prEN 16125

SLOVENSKI STANDARD
01-oktober-2010
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LPG equipment and accessories - Pipework systems and supports - LPG liquid phase
and vapour pressure phase
Flüssiggas-Geräte und -Ausrüstungsteile - Rohrleitungssysteme und -befestigungen -
Flüssigphase und ungeregelte Gasphase von Flüssiggas (LPG)
Ta slovenski standard je istoveten z: prEN 16125
ICS:
23.040.01 Deli cevovodov in cevovodi Pipeline components and
na splošno pipelines in general
75.200 2SUHPD]DVNODGLãþHQMH Petroleum products and
QDIWHQDIWQLKSURL]YRGRYLQ natural gas handling
]HPHOMVNHJDSOLQD equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
DRAFT
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2010
ICS 23.040.01
English Version
LPG equipment and accessories - Pipework systems and
supports - LPG liquid phase and vapour pressure phase
Flüssiggas-Geräte und Ausrüstungsteile -
Flüssiggas(LPG)-Verrohrung
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 286.

If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the
same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to
provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16125:2010: E
worldwide for CEN national Members.

Contents Page
Foreword .4
Introduction .5
1 Scope .6
2 Normative references .6
3 Terms and definitions .8
4 Design safety considerations . 10
4.1 General . 10
4.2 Environmental considerations . 10
4.3 Protection against hazards . 10
4.3.1 Resistance to corrosive substances and atmospheres . 10
4.3.2 Protection against variations in the operating pressure . 10
4.4 Protection against condensation . 11
5 Materials . 11
5.1 General . 11
5.2 New materials and new components . 11
5.3 Reuse of materials and components . 11
5.4 Pipe threads, threaded pipe fittings, flanged pipe joints and welded pipe joints . 12
5.5 Regulators and accessories . 12
5.6 Gaskets and ring joints . 12
5.7 Valves and fittings . 12
6 Design . 12
6.1 General . 12
6.2 Installation drawings . 13
6.3 Measuring instruments . 13
6.4 Pressure protection . 13
6.5 Fluid velocity . 14
6.6 Aboveground pipework . 14
6.6.1 Clearance above ground . 14
6.6.2 Pipework separation distances from above ground electrical conduit, wire, cable or
earthing electrode . 14
6.6.3 Ventilation of concealed piping . 14
6.7 Pipe supports . 15
6.8 Underground piping . 16
6.8.1 General . 16
6.8.2 Pipework separation distances from other underground services . 16
6.8.3 Pipework crossover separation distances from other services . 16
6.9 Jointing . 17
6.10 Flexibility of Piping . 17
6.11 Earthing & Bonding . 17
6.12 Plant piping materials and duty limits for Liquid/vapour phase . 17
7 Identification & corrosion protection of above ground pipework . 21
7.1 General . 21
7.2 Paint . 21
7.3 Pipework markers for above ground LPG pipework . 21
7.4 Colour Coding . 21
7.5 Reflectivity . 21
8 Documentation, inspection and testing. . 22
8.1 General . 22
8.2 Documentation . 22
8.2.1 General . 22
8.2.2 Technical file . 22
8.3 Inspection and testing . 23
9 Maintenance . 23
Annex A (informative) Pipework Integrity Management Systems (PIMS) . 24
A.1 Pipework Integrity Management . 24
A.2 Basic PIMS for LPG plants . 24
A.3 Inspection (measurement) . 24
A.4 Assessment of condition . 25
A.5 Response (remedial action/ future monitoring or inspection) . 25
A.6 Frequency of inspection and maintenance . 26
Annex B (normative) Pipe sizing tables – liquid phase . 29
B.1 General . 29
B.2 Viscosity of LPG . 29
B.3 Calculation of liquid velocity flow in pipework . 29
B.4 Calculation of Reynolds number . 30
B.5 Liquid flow capacity and pressure drop in pipework . 30
B.6 Liquid flow capacity and pressure drop through valves and fittings . 31
Annex C (normative) Pipe sizing tables – Gas phase . 33
C.1 General . 33
C.2 Calculation of full vapour flow and pressure drop in pipework . 33
C.3 Vapour flow capacity and pressure drop through valves and fittings . 34
Annex D (informative) Purging of pipework . 35
D.1 General . 35
D.2 Precautions before purging. 35
D.3 Purging procedures . 35
D.4 Purging guidelines – clearing purge . 36
D.5 Design considerations . 36
D.5.1 Vents . 36
D.5.2 Purge pressure . 36
D.5.3 Purge rate . 36
D.5.4 Purge time . 37
Annex E (informative) Environmental checklist. 38

Foreword
This document (prEN 16125:2010) has been prepared by Technical Committee CEN/TC 286 “Liquefied
petroleum gas equipment and accessories”, the secretariat of which is held by NSAI.
