CEN/TS 14632:2006

SLOVENSKI STANDARD
01-januar-2007
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Plastics piping systems for drainage, sewerage and water supply, pressure and non-
pressure - Glass-reinforced thermosetting plastics (GRP) based on polyester resin (UP) -
Guidance for the assessment of conformity
Kunststoff-Rohrleitungssysteme für die Entwässerung und Wasserversorgung mit und
ohne Druck - Glasfaserverstärkte duroplastische Kunststoffe (GFK) auf der Basis von
Polyesterharz (UP) - Empfehlungen für die Beurteilung der KonformitätK
Systemes de canalisations en plastique pour les branchements, les collecteurs
d'assainissement et l'alimentation en eau, avec ou sans pression - Plastiques
thermodurcissables renforcés de verre (PRV) a base de résine polyester (UP) - Guide
pour l'évaluation de conformité
Ta slovenski standard je istoveten z: CEN/TS 14632:2006
ICS:
23.040.20 Cevi iz polimernih materialov Plastics pipes
91.140.60 Sistemi za oskrbo z vodo Water supply systems
91.140.80 Drenažni sistemi Drainage systems
93.030 Zunanji sistemi za odpadno External sewage systems
vodo
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL SPECIFICATION
CEN/TS 14632
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
June 2006
ICS 23.040.01; 91.140.60; 91.140.80; 93.030

English Version
Plastics piping systems for drainage, sewerage and water
supply, pressure and non-pressure - Glass-reinforced
thermosetting plastics (GRP) based on polyester resin (UP) -
Guidance for the assessment of conformity
Systèmes de canalisations en plastique pour les Kunststoff-Rohrleitungssysteme für die Entwässerung und
branchements, les collecteurs d'assainissement et Wasserversorgung mit und ohne Druck -
l'alimentation en eau, avec ou sans pression - Plastiques Glasfaserverstärkte duroplastische Kunststoffe (GFK) auf
thermodurcissables renforcés de verre (PRV) à base de der Basis von Polyesterharz (UP) - Empfehlungen für die
résine polyester (UP) - Guide pour l'évaluation de Beurteilung der KonformitätK
conformité
This Technical Specification (CEN/TS) was approved by CEN on 17 December 2005 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.
CEN members are the national standards bodies of Austria, Belgium, 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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 14632:2006: E
worldwide for CEN national Members.

Contents
Page
Foreword.3
Introduction.4
1 Scope.5
2 Normative references .5
3 Definitions and abbreviations.6
3.1 Definitions.6
3.2 Abbreviations.8
4 Requirements .9
4.1 General.9
4.2 Testing and inspection.9
Annex A (informative) Typical statistical methods to compare means and variances.19
A.1 General.19
A.2 Example of comparison of means and variance .19
Annex B (normative) Procedures for dealing with test data provided by the manufacturer and for
witnessed tests in a manufacturer's laboratory .23
B.1 General.23
B.2 Test data provided by the manufacturer.23
B.3 Witnessed tests in a manufacturer's laboratory .23
Annex C (normative) Definitions of changes in material, design and process.24
C.1 General.24
C.2 Change in materials.24
C.3 Change in design.25
C.4 Change in process.26
Annex D (normative) Tests to assess the effects of changes .27
D.1 Tests .27
D.2 Evaluation of test results .27
Annex E (normative) Parameters and criteria for reduced long-term tests (RLTT).29
E.1 General.29
E.2 Reduced long-term test parameters.29
E.3 Other test parameters.31
E.4 Evaluation of results of destructive RLTTs (see E.2.2, E.2.3 and E.2.4) .32
Bibliography.37

Foreword
This Technical Specification (CEN/TS 14632:2006) has been prepared by Technical Committee CEN/TC155
"Plastics piping systems and ducting systems", the secretariat of which is held by NEN.
This Technical Specification can be used to support elaboration of national third party certification procedures for
GRP products (glass-reinforced thermosetting resins based on unsaturated polyesters) to be used in piping
systems for the transport of water, drainage and sewage.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Specification: Austria, Belgium, 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.
Introduction
This Technical Specification covers procedures and requirements for the assessment of conformity of materials,
components, joints and assemblies made from GRP (glass-reinforced thermosetting resins based on unsaturated
polyesters) intended to be used for drainage, sewerage or water supply. Requirements and test methods for
materials, pipes, fittings and joints are specified in the relevant system standards.

