Loading facilities for truck loadings.

DEP SPECIFICATION

Copyright Shell Group of Companies. No reproduction or networking permitted without license from Shell. Not for resale

LOADING FACILITIES FOR BULK ROAD VEHICLES

DEP 31.06.11.11-Gen. February 2011 (DEP Circular 83/11 has been incorporated)

DESIGN AND ENGINEERING PRACTICE

DEM1

© 2011 Shell Group of companies All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, published or transmitted, in any form or by any means, without the prior written permission of the copyright owner or Shell Global Solutions International BV.

This document has been supplied under license by Shell to: Petroleum Development Oman [email protected] 16/01/2013 09:57:24

DEP 31.06.11.11-Gen. February 2011 Page 2

PREFACE DEP (Design and Engineering Practice) publications reflect the views, at the time of publication, of Shell Global Solutions International B.V. (Shell GSI) and, in some cases, of other Shell Companies. These views are based on the experience acquired during involvement with the design, construction, operation and maintenance of processing units and facilities. Where deemed appropriate DEPs are based on, or reference international, regional, national and industry standards. The objective is to set the recommended standard for good design and engineering practice to be applied by Shell companies in oil and gas production, oil refining, gas handling, gasification, chemical processing, or any other such facility, and thereby to help achieve maximum technical and economic benefit from standardization. The information set forth in these publications is provided to Shell companies for their consideration and decision to implement. This is of particular importance where DEPs may not cover every requirement or diversity of condition at each locality. The system of DEPs is expected to be sufficiently flexible to allow individual Operating Units to adapt the information set forth in DEPs to their own environment and requirements. When Contractors or Manufacturers/Suppliers use DEPs, they shall be solely responsible for such use, including the quality of their work and the attainment of the required design and engineering standards. In particular, for those requirements not specifically covered, the Principal will typically expect them to follow those design and engineering practices that will achieve at least the same level of integrity as reflected in the DEPs. If in doubt, the Contractor or Manufacturer/Supplier shall, without detracting from his own responsibility, consult the Principal. The right to obtain and to use DEPs is restricted, and is typically granted by Shell GSI (and in some cases by other Shell Companies) under a Service Agreement or a License Agreement. This right is granted primarily to Shell companies and other companies receiving technical advice and services from Shell GSI or another Shell Company. Consequently, three categories of users of DEPs can be distinguished: 1) Operating Units having a Service Agreement with Shell GSI or another Shell Company. The use of DEPs by these Operating Units is subject in all respects to the terms and conditions of the relevant Service Agreement. 2) Other parties who are authorised to use DEPs subject to appropriate contractual arrangements (whether as part of a Service Agreement or otherwise). 3) Contractors/subcontractors and Manufacturers/Suppliers under a contract with users referred to under 1) or 2) which requires that tenders for projects, materials supplied or - generally - work performed on behalf of the said users comply with the relevant standards. Subject to any particular terms and conditions as may be set forth in specific agreements with users, Shell GSI disclaims any liability of whatsoever nature for any damage (including injury or death) suffered by any company or person whomsoever as a result of or in connection with the use, application or implementation of any DEP, combination of DEPs or any part thereof, even if it is wholly or partly caused by negligence on the part of Shell GSI or other Shell Company. The benefit of this disclaimer shall inure in all respects to Shell GSI and/or any Shell Company, or companies affiliated to these companies, that may issue DEPs or advise or require the use of DEPs. Without prejudice to any specific terms in respect of confidentiality under relevant contractual arrangements, DEPs shall not, without the prior written consent of Shell GSI, be disclosed by users to any company or person whomsoever and the DEPs shall be used exclusively for the purpose for which they have been provided to the user. They shall be returned after use, including any copies which shall only be made by users with the express prior written consent of Shell GSI. The copyright of DEPs vests in Shell Group of companies. Users shall arrange for DEPs to be held in safe custody and Shell GSI may at any time require information satisfactory to them in order to ascertain how users implement this requirement. All administrative queries should be directed to the DEP Administrator in Shell GSI.



TABLE OF CONTENTS 1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7

INTRODUCTION ........................................................................................................5 SCOPE........................................................................................................................5 DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS .........5 DEFINITIONS .............................................................................................................5 CROSS-REFERENCES .............................................................................................9 SUMMARY OF MAIN CHANGES...............................................................................9 COMMENTS ON THIS DEP .......................................................................................9 DUAL UNITS...............................................................................................................9

2. 2.1 2.2 2.3 2.4 2.5 2.6 2.7

BASIC DESIGN OF A LOADING TERMINAL .........................................................10 GENERAL .................................................................................................................10 PEAK DEMAND........................................................................................................10 LOADING FLOW RATES .........................................................................................10 SIMULTANEOUS LOADING USING TWO OR MORE ARMS/HOSES ...................13 CALCULATION OF NUMBER OF LOADING BAYS ................................................13 ALLOCATION OF LOADING ARMS TO BAYS........................................................14 PUMP CAPACITIES .................................................................................................14

3. 3.1 3.2 3.3 3.4 3.5

ROAD VEHICLE LOADING SYSTEMS...................................................................15 INTRODUCTION ......................................................................................................15 TYPICAL FLOW DIAGRAMS ...................................................................................15 THE CHOICE BETWEEN TOP AND BOTTOM LOADING ......................................15 BOTTOM LOADING ARMS/HOSES AND COUPLINGS .........................................16 TOP LOADING ARMS ..............................................................................................17

4. 4.1 4.2 4.3 4.4 4.5 4.6 4.7

FLOW CONTROL AND INTERLOCKS ...................................................................19 FLOW CONTROL SYSTEM .....................................................................................19 PUMP CONTROL SYSTEM .....................................................................................19 FLOW MEASUREMENT...........................................................................................19 CONTROL VALVES .................................................................................................21 OVERSPILL PROTECTION SYSTEM .....................................................................22 BONDING INTERLOCK............................................................................................23 INTERLOCK SYSTEM..............................................................................................23

5. 5.1 5.2

AUTOMATION..........................................................................................................24 ADVANTAGES OF AUTOMATION ..........................................................................24 ASSESSMENT OF FUNCTIONAL REQUIREMENTS .............................................24

6. 6.2 6.3 6.4

ADDITIVE INJECTION .............................................................................................25 DOSING LOCATION ................................................................................................25 GENERAL DESIGN GUIDELINES ...........................................................................25 GANTRY ADDITIVE INJECTION SYSTEM .............................................................25

7. 7.1 7.2 7.3 7.4

VAPOUR EMISSION CONTROLS...........................................................................27 APPLICATION OF VAPOUR EMISSION CONTROLS ............................................27 VAPOUR COLLECTION SYSTEM ...........................................................................27 VAPOUR RECOVERY UNITS..................................................................................27 FIRE AND EXPLOSION PROTECTION...................................................................28

8 8.1 8.2 8.3

LOADING TERMINAL DESIGN ...............................................................................29 LOADING TERMINAL LAYOUT ...............................................................................29 LOADING ISLAND/ BAY LAYOUT AND DESIGN ...................................................30 GANTRY DESIGN ....................................................................................................31

9 9.1 9.2 9.3 9.4 9.5 9.6

MISCELLANEOUS...................................................................................................32 EMERGENCY AND FIRE PROTECTION ................................................................32 PIPING ......................................................................................................................33 LOADING PUMPS ....................................................................................................34 ELECTRICAL REQUIREMENTS, EARTHING AND BONDING ..............................34 ILLUMINATION.........................................................................................................36 PAINTING .................................................................................................................36


DEP 31.06.11.11-Gen. February 2011 Page 4 9.7 9.8

DRAINAGE AND PAVEMENT..................................................................................37 PRODUCT WATER DETECTION ............................................................................37

10.

REFERENCES .........................................................................................................38 APPENDICES

APPENDIX A

PLASTIC MATERIALS ....................................................................................41

APPENDIX B

FIGURES.........................................................................................................42


DEP 31.06.11.11-Gen. February 2011 Page 5 1.

INTRODUCTION

1.1

SCOPE This DEP specifies requirements and gives recommendations for the design of loading facilities for bulk road vehicles for common white and black oil products. Today, these fuels may contain considerable amounts of bio components (specifically blends of gasoline with ethanol, and blends of Automotive Gas Oil (AGO) with FAME (Fatty Acid Methyl Esters)). This DEP may also be applied to other hydrocarbon and chemical products such as bitumen and solvents, however, the Principal should be consulted for such applications. This DEP clarifies the design issues and describes the hardware required but it does not cover detailed design or engineering. This DEP contains mandatory requirements to mitigate process safety risks in accordance with Design Engineering Manual DEM 1 – Application of Technical Standards. This is a revision of the DEP of the same number dated January 2010; see (1.5) regarding the changes.

1.2

DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS Unless otherwise authorised by Shell GSI, the distribution of this DEP is confined to Shell companies and, where necessary, to Contractors and Manufacturers/Suppliers nominated by them. Any authorised access to DEPs does not for that reason constitute an authorization to any documents, data or information to which the DEPs may refer. This DEP is intended for use in facilities related to oil refineries, chemical plants, gas plants, exploration and production facilities and supply/distribution installations. This DEP may also be applied in other similar facilities. When DEPs are applied, a Management of Change (MOC) process should be implemented; this is of particular importance when existing facilities are to be modified. If national and/or local regulations exist in which some of the requirements could be more stringent than in this DEP, the Contractor shall determine by careful scrutiny which of the requirements are the more stringent and which combination of requirements will be acceptable with regards to the safety, environmental, economic and legal aspects. In all cases the Contractor shall inform the Principal of any deviation from the requirements of this DEP which is considered to be necessary in order to comply with national and/or local regulations. The Principal may then negotiate with the Authorities concerned, the objective being to obtain agreement to follow this DEP as closely as possible.

1.3

DEFINITIONS

1.3.1

General definitions The Contractor is the party that carries out all or part of the design, engineering, procurement, construction, commissioning or management of a project or operation of a facility. The Principal may undertake all or part of the duties of the Contractor. The Manufacturer/Supplier is the party that manufactures or supplies equipment and services to perform the duties specified by the Contractor. The Principal is the party that initiates the project and ultimately pays for it. The Principal may also include an agent or consultant authorised to act for, and on behalf of, the Principal. The word shall indicates a requirement. The capitalised term SHALL [PS] indicates a process safety requirement. The word should indicates a recommendation.


DEP 31.06.11.11-Gen. February 2011 Page 6 1.3.2

Specific definitions Term

Definition

air eliminator

A device installed in a petroleum piping system to separate free vapour to a specified level from a flowing product stream, and discharge the separated vapour either automatically or by manual venting

bay

(1)

area at each side of a top-loading gantry at which road vehicles can be filled at both sides.