This document is currently submitted to the CEN Enquiry.
Introduction
This European Standard calls for the use of substances and procedures that may be injurious to health and/or
the environment if adequate precautions are not taken. It refers only to technical suitability and does not
absolve the user from legal obligations at any stage.
Protection of the environment is a key political issue in Europe and elsewhere. Protection of the environment
is taken in a very broad sense. What is meant is the total life cycle aspects of, e.g. a product on the
environment, including expenditure of energy and during all phases from mining of raw materials, fabrication,
packaging, distribution, use, scrapping, recycling of materials, etc.
NOTE Annex F indicates which clauses in this standard address environmental issues.
It is recommended that manufacturers develop an environmental management policy. For guidance see
ISO 14000 series It has been assumed in the drafting of this European Standard that the execution of its
provisions is entrusted to appropriately qualified and experienced people.
All pressures are gauge unless otherwise stated.
NOTE This standard requires measurement of material properties, dimensions and pressures. All such
measurements are subject to a degree of uncertainty due to tolerances in measuring equipment etc. It may be beneficial
to refer to the leaflet “measurement uncertainty leaflet (SP INFO 2000 27 uncertainty pdf)”
1 Scope
This standard specifies the requirements for the design, construction, testing, commissioning, operation and
maintenance of LPG pipework in the liquid phase and at full vapour pressure.
This standard is not applicable to:
 pipelines and their accessories;
 pipework for the propulsion of road vehicles or boats;
 pipework on ships.
This standard is applicable to installation pipework having a maximum operating pressure less than or equal
to 30 bar.
This standard is applicable to new installation pipework as well as to replacements of, or extensions to,
existing installation pipework.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 751-1, Sealing Materials for Metallic Threaded Joints in Contact with 1st, 2nd and 3rd Family Gases and
Hot Water - Part 1: Anaerobic Jointing Compounds
EN 751-2, Sealing Materials for Metallic Threaded Joints in Contact with 1st, 2nd and 3rd Family Gases and
Hot Water - Part 2: Non-Hardening Jointing Compounds
EN 751-3, Sealing Materials for Metallic Threaded Joints in Contact with 1st, 2nd and 3rd Family Gases and
Hot Water - Part 3: Unsintered PTFE Tapes
EN 1044, Brazing - Filler Metals
EN 1045, Brazing - Fluxes for Brazing - Classification and Technical Delivery Conditions
EN 1057, Copper and Copper Alloys - Seamless, Round Copper Tubes for Water and Gas in Sanitary and
Heating Applications
EN 1092-1, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories, PN
designated - Part 1: Steel flanges,
EN 1092-3, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories, PN
designated Part 3: Copper alloy flanges.
