineer

Designing from Civil Engineer

Note So there need to convert the load axis when putting the piping load to pipe support model. And then we need to change axis for giving the clip loading to the Vendor.


12.0

INPUT AND OUTPUT ± SIGN

There need to do the model for ± of horizontal loadings to be safe side. There also need to give the result of ± horizontal clip loadings to be safe side.

13.0

DESIGN PARA RMETER Actually need to design parameter as the project specification. Generally the basic of design parameter are as under described. CODE

-

CODE as under project

ALPHA

-

α Factor for combined bending and axial force checks

BEAM

-

Number of selections to be checked per beam

BETA

-

β Factor for combined bending and axial force checks

CMM

-

Loading Type

CMN

-

End Restraint

FU

-

Ultimate tensile strength of steel

PY

-

Yield stress of steel

SBLT

-

Select type of section

TORSION

-

Method to be used for a specific member or group of members

RATIO

-

Permissible ratio of applied loading to section capacity

KY

-

K value in local Y axis for slenderness value KL/r

KZ

-

K value in local Z axis for slenderness value KL/r

LY

-

Length in local Y axis for slenderness value KL/r

LZ

-

Length in local Z axis for slenderness value KL/r

UNL

-

Unrestrained member length in lateral torsion buckling checks


14.0

CLIPS LOA DING TO VENDOR

14.1

CONSTRUCTABILITY EXAMPLE 

Especially difference of beam depth is less than 100mm, it will bring narrow space not be able to able to work welding grinding coating and inspection.



Same depth could be selected provided that;



The difference of depth (h) shall be kept over minimum 100mm for ease connection from constructability point of view.



15.0

Any narrow spaces shall be avoided as much as possible.

SCOPE OF WORKING RESPONSIBIL ITY Only beam and bracing from Vessel and Pipe rack are under Civil Scope. Unless noted otherwise, other parts are under Piping Scope.

16.0

CONNECTION OF PIPE SUPPORT The connection of pipe-support to Vessel is under vendor responsibility. We need to give the clips loading to Vendor by VDB. And after checking the clip load and give us comment from VDB.

Pipe Support

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