(2)

area alongside the island of a bottom-loading facility.

bio component

biofuel component (in liquid form) derived from organic materials. Ethanol and FAME (Fatty Acid Methyl Ester) are examples of bio components

biodiesel

diesel fuel derived from vegetable oil or animal fat consisting of longchain alkyl (methyl, propyl or ethyl) esters

biofuel

a blend of main fuel grade (typically gasoline or diesel fuel) with a bio component.

bonding

the connecting together of metal parts to ensure electrical continuity

bottom-loading envelope

the positioning of road vehicle adapter connections as recommended by API RP 1004

bulk road vehicle

a tank or other container mounted on a road-going chassis that is towed or self-propelled and capable of carrying petroleum products in bulk NOTE:

Class I, II, or III petroleum products

For road transport vehicle specifications, reference should be made to national standards.

the method by which petroleum products and biofuels are classified for storage and handling by their flash point temperature, in accordance with IP-Part 2, as follows: Class I products have a flash point below 21°C (70°F); Class II products have a flash point between 21°C (70°F) and 55°C (131°F) inclusive; Class III products have a flash point above 55°C (131°F) - refer to IPPart 2.

common black oil products

class III oil products such as heavy fuel oils and residual fuel oils

common white oil products

gasolines, kerosenes, gasoils and distillates of oil products with a viscosity (unheated) of less than 20 mm2/s (20 cSt) and a Final Boiling Point (FBP) of less than 385°C (725°F) (e.g. white spirits, toluene).

NOTE:

NOTES

This excludes bitumen and contaminated products (e.g. products with free water, particle matter, H2S).

This excludes: 1. contaminated products, e.g. with free water, particulate matter H2S; 2. products with true vapour pressures above 0.86 bar (12.5 psi), e.g. LPG, pentanes; 3. very toxic substances (see DEP 01.00.01.30-Gen); 4. chemicals, e.g. ketones, alcohols, ethers, MTBE.

denatured ethanol

ethanol that has been rendered unfit for human consumption (often by adding unleaded gasoline).


DEP 31.06.11.11-Gen. February 2011 Page 7 Term

Definition

ethanol

Ethyl alcohol made primarily from corn, various other grains and non grain feedstock. Ethanol comes in hydrous and anhydrous form. Anhydrous is the most pure type and is preferred for blending.

FAME – fatty acid methyl ester

FAME is an acronym for Fatty Acid Methyl Ester, the most common type of biodiesel produced from natural oil. The natural oils react with methanol and form the FAME. The type of FAME depends on the type of natural oil used (rapeseed, soy, tallow etc).

flame arrestor

device used in gas vent lines to prevent the passage of flames into enclosed spaces

foot valve

valve fitted at the outlet of a road vehicle tank compartment and sometimes referred to as an emergency valve or bottom outlet valve

gantry

structure associated with a product supply system and provided with all equipment necessary for loading, and providing safe access to, road vehicles

hose loader assembly

system consisting of pipe, swivel and hose connection for bottom loading

loading area

area comprising all filling islands and bays but excluding vehicle waiting areas.

loading arm

system of pipes and swivels, balanced for easy movement, through which product is transferred from the supply pipe into a road vehicle tank

loading island

area on which the equipment necessary to load a vehicle is mounted, e.g. meters, control valve, loading arms, hose loaders, control equipment etc. NOTE:

Islands can be designed for multi-product or single product loading

loading terminal or facilities

combination of one or more loading bays or gantries, including additional facilities such as parking areas, waiting lanes, dispatch office, social amenities, and the product and utilities supply piping, from the point at which the piping enters the loading area

meter pre-set control

device or system which controls the quantity of incoming product loaded into a compartment of a road vehicle, sometimes called primary level control. This may be manual or electronic

neat biofuels

is the term used for pure biofuels (before any mixing with main grade fuels, such as gasoline or diesel, has taken place)

neat ethanol

is the term used for pure alcohol

occupancy ratio

proportion of any particular period for which the loading bay is in use for the loading of bulk road vehicles

overfill protection

system installed in addition to the meter pre-set control and designed to cut off flow if the product rises above a predetermined level in the compartment of the bulk road vehicle being filled. The equipment comprises sensors in the form of thermistors, opto electronic or floatcontrolled reed switches, solenoid or air-operated flow-control valves, etc.

static electricity

electric charge on a non-conductor or poor conductor, often caused by mechanical friction (e.g. product flow in a pipe)

ullage

depth of free space left in a tank above the liquid

vapour

one or more of the components of petroleum when in the vapour phase



1.3.3

Term

Definition

vent

device for the release of hydrocarbon vapour or air from pipes, tanks, or fittings, and for the entry of air

vent lines

piping system for the transfer of hydrocarbon vapour or air to or from pipes, tanks, or pipe fittings, e.g. air eliminators

working platform

area of the gantry structure from which the person loading the vehicle from the top operates the meters, loading arms etc., and from which access is gained to the top of the tank of the bulk road vehicles

Abbreviations ADR

Accord Dangereux Routier

AFFF

Aqueous Film Forming Foam

AGO

Automotive Gas Oil

AR

Alcohol Resistant

BOL

Bill of Lading

Bxx

FAME mixed with diesel or AGO (xx indicates the percentage of FAME)

COPS

Cross Over Protection System

CROSS

Customisable Routing and Scheduling System (for Road Transport)

EPA

Environmental Protection Agency

ERP

Enterprise Resource Planning

ESD

Emergency Shut Down

Exx

Ethanol mixed with gasoline (xx indicates the percentage of Ethanol)

FAME

Fatty Acid Methyl Ester

IGO

Industrial Gas Oil

JDE

Enterprise Resource Planning System

MTBE

Methyl Tertiary Butyl Ether

NRV

Non-Return Valve

OEL

Occupational Exposure Limit

PD

Positive Displacement

pS/m

Pico Siemens per meter

ppm

parts per million

PVC

Poly Vinyl Chloride

SAP

Shell Standard Enterprise Resource Planning System

SDA

Static Dissipator Additive

STEL

Short Term Exposure Limit

SWA

Steel Wire Armoured

TMS

Transportation Management System

VFD

Variable Frequency Drive

VOC

Volatile Organic Compound

VRU

Vapour Recovery Unit

XLPE

Cross Linked Polyethylene


DEP 31.06.11.11-Gen. February 2011 Page 9 1.4

CROSS-REFERENCES Where cross-references to other parts of this DEP are made, the referenced section number is shown in brackets. Other documents referenced by this DEP are listed in (10).

1.5

SUMMARY OF MAIN CHANGES This DEP is a revision of the DEP of the same number dated January 2010. The following are the main, non-editorial changes.

1.6

Old section

New section

Change

General

General

Split of document in 2 parts. In DEP Spec which contains all mandatory requirements and in DEP Inf, its companion tha contains additional supporting information.

General

Gerneral

Process safety requirements have been indicated by the use of the capitalised term "SHALL [PS]"

COMMENTS ON THIS DEP Comments on this DEP may be sent to the Administrator at [email protected], using the DEP Feedback Form. The DEP Feedback Form can be found on the main page of “DEPs on the Web”, available through the Global Technical Standards web portal http://sww.shell.com/standards and on the main page of the DEPs DVD-ROM.

1.7

DUAL UNITS

Amended per Circular 83/11 Dual units have been incorporated throughout this DEP.

This DEP contains both the International System (SI) units, as well as the corresponding US Customary (USC) units, which are given following the SI units in brackets. When agreed by the Principal, the indicated USC values/units may be used.



BASIC DESIGN OF A LOADING TERMINAL

2.1

GENERAL In the design of a loading terminal, the total cost of loading vehicles should be minimised. The costs of the loading terminal include: •

capital charges for the loading facilities (e.g. gantry, structures, pumps, lines, automation system, VRU etc.).

•

manpower costs for the administration and surveillance of the loading activities.

•

maintenance costs of the loading facilities.

The above costs should be balanced against: •

the cost of vehicle time while “in the yard”, queuing for a loading bay, occupying the loading bay and exiting the terminal.

Wherever possible, for products lighter than diesel fuel, Bottom Loading configurations shall be used for all new gantry development works including refurbishment to achieve maximum possible loading efficiency and truck utilisation, reduce group HSSE risks by improving occupational health and minimise VOC emissions to the environment. Top loading shall only be used when bottom-loading alternatives are not available and only after carrying out an HSE risk assessment of the operations. Approved fall protections systems shall be installed and used as designed. 2.1.1

Biofuels When introducing neat biofuels, or fuels containing biofuels, into a Terminal, there are several issues that shall be checked at the design stage, such as: product contamination; materials compatibility with piping, pump seals and vapour recovery units; reduction of conductivity with certain mixtures of FAME; product classification; type of fire fighting systems and foam required; and spill containment facilities to deal with ethanol mixtures. Usually conventional slops are fed back to refinery for reprocessing. Slops containing Ethanol, FAME, MTBE, ETBE etc. shall not be fed back to the refinery and should be treated differently than conventional slops (eg. incineration). The terminal shall implement a proper Slops Management System for oxigenized products. At terminals, any contamination of Jet Fuels with FAME (or with diesel containing FAME) shall be avoided to ensure that the average level of FAME in a batch of jet fuel is below the maximum level as specified in DEFSTAN91-91 for Jet A-1. FAME shall be handled using procedures that do not allow the temperature to drop below 6°C above the FAME’s cloud point to avoid formation of solids that can cause blockages of fuel lines and filters. In areas of cold climate, depots should consider whether heating of transfer lines is necessary to maintain the temperature at the correct level.

2.2

PEAK DEMAND Any loading facility should be designed to meet the forecast loading demand during peak periods. A statistical analysis of historical figures should be the starting point, but the effects of planned improvements in methods and loading equipment and any changes likely to occur in working hours, shift patterns, vehicle sizes and types, variations in demand growth of different products, requirements for additional or fewer grades etc., shall be taken into account.

2.3

LOADING FLOW RATES

2.3.1

Determination of loading flow rate Flow rates are restricted by the economic size of pumps, piping and measuring equipment or by the hazard of static electricity, (see 2.3.2).


DEP 31.06.11.11-Gen. February 2011 Page 11 High loading flow rates reduce the time spent by a vehicle at a loading gantry, resulting in the following: (i)

a reduction in vehicle idle time, i.e. standing charges;

(ii)

a reduction in the bay occupancy time, which could reduce the total number of required loading bays.

On the other hand, the additional costs of pumps, larger bore piping, loading arms, flow meters and other equipment, together with increased energy consumption, shall also be taken into account. For bottom loading, a 4-inch system should be employed (see 3.4.1). 2.3.2

Maximum flow rates of uncontaminated liquids due to static electricity hazards If a flammable atmosphere may be present (e.g. when loading flammable products and/or when switch loading is applied), the loading velocities SHALL [PS] be determined using the flowchart in (2.3.3). Before loading, if a flammable atmosphere may be present, the following are the key issues to be taken into account when using the flowchart in (2.3.3) to determine the safe loading speed. 1)

Determine whether a flammable atmosphere could occur

2)

Classify the product conductivity (≤ 50 pS/m, > 50 pS/m or unknown) (≤ 50 micromhos/cm, > 50 micromhos/cm or unknown)

3)

Classify the product sulphur content (≤ 50 mg/kg, > 50 mg/kg) (≤ 50 ppmw, > 50 ppmw)

4)

Detemine whether the vehicle / tanker is suitable for high speed loading

There are High Speed Loading vehicles / tankers that allow for higher loading rates and are designed to meet certain specific requirements. If a vehicle/tanker is to be classed as suitable for high speed loading, then all compartments on that vehicle SHALL [PS] be high speed loading compartments.