EN 1254-1, Copper and Copper Alloys - Plumbing Fittings - Part 1: Fittings with Ends for Capillary Soldering
or Capillary Brazing to Copper Tubes
EN 1254-2, Copper and Copper Alloys - Plumbing Fittings - Part 2: Fittings with Compression Ends for Use
with Copper Tubes
EN 1254-5, Copper and Copper Alloys - Plumbing Fittings - Part 2: Fittings with Compression Ends for Use
with Copper Tubes Part 5: Fittings with Short Ends for Capillary Brazing to Copper Tubes
EN 1515-1, Flanges and their joints - Bolting - Part 1: Selection of bolting
EN 10088-3, Stainless steels Part 3: Technical delivery conditions for semi-finished products, bars, rods, wire,
sections and bright products of corrosion resisting steels for general purposes
EN 10208-1, Steel pipes for pipelines for combustible fluids — Technical delivery conditions Part 1: Pipes of
requirement class A
EN 10216-5, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 5: Stainless
steel tubes
EN 10217-7, Welded steel tubes for pressure purposes Technical delivery conditions Part 7: Stainless steel
tubes
EN 10226-1, Pipe threads where pressure tight joins are made on the threads Part 1: Taper external threads
and parallel internal threads dimensions, tolerances and designation
EN 10226-2, Pipe threads where pressure tight joins are made on the threads - Part 2: Taper, external
threads and taper internal threads
EN 10226-3, Pipe threads where pressure tight joins are made on the threads - Part 3: Verification by means
of limit gauges
EN 10253-2, Butt-welding pipe fittings — Part 2: Non alloy and ferritic alloy steels with specific inspection
requirements
EN 10255, Non-alloy steel tubes suitable for welding and threading — Technical delivery conditions
EN 12007-1, Gas infrastructure - Pipelines for maximum operating pressure up to and including 16 bar - Part
1: General functional recommendation
EN 12007-3, Gas infrastructure - Pipelines for maximum operating pressure up to and including 16 bar - Part
3: Specific functional requirements for steel
EN 12266-1, Industrial valves - Testing of metallic valves - Part 1: Pressure tests, test procedures and
acceptance criteria - Mandatory requirements
EN 12266-2, Industrial valves - Testing of metallic valves - Part 2: Tests, test procedures and acceptance
criteria - Supplementary requirements
EN 13175, LPG equipment and accessories - Specification and testing for Liquefied Petroleum Gas (LPG)
tank valves and fittings
EN 13480-2, Metallic industrial piping - Part 2: Materials
EN 14324, Brazing - Guidance on the application of brazed joints
EN 15001-1:2006, Gas Infrastructure - Gas installation pipework with an operating pressure greater than
0,5 bar for industrial installations and greater than 5 bar for industrial and non-industrial installations - Part 1:
Detailed functional requirements for design, materials, construction, inspection and testing
EN ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads - Part 1: Dimensions,
tolerances and designation (ISO 228-1:2000)
EN ISO 9453, Soft solder alloys - Chemical compositions and forms (ISO 9453:2006)
EN ISO 9454-2, Soft soldering fluxes - Classification and requirements - Part 2: Performance requirements
(ISO 9454-2:1998)
EN ISO 10497, Testing of valves - Fire type-testing requirements (ISO 10497:2010)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
accessible
access can be gained without hazard or undue difficulty for inspection, repair, renewal, or operational
purposes
3.2
commissioning
Activities performed to put pipework into operation in accordance with the design.
3.3
competent person
Person, who is trained, experienced and approved to perform activities relating to gas pipework.
3.4
critical velocity
The velocity at which turbulent flow begins.
3.5
design pressure (DP)
Pressure at which the design calculations are based
3.6
fitting
A component used to join pipes, or to change direction or diameter of a pipe, or to provide a branch, or to
terminate a pipe.
3.7
gas installation
A combination of the following used or intended to be used in the supplying and utilisation of gas, taken as
separate items or as a whole: Consumer piping, fittings, components, appliances, flues, sub-meters,
apparatus or other devices and associated requirements.
3.8
interlock
A device or function that ensures that the operation of items of equipment is dependent upon the fulfilment of
predetermined conditions by other items of equipment.
3.9
joint
Means of joining elements of a gas installation
3.10
LPG (liquefied petroleum gas)
mixture of predominantly butane or propane with traces of other hydrocarbon gases classified in accordance
with UN number 1965, hydrocarbon gases mixture, liquefied, NOS or UN number 1075, petroleum gases,
liquefied
NOTE In some countries, UN numbers 1011 and 1978 may also be designated LPG.
3.11
maximum incidental pressure (MIP)
Maximum pressure at which a system can experience during a short time, limited by the safety devices
3.12
maximum operating pressure (MOP)
Maximum pressure at which a system can be operated continuously under normal operating conditions
3.13
mechanical joint
Joint in which gas tightness is achieved by compression with or without a seal.
Note This joint can be readily disassembled and reassembled.