1 Scope
This Technical Specification gives guidance for parties involved in the assessment of conformity of piping systems
made from GRP-UP (glass-reinforced thermosetting resins based on unsaturated polyesters) intended to be used
for drainage, sewerage or water supply. It contains procedures for the assessment of conformity to the
requirements in the relevant system standards for materials, pipes, fittings and joints.
NOTE 1 These procedures can be included in the manufacturer’s quality plan as part of his quality system, which should
[1]
conform to EN ISO 9001 or other systems, as applicable.
NOTE 2 This Technical Specification can be included in a quality system subject to third party certification of conformity by a
[2] [3]
certification body that is accredited to EN 45011 or EN 45012 , as applicable.
2 Normative references
The following referenced documents are indispensable for the application of this Technical Specification. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
EN 637, Plastics piping systems  Glass-reinforced plastics components  Determination of the amounts of
constituents using the gravimetric method
EN 681-1, Elastomeric seals — Materials requirements for pipe joint seals used in water and drainage applications
— Part 1: Vulcanized rubber
EN 705:1994, Plastics piping systems  Glass-reinforced thermosetting plastics (GRP) pipes and fittings 
Methods for regression analysis and their use
EN 761, Plastics piping systems  Glass-reinforced thermosetting plastics (GRP) pipes  Determination of the
creep factor under dry conditions
EN 978, Underground tanks of glass-reinforced plastics (GRP)  Determination of factor alpha and factor beta
EN 1119 Plastics piping systems  Joints for glass-reinforced thermosetting plastics (GRP) pipes and fittings 
Test methods for leaktightness and resistance to damage of flexible and reduced-articulation joints
EN 1120, Plastics piping systems  Glass-reinforced thermosetting plastics (GRP) pipes and fittings 
Determination of the resistance to chemical attack from the inside of a section in a deflected condition
EN 1226, Plastics piping systems  Glass-reinforced thermosetting plastics (GRP) pipes  Test method to prove
the resistance to initial ring deflection
EN 1228:1996, Plastics piping systems  Glass-reinforced thermosetting plastics (GRP) pipes  Determination
of initial specific ring stiffness
EN 1393, Plastics piping systems  Glass-reinforced thermosetting plastics (GRP) pipes  Determination of
initial longitudinal tensile properties
EN 1394, Plastics piping systems  Glass-reinforced thermosetting plastics (GRP) pipes  Determination of
initial apparent circumferential tensile strength
EN 1447, Plastics piping systems  Glass-reinforced thermosetting plastics (GRP) pipes  Determination of
long-term resistance to internal pressure
EN 1796:2006, Plastics piping systems for water supply with or without pressure — Glass-reinforced thermosetting
plastics (GRP) based on unsaturated polyester resin (UP)
EN 14364:2006, Plastics piping systems for drainage and sewerage with or without pressure — Glass-reinforced
thermosetting plastics (GRP) based on unsaturated polyester resin (UP) — Specifications for pipes, fittings and
joints
EN ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions (ISO 3126:2005)
ISO 7432, Glass-reinforced thermosetting plastics (GRP) pipes and fittings  Test methods to prove the design of
locked socket-and-spigot joints, including double-socket joints, with elastomeric seals
ISO 8483, Glass-reinforced thermosetting plastics (GRP) pipes and fittings  Test methods to prove the design of
bolted flange joints
ISO 8533, Glass-reinforced thermosetting plastics (GRP) pipes and fittings  Test methods to prove the design of
cemented or wrapped joints
ISO 10468, Glass-reinforced thermosetting plastics (GRP) pipes  Determination of the long-term specific ring
creep stiffness under wet conditions and calculation of the wet creep factor
ISO 10471, Glass-reinforced thermosetting plastics (GRP) pipes  Determination of the long-term ultimate
bending strain and the long-term ultimate relative ring deflection under wet conditions
ISO 14828, Glass-reinforced thermosetting plastics (GRP) pipes  Determination of the long-term specific ring
relaxation stiffness under wet conditions and calculation of the wet relaxation factor
3 Terms, definitions and abbreviations
For the purposes of this Technical Specification, the terms, definitions and abbreviations given in EN 14364:2006
and EN 1796:2006 and the following apply.
3.1 Definitions
3.1.1
certification body
impartial body, governmental or non-governmental, possessing the necessary competence and responsibility to
carry out certification of conformity according to given rules of procedure and management
3.1.2
inspection body
impartial organization or company, approved by a certification body, as possessing the necessary competence to
verify and/or to carry out initial type testing, audit testing and/or inspection of the manufacturer's factory production
control in accordance with the relevant European Standard
3.1.3
testing laboratory
laboratory which measures, tests, calibrates or otherwise determines the characteristics of the performance of
materials and/or products
3.1.4
quality system
organizational structure, responsibilities, procedures, processes and resources for implementing quality
[4]
management (see EN ISO 9000 )
3.1.5
quality plan
document setting out the specific quality practices, resources and sequence of activities relevant to a particular
product or range of products
3.1.6
acceptable quality level
(AQL)
when a continuous series of lots or batches is considered, the quality level which for the purposes of sampling
[5]
inspection is the limit of a satisfactory process average (see ISO 2859-1 and ISO 3951)
NOTE The designation of an AQL does not imply that a manufacturer has the right knowingly to supply any non conforming
unit of product.
