Buried, high-impact poly(vinyl chloride) (PVC-HI) piping systems for the supply of gaseous fuels

ISO 6993-4:2006 specifies a code of practice for the design, handling and installation of high-impact poly(vinyl chloride) (PVC-HI) pipes and fittings intended to be used for the supply of gaseous fuels through buried pipelines having an operating temperature range of 0 degrees Celsius up to and including +30 degrees Celsius and a maximum operating pressure of 1 bar (100 kPa).

Systèmes de canalisations enterrées en poly(chlorure de vinyle) à résistance au choc améliorée (PVC-HI) pour réseaux de combustibles gazeux

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Published
Publication Date
13-Jun-2006
Current Stage
9060 - Close of review
Start Date
04-Jun-2020
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INTERNATIONAL ISO
STANDARD 6993-4
First edition
2006-06-01
Buried, high-impact poly(vinyl chloride)
(PVC-HI) piping systems for the supply of
gaseous fuels —
Part 4:
Code of practice for design, handling and
installation
Systèmes de canalisations enterrées en poly(chlorure de vinyle) à
résistance au choc améliorée (PVC-HI) pour réseaux de combustibles
gazeux —
Partie 4: Code de pratique pour la conception, la manutention et
l'installation
Reference number
ISO 6993-4:2006(E)
ISO 2006
---------------------- Page: 1 ----------------------
ISO 6993-4:2006(E)
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© ISO 2006

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ii © ISO 2006 – All rights reserved
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ISO 6993-4:2006(E)
Contents Page

Foreword............................................................................................................................................................ iv

Introduction ........................................................................................................................................................ v

1 Scope ..................................................................................................................................................... 1

2 Normative references ........................................................................................................................... 1

3 Terms and definitions........................................................................................................................... 2

4 Design .................................................................................................................................................... 4

5 Installation ............................................................................................................................................. 7

6 Storage, handling and transportation............................................................................................... 14

7 Quality control..................................................................................................................................... 15

Bibliography ..................................................................................................................................................... 17

© ISO 2006 – All rights reserved iii
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ISO 6993-4:2006(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 6993-4 was prepared by Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for the

transport of fluids, Subcommittee SC 4, Plastics pipes and fittings for the supply of gaseous fuels.

This first edition of ISO 6993-4, together with ISO 6993-1, ISO 6993-2 and ISO 6993-3, cancels and replaces

ISO 6993:2001, of which it constitutes a technical revision.

ISO 6993 consists of the following parts, under the general title Buried, high-impact poly(vinyl chloride)

(PVC-HI) piping systems for the supply of gaseous fuels:
⎯ Part 1: Pipes for a maximum operating pressure of 1 bar (100 kPa)
⎯ Part 2: Fittings for a maximum operating pressure of 200 mbar (20 kPa)

⎯ Part 3: Fittings and saddles for a maximum operating pressure of 1 bar (100 kPa)

⎯ Part 4: Code of practice for design, handling and installation
iv © ISO 2006 – All rights reserved
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ISO 6993-4:2006(E)
Introduction

This part of ISO 6993 addresses the common basic principles for gas supply systems. Its users need to be

aware that more detailed national standards and/or codes of practice might exist in the ISO member countries

and that these will take precedence over this part of ISO 6993, which is intended to be applied in association

with those national standards and/or codes of practice related to the above-mentioned basic principles.

© ISO 2006 – All rights reserved v
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INTERNATIONAL STANDARD ISO 6993-4:2006(E)
Buried, high-impact poly(vinyl chloride) (PVC-HI) piping
systems for the supply of gaseous fuels —
Part 4:
Code of practice for design, handling and installation
1 Scope

This part of ISO 6993 specifies a code of practice for the design, handling and installation of high-impact

poly(vinyl chloride) (PVC-HI) pipes and fittings intended to be used for the supply of gaseous fuels through

buried pipelines having an operating temperature range of 0 °C up to and including +30 °C and a maximum

operating pressure of 1 bar (100 kPa) .

The code of practice covers mains and service lines, and gives provisions for the design, installation, storage,

handling, transportation and quality control of PVC-HI pipes and fittings up to and including an outside

diameter of 400 mm, as well as backfilling, pipe system testing and commissioning.

The pipes and fittings are suitable for those gases which do not contain potentially damaging components in

such concentrations as to impair the properties of the pipe/fitting material.
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.