3.14
nominal size (DN)\nominal diameter (DN)
A numerical designation of size, in millimetres (mm) which is common to all components in a piping system
other than components designated by outside diameters or by thread size. It is a convenient round number
for reference purposes and is only loosely related to manufacturing dimensions.
3.15
non-return valve
A valve designed to operate automatically to prevent reversal of flow in a pipe.
3.16
operation pressure(OP)
Pressure which occurs within a system under normal operating conditions
3.17
design pressure
pressure for which the designer allows in specifying materials and construction methods in order that the
pipework will withstand the maximum incidental pressure, tightness test pressure or strength test as
applicable
3.18
pressure
Pressure above atmospheric pressure, or gauge pressure.
3.19
purge/purging/purged
With respect to consumer piping means—
(a) replacing the air in consumer piping with gas or inert gas; or
(b) removing the gas, liquid or vapour phase from consumer piping by replacing the gas with either air or an
inert gas.
NOTE The purpose of purging is to prevent the presence in the piping of an explosive mixture of gas and air.
3.20
sleeve
Protective pipe through which a gas pipe passes.
3.21
strength test
Specific procedure intended to verify that the pipework meets the requirements for mechanical strength.
3.22
strength test pressure (STP)
pressure applied to pipework during strength testing
3.23
thread joint
joint in which tightness is achieved by metal to metal contact within threads with the assistance of a sealant.
3.24
tightness test pressure
Pressure applied to pipework during tightness testing
3.25
pipeline
Piping designed for the conveyance of any fluid or substance to or from an installation (onshore or offshore)
starting from and including the last isolation device located within the confines of the installation, including all
the annexed equipment designed specifically for pipelines
NOTE This definition is extracted from 97/23/EC (PED)
4 Design safety considerations
4.1 General
4.1.1 Any person who is responsible for the design of a LPG installation shall be a competent person.
4.1.2 The pipework designer shall provide information on the design and location of pipework to the
persons responsible for construction, installation and operation of pipework.
4.1.3 The pipework shall be designed, installed and constructed to allow testing and purging to be carried
out.
4.1.4 Above ground piping shall be protected against mechanical damage where necessary.
4.1.5 Pipework joints shall be kept to a minimum.
4.2 Environmental considerations
The designer shall consider the selection of pipe material and components with regard to the use of
production processes, practices, materials or products that avoid reduce or control pollution, including
recycling, treatment, process changes, control mechanisms, efficient use of materials and material
substitution.
NOTE Every product has some impact on the environment. These impacts may occur at any or all stages of the
product’s life cycle and can be local, regional or global, or a combination of all three.
4.3 Protection against hazards
4.3.1 Resistance to corrosive substances and atmospheres
Pipework including supports in contact with soil or building materials, which can be expected to contain
corrosive substances, or in contact with corrosive atmosphere shall be resistant to or protected against these
substances.
4.3.2 Protection against variations in the operating pressure
The designers of pipework shall take into consideration variations of operating pressures resulting from
ambient temperature fluctuation.
4.4 Protection against condensation
For vapour pressure pipework covered by this standard, precaution shall be taken to avoid condensation
occurring in the pipe. The selection of pressure to be used is of great importance, especially in cold climates.
If the design pressure is too high or the temperature too low, the LPG will condense to a liquid. This is known
as the due point. The due point graph figure 1 indicates temperatures and pressures for propane, mixes of
propane/butane and butane. The area above each curve will cause gas to condense to a liquid.

Figure 1 – Due point graph
This may take the form of heat tracing the pipework or alternatively making the use of LPG air-mixture.
Alternatively a suitably located knock-out pot shall be installed in the line to allow condensation to collect and
subsequently boil off without causing overpressure problems.
5 Materials
5.1 General
Materials and components shall be free from damage and defects and shall be suitably selected for the
intended use.
5.2 New materials and new components
New materials and new components shall comply with one or more of the standards listed in Tables 3 and 4.
5.3 Reuse of materials and components
Materials and components can be reused if they comply with the following requirements:
a) Be manufactured to one of the standards listed in Tables 3 and 4;
b) Be suitable for the proposed service in light of the history of the material or component, and;
c) Be inspected since its previous use to reveal any defect that could impair its safety, strength or pressure
tightness.