3.1.7
preliminary type test
(PTT)
test carried out by or on behalf of the manufacturer to prove that a material, component, joint or assembly is
capable of conforming to the relevant requirement
3.1.8
initial type test
(ITT)
test carried out by or on behalf of a certification body for certification purposes
3.1.9
batch release test
(BRT)
test performed by the manufacturer on a batch of components, which has to be satisfactorily completed before the
batch can be released
3.1.10
reduced long-term test
(RLTT)
test using shorter time periods than those specified for the long-term test. The RLTT results are to be compared to
the results from the long-term test to verify that the current performance of a material or component conforms to the
initially established long-term performance
3.1.11
process verification test
(PVT)
test performed by or on behalf of the manufacturer on materials, components, joints or assemblies at specified
intervals to confirm that the process continues to be capable of producing components conforming to the
requirements given in relevant standards
NOTE Such tests are not required to release batches of components and are carried out as a means of process control.
3.1.12
audit test
(AT)
test performed by, or on behalf of the certification body to confirm that a material, component, joint or assembly
continues to conform to the requirements of the relevant standard and to provide information to assess the
effectiveness of the quality system (see 3.1.4)
3.1.13
witnessed test
(WT)
test accepted by the certification body for initial type testing (ITT) (see 3.1.8) and/or audit testing (AT) (see 3.1.12),
which is carried out by, or on behalf of, the manufacturer and supervised by a representative of the certification
body who is qualified in testing
3.1.14
indirect test
(IT)
test performed by the manufacturer using a different parameter and/or test method from that specified, for which
the correlation with the specified parameter or test has been verified
3.1.15
batch
clearly identifiable collection of units, manufactured consecutively or continuously under the same conditions, using
material conforming to the same specification
3.1.16
lot
clearly identifiable sub-division of a batch for inspection purposes (see 3.1.15)
3.1.17
group
collection of similar components from which samples are selected for testing purposes
3.1.18
sample
one or more units drawn from a batch (see 3.1.15) or a lot (see 3.1.16) selected at random without regard to quality
NOTE The number of units in the sample is the sample size.
3.1.19
inspection level
[5]
relationship between the lot or batch size and the sample size (see ISO 2859-1 )
3.2 Abbreviations
NOTE 1 For reasons of avoiding misunderstanding the following abbreviations are kept the same in each of the languages.
For the same reason the terms are given in the three languages.
NOTE 2 In the French language the abbreviation for "acceptable quality level" (AQL) is NQA, however for the purposes of
this Technical Specification for all three languages the same abbreviation (AQL) is used.
AQL en: acceptable quality level
fr: niveau de qualité‚ acceptable
de: annehmbares Qualitätsniveau
AT en: audit test
fr: essai d'audit
de: Überwachungsprüfung
BRT en: batch release test
fr: essai de libération de campagne de fabrication
de: Freigabeprüfung einer Charge
IT en: indirect test
fr: essai indirect
de: indirekte Prüfung
ITT en: initial type test
fr: essai de type initial
de: Erst-Typprüfung
PTT en: preliminary type test
fr: essai de type préliminaires
de: vorausgehende Typprüfung
PVT en: process verification test
fr: essai de vérification du procédé de fabrication
de: Prozessüberprüfung
RLTT en: reduced long-term test
fr: essai à long terme écourté
de: verkürzte Langzeitprüfung
WT en: witnessed test
fr: essai de témoins
de: beaufsichtigte Prüfung
4 Requirements
4.1 General
4.1.1 The materials, pipes, fittings and joints shall conform to the requirements in the referring standard taking
into account the applicable AQL. The quality plan shall show how an AQL of 6,5 % will be achieved.
4.1.2 Pipes, fittings and joints shall be produced by the manufacturer under a quality system including a quality
plan.
4.2 Testing and inspection
4.2.1 General
4.2.1.1 Records of inspection and test
Records should be maintained for a minimum of ten years or as required by national regulations.
4.2.1.2 Indirect testing
Generally, testing shall be performed according to the test method referred to in the relevant standard. Indirect
testing may be used for the BRT and PVT characteristics as indicated in 4.2.3.1 and 4.2.3.2. Indirect testing shall
not be applied to type testing. The correlation or safe relationship of the indirect testing to the specified testing shall
be documented in the manufacturer's quality plan and if third party certification is involved the IT shall be accepted
by the certification body. The continuing validity of the indirect testing shall be checked at regular intervals. In cases
of dispute the test methods referred to in the relevant standard shall be used for BRT or PVT, using RLTT where
applicable.
4.2.1.3 Testing classification
In the relevant standard, reference is made to type tests and quality control tests. These are classified as follows:
a) type tests:
1) preliminary type tests (PTT);
2) initial type tests (ITT);
3) audit tests (AT).
b) quality control tests:
1) batch release tests (BRT);
2) process verification tests (PVT).
4.2.1.4 Sampling
4.2.1.4.1 General
Where different concepts of design or production are used then these are different products and shall be treated
separately.
4.2.1.4.2 Sampling for type testing
For type test purposes (see 4.2.1.3 and 4.2.2) samples shall be obtained from type test groups defined by the
conditions in Table 1.
Table 1 — Groups for type test purposes
Group Limitation of groups
1 100 ≤ DN < 600
0,5
2 DN ≥ 600 and DN × PN ≤ 3 800
0,5
3 DN ≥ 600 and DN × PN > 3 800