ISO 4437:1997, Buried polyethylene (PE) pipes for the supply of gaseous fuels — Metric series —

Specifications

ISO 6993-1, Buried, high-impact poly(vinyl chloride) (PVC-HI) piping systems for the supply of gaseous

fuels — Part 1: Pipes for a maximum operating pressure of 1 bar (100 kPa)

ISO 6993-3, Buried, high-impact poly(vinyl chloride) (PVC-HI) piping systems for the supply of gaseous

fuels — Part 3: Fittings and saddles for a maximum operating pressure of 1 bar (100 kPa)

ISO 7005 (all parts), Metallic flanges

ISO 7387-1:1983; Adhesives with solvents for assembly of PVC-U pipe elements — Characterization —

Part 1: Basic test methods

ISO 8085 (all parts), Polyethylene fittings for use with polyethylene pipes for the supply of gaseous fuels —

Metric series — Specifications

EN 682:2002, Elastomeric seals — Material requirements for seals used in pipes and fittings carrying gas and

hydrocarbon fluids

EN 12327:2000, Gas supply systems — Pressure testing, commissioning and decommissioning

procedures — Functional requirements
5 2
1) 1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm
© ISO 2006 – All rights reserved 1
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ISO 6993-4:2006(E)
3 Terms and definitions

For the purposes of this document, the following terms and definitions and symbols apply.

3.1
clearance
shortest distance between the outer limits of two objects
3.2
design pressure
pressure on which design calculations are based
3.3
gas supply system

pipeline systems, including pipe work and their associated stations or plants, for the transmission and

distribution of gas
3.4
nominal outside diameter

numerical designation of size which is common to all components in a thermoplastics piping system other than

flanges and components designated by thread size
NOTE It is a convenient round number for reference purposes.

NOTE For metric pipes conforming to ISO 161-1, the nominal outside diameter, expressed in millimetres, is the

minimum mean outside diameter d .
em,min
3.5
nominal wall thickness

numerical designation of the wall thickness of a component, approximately equal to the manufacturing

dimension
NOTE 1 It is a convenient round number for reference purposes.
NOTE 2 It is expressed in millimetres (mm).
3.6
main

pipework in a gas supply system to which a number of gas consumers are connected via service lines

3.7
out-of-roundness

difference between the measured maximum outside diameter and the measured minimum outside diameter in

the same cross-sectional plane of the pipe
3.8
maximum operating pressure
MOP

maximum effective pressure of the gas in a piping system, expressed in bars, which is allowed in continuous

use

NOTE 1 It takes into account the physical and the mechanical characteristics of the components of the piping system.

NOTE 2 The MOP is given by the equation:
20×MRS
MOP=
C×−(SDR 1)
2 © ISO 2006 – All rights reserved
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ISO 6993-4:2006(E)
where
MRS is the minimum required strength (see ISO 6993-1);
SDR is the standard dimension ratio.
3.9
standard dimension ratio
SDR

numerical designation of a pipe series, which is approximately equal to the ratio of the nominal outside

diameter, d , to the nominal wall thickness, e :
n n
SDR=
NOTE It is a convenient round number for reference purposes.
3.10
pipeline components

elements from which a pipeline is constructed including, in PVC-HI pipeline systems, the distinct elements of

straight pipes, fittings and ancillaries

EXAMPLE 1 Fittings: socket joint, saddle, reducer, tee, factory-made bend/elbow, end-cap.

EXAMPLE 2 Ancillaries: valve, flange.
3.11
installer

trained person authorized by the pipeline operator to assemble PVC-HI systems from pipes and fittings, based

on a written procedure agreed by the pipeline operator
3.12
overall service [design] coefficient

overall coefficient with a value greater than 1, which takes into consideration service conditions as well as

properties of the pipeline components
3.13
pipeline operator

private or public organization responsible for the design, construction, operation and maintenance of a gas

supply system
3.14
service line
pipework in a gas supply system that connects a gas consumer with a main
3.15
depth of cover

vertical distance between the top of a buried pipe and the normal surface after finishing work

3.16
high-impact poly(vinyl chloride)
PVC-HI
mixture of unplasticized PVC and an impact-resistance modifier
© ISO 2006 – All rights reserved 3
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ISO 6993-4:2006(E)
4 Design
4.1 General

Written laying procedures, authorized by the pipeline operator, shall be made available prior to the

construction of a pipeline. The laying procedure shall include specification of the pipe and fitting materials to

be used, the trenching and backfilling requirements, the pressure testing and commissioning procedures.

The selection of materials, SDR series, dimensions and assembly techniques shall be the responsibility of the

pipeline operator.

It is an established practice in PVC-HI distribution systems to construct service lines in polyethylene in order

to take advantage of the natural flexibility of this material.
4.2 Materials and components

The maximum operating pressure (MOP) for PVC-HI gas supply systems is 1 bar (100 kPa). Pipes shall meet

the requirements of ISO 6993-1. The most commonly used SDR values are 41 and 33. For specific

applications, other SDR values can be taken from all series stated in ISO 4065 and ISO 161-1.

Assembly techniques in systems with a MOP above 200 mbar (20 kPa) and up to and including 1 bar

(100 kPa) shall be of the end thrust type in accordance with ISO 6993-3.

For systems with a MOP up to and including 200 mbar (20 kPa) both the end thrust type assembly or the

push-in type of fittings in accordance with ISO 6993-2 may be used.