5.4 Pipe threads, threaded pipe fittings, flanged pipe joints and welded pipe joints
Pipe threads, threaded pipe fittings, flanged pipe joints and welded pipe joints shall comply with Tables 3 and
4.
Attention shall be given to prevention of electrolytic corrosion of dissimilar metals joined in buried systems see
6.8.
5.5 Regulators and accessories
Regulators and accessories shall be capable of withstanding the service conditions for which the system is
designed.
5.6 Gaskets and ring joints
Gaskets and ring joints shall be resistant to the gases that will be and are likely to be in contact with them.
They shall withstand the maximum allowable operating pressure and the full range of operating temperatures
to which they will be subjected.
5.7 Valves and fittings
Valves and fittings shall comply with the following requirements:
a) Lubricants and sealants shall be suitable for the service conditions.
b) Working pressure ratings of steel parts of valves and fittings shall apply within the temperature range
of -40 °C to + 50 °C. However, if temperatures lower than –20 °C are envisaged, the manufacturer shall
demonstrate that the material from which the valves and fittings are constructed shall have properties
suitable for a range of temperatures –40 °C to 50 °C.
c) Non-metallic materials used for seats and seals shall be capable of withstanding the design pressure and
temperature.
d) Parts in contact with gas shall be of materials that are compatible with the gas.
e) Ball, globe, cylinder and non-return types of valves shall be pressure tested to the relevant requirements
of EN 12266-1 and EN 12266-2 or EN 13175 where appropriate.
f) Other than non-return or excess flow valves, valves shall have means for indicating the setting of the
valve (e.g., closed, open).
g) First and second line valves in liquid service from LPG vessels shall be fire safe in accordance with
EN ISO 10497
6 Design
6.1 General
6.1.1 Pipework shall be designed to allow for easy access for inspection and maintenance.
6.1.2 The design pressure for both liquid and full vapour pressure pipework shall normally be -0,3 bar to
30,0 bar unless otherwise stated.
6.1.3 The design temperature range shall be (–20 to 50) °C. However, where temperatures lower
than -20 °C are envisaged, the manufacturer shall demonstrate that the material from which the pipework is
constructed shall have properties suitable for a range of temperatures (–40 to 50) °C.
6.1.4 Pipe sizing for liquid pipework shall be in accordance with EN 15001-1 for pipe integrity and Annex B
for design flow and pressure drop.
6.1.5 Pipe sizing for vapour pipework shall be in accordance with EN 15001-1 for pipe integrity and
Annex C for design flow and pressure drop.
6.2 Installation drawings
The designer shall ensure that technical documentation contains the following information (with parts lists
where appropriate);
a) the location and design of supports;
b) the location and design of wall and floor transits, points where pipework crosses or runs parallel with other
systems, etc;
c) location of, pumps, compressors, meters and other equipment, stating the make, type, connection sizes;
d) joints, gaskets, bolts, etc.;
e) the pipe diameters, MIP, DP, OP, materials and coatings;
f) the location and sizes of valved points for testing and purging;
g) maximum flow;
h) cathodic protection system, where fitted.
6.3 Measuring instruments
Gas installations shall incorporate such measuring instruments and test points as are necessary for their safe
operation.
6.4 Pressure protection
6.4.1 For sections that can be blocked in between isolation valves and contain liquid LPG, suitable
protection shall be provided (e.g. by a hydrostatic relief valve discharging to a safe location).
6.4.2 Where hydrostatic relief valves are used they shall be set to discharge above the maximum working
pressure of the system but not greater than the design pressure of the pipework at ambient temperature and
the components being protected.
6.4.3 The positioning and discharge point of hydrostatic valves shall be located so as not to impinge on
personnel, vessels or equipment in the event of a release.
6.4.4 Hydrostatic relief valves shall have caps fitted to prevent the entry of debris and water.
6.4.5 When hydrostatic relief valves are installed in enclosed spaces, especially where personnel are
present, suitably sized discharge pipework, so as to no restrict the capacity of the hydrostatic relief valve shall
be taken to an outside area and discharged at high level.