Flowchart for determining the maximum safe loading velocity for road tankers Flammable atm possible in compartments?

No

Yes

Gasoline (or other over- rich)

Yes

No

Middle distillate?

=<10 pS/ m or unknown

Yes

Conductivity?

>50 pS/m

>10 pS/m No

S content?

S content ?

>=50 mg/kg

<50 mg/kg

>=50 mg/kg

<50 mg/kg

H igh speed loading vehicle?

High speed loading vehicle?

No

Yes

vd<0.25, v<7?

vd<0.35, v<7?

No

vd<0.5, v<7?

vd<0.38, v<7?

Yes

Yes

No

Yes

No

Reduce loading speed till vd<0. 25, v<7

Yes

Reduce loading speed till vd<0.35, v<7

O K to load

Yes

No

No

Reduc e loading speed till vd<0.38, v<7

OK to load

Reduce loading speed till vd<0.5, v<7

OK to load

O K to load

v is the velocity in m/s and d is the internal pipe diameter in metres, and the variable (vd) is the velocity times the internal pipe diameter expressed. The variable vd is expressed in m2/s. Flow limits a)

With a possible flammable atmosphere, conductivity ≤ 10 pS/m (10 micromhos/cm) or unknown, middle distillate with a sulphur content ≤50 mg/kg (≤50 ppmw) and I.

a non-high-speed-loading vehicle, loading speed SHALL [PS] give vd ≤ 0.25 m2/s (≤ 2.7 ft2/s); (max. 1200 L/min (11 ft3/min) with standard 10 cm (4 in) pipework).

II.

a high-speed loading vehicle, loading speed SHALL [PS] give vd ≤ 0.35 m2/s (≤ 3.8 ft2/s) (max. 1650 L/min (58 ft3/min) with standard 10 cm (4 in) pipework).


DEP 31.06.11.11-Gen. February 2011 Page 13 b)

With a possible flammable atmosphere and: I.

conductivity between 10 and 50 pS/m (10 and 50 micromhos/cm) and middle distillate with a sulphur content ≤50 mg/kg (≤50 ppmw); or

II.

conductivity ≤10 pS/m (≤10 micromhos/cm) and sulphur content >50 mg/kg (>50 ppmw) or product other than middle distillate loading speed SHALL [PS] give vd ≤ 0.38 m2/s (≤ 4.1 ft2/s) (max. 1800 L/min (64 ft3/min) with standard 10 cm (4 in) pipework).

c)

With: I.

no flammable atmosphere; or

II.

loading gasoline or other liquid that produces an over-rich atmosphere; or

III.

a possible flammable atmosphere; and i.

conductivity > 50 pS/m (< 50 micromhos/cm) or

ii.

conductivity between 10 pS/m and 50 pS/m and sulphur content >50 mg/kg (> 50 ppmw) or non-middle distillate product or

iii.

conductivity ≤10 pS/m and sulphur content >50 mg/kg (>50 ppmw) or non middle distillate product and high speed loading vehicle

loading speed SHALL [PS] give vd ≤ 0.5 m2/s (≤ 5.4 ft2/s) (max. 2400 L/min (85 ft3/min) with standard 10 cm (4 in) pipework). Diameter d should normally be the diameter of the smallest section upstream of the tank being filled, but if the smallest section is less than 10 m (33 ft) long and has a diameter of at least 67 % of the next smallest section, the diameter of the next smallest section may be taken. This commonly allows the use of 3 inch meters (10 in ft) in DN 100 (NPS 4) bottom loading systems, where vd>0.5 m2/s (5.4 ft2/s), but pipe length is limited to around 2 m (6 ft) where flow conditioning straighteners are used. If contaminated non-conductive liquids are loaded, the loading velocity should be limited to 1 m/s (3 ft/s). For liquids with a conductivity of more than 50 pS/m (50 micromhos/cm), no loading velocity restrictions apply for static electricity reasons, but the loading velocity should still be limited to 7 m/s (23 ft/s). 2.4

SIMULTANEOUS LOADING USING TWO OR MORE ARMS/HOSES For top loading, the simultaneous use of two or more arms will result in the need for additional equipment to prevent overfilling which may otherwise not be necessary (see 4.5.1). The cost and other operational consequences (HSSE) arising from such equipment shall be taken into account in the economic comparison but this is not a recommended configuration for products lighter than diesel fuel.

2.5

CALCULATION OF NUMBER OF LOADING BAYS

2.5.1

General Depending on local circumstances the design of loading facilities should distinguish between two design concepts as detailed below:

2.5.2

(i)

the 'morning peak period' design concept,

(ii)

the 'waiting time' design concept.

The 'morning peak period' design concept The demand in this 'peak period' has a considerable effect on the size of the final arrangement and hence shall be ascertained by consulting local staff. If all waiting vehicles have to be loaded in one hour (resulting in an average waiting time of half an hour for those vehicles which cannot be served at once), the loading facility will be twice as large as one


DEP 31.06.11.11-Gen. February 2011 Page 14 where all the vehicles have to be loaded in two hours (resulting in an average waiting time of one hour for those vehicles which cannot be served immediately). 2.5.3

The 'waiting time' design concept If the arrival of vehicles is irregular, the design procedure should be based on a specified maximum average waiting time per vehicle. Such is the case, for example, in terminals operating 24 hours per day, or in terminals which try to spread the working load as evenly as possible over the working day.

2.5.4

Manual estimation of the number of loading bays required The first step is the calculation of the 'peak period' demand; this is defined as follows for each method:

2.6

•

in the 'morning peak period' method, the peak period demand is the offtake by those vehicles which queue outside the gate and which shall be loaded in the first morning period (one or more hours).

•

in the 'waiting time' design method, the peak period demand is defined as the offtake during (any) one hour in a period, which has the highest vehicle arrival frequency. This period may be longer than one hour and can occur on more than one occasion in any one day.

ALLOCATION OF LOADING ARMS TO BAYS For operational reasons, it is desirable to limit the number of loading arms at one gantry/loading bay to six. Allocation of loading arms should take into consideration the combination of products each tanker will carry so that tankers do not have to move from one bay to another during loading. Also, the product-grouping requirement (see 8.1.5) shall be taken in account. The accommodation of more than 6 arms may be considered where product loading grouping and speciality products require single load arms. Special consideration then should be paid to access, loading envelope and drainage requirements.

2.7

PUMP CAPACITIES

2.7.1

Single loading arm If only one product loading arm or hose is allocated for any product, a single pump rated for the maximum design flow rate of the loading system (meters, piping, loading arm/hose) should be provided.

2.7.2

Two loading arms If two product loading arms/hoses are allocated for any product, a single pump rated for the maximum design flow rate of the loading systems for two arms/hoses, operating together, should be provided.

2.7.3

More than two loading arms per product If more than two loading arms/hoses are allocated for any product, as a means of optimising pump numbers and sizes, a reduced total pumping capacity may be provided to allow for the time when vehicles occupy a loading bay but product is being loaded slowly or not at all, i.e. at the beginning or end of the filling cycle. By reducing the pumping capacity, the VRU and pipe work capacity may also be reduced.



ROAD VEHICLE LOADING SYSTEMS

3.1

INTRODUCTION Wherever possible, for products with a flash point lower than diesel fuel, Bottom Loading configurations shall be used for all new gantry development works including refurbishment. This Section describes the choice between the two systems and the construction details of the loading arms/hoses including the provisions for vapour collection. Typical flow schemes are also presented.

3.2

TYPICAL FLOW DIAGRAMS Figures 3.1a and 3.1b give a typical flow diagram of a bottom loading installation. A fully equipped automatic system includes the following main elements: a)

loading pump: pumps the product to the gantry to one or more loading arms (see 9.3); b) emergency Shut Down (ESD) system and (optional) ESD valve: to isolate the loading system rapidly in an emergency (see 4.4.4); c) air eliminators: to eliminate air from the product if there is an operational need or required by regulations. (see 4.3.7); d) a filter or strainer: to ensure product cleanliness and to protect the flow meter and couplings (see 4.3.6); e) additive injection system (see 6.); f) flow meter (see 4.4); g) flow control valve: to control the flow (see 4.4); h) loading arm connected to a dry-break coupling (see 3.4); i) vapour return hose to VRU or to move vapours to a low risk location without receptors. (see 3.4); j) overfill protection sensor: to give a signal if the road vehicle is overfilled (see 4.5); k) bonding connection (combined with overfill protection connection): to discharge static electricity generated during loading (see 4.6); l) interlock system: to prevent loading unless all conditions for safe operation are fulfilled (earth connected, no overfill, vapour return hose connected etc.) (see 4.7); m) isolation valves: to make maintenance possible and to stop the product flow in emergencies (see 9.2.9); n) drains and vents: to empty the system in case of maintenance (see 9.2.6); o) meter prover connections: to connect a meter prover flow meter (see 4.3.5); p) relief valves: to protect the system against overpressure, especially against thermal expansion (see 9.2.10); q) temperature sensors for volume correction (see 4.3.2); r) pressure point: to enable the connection of a pressure gauge (see 4.3.5) The flow scheme of a top loading facility is similar, apart from the loading arm and the "dead man" valve, see Figure B.1c. Figures 3.2, 3.3 and 3.4 clarify the special symbols used for bulk road loading vehicle flow schemes. 3.3

THE CHOICE BETWEEN TOP AND BOTTOM LOADING For products lighter than diesel fuel, bottom loading configurations should be used for all new gantry development works including refurbishment to achieve maximum possible loading efficiency and truck utilisation, reduce group HSSE risks by improving occupational health and minimise VOC emissions to the environment.


DEP 31.06.11.11-Gen. February 2011 Page 16 Top loading shall only be used for black oil products and heated oils in combination with a dedicated vehicle fleet. In case of switch-loading, vapour collection and treatment shall be installed, see also 7.3.1. A HSE risk assessment should be performed of the operations including but not limited to: •

OELs (Occupational Exposure Limits)

•

working at heights

•

manual handling

•

escape routes

Approved fall protections systems shall be installed and used as designed. Preffered fall protections are adequate posisionned guard rails. Ropes (life lines) should be used in case existing guard rails would not offer sufficient protection against falling. Bottom loading should be employed for solvents and common white oil products. If changing over to bottom loading is considered, the following costs should be taken into consideration: a)

vehicle conversion costs,

b)

vehicle recalibration costs (see 3.4.3),

c)

gantry conversion costs (bottom loading is a one-sided operation).

Top loading may be employed for the loading of black oil and heated products and for locations where operating conditions would not allow any alternative. This should be based solely on economics taking into account health/safety and future legislative requirements (Fuel Oils can be loaded via bottom fill gantries). 3.4

BOTTOM LOADING ARMS/HOSES AND COUPLINGS

3.4.1

Couplings Liquid and vapour shear or break away couplings for loading systems and vehicles should be in accordance with API RP 1004 (or equivalent). No widely accepted standards for nominal DN 80 (NPS 3) loading couplings are yet available. If couplings of nominal DN 80 (NPS 3) size have to be used, similar provisions to those described in API RP 1004 should be applied. Although operational reasons may justify the DN 80 (NPS 3) size system, the DN 100 (NPS 4) API system is generally preferred due to its higher loading rates and wide acceptance.