If, when using the above groupings, there is only one product in a type test group then that product may be
included in an adjacent group.
When two or more type test groups are manufactured the full range of long-term type tests (see Table 3 and
Table 4) shall be performed on products from one group. The other type test group(s) may be covered by RLTT.
Grouping does not apply to joints (see Table 4).
4.2.1.4.3 Sampling for quality control testing
For quality control test purposes samples shall be obtained from either groups or individual products. A quality
control group consists of a range of:
 diameter (DN)
 stiffness (SN)
 pressure class (PN)
An individual product consists of
 a particular diameter
 having a particular stiffness
 and a particular pressure class
When quality control grouping is used, the manufacturer shall document his grouping system based on his process
and production activity. The grouping plan shall assure that over an extended period of time, as defined by the
manufacturer in his quality plan, all products produced are sampled.
4.2.1.5 Sample size and sampling rate
The sample size to be used for either of the testing classes in 4.2.1.4 is detailed in the relevant standard when the
characteristic is specified. For batch release testing the sampling size and sampling rate shall conform to the
requirements detailed in 4.2.3.1.
4.2.2 Type tests
4.2.2.1 General rules
Type tests shall be conducted in accordance with the requirements and rules given in Annex B and, as applicable,
the requirements given in 4.2.2.2 to 4.2.2.5 inclusive.
4.2.2.2 Preliminary type testing (PTT)
The manufacturer shall demonstrate conformance to the characteristics given in Table 2, Table 3 and Table 4 that
require PTT. In addition, the relevant preliminary type test(s) are to be carried out by the manufacturer whenever
there is a change, other than routine in-process adjustments, in material, design or process (see Annex C).
Reduced long-term tests as detailed in 4.2.2.5 may be used for satisfying the preliminary type test requirements.
The characteristics listed in Table 2, Table 3 and Table 4 shall be tested using sample sizes meeting the
requirements for type tests in the relevant standard.
Table 2  Characteristics for preliminary (PTT) and initial type test (ITT) —
Characteristics covered by a certificate of conformity to the pipe-
manufacturer's specification from the material producer
General
Characteristic Sampling requirements for ITT
Reinforcements
Thermosetting resins
Fillers
Aggregates Not applicable
Thermoplastic liners
Elastomers
Metals
Table 3  Characteristics for preliminary (PTT) and initial type test (ITT) —