NOTE Where possible discharges from hydrostatic relief valves should be taken back to storage
6.4.6 Where components of LPG are handled as individual grades/products (e.g. propane, butane) storage
and handling systems shall be totally segregated or physically separated using valve interlocks etc. Where
product mixes are handled components shall be designed for the worst/most onerous case (e.g. propane
design pressure and minimum design temperature, relief system capacity, ability to withstand vacuum
conditions etc).
6.5 Fluid velocity
6.5.1 Where the velocity of the gas in the pipe exceeds 10 m/s flow-induced pulsation calculations are
necessary to investigate whether further precautions need to taken to prevent excess noise or erosion. See
EN 15001-1.
6.5.2 Where the velocity of the liquid in the pipe exceeds 5 m/s then further calculations shall be carried
out to see if special precautions against static generation are necessary.
6.6 Aboveground pipework
6.6.1 Clearance above ground
Pipework shall not be laid directly on the ground. Pipework above the ground must have at least a 50 mm
clearance from the finished ground level. Pipework shall be suitably located so as not to cause a trip hazard
and be protected from vehicular damage.
6.6.2 Pipework separation distances from above ground electrical conduit, wire, cable or earthing
electrode
The separation shall be at least 25 mm between any pipework and any above ground:
a) metal electrical conduit;
b) metal-armoured or metal-sheathed electrical wire or cable; or
c) electrical earthing electrode.
6.6.3 Ventilation of concealed piping
Where pipework is to be installed in a void, duct or sleeve all of the following shall apply:
 Ventilation openings are to be provided at each end of the area.
 The openings are to terminate in a safe location.
 Each opening is to have a free ventilation area that complies with table 1.
Table 1 — Ventilation for concealed piping
Cross sectional area of void, duct or sleeve m Minimum free ventilation area of each opening
Not exceeding 0,05 Full cross-sectional area
Exceeding 0,05 but not exceeding 7,5 0,05 m
Exceeding 7,5 0,007 x cross-sectional area of void, duct or sleeve
6.7 Pipe supports
6.7.1 Pipe supports shall comply with all of the following:
a) Be capable of supporting the piping system.
b) To satisfy this requirement consideration needs to be given to:
 the construction and dimensions of the supporting device and its components;
 the method and strength of attachment to the supporting structure as well as the stability of the
supporting structure; and
 the possibility of damage to exposed piping spanning joists or bearers.
c) Firmly restrain the piping in the intended position and control movement of the piping system.
d) Have any component of the supporting system, which is to be in contact with the pipe, made of material
that is compatible with the piping material.
6.7.2 Vibration, surge pressures and valve operating torque shall be considered in the design of pipework
and supports incorporating mechanical equipment such as pumps and valves.
Table 2 — Spacing of pipe supports

Nominal size (DN) Vertical or horizontal run spacing
(mm) (m)
Steel pipe Copper pipe Stainless steel
8 2 1 1
10 2 1.5 1.5
15 2 1.5 1.5
18 - 1.5 1.5
20 2.5 1.5 1.5
25 2.5 2 2
32 3 2.5 2.5
40 3 2.5 2.5
50 3 3 3
65 3 3 3
80 4 4 4
100 5 4 4
125 7 4 4
150 8 4 4
200 9 4 4
6.8 Underground piping
6.8.1 General
When installing underground pipework the following shall be considered:
a) except at the point where the pipe enters a building, pipework shall be located at least 1 m away from any
building or structure.
b) routes shall be chosen to minimise the length of pipe required.
c) buried metallic piping shall have active or passive means of protection (e.g. cathodic protection,
protective coating or wrapping etc.) or shall be inside a buried outer pipe or conduit which terminates
above ground level or in a suitable inspection pit. Provision shall be made to facilitate periodic leak
testing.
d) underground piping shall have a sufficient depth of cover of at least 600 mm or be covered in such a way
as to protect the pipe from physical damage.
e) pipework installed under ground shall be bedded on a firm compacted surface along its entire length.
This requirement is satisfied by the use of 75 mm of sand.
NOTE To satisfy this requirement it may be necessary to trim the trench base to ‘let in’ the fittings, collars or flanges
to ensure the whole length of pipe is evenly supported.