3.4.2

Couplings for aviation products All aviation product grades should, wherever possible, be bottom loaded into dedicated single product vehicles equipped with product-selective couplers. Selective couplings SHALL [PS] not only provide selectivity between all aviation grades, but also prevent connection to non-selective couplings at the loading facilities. Where this is not possible, the provisions of the Shell Aviation Quality Control Manual SHALL [PS] be followed.

3.4.4

Loading arms and hoses Bottom loading systems use either swivelling piping systems or a flexible hose system, or combinations of both, to make the filling connection and the vapour return connection between the bay and the vehicle. A flexible hose is too heavy to handle by hand in any size over DN 80 (NPS 3) when full of product, and even in DN 80 (NPS 3) size the hose should be suspended or supported as much as possible to allow easier handling. Consequently it is a non-preferred solution and shall be avoided wherever possible. If hoses are used these should contain a bonding wire connected to each hose end’s connection fittings for continuity.


DEP 31.06.11.11-Gen. February 2011 Page 17 Regardless of which type of loading arm is used, all arms/hoses etc. should be electrically conductive with a resistance less than 10 Ω . 3.4.5

Coupling location and reach of loading arms/hoses The loading system should be designed so that connections can be readily made for multicompartment loading, with the liquid and vapour adapters being situated within loading envelopes based on national or international standards.

3.4.7

Provisions for vapour collection Whether or not vapour collection is required by local regulations, new/modified loading facilities and new bulk vehicles shall be designed to allow for the collection of vapour. Collected vapour should be vented to a safe location if a vapour recovery unit is not yet available. When bottom loading, vapours SHALL [PS] be directed away from the immediate loading area to ensure persons operating/loading are not exposed to vapours though a simple vapour collection and dispersion system. This is vented in a safe area away from normal operations, buildings etc, or high enough to effect adequate dispersion. When the terminal is operating at peak throughput, the loading gantry vapour collection system, including the vapour recovery unit, shall not generate a counter pressure at the vehicle side of the vapour collection adapter in excess of 55 mbar (0.8 psi). Bulk road vehicles are normally not designed as pressure vessels and therefore they are not built to withstand the maximum discharge pressure of loading pumps that may arise in the event of a failure of the overfill shutdown system or blockage of the vapour return line. Each compartment SHALL [PS] therefore be fitted with a liquid relief system, capable of handling the maximum loading flow rate, so that the compartment cannot be pressurised beyond its normal working pressure. This is normally achieved by fitting a manlid, which lifts against a spring once a pre-set pressure is exceeded. The vapour collection system fitted to the vehicle is often the limiting factor to the number of loading arms that can be connected to a vehicle at any one time during bottom loading operations. Reference shall be made to the Manufacture’s nameplate fitted to the vehicle for details of the flow limits.

3.5

TOP LOADING ARMS Although use of top loading is discouraged, the following shall apply for cases where top loading is the only feasible option.

3.5.1

Loading arms A wide variety of loading arm configurations is available. The main points governing selection are: a)

operation on one or both sides of the loading platform,

b)

loading of single or multiple product vehicles,

c)

loading rates,

d)

reach (design envelope) of the loading arm,

e)

accessories,

f)

whether vapour collection is required.

The two main types of loading arms that should be employed are: a)

Articulated or Scissor type arms

b)

Boom type arms

Provisions should be made to secure the arms during loading. When loading any volatile product, the operator shall load from the platform and not while standing on the truck top.


DEP 31.06.11.11-Gen. February 2011 Page 18 The use of loading arms at both bays of a loading gantry SHALL [PS] be allowed for in any automatic interlocking earthing systems. 3.5.2

Provisions to minimise product loss and static electricity build up To prevent evaporation and the generation of static electricity due to splashing during loading of Class I and Class II products, the loading arm or filling pipe SHALL [PS] be long enough to reach the bottom of the tank compartment to be filled. The loading arm should be provided with a T deflector at its lower end to divert flow from the vertical to the horizontal. The deflector should direct the flow to at least two opposite sides. For Class III products, a straight filling pipe or drop tube of shorter length may be considered (to minimise clingage and drips) only if these products are loaded into dedicated vehicles. When switch loading is required, the normal Class I/II type load arm SHALL [PS] be used. A drip bucket shall be provided for each loading arm to collect drips when the arm is stowed after use; these products should be sent to slops. Loading arms should be installed so that the contents of the arm downstream of the manual shut off-valve will drain into the filled tank compartment prior to stowing the arm. This may entail raising the height of the pedestal base flange and the use of vacuum breaker valves on the top of the load arms.

3.5.3

Provisions for vapour collection Where vapour collection is not yet required by regulations, new and/or modified top loading loading facilities and new bulk loading vehicles should be designed for the appropriate equipment so that they may be easily converted at a later stage. Bulk road vehicles are normally not designed as pressure vessels and therefore are not built to withstand the maximum discharge pressure of loading pumps that may arise in the event of a failure of the overfill shutdown system or blockage in the vapour line. Each compartment SHALL [PS] therefore be fitted with a liquid relief system capable of handling the maximum loading flow rate so that the compartment cannot be pressurised beyond its normal working pressure. There are 3 types of collector arrangements, see a) to c) in section 3.5.5. of the informative DEP companion. For the vapour collection arrangements (a) and (b) this can be achieved by a pressure relief arrangement which releases the manhole seal at typically 0.3 barg (4.4 pisg). For option (c) this can be achieved by fitting a man lid that lifts against a spring once a pre-set pressure is exceeded. For top loading with vapour collection, overfill protection is required as described in (4.5). If no vapour collection systems are used for top loading, measures shall be taken to avoid OELs being exceeded (e.g. for benzene or toluene).



FLOW CONTROL AND INTERLOCKS

4.1

FLOW CONTROL SYSTEM The product flow should only be enabled when all safety interlock conditions have been satisfied. The interlock system is described in (4.6). The flow control system should start the loading operation with a loading rate substantially lower than the normal high flow rate of the loading system to avoid generating static charges that could result in an electrostatic ignition. The system should be regulated in such a way that the high flow rate is only achieved when the loading arm or deflector has been completely submerged. This will prevent splashing. This can be achieved by using a system with a two-stage flow control, with a low flow and a high normal flow. As all other components of the liquid handeling system, the flow control system SHALL [PS] be electrically connected to the loading system structure with an electrical contact resistance of less than 10Ω. At the end of the loading cycle when the required loading quantity is almost reached, say the last 150 L (5 ft3) or 200 L (7 ft3), the flow control system should reduce the loading rate (typically to 10 % of max. flow). This will ensure that the pre-set quantity will be loaded with the required precision (normally within 3 L (0.1 ft3) or 4 L (0.15 ft3)). This can be achieved, as during start-up, by a two-stage flow control. The flow control system SHALL [PS] be capable of stopping the flow in an emergency within a minimum of time, considering allowed surge pressure calculation for exsiting pipeline (pipeclass).

4.2

PUMP CONTROL SYSTEM The pump control system SHALL [PS] be interlocked with the ESD system whereby gantry loading pumps will stop when an emergency switch or a fire/gas alarm is activated. Pressure transmitters installed on product lines intended for use in controlling load rack flow rates should not be installed / located in the end cap or within a dead leg of the product line.

4.3

FLOW MEASUREMENT

4.3.1

Product temperature measurement For this measurement Platinum Resistance Elements accurate to ±0.2°C (± 0.35°F) shall be used, inserted in a stainless steel thermowell. RTD (Resistance Temperature Detectors) Thermowells shall be installed into the center 1/3 of the way into the pipe and filled with a heat conducting fluid. A test thermowell should be installed in the same manner and adjacent to the RTD/Thermowell for RTD verification purposes. Coriolis meters are often provided with a contact RTD measuring the meters tubes external temperature. Use of such an RTD without a thermowell for temperature correction volumes is not acceptable.

4.3.2

Product Pressure Measurement Pressure gauges used for pipe/small volume prover operation or pressure transmitters used for BOL (Bill of Lading) net calculations, shall be located directly upstream of the flow control valve.

4.3.3

Custody transfer requirements Flow meters used at the points of sales (i.e. where custody transfer takes place) shall be approved for use by the local Weights and Measures Authority. Flow meters used for custody transfer may require sealing. When turbine meters are installed, care shall be taken to assure the proper flow conditioning is achieved for proper meter operation and accuracy.

4.3.4

Meter proving Meters, particularly those used for custody transfer, should be proved periodically to determine whether the indicated quantity in relation to actual quantity has changed as result of wear or other factors. Any inaccuracies that have developed can be corrected by adjustment of the calibrating mechanism, or by use of a factor derived from the proving runs.


DEP 31.06.11.11-Gen. February 2011 Page 20 Generally, bulk meters are proved 'in situ' by one of the following methods: 1) volumetric proving tanks; 2) reference “master” meters; 3) mechanical displacement provers including pipe and captive displacers. 4) small volume “loop” provers Methods (1), (2) and (4), using mobile proving equipment, are generally applied to road loading gantry meters, with method (4) being the preferred method. It is essential that a gantry be designed to accommodate and safely operate the proving equipment. This means that suitable connections/stubs with double block and bleed valves, in between should be provided for easy connection. Double block and bleed valves should be located between the two stub connections, not on the stub. For bottom and for top loading applications with appropriate adapters, the proving valves and stubs are not required (i.e., proving is accomplished through the loading arms). Alternatively it shall be possible to correctly position a mobile proving tank in order to achieve easy and safe filling and pump out the contents. The layout of the proving system shall also allow easy and safe access to sight glasses, thermometers, registers and scales for accurate measurement. If a meter prover is installed the following applies: a) The meter prover SHALL [PS] be bonded to the truck and the gantry. b) All prover components SHALL [PS] be electrically connected with a constant resistance of less than 10 Ω. c) The meter prover SHALL [PS] not incorporate a fine filter (< 150 µm) to protect the reference meter although a coarse strainer (> 150µm) is acceptable. This is essential as there will not be an adequate residence time between the meter prover and the truck for the dissipation of any excess charge generated in the prover system. d) Meters should be proved under conditions of temperature, pressure and flow rate closely resembling those of actual operation. This would encompass the usual delivery flow rate into a tank prover. Another acceptable consideration is to prove via pipe prover with the prover return line delivering to the transport truck. Some designs include terminal return lines where, following the proving, the fluid is delivered back to the originating tank. Further information can be found in the API Manual of Petroleum Measurements Standards – Chapter 6 – Metering Assemblies – Section 2 – Loading Rack Metering Systems. e) Meters should be proved with products having a viscosity similar to those for which they are normally used. f) When using proving equipment, there is always a chance of introducing air or vapour into the system. Air or vapour shall be eliminated before proving. g) Since product and proving equipment temperatures and pressures have to be taken into account, thermometers and pressure gauges traceable to the local standards organization shall be used for accurate measurement. h) To ensure proper operating performance, meters should be installed according to manufacturers’ recommendations. Make certain that any areas that may trap or build up with debris are avoided. Avoid installing the meter at high point in the piping to prevent trapping air in pockets and causing problems with equipment and perhaps creating safety issues. i) Standard national or internationally accepted equipment and procedures shall be rigorously adopted. j) In the absence of clear national procedures the guidelines given in the EI Petroleum Measurement Manual Part X (Meter Proving), or Petroleum Measurement Paper Number 4 “Code of Practice for the Proving of loading Gantry Meters” should be followed. Alternatively, API MPMS 4.1, 4.2, 4.4, 4.5, 4.6, 4.8 and 5.6 may be applied.