Characteristics declared by the manufacturers
Design
a
Characteristic Sampling requirements for ITT
Wall construction Not applicable
Wall thickness Not applicable
a
The wall construction (the sequence and composition of the individual layers comprising the pipe wall) shall be
documented by the manufacturer. The manufacturer shall translate the product design into detailed process

specifications to control the amount and placement of materials components.

Table 4  Characteristics for preliminary (PTT) and initial type test (ITT) -
Characteristics verified by test
Characteristic Test method Sampling Requirements for ITT
Pipes
Specified diameters EN ISO 3126
a
Dry creep factor EN 761
Three samples per group
Wall thickness EN ISO 3126
Length EN ISO 3126
Initial specific ring stiffness EN 1228
Creep or relaxation factor under wet conditions ISO 10468 or
RLTT on one DN
ISO 14828
a
α and β factors EN 978 Three samples per group
Resistance to initial ring deflection EN 1226 Three samples per group
Resistance to long-term ultimate ring deflection ISO 10471 RLTT on one DN
Initial longitudinal tensile properties EN 1393 Three samples per group
Initial failure pressure EN 1394 Three samples per group
Long-term failure pressure EN 1447 RLTT on one DN
Resistance to strain corrosion for sewer pipe only EN 1120 RLTT on one DN
Fittings
Fittings general
b
Mechanical characteristics of fittings See RLTT and grouping according to
Table 1
b
Long-term chemical resistance of fittings for sewer See RLTT on one DN
application only
Bends
Fitting angle and angular tolerances EN ISO 3126
Length EN ISO 3126
Branches
Length EN ISO 3126
Reducers One component to be tested
Wall thickness EN ISO 3126
Length EN ISO 3126
Flanged adaptors
Wall thickness EN ISO 3126
Length EN ISO 3126
Joints
Flexible joints with elastomeric sealing components EN 1119
c
Locked socket and spigot joints with elastomeric sealing ISO 7432
components
One joint per design
c
Wrapped and cemented joints ISO 8533
c
Bolted flange joints ISO 8483
a
These characteristics are not required by the system standards, but are necessary to assess changes.
b
When a manufacturer makes fittings using pipes of the same classification with which the fittings are to be used, the initial and preliminary
type tests for the pipes covering mechanical and chemical characteristics cover these fittings.
c
An alternate bending test procedure for evaluating joints capable of bearing end trust loading is given in EN 1796 and EN 14364.