Rubber parts for other components shall be in accordance with EN 682:2002, type G. Polyethylene service

line materials shall be in accordance with ISO 4437 and the relevant part of ISO 8085.

Other components not covered by the above-mentioned International Standards shall conform to the relevant

International Standards or national standards, and/or national or international specifications.

4.3 Assembly techniques
4.3.1 Slip-on socket joints (for gas supply systems with MOP u 20 kPa)

Because of the relatively low operating pressure, the joints in PVC-HI gas supply systems with a MOP up to

and including 200 mbar (20 kPa) do not normally need to be tensile-resistant. In special situations, provision

shall be made to prevent pipes from sliding out of the sockets by using external clamps or anchors.

Socket joints consist of a spigot (end) and a PVC-HI socket, in which gas tightness is achieved by the use of a

rubber ring, tightened between the spigot and the socket. Distinction is made between sockets with, and those

without, a stop shoulder or dead stop (see Figure 1).
Tees, reducers and elbows also may bear socket joints or have spigot ends.
4.3.2 Solvent-cement socket joints

Solvent cement is used to effect a seal between close-fitting spigots and sockets. The resulting joint is

end-load bearing.
4.3.3 Tapping saddles
Tapping saddles are used for connecting service lines to a main (see Figure 2).
4 © ISO 2006 – All rights reserved
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ISO 6993-4:2006(E)
a) Socket joint b) Sleeve joint
Figure 1 — Straight socket joints
Key
1 sealing cap 5 main
2 upper half of saddle 6 lower half of saddle
3 clamp 7 rubber seal
4 wedge 8 O-ring
Figure 2 — Tapping saddle with PE service line
4.3.4 Bag stopper saddles

Bags stoppers are used for temporarily stopping the gas stream, thereby making it possible to work on the

pipe system without gas pressure. A bag is inserted in the pipe via a bag stopper saddle, and then inflated by

means of a hand pump (see Figure 3). When the work is done, the bag stopper is deflated and removed, after

which the saddle is sealed with a cap.
© ISO 2006 – All rights reserved 5
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ISO 6993-4:2006(E)
Figure 3 — Insertion of bag stopper via bag stopper saddle
4.3.5 Mechanical joints for ancillaries

Joints of this type are assembled in a mechanical way, whereby gas tightness is achieved by compression

using a rubber ring, see, for example, Figure 4.

Other types of mechanical jointing systems exist. The manufacturer’s instructions shall be followed at all times.

Mechanical jointing systems also include metal-to-PVC-HI transition fittings.
Figure 4 — Mechanical metal joints
4.3.6 Flange joints for ancillaries
Flanged joints shall comply with ISO 7005.
6 © ISO 2006 – All rights reserved
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ISO 6993-4:2006(E)
5 Installation
5.1 Assembly procedures

All joints shall be assembled in accordance with the manufacturer’s written instructions.

5.2 Training

The installer shall be competent in the appropriate laying and jointing of the pipes. He/she shall possess the

necessary skill and knowledge to produce good quality work. Installers shall receive formal training under the

supervision of a qualified instructor. The pipeline operator may require a certificate indicating that he/she has

attained an adequate standard of competence in accordance with national or local regulations.

5.3 Jointing of systems
5.3.1 Slip-on socket joints MOP u 20 kPa

PVC-HI pipes for low pressure systems are typically supplied with bevelled ends. These pipe ends need

therefore not be treated any further. Pipe sections can be cut to length using a fine-tooth saw or a

special-purpose cutter, see Figure 5.

The pipe end shall be squared off. In the case of sawing it is advisable to use a mitre box. After sawing, the

pipe end is bevelled off using a file or a special-purpose bevelling tool (see Figure 6).

Figure 5 — Special-purpose cutter for plastics pipes Figure 6 — Special-purpose bevelling tool

Burrs, if any, shall be removed. If the pipe is bevelled off with a file, it is important to use approximately the

same bevel angle as that of the factory-supplied pipe. Blunt edges can damage the rubber sleeve.

Before making the joint, it is checked that the inside and outside of the pipe, the socket and the rubber sleeve

are free from dirt. In doing so, special attention shall be paid to the back of the sleeve. If necessary, the parts

shall be cleaned.

A lubricant specified by the pipe and socket manufacturer is applied evenly on the pipe ends and socket.

Measures shall be taken to prevent sand or other impurities from sticking to the lubricant and from entering

the joint. Consequently, the joint shall be made off the ground, for instance by putting blocks under the pipes.

© ISO 2006 – All rights reserved 7
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ISO 6993-4:2006(E)

The socket is slid over the pipe up to the stop shoulder or dead stop. In the case of larger diameters, a lever

can be used to apply the required force (see Figure 7). The socket shall be protected from damage by the

placing of a wooden block between the socket
...

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