Filters/Strainers Where fuels are loaded through a micro filter or filter water-separator, the residence time of the liquid in the line between the outlet of the filter and the receiving tank should be sufficient for any exess charge they generate to be dissipied before the fuel reaches the receiving tank. The maximum velocity of the liquid in the line should be determined in accordance with section 2.3.3.

4.4

CONTROL VALVES

4.4.1

Manual product start/stop control valves In traditional top loading a 'deadman control' in the form of a 'hold-open' valve SHALL [PS] be provided. This enables the operator, when filling through an open manhole, to watch the level of the product and to stop the flow immediately in an emergency. The valve-operating lever (or control rod) shall be located so that the operator can see the product in the compartments at high level, while avoiding the vapour plume emitted from the manhole. Where operators operate from the loading platform, rather than the top of the truck (e.g. as a means of reducing exposure to vapour emissions) alternative arrangements featuring electronic deadman systems for use in top loading SHALL [PS] be applied.

4.4.2

Automatic flow control valves In the design of the system the surge pressure due to rapid closure of the control valve SHALL [PS] be taken in account (see 4.4.5).

4.4.3

Flow-limiting valves At non-automated loading gantries, flow-limiting valves SHALL [PS] be fitted on each of the loading arms because pump output is not controlled to match product demand. These valves are used to protect equipment against excessive flow rates, which can occur when only one loading arm out of several delivering similar product is used and more than the required number of pumps are running.

4.4.4

Emergency shutdown (ESD) valve In unmanned terminals or other terminals with increased risks due to spillage (e.g. terminals in built-up residential areas or large terminals) an additional ESD valve SHALL [PS] be included. In the design of the system the surge pressure due to rapid closure of the ESD valve SHALL [PS] be considered (see 4.4.5).

4.4.5

Surge pressure The piping system shall be designed to allow for the maximum surge pressure expected, see DEP 31.38.01.11-Gen. To reduce the maximum surge pressures and thus the design pressure of the pipe system, the following measures shall be considered: •

Slow valve closure Typically shutdown systems closure time shall be minimized. The closing time shall be set considering allowed surge pressure calculation for exsiting pipeline (pipeclass). The valve closing time has an impact on the filling level of the vehicle’s compartment and therefore the compartimet hullage shall be reconsidered in order to avoid spills. See also 4.5.5.

•

Valve characteristic

•

Pressure relief systems

•

Surge pressure alleviator A flanged tee should be installed upstream of the ESD valve, to facilitate installation of an alleviator if surge pressure is found to be a problem.


DEP 31.06.11.11-Gen. February 2011 Page 22 No surge pressure alleviator shall be installed between a PD meter and the control valve, because this will result in extra pulses being generated by the pulse transmitter as the alleviator first absorbs product and then pushes it back down the line. In such cases the alleviator (or 'T' piece) should be installed directly upstream of the PD meter. •

Limiting the liquid velocity Loading systems should be designed to operate at the maximum safe flow limits to avoid build up of electrostatic charges. The design should also contemplate the loading system to withstand an emergency closure surge pressure impact

4.5

OVERSPILL PROTECTION SYSTEM

4.5.1

Necessity of overfill prevention systems For all closed systems where it is not possible to monitor visually the liquid level (i.e. for bottom loading and top loading with vapour collection), an overfill protection system SHALL [PS] be installed.

4.5.2

Overfill protection systems Floaters and displacers SHALL [PS] not be employed for overfill protection. Air reaction systems shall be limited in use to special applications such as liquid sulphur or bitumen.

4.5.3

Ullage of compartments and valve closure time The total elapsed time between the high level signal initiated by the liquid level control sensor and the final closure of the valve SHALL [PS] be such that there is no possibility of a spill over from compartments. However, in order to minimise the shock pressure (surge) in the piping system due to valve closure, it is often necessary to slow down the valve closure, (see 4.4.5). Hence the quantity of product that passes through the valve during the closure period SHALL [PS] be taken into account when setting ullage in vehicle compartments, especially in those with small capacity. The response time of the overpressure protection system is either constrained by pressure surge considerations or by the instrumentation. Where the resulting ullage requirements cannot be met, one or more of the following options shall be explored:”

4.5.4

a)

plan for the elimination of small compartments;

b)

use hydraulic analysis of the loading system to minimise the likelihood of pressure surges. If high pressure surges cannot be avoided, consider fitting flow control valves with 'equal percentage' characteristic to reduce surge pressure;

c)

downrate the compartments of existing vehicles where required by the amount necessary for safe liquid cut-off;

d)

allow for appropriate ullage in the design of new bulk vehicle compartments.

Requirements for design and maintenance of overfill systems Overfill systems, including connectors and connector envelopes, should be designed according to a recognised standard such as the IP “Code of Practice for Bottom Loading, Vapour Collection and Overfill Prevention”. Sensor systems should be fail-safe, i.e. not permitting loading in case of failure. This may be achieved by using self-checking systems. Sensing probes SHALL [PS] be suitable for use in petroleum products and electrical/electronic probes SHALL [PS] be certified safe for operation in Zone 0 when connected to a certified controller. The wiring for the sensing probe system on the vehicle should be both physically and electrically isolated from other vehicle circuits, by the use of dedicated conduits and vehicle boxes.



Consideration for liquid detectors in vapour return lines The VRU system shall be provided with means to collect and drain condensate from low points in the system. The sump shall be equipped with a high-level switch which activates an alarm and the VRU ESD, as well as being fitted with a means to test the operation of the switch and a suitable drainage point. A sight glass should be installed in the sump.

4.6

BONDING INTERLOCK A bonding cable SHALL [PS] be connected to the vehicle before any other operations are carried out (e.g. opening manlids, connecting hoses etc.). The bonding resistance between the vehicle and the gantry SHALL [PS] be less than 10 Ω, and this bonding SHALL [PS] remain in position until all other loading operations have been completed. Loading SHALL [PS] not be permitted by the flow control system/interlock system if the vehicle is not bonded effectively. If an overfill protection system is provided, the overfill protection connection should be combined with the earthing connection. The driveaway traffic light turn green and/or the exit barrier shall only open after the bonding cable has been disconnected. A similar requirement exists for: •

the safe storage of the loading arms, if applied (see 3.4.6);

•

the position of the ramps providing access to the top of the road truck (see 8.3.2.2).

For non-automated loading gantries (e.g. top loading with mechanical pre-set), the bonding cable between the loading facilities and the road car SHALL [PS] be clearly visible and equipped with a status warning light indicating its connection/non-connection to the road car. Further information can be found in: API RP 2003 Protection against ignitions arising out of static, lightning and stray currents and NFPA 30 Flammable and combustibles liquids code. 4.7

INTERLOCK SYSTEM On the vehicle the following interlocks shall be considered: a)

driveaway interlock, e.g. a lift bar normally covers all product connections: when lifted the brakes are applied.

b)

air pressure interlock: a pressure switch contact should be connected to the overfill detection system, so that a loss of vehicle air pressure will cause the gantry loading valve to be closed.

c)

vapour vent interlocks: the vapour vent valves which connect each compartment to the vapour collection manifold on the vehicle should be open before loading is permitted.

d)

verification of vapour collection connection: a proximity switch contact shall be connected to the overfill protection system so that loading is only permitted if the vapour collection connection is made.



AUTOMATION

5.1

ADVANTAGES OF AUTOMATION Automation offers many advantages over manual systems. New installations shall be automated and the automation of existing installations should be considered at the earliest opportunity. Automation should be fit for purpose and follow a standard approach in terms of vendor, system functionality and implementation.

5.2

ASSESSMENT OF FUNCTIONAL REQUIREMENTS A rigorous assessment of functional requirements shall be made prior to automation.



ADDITIVE INJECTION

6.2

DOSING LOCATION Before it is decided to inject additives at the loading gantry the advantages and disadvantages of dosing at other locations should be considered. When loading gantry dosing is selected, the following aspects shall be implemented: •

a secure additive selector system (automatic selection is preferred to manual or key selectors);

•

the injector control system to incorporate a feedback signal that confirms that dosing is taking place. If dosing does not take place within the specified limits, loading should be interrupted;

•

additive volume totaliser meters, in order to enable a periodic check on the correct injection ratio (at least daily, but preferably at the end of each shift).

6.3

GENERAL DESIGN GUIDELINES

6.3.1

Additive type The pump seals should be compatible with the type of additives to be used.

6.3.3

Injection methods When different additives can be selected, care should be taken to avoid crosscontamination of additives. For these applications modified flow-proportional additive injection should be employed. With this method no additive is injected during the final amount (say 200 L) (say 7 ft3) of the batch, thus leaving the loading linework purged of all additivated products.

6.4

GANTRY ADDITIVE INJECTION SYSTEM

6.4.1

Additive receipt facilities To ensure that the correct additive is safely discharged and received into the right storage tank the following measures shall be taken:

6.4.2

a)

vehicle/rail discharge points shall be clearly marked to identify the additives in accordance with their delivery documents;

b)

the systems for different types of additives and additives of competitors shall be kept completely segregated. Thus separate connections and pumping systems shall be used. Valve cross-overs shall be avoided. Dedicated connections should be employed wherever possible.

Additive storage vessel Pre-mixing of the additive by the supplier makes the on-site operating procedure simpler, but could add to the transportation costs. If mixing on site is selected then the quality control procedures shall be defined. Care should be taken with the maximum storage temperature of many additives, in particular ignition improvers. Temperature alarms SHALL [PS] then be provided, as well as e.g. water-spray cooling for fire protection or the use of underground storage tanks. Tank mixers and tank filling/draining facilities shall be provided. For storage of light additives, pressure/vacuum valves should be fitted to prevent emissions. For storage and handling of very toxic additives DEP 01.00.01.30-Gen and DEP 31.38.01.11-Gen. shall apply. Means of establishing the amount of additive in the storage tank (dipping or level gauging) shall be provided to allow reconciliation of stocks.



Injection system The following Injection systems may be applied. Requirements depend on the system selected:

6.4.4

•

Electronic injector systems The additive piston injector should be fitted with a proximity sensor, which sends feedback pulses to the controller, thus confirming that the injector is operating correctly. Depending on the control system these systems are capable of ‘modified proportional injection’ (e.g. line clearing).

•

Electronic flow-proportioning control

•

Pneumatically driven injectors

•

Turbine driven injectors

•

Mechanical systems

•

Gantry Blending Where blending is performed downstream of the final meter, the blending component meter shall be considered as a custody transfer meter and tested accordingly.