4.2.2.3 Permitted special procedure
Where a factory, factory A, uses the same manufacturing procedures, raw materials and design (see Annex C) as
another factory, factory B, then data from factory B may be used by factory A to demonstrate conformity to the
long-term properties subject to all the following conditions:
a) the data provided by factory B fulfil the conditions in 4.2.2.1 and factory A performs RLTT (see 4.2.2.6) to
confirm that both factories products have the same long-term properties;
b) if a third party certifying body is involved it shall be informed prior to conducting the RLTT that these
procedures are being used to satisfy the PTT requirements.
The procedures detailed in this clause can be applied to PTT (see 4.2.2.2.) and AT (see 4.2.2.5), but not quality
control tests (see 4.2.3).
4.2.2.4 Initial type testing (ITT)
If third party certification is involved, the certification body shall assess the conformity of the range of products to be
covered by the certificate to the applicable requirements for the characteristics given in Table 2, Table 3 and
Table 4 and the applicable declarations made by the manufacturer.
The assessment shall be performed by validation or testing in an approved testing laboratory or by witnessed
testing.
Validated preliminary type test (PTT) data, including long-term characteristics, supplied by the manufacturer and
traceable to material and process, shall be considered to meet the requirements for initial type testing (ITT) (see
Annex B).
4.2.2.5 Audit tests (AT)
Those characteristics specified in the relevant standard, and listed in Table 5 are intended to be audit tested at the
minimum sampling frequency as given in Table 5.
Samples should be taken from one group. Where possible the classes selected for tests should be primarily those
which have not previously been subject to audit testing.
When a manufacturer makes fittings using pipes of the same classification with which the fittings are to be used the
audit test for the pipes covering mechanical and chemical characteristics cover these fittings. Where tests have
been witnessed during routine inspections additional tests for audit purposes will not be required.
Reduced long-term tests as detailed in 4.2.2.6 may be used for satisfying the relevant audit test requirements, as
well as proving that products still conform to the original specifications. Reduced long-term tests can thus be used
as a comparison with existing long-term data, but not as a basis for a new design.
Table 5 — Characteristics and minimum sampling frequencies for AT
Characteristic Minimum sampling frequency
General
Wall construction (content of glass plus resin) Once/year

Pipes
Specified diameters
Wall thickness
Once/year
Length
Initial specific ring stiffness
NOTE 3
Creep or relaxation under wet conditions Once/2 years
Resistance to initial ring deflection Once/year
NOTE 3
Resistance to long-term ultimate ring deflection Once/5 years
NOTE 3
Initial longitudinal tensile properties
Once/year
NOTE 1
Initial failure pressure
NOTE 3
Long-term failure pressure Once/3 years
Resistance to strain corrosion for sewer pipe Once/5 years

Fittings
NOTE 3
Mechanical characteristics of fittings Once/year
Long-term chemical resistance of fittings Once/5 years
Bends
Fitting angle and angular tolerances
Once/2 years
Length
Branches
Length Once/2 years
Reducers
Wall thickness
Once/2 years
Length
Flanged adaptors
Wall thickness
Once/2 years
Length
a
Joint performance
Flexible joints with elastomeric sealing components
Locked socket and spigot joints with elastomeric sealing components
See NOTE 2
Wrapped and cemented joints
Bolted flange joints
NOTE 1 When a manufacturer makes fittings using pipes of the same classification with which the fittings are to be used, the
tests for the pipes covering mechanical and chemical characteristics also cover fittings.
NOTE 2 Joint types manufactured infrequently need only be audit tested once every five years or when manufactured
whichever is the longer period.
NOTE 3 Sampling according to 4.2.1.4.2 should be carried out.
NOTE 4 The test frequencies for pipes are not related to the group because not all of the possible groups may be produced. In
such circumstances the audit tests can only apply to groups that have been produced. Where tests have been witnessed during
routine inspections additional tests for audit purposes will not be required.
NOTE 5 The sizes, types and classes selected for tests should be primarily those which have not previously been selected for
audit testing. Samples should be preferably taken from the largest volume of production per group. When selecting the sizes to
be tested the availability and costs of the equipment for the long-term tests should be considered.
NOTE 6 For manufacturers with limited production and infrequent changes the frequency can be reconsidered.

a
Only the joint type most commonly used by a manufacturer may be subject to audit testing. Audit tests covering the joint
profiles most commonly used shall be witnessed over a period of five years.