f) Bedding material and backfill shall be of a type which will not have an adverse effect on the pipe or pipe
coating and within 75 mm of the pipe, be free of stones or other materials, which could damage the pipe
or pipe coating.
NOTE For pipe within a pipe systems bedding is not required.
g) Identification warning tape shall be placed at least 150 mm above the top of the pipe.
6.8.2 Pipework separation distances from other underground services
a) 300 mm where the electrical supply cable
b) 500 mm for an electrical earthing electrode, for an electrical supply not exceeding 1 000 volts.
c) 100 mm for a communiation cable.
d) 100 mm for any other service for pipework not exceeding DN 65
e) 300 mm for any other service for pipework exceeding DN 65
6.8.3 Pipework crossover separation distances from other services
Any underground pipework crossing any other service shall:
a) cross at an angle of not less than 45°; and
b) have a vertical separation of not less than 100 mm
6.9 Jointing
6.9.1 Bolted flanged connections shall be used for the first valve connected to the LPG vessel for the liquid
fill, liquid off-take and drain connections. Other connections may be by threaded connections, provided they
are vapour service in 75 mm nominal bore or less, or liquid service in 50 mm nominal bore or less.
6.9.2 For tanker pipework connections up to and including 50 mm nominal bore, or for proprietary items
such as pumps, valves and meters up to 80 mm nominal bore, may be threaded.
6.9.3 Where seals are made on threaded joints they shall meet the requirements of EN 751-1, EN 751-2 or
EN 751-3.
6.10 Flexibility of Piping
6.10.1 All piping shall be designed to allow sufficient flexibility to prevent the following:
 excessive stress in the piping material and attached equipment caused by thermal expansion and
contraction;
 excessive bending or loading at joints, and
 undesirable forces or movements at points of connections to equipment or at anchorage points or guide
points.
This may be achieved by the use of bends loops or offsets formed in the piping system.
6.10.2 Flexible or hose connections shall be as short as possible. Operating conditions shall not exceed the
manufacturers recommendations and shall not be subjected to strain, abrasion, kinking or permanent
deformation.
6.11 Earthing & Bonding
6.11.1 Electrical continuity between pipe sections and earth connection of pipes shall be provided (e.g. by
connecting straps or wires) and the efficiency of this confirmed on a regular basis.
6.11.2 Underground or mounded vessels shall be equipped with a cathodic protection system. The cathodic
protection system shall require electrical isolation of the pipework. Specialist advice on the earthing of
pipework and other equipment shall be provided by competent persons where appropriate.
6.12 Plant piping materials and duty limits for Liquid/vapour phase
Details of plant piping materials are given in Table 3 and 4.
Table 3 – Criteria for pipe - Steel

Operating Acceptable pipe Acceptable fittings Acceptable jointing
limit
(bar) Pipe Limiting conditions Fitting Limiting conditions Method Limiting conditions
≤30
Carbon steel to External corrosion Screwed flange, carbon Not to be used for joining Taper external and Maximum permissible
EN 10208-1 or protection required. steel to EN 1092-1 pipe lengths unless other taper internal threads to nominal size is DN 150.
EN 10255 as joining methods are EN 10226-1, 2 & 3
appropriate impracticable
Not permitted in the External corrosion
ground unless wrapped Seals to EN 751-1, protection required.
ANSI/ASME API 5L with a protective Flanges forming a joint are EN 751-2 and
schedule 40 covering, painted or to be of the same size and EN 751-3.
sheathed or, also, if face type
B31.4 - 2002 buried can be fitted with
cathodic protection, in External corrosion
which case reference
protection required
should be made to
EN 12007-1 and
Only above ground.
EN 12007-3.
Not suitable for use with
Not permitted in the
Steel butt-welded pipe
External corrosion Butt weld to Where welding is to be
ground beneath a
fitting to EN 10253-2
protection required EN 15001-1 carried out, the welder is to
building.
be an authorized person
Socket-welded fittings External corrosion
External corrosion Fillet weld to
such as tee, bend
protection required
protection required EN 15001-1
,reducer and cap to
EN 10253-2
...