Injection nozzle The additive injection point shall be positioned upstream of the flow meter. The simultaneous injection of multiple additives/components at the same location in the pipe shall be avoided to assure a homogenous mixture



VAPOUR EMISSION CONTROLS

7.1

APPLICATION OF VAPOUR EMISSION CONTROLS For common white products, the vehicle loading gantries shall be of the bottom loading type with vapour collection systems and existing top loading facilities shall be converted into bottom loading during a defined conversion period. Such conversion periode should be minimized to ALARP. For black oil products and heated oils, top loading gantries are allowed and do not require vapour collection and recovery, provided a dedicated vehicle fleet (no switch loading) is used. In case mixed vehicle fleet is used, vapour collection and recovery shall be applied.

7.2

VAPOUR COLLECTION SYSTEM The requirements depend on the system selected:

7.3

•

Direct system With bottom loading of road tankers the vapours from all compartments will be collected, including those from non-gasoline loading (e.g. automotive gasoil). These additional vapours, plus the vapours generated during the loading itself (e.g. by evaporation of the product), shall be taken into account when sizing the vapour collection and vapour recovery unit or incinerator.

•

Direct system with vapour holding tank The vapour holding tank shall be protected against over-and-underpressure. If a flexible diaphragm is used in the holder then its material shall be compatible with the composition of the vapours and it shall be designed to eliminate static electricity hazards.

•

Vapour balancing system

•

Design of vapour collection systems Vapour collection systems should be designed and sized according to the IP “Guidelines for the Design and Operation of Gasoline Vapour Emission Controls” or equivalent API Standard. The vapour collection system SHALL [PS] be adequate to cater for the highest loading rate anticipated at the loading gantry, including displacement from gasoil compartments on mixed loads in multi-product gantries. In direct systems the vapour generation in product tanks due to ambient temperature changes and solar radiation should also be considered.

VAPOUR RECOVERY UNITS The main types of vapour recovery units on the market are:

7.3.1

•

Carbon adsorption

•

Liquid absorption

•

Refrigeration/Condensation

•

Membranes

The choice of vapour recovery unit The different types of units have different fields of application. The following should be taken into account in the choice of a VRU: a)

throughput profile (peak, 15 minutes, hourly, four hourly and daily capacity);

b)

required outlet concentration;

c)

type of vapours to be processed (only gasoline, or also diesel, solvent, chemicals, additive, ethanol or MTBE vapours);

d)

consumption of energy, utility and other consumables (anti-icing additives, absorption liquid, carbon, glycol etc.);



7.3.2

e)

availability of utilities at the site (steam, electricity, cooling water, hot oil, sewage system, absorption liquid, instrument air, nitrogen etc.);

f)

simplicity of operation and maintenance;

g)

environmental aspects (waste water, spent active carbon, refrigeration medium);

h)

accuracy of recovered gasoline measurement (to allow the prepaid duty on the recovered gasoline to be reclaimed);

i)

experience of and technical back-up (service organisation / spare parts) supplied by the Manufacturer;

j)

safety.

k)

materials compatibility with products being recovered.

Design of VRUs VRUs should be designed and sized according to the IP “Guidelines for the Design and Operation of Gasoline Vapour Emission Controls”. Area classification SHALL [PS] be in accordance with IP-Part 15 or alternative recognised codes. The electrical requirements SHALL [PS] be in accordance with (9.4). Most Manufacturers build their VRUs according to a standardised design. If a Manufacturer’s design is proven in practice in similar situations, that design should be adopted (as far as possible) in order to avoid redesign which would result in excessive cost and the risk of improperly functioning units.

7.4

FIRE AND EXPLOSION PROTECTION The vapour collection system SHALL [PS] be protected from internal fire and explosion. To limit the consequences of an ignition the following techniques or a combination of them shall be applied. •

Containment

•

Explosion venting Explosion venting should only be applied if no other feasible alternative exist. The vents should be placed at intervals less than the predicted run-up distance to detonation and should be at least equal to the cross sectional area of the pipe. In normal operation the discharge of flame and pressure from the pipe can be considerable; therefore great care should be taken with the location of the vent and the direction in which the flame will be released.

•

Active explosion suppression or isolation Due to their complicated design these techniques should not be employed.

•

Flame and detonation arresters In the design of the vapour collection system the often considerable pressure drop of flame arresters shall be taken into consideration and an extra allowance for fouling of the flame arresters shall be made. Flame arresters SHALL [PS] have been demonstrated to work under actual conditions and SHALL [PS] have been tested to an appropriate standard, e.g. BS 7244 or EN 12874.

•

Risk assessment and cost effectiveness of protection Especially for large installations (more than 4 connected loading bays or more than 8 connected tanks) a Quantitative Risk Analysis study should be performed to determine the most cost effective arrangement of detonation arresters.


DEP 31.06.11.11-Gen. February 2011 Page 29 8

LOADING TERMINAL DESIGN

8.1

LOADING TERMINAL LAYOUT

8.1.1

Loading area classification Area classification drawings SHALL [PS] be prepared based on IP-Part 15 or equivalent code.

8.1.2

Safety distances The minimum safety distances SHALL [PS] comply with the IP Part 2 or NFPA 30, and local regulations. Where possible, larger safety distances should be provided, particularly for separation from areas where personnel may be present.

8.1.3

Traffic and parking If sufficient space is available, (sharp) bends shall be avoided to prevent/reduce truck tyre wear and the degradation of the pavement of the area. Crossing of incoming and outgoing traffic lanes and contra-flow of vehicle movements is not permitted. For loading terminals with automated entry/exit, consideration shall be given to access by rescue services and to site evacuation by vehicles and personnel in case of emergencies or power failures. Slip or bypass roads around the loading facilities should be provided to allow vehicles to evacuate the loading area without driving through the loading bays or crossing traffic in the event of an emergency.

8.1.4

Product grouping Similar products should be grouped together at loading facilities, e.g. common white oil products together and common black oil products together. Where both common white oil and common black oil products are filled at the same loading facilities, one side of the available area should be reserved for each group of products and to allow space for future extension in both directions, see Figures 8.5 and 8.6. For safety reasons and operational convenience it may be desirable to separate some Class I and special products (e.g. cutbacks) from others, and always ensure that aviation products are properly separated from other grades with top loading installations. For bottom loading, care should be exercised with the installation of aviation grades in high volume bays due to the extra time required to load and test aviation fuels. Loading facilities for all products should be concentrated in one area to minimise traffic movement within refineries/depots. If storage facilities for heated black products are distant from the planned loading centre, it may be advisable for economic and operational reasons (to prevent long heated and insulated pipes) to provide separate facilities for these products close to the storage areas. However, where separate loading areas are used, vehicles should follow the same traffic pattern so that the documentation for all products can be handled at one office.

8.1.5

Dispatch office Supervision and documentation of road vehicle loading operations can be carried out most effectively from an office overlooking the loading operations and located near the installation boundary or between the incoming and outgoing vehicle streams. Office facilities should be designed and constructed taking into account the higher-thannormal noise levels caused by nearby vehicles. They should be large enough to accommodate at least all personnel involved in order-taking (bulk and packed), road vehicle routing, scheduling and dispatching, and stock control, and also include a waiting room for drivers, social areas and space for document files and automation equipment.


DEP 31.06.11.11-Gen. February 2011 Page 30 8.2

LOADING ISLAND/ BAY LAYOUT AND DESIGN

8.2.1

General The loading system layout should not permit more than one vehicle in line on either side of any island. In the loading position, vehicles shall face the exit gate at all times so they can be driven away quickly in an emergency.

8.2.2

Top loading island/bays Examples of top loading islands are illustrated in DEP Informative Figures 8.7 and 8.11. The design of double-sided bays should allow for two of the widest vehicles to park between gantries with at least one metre clearance between them. The gantry structure shall not obstruct the opening of cab doors or prevent drivers from leaving or entering their cabs.

8.2.3

Bottom loading island/bays The island surface should be graded to prevent product from accumulating under the platform. The gantry structure shall not obstruct the opening of cab doors or prevent drivers from leaving or entering their cabs.

8.2.4

Protection of equipment against vehicles To protect loading equipment installed on loading islands, particularly those at the ends, against accidental damage by poor or careless driving, the following safeguards should be considered in the design of loading islands:

8.2.5

a)

provision of a kerb, at least 200 mm (8 in) high, on loading islands. This step between the island and the ground level should be clearly marked (i.e. properly painted) to warn personnel working in the area against tripping;

b)

where modular pre-fabricated bottom loading gantries are installed they can be positioned flush with the surrounding concrete, thus avoiding trip hazards whilst the gantry steelworks still provides protection;

c)

installation of protective barriers and/or bollards at the entrance of loading bays;

d)

provision of breakaway connections (shear couplings) on loading arms/hoses;

e)

ensuring that no parts of the equipment or pipes protrude over the edge of the islands.

Paving and drainage The general area of access to and from loading bays should be concrete surfaced. Bitumen surfacing should not be used. The concrete should be of a type resistant to oil penetration. Loading bays should be paved with heavy duty concrete, rather than bitumen asphalt, to help dissipate static charge built up during movement of the vehicle. The waiting and parking areas may be paved with either heavy duty concrete or bitumen asphalt. Drainage should be provided at each bay to collect spillage of products. Drainage should be directed away and contained to protect the vehicles in event of a fire (product should not drain to other bays and/or collect beneath vehicles). The area extending to 1 m (3 ft) beyond all loading islands and the outermost loading bays should be designed to collect product spillage, which should be routed to collecting pits or oil interceptors. Spillages of ethanol blends should not be allowed to drain to the sewer. Ethanol will go into the aqueous phase, and the wastewater is more difficult to treat. In case of an ethanol blend spill, a proper evaluation needs to be carried out and appropriate considerations taken to meet local environmental regulations. In the event of a neat or blended ethanol spill, the ability to retain the flow on site is imperative. If tank drainage connections exist they shall be blind flanged shut. Furthermore,


DEP 31.06.11.11-Gen. February 2011 Page 31 it is recommended to separate binding with spillage containment pits instead of applying interceptors. Paving and drainage facilities shall comply with local regulations. 8.3

GANTRY DESIGN

8.3.1

Top loading gantry The working platform should be provided with stairs at each end. If space is restricted then stairs should be provided at one end and at the other end either access to a passway connecting all gantry islands or a ladder. Approved fall protections systems shall be installed and used as designed. Preffered fall protections are adequate posisionned guard rails. Ropes (life lines) should be used in case existing guard rails would not offer sufficient protection against falling. Bottom loading should be employed for solvents and common white oil products.

8.3.2

Roofs/shelters Shelters, where installed, shall have suitable ventilation to prevent accumulation of vapour within the roof space. Similarly, ventilation at ground level is also essential to dissipate any vapour pockets.

8.3.3

Other requirements Meter heads or meter pre-set readings should be clearly visible and readable from the product loading control points. Control valve equipment should be within easy reach of the operator in normal loading positions. All handles of valves should be operated in the same direction. Bays and loading islands should be clearly numbered to enable vehicles to be directed to filling points. Product grade plates should be provided at the entry side of the gantry to clearly indicate product availability at the bay concerned. Loading arms, meters and connections should be clearly marked for product identification. Sufficient illumination should be provided for night operations (see 9.5). The construction of barriers at the exit of loading bays (when used) should be such that they can be driven through in an emergency (e.g. barrier bends or snaps off).


DEP 31.06.11.11-Gen. February 2011 Page 32 9

MISCELLANEOUS

9.1

EMERGENCY AND FIRE PROTECTION

9.1.1

General Typically foam deluge systems are not employed or if the facility is assessed to constitute a significant business risk in the event of total loss and alternatives are not available. Where such systems are deemed to be required, they shall be in accordance with DEP 80.47.10.30-Gen. and DEP 80.47.10.31-Gen.

9.1.2

Requirements of fire fighting facilities At unmanned terminals and terminals with low manning levels, an automatic foam spray system should be installed.

9.1.3

Fire hydrant main and mobile monitors Facilities for generating foam (with appropriate capacity) should be provided on site e.g. mobile foam generators or foam stations.

9.1.4

Fixed or oscillating monitors As above, but fixed or oscillating water/foam monitors are used instead. These monitors SHALL [PS] be located at least 20 m (65 ft) away from the gantries on the prevailing upwind side in order to facilitate access in the event of obstruction by abandoned vehicles.

9.1.5

Automatic foam spray systems Such systems if employed shall comply with NFPA 16 or equivalent The automatic fire detection system should be capable of quickly detecting flames/fire/heat in the gantry area and activating the spray system. An alarm should be raised at the loading terminal dispatch office/control room and at the local fire service if the terminal is unmanned. The system shall be designed to protect the whole surface area of the road tanker including the driver’s cab, engine, underside and an area of 2 m (7 ft) around the tanker. The design should be sufficient to provide protection for all bays in the gantry simultaneously. The system should have an emergency stop valve at each loading bay. Ethanol is soluble in water and breaks down regular foam almost immediately. Therefore, it is difficult to extinguish a fire involving ethanol using regular foam. Water is not effective to fight an ethanol fuelled fire, until the ethanol contains ~80% water. For this reason alcohol resistant (AR) foams need to be used for sustained fire cases (e.g. large and/or long duration pool fires) for neat ethanol or Gasohol blends with ethanol concentration above 15%. Special foam is not required for E5 and E10.

9.1.6

Mobile and/or portable equipment The minimum requirements for fire fighting systems at loading gantries are mobile and portable equipment comprising: a)

11 kg (24 lbm) dry-powder chemical extinguishers: •

top loading: Two extinguishers per loading island: one positioned on the working platform adjacent to the top of the stairway, and one at ground level adjacent to the stairway.

•

bottom loading: One extinguisher per island at a convenient location (e.g. shelter).

b)

one 70 kg (150 lbm) dry-powder chemical extinguisher (or one 90 L (3 ft3) AFFF unit) per four loading bays.


DEP 31.06.11.11-Gen. February 2011 Page 33 c) 9.1.7

one or more fire blanket(s) should be provided at a strategic point close to the loading facilities.

Emergency and fire alarm Independently of any other control, an emergency switch should be provided at each of the following positions: •

top loading gantry: at the bottom of each stairway,

•

bottom loading gantry: at each end of the island,

•

at no less than two easily accessible locations in the loading area, at least 30 m ( 100 ft) away from the nearest loading gantry,

•

in/outside the dispatch office/control room.

The emergency switch SHALL [PS] override all other controls and immediately cease all product flow by stopping the loading pumps and closing flow control valves. If there is any risk of product gravitating to the loading area after the pumps have been stopped, clearly indicated isolation valves SHALL [PS] be fitted at a safe distance from the loading gantry. Restarting of product flow should only be possible after manually resetting the appropriate shutdown system (i.e. systems should not be self-resetting). The fire alarm system should also initiate an emergency shutdown and, where automatic entry/exit gates are installed, cause the gates to open. The fire alarm signal SHALL [PS] be directly relayed to the local fire brigade in case of unmanned depot operations. 9.1.8

Emergency shower and eye wash At least one emergency shower and eyewash should be provided at easily accessible locations at the loading gantry. The installing of at least one unit at each end of the loading gantry should be seriously considered.

9.2

PIPING Piping shall be in accordance with DEP 31.38.01.11-Gen. and DEP 31.38.01.12-Gen.

9.2.1

Delivery piping For the purposes of sizing the delivery piping at loading terminals, the maximum product velocity in main piping should be 5 m/s (16 ft/s). If lines are long, consideration shall be given to using a lower velocity to avoid an excessive pressure drop and limit surge pressures. To prevent static electricity hazards the flow velocities in delivery piping, including loading arms, is limited as required in (2.3.2). Where no hazards exist, a maximum velocity of 7 m/s (23 ft/s) may be applied in short lengths of connecting pipework, loading arms and hoses. Piping shall be designed to allow for maximum loading rates at the loading gantry.

9.2.2

Pump suction piping Pump suction piping should be kept as short as possible and without kinks (e.g. over bund wall or other pipes). If it is necessary for a pump to operate under negative static head conditions, the suction piping should be laid level or preferably with a slight upward slope towards the pump. Under negative head conditions, the maximum velocity in the suction line should be limited to 1.5 m/s (5 ft/s).



Routing To minimise pressure losses, pressure surges and heat losses, the shortest practicable route should be chosen for pipes, with a minimum use of bends, tees, valves and other fittings. Pipes should not be laid in open trenches below the adjacent ground level.

9.2.4

Piping material Aluminium, copper or plastic pipes SHALL [PS] not be used at the loading gantry because of their lower survivability in fire. Aluminium may only be used and is acceptable for loading arms downstream of the metering system and control valve.

9.2.5

Fire protection of piping In the event of a fire, the piping structure supports should be protected to prevent collapse of the overhead pipes (see DEP 34.19.20.11-Gen.). Heavy equipment (e.g. meters) in the piping system should be independently supported to reduce the chance of collapse in case of fire.

9.2.6

Air vents and product drains on equipment Vents fitted at high points in product lines shall be kept to a minimum, and piping should be designed to be self-draining. Manually operated drain valves should be located at low points to enable pipework to be drained.

9.2.7

Isolating valves The isolation valves should be fitted with bypass (thermal) pressure relief valves (see 9.2.10).

9.2.10

Relief valves Vent points of relief valves and automatic vents of piping systems SHALL [PS] not discharge directly into atmosphere. These points should be piped away to the nearest drainage (liquid) or to a safe location (gas phase). Cascading relief systems (relief valves discharging into another closed system) should not be used without proper detailed design.

9.3

LOADING PUMPS If a location outside the bund is not practical, pumps may be elevated on plinths to reduce exposure in the event of a spill and shall be positioned away from drains.

9.4

ELECTRICAL REQUIREMENTS, EARTHING AND BONDING

9.4.1

General Electrical equipment, electrical power distribution systems, and systems for protection against lightning or the accumulation of static electricity SHALL [PS] comply with DEP 33.64.10.10-Gen or applicable local statutory and industry codes.

9.4.2

Electrical installations Electrical equipment should be located in the least hazardous area (see 8.1) as far as practical and economical. Where electrical equipment has to be installed in hazardous areas, equipment with a type of protection suitable for the relevant zones as classified in (8.1.1) SHALL [PS] be selected, specified and installed in accordance with recognised standards. Electrical cables associated with loading arms (e.g. heating cables for black oils, cables to limit switches, cables to switches for electronic earthing units etc.) shall allow full movement of the loading arm without stretching the cable, sufficiently flexible to allow frequent movement, even at the lowest possible ambient temperature and resilient against external


DEP 31.06.11.11-Gen. February 2011 Page 35 damage. Stops shall be fitted to prevent excessive movement, which otherwise could damage cables In existing facilities where improvements are planned, the electrical requirements associated with the installation of automatic data capture and transmission facilities (automation) shall be considered. Whether or not automation is likely, a pipe (duct) of at least 150 mm diameter shall be installed at normal cable laying depth between the gantries and the edge of the loading area near the office location, to accommodate future cabling for automation, if required. Cabling for automation shall be laid separately from power supply cables and shall be suitably shielded. Consideration should be given to the use of fibre optic cables to allow for efficient long distance communications. Pipe ends shall be sealed to prevent ingress of hydrocarbons or water. All cable pipes at new facilities should be large enough to allow 50 % spare capacity for future extension of electrical systems. 9.4.3

Earthing and bonding The whole of the loading bay canopy structure, gantry, product piping and fittings SHALL [PS] be electrically bonded and earthed. Electrical equipment SHALL [PS] be earthed as specified by DEP 33.64.10.10-Gen. Loading arms SHALL [PS] be bonded to the gantry earth and SHALL [PS] be electrically continuous (resistance less than 10 Ω). Where this is not ensured, then bonding straps should be fitted and/or conductive grease used on swivels. Flexible hoses are normally used for bottom loading. They SHALL [PS] not be used for top loading unless the tanker vehicle is fitted with fill tubes reaching the base of the compartment to avoid splash loading. Flexible hoses used for loading SHALL [PS] meet the required standards for fuel hoses including either the conductive or dissipative resistance standards. Conductive hoses SHALL [PS] have a resistance of less than 10 Ω and dissipative hoses SHALL [PS] have a resistance per unit length of less than 1 MΩ/m (0.3 MΩ/ft) For definitions of conductive, dissipative and non-conducting materials: see Appendix A. All pipes in the loading system SHALL [PS] be conductive. All components of the liquid handling system (pipework, filters, metering or loading arm) SHALL [PS] be electrically connected to the loading system structure. The electrical contact resistance SHALL [PS] be less than 10 Ω for items that are connected metal to metal. All parts of the bulk vehicle should be bonded together (chassis, tank, piping, dip pipes, fittings etc.) and SHALL [PS] have a bonding resistance of less than 10 Ω. A bonding cable SHALL [PS] be connected to the vehicle before any other operations are carried out (e.g. opening man-lids, connecting hoses etc.). The bonding resistance between the vehicle and the gantry SHALL [PS] be less than 10 Ω, and this bond SHALL [PS] remain in position until all other loading operations have been completed. See also bonding interlocks (4.6). Where there is no continuous metal-to-metal contact (e.g. across greased swivel joints or with non-metallic pipes), the resistance SHALL [PS] be less than 1 MΩ. These levels of resistance will normally be provided inherently by the construction of the system but it may be necessary to provide specific bonding links. Generally, swivel joints have a low enough resistance (<1 MΩ) but some greases can be highly insulating and electrical continuity across swivel joints needs to be checked annually or whenever the grease is changed. Checks should be done for several positions of each joint because the resistance can vary. If continuity over a swivel joint is inadequate, the resistance can be reduced by changing to more conductive grease or by providing a bonding link across the joint.


DEP 31.06.11.11-Gen. February 2011 Page 36 For most top-filling applications (for exceptions), the drop-tube SHALL [PS] be metal and SHALL [PS] be long enough to reach the base of all compartments that might be loaded. There should be a T-piece on the end of the drop-tube to deflect the flow along the base of the compartment. The T-piece should preferably be made of a dissipative rubber to avoid mechanical damage. NOTE:

The usual long-tube requirement is for cases where there could be a flammable atmosphere. It may be permissible to use a short drop tube to splash-load flammable liquids of low volatility (e.g. luboils) that are incapable of producing a flammable vapour atmosphere at the maximum handling temperature. However with this approach it is essential that there is no switch-loading or other possible source of flammable vapour, and that the loading process does not produce enough mist or suspended droplets to render the atmosphere flammable.

Filter socks (as sometimes used for conductive solvents such as alcohols) SHALL [PS] not be used on the end of loading arms for hydrocarbon fuels. It is particularly important that the drop tube meets the general earthing or bonding requirements outlined above. Where drop tubes are removable from the loading arms, e.g. with camlock fittings, adequate electrical contact across the joint SHALL [PS] be established and checked each time the arm is re-connected. Plastic materials can be classified by their electrical resistivity as non-conductive (insulating), dissipative or (rarely) conductive. The use of dissipative or conductive plastics does not generally give rise to concerns arising from static electricity but the use of insulating plastics needs to be carefully controlled. •

As a general principle the use of insulating plastics should avoided in hazardous areas including those around vehicle loading points. Despite this they may be acceptable in locations where they would not be subject to any electrostatic charging.

•

Within hazardous areas and where the materials could be subjected to electrostatic charging (most commonly by the flow of product but also, possibly, by rubbing) either: o

the maximum area of plastic SHALL [PS] not exceed the values given in Appendix A; or

o

a larger area may be used provided it is subdivided by a mesh or grid of earthed, conductive or dissipative material on or near the surface. In this case the maximum area enclosed by any cell of the mesh SHALL [PS] be less than four times the limits given in Appendix A.

NOTE:

9.5

Larger areas can be tolerated for subdivided sheets because the presence of the earthed mesh holds potentials lower than for a completely isolated piece of plastic of the same size.

ILLUMINATION Lighting fittings should conform to the area requirements as specified in (8.1.1). Generally, in Zone 1 and 2 hazardous areas, fluorescent luminaries with type of protection Ex’e’ SHALL [PS] be used. In these areas, high pressure discharge luminaries are also acceptable and if used, SHALL PS] have type of protection Ex’d’. Low pressure sodium discharge lamps SHALL [PS] not be used because of the potential fire hazard in the event of breakage. To allow safe movement of personnel in the event of a power failure, consideration should be given to the installation of at least one emergency light fitting per loading bay with battery back up of 30 minutes.

9.6

PAINTING DEP 30.48.00.31-Gen. should be applied. Colour schemes should be chosen according to: •

API RP 1637; and


DEP 31.06.11.11-Gen. February 2011 Page 37 • 9.7

API/IP Standard 1542.

DRAINAGE AND PAVEMENT See for pavement and drainage (8.2.5).

9.8

PRODUCT WATER DETECTION Not all water-finding pastes are suitable for water/alcohol mixtures and some can give misleading results; paste suitable for ethanol blends shall be used. It is strongly recommended that neat ethanol and ethanol blends be stored in fixed roof storage tanks to avoid water ingress.



REFERENCES In this DEP, reference is made to the following publications: NOTES:

1. Unless specifically designated by date, the latest edition of each publication shall be used, together with any amendments/supplements/revisions thereto. 2. The DEPs and most referenced external standards are available to Shell staff on the SWW (Shell Wide Web) at http://sww.shell.com/standards/.

SHELL STANDARDS Definition of temperature, pressure and toxicity levels

DEP 01.00.01.30-Gen.

Protective coatings for onshore facilities

DEP 30.48.00.31-Gen.

Piping – General requirements

DEP 31.38.01.11-Gen.

Piping classes – Refining and chemicals

DEP 31.38.01.12-Gen.

Electrical engineering design

DEP 33.64.10.10-Gen.

Fire proofing of steel structures

DEP 34.19.20.11-Gen.

Assessment of the fire safety of onshore installations

DEP 80.47.10.30-Gen.

Active fire protection systems and equipment for onshore facilities

DEP 80.47.10.31-Gen.

AMERICAN STANDARDS Bottom loading and vapour recovery for MC-306 and DOT406 tank motor vehicles

API RP 1004

Using the API Color-Symbol System to Mark Equipment and Vehicles for Product Identification at Gasoline Dispensing Facilities and Distribution Terminals

API RP 1637

Identification markings for dedicated aviation fuel manufacturing and distribution facilities, airport storage and mobile fuelling equipment

API/IP Standard 1542

Protection against ignitions arising out of static, lightning and stray currents

API RP 2003

Manual of Petroleum Measurement Standards: Chapter 4 - Proving systems, Section 1 – Introduction Chapter 4 - Proving systems, Section 2 - Displacement provers Chapter 4 - Proving systems, Section 5 - Master-meter provers Chapter 4 - Proving systems, Section 6 - Pulse interpolation Chapter 4 - Proving systems, Section 8 - Operation of proving systems Chapter 5 - Metering, Section 6 - Measurement of liquid hydrocarbons by Coriolis meters Chapter 6 – Metering Assemblies, Section 2 –Loading Rack Metering Systems

API MPMS 4.1 API MPMS 4.2 API MPMS 4.5 API MPMS 4.6 API MPMS 4.8 API MPMS 5.6 API MPMS 6.2

Issued by: American Petroleum Institute Publications and Distribution Section 1220 L Street Northwest Washington DC. 20005 USA.

Specification for horizontal end suction centrifugal pumps for chemical process

ASME B73.1


DEP 31.06.11.11-Gen. February 2011 Page 39 Specification for vertical in-line centrifugal pumps for chemical process

ASME B73.2

Issued by: American Society of Mechanical Engineers Three Park Avenue, M/S 10E New York NY 10016 USA.

Standard for the installation of foam-water sprinkler and foam-water spray systems

NFPA 16

Flammable and combustible liquids code

NFPA 30

Issued by: National Fire Protection Association One Batterymarch Park PO Box 9101 Quincy, MA 02269-9101 USA

Standard test methods for electrical conductivity of aviation and distillate fuel

ASTM D 2624

Issued by: American Society of Testing Materials (ASTM) International 100 Barr Harbor Drive PO Box C700 West Conshohocken, PA 19428-2959 USA

BRITISH STANDARDS Flame arresters for general use

BS 7244

Issued by: British Standards Institution 389 Chiswick High Road London W4 4AL UK.

Institute of Petroleum - Model Code of Safe Practice in the Petroleum Industry: Part 2: Design, Construction and Operation of Distribution Terminals

IP Part 2

Part 15: Area Classification Code for Petroleum Installations

IP Part 15

Institute of Petroleum - Guidelines for the design and operation of gasoline vapour emission controls at Distribution Terminals Institute of Petroleum - Code of Practice for bottom loading, vapour collection and overfill prevention Institute of Petroleum - Petroleum measurement manual part X (meter proving), subdivided in various (11) sections Institute of Petroleum - Paper number 4, Code of Practice for the proving of loading gantry meters Issued by: Institute of Petroleum Willoughby Road Bracknell, Berkshire RG12 8DW UK

Ministry of Defence Standard 91-91 – Turbine Fuel, Aviation Kerosine Type, Jet A-1. Nato Code: F-35. Joint Service Designation: AVTUR

DEF STAN 91-91


DEP 31.06.11.11-Gen. February 2011 Page 40 Issued by: Defence Equipment and Support UK Defence Standardization Kentingem House 65 Brown Street Glasgow G2 8EX UK

EUROPEAN STANDARDS Flame arresters – Performance requirements, test methods and limits for use.

EN 12874

Electrical Apparatus for Potentially Explosive Atmospheres – General Requirements.

EN 50014

Accord Dangereux Routier (European agreement concerning the International carriage of dangerous goods by road)

ADR

Issued by: United Nations Economic Commission for Europe Information Office Palais des Nations CH-1211 Geneva 10 Switzerland

European Parliament and Council Directive 94/63/EC on the control of volatile organic compound (VOC) emissions resulting from the storage of petrol and its distribution from terminals to service stations

European VOC directive

Issued by: CEN Secrétariat Central Rue de Stassart 36 B-1050 Brussels Belgium. Copies can also be obtained from national standards organizations

INTERNATIONAL STANDARDS Technical specifications for centrifugal pumps, class II

ISO 5199

Issued by: ISO Central Secretariat 1, ch. de la Voie-Creuse Case postale 56 CH-1211 Genève 20 Switzerland Copies can also be obtained from national standards organizations.


DEP 31.06.11.11-Gen. February 2011 Page 41 APPENDIX A PLASTIC MATERIALS A.1 Definitions Conductive: Will not retain a significant electrostatic charge when in contact with earth and can transmit electric shocks from power systems. These materials have a volume resistivity lower than or equal to 104 Ωm (for certain items e.g. conductive hose there are special definitions). Dissipative (previously known as anti-static): Will not retain a significant amount of electrostatic charge when in contact with earth but too resistive to transmit electric shocks from power systems. These materials have a volume resistivity higher than 104 Ωm but equal to or lower than 109 Ωm, or a surface resistivity less than 1010 Ω (or surface resistance less than 109 Ω) measured at ambient temperature and 50% relative humidity. Non-conductive (insulating): Neither conductive nor dissipative. Electrostatic charges can accumulate and will not readily dissipate even if part of the material is in contact with earth. These materials have a volume resistivity higher than 109 Ωm, and a surface resistivity more than 1010 Ω (or a surface resistance more than 109 Ω) measured at ambient temperature and 50% relative humidity. Most common plastics are insulating. A.2

Size Limits Large areas of plastic can hold enough charge to produce electrostatic discharges capable of igniting flammable materials. To avoid this possibility it is essential that wherever nonconductive plastics are used in hazardous areas at locations where they could be subject to charging mechanisms (e.g. liquid flow or rubbing), they SHALL [PS] not exceed certain size limits. These limits SHALL [PS] be adopted unless it can be shown that hazardous electrostatic charges are not to be expected and that charging mechanisms will not occur at any time. A sheet of insulating plastic that exceeds the size limits given in Table A.1 may be used if it is subdivided into smaller areas by a closed mesh or grid of earthed conductive or dissipative material at or near the plastic surface. In this case, the maximum area of any cell in the mesh SHALL [PS] not exceed 4 times the areas given in Table A.1. (Mesh cell areas can be larger than the areas of isolated pieces of plastic because the presence of the earthed mesh holds potentials down.) Table A.1

Restriction on size of non-conductive plastics in hazardous areas containing potentially flammable atmospheres of group IIA Zone

Maximum area 2

2

Maximum width

0

50 cm (7.8 in )

0.3 cm (1/8 in)

1

100 cm2 (15.5 in2)

3.0 cm (1-3/16 in)

2

No limit

No limit


DEP 31.06.11.11-Gen. February 2011 Page 42 APPENDIX B

FIGURES

For PD Meters, meter proving point can also be positioned upstream of flow meter. For turbine meters, the proving point shall be located downstream of the meter

FIGURE B.1a

Typical flow diagram of automated bottom loading installation; gantry based equipment



Figure B.1b

Typical flow diagram of automated bottom loading installation



Figure B.1c

Typical flow diagram of automated top loading installation without vapour recovery



Figure B.2 Symbols for bulk road vehicle loading installation flow schemes


Loading facilities for truck loadings.

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