4.2.2.6 Reduced long-term tests (RLTT)
Those characteristics that can be subject to reduced long-term tests to show conformance to the long-term test
requirements are detailed in Table 6.
The reduced long-term test procedures and parameters together with the applicable consequences are given in
Annex E.
Table 6 — Characteristics that can be subject to RLTT
Characteristic
Pipes
Resistance to long-term ultimate ring deflection
Long-term failure pressure
Resistance to strain corrosion
a
Fittings
Mechanical characteristics of fittings
Long-term chemical resistance of fittings
a
When a manufacturer makes fittings using pipes of the same classification with which
the fittings are to be used, the tests for the pipes covering mechanical and chemical
characteristics also cover these fittings.

4.2.3 Quality control tests
4.2.3.1 Batch release tests (BRT)
4.2.3.1.1 Procedure
The manufacturer shall describe in his quality plan the limits used to define a batch for testing purposes.
Samples for BRT can be obtained randomly from a pre-manufactured batch, periodically from a continuous
production or other appropriate method, depending on the manufacturing process. At least 1 % of the production
shall be sampled for testing the characteristics detailed in Table 7.
Table 7 — Characteristics for BRT
Characteristic
Pipes
Specified diameters
Wall thickness
Length
Initial specific ring stiffness
Resistance to initial ring deflection
Initial failure pressure (for pressure pipe only)
Initial longitudinal tensile properties
Fittings
Bends
Fitting angle and angular tolerances
Length
Branches
Length
Reducers
Wall thickness
Length
Flanged adaptors
Wall thickness
Length
Joint performance
All joint types
Dimensions
A batch can be released for supply when all the relevant tests and inspections have been carried out and the
requirements have been met. If one or more items fail one or more tests or inspections, then the retest procedures
detailed in 4.2.3.1.2 shall be performed.
4.2.3.1.2 Retesting procedures
4.2.3.1.2.1 General
The manufacturer’s quality plan shall include a rejecting/retesting procedure to deal with non-conformities.
In the event of non-conformity with one or more characteristic(s) the following procedures apply:
4.2.3.1.2.2 When using random sampling
Retest procedures such as those detailed in ISO 2854 or ISO 3951 shall be followed. If one or more items fail then
the batch shall be rejected and the procedures detailed in 4.2.3.1.3 shall be followed.
4.2.3.1.2.3 When using periodic sampling
Find the last product, which conforms to the requirements. Release all products produced before that point and
reject all produced after that point. Alternatively the procedures detailed in 4.2.3.1.3 shall be followed.
4.2.3.1.2.4 When using other sampling methods
A procedure based on similar logic to that described in 4.2.3.1.2.2 or 4.2.3.1.2.3 shall be established.
4.2.3.1.3 Procedure to be followed when a batch or lot is rejected
When a batch or lot is rejected one of the following actions shall be taken:
a) the batch or lot shall be scrapped;
or
b) all items in the batch or lot shall be subjected to the test or tests that were failed and only those that pass shall
be released;
or
c) the batch or lot shall be reclassified into a class where the results of the tests meet the requirements of that
class.
4.2.3.2 Process verification tests (PVT)
The manufacturer shall detail in his quality plan a verification procedure of such a nature and of such a frequency
as to ensure, with reasonable probability, that the long-term properties are maintained. The frequency of these
tests shall complement the frequency of the audit tests, if applicable.
The purpose of PVT tests is to assess the conformity of the long-term properties of the product. The characteristics
listed in Table 8 shall be addressed. Test methods referred to in the relevant standard or indirect tests and
observations shall be used (see 4.2.1.2). Indirect tests and observations may include alternate accelerated tests or
continuous verification of the detailed process specifications (see Table 3 – Footnote). Combination of tests that
are indicative of the same property can be considered.
Where the long-term properties are verified according to the test methods referred to in the relevant standard,
RLTT is recommended when establishing the PVT procedures for use in the manufacturer’s quality plan.
If third party certification is involved, the appropriate procedure shall be agreed upon with the certification body.
When the results from a PVT show non-compliance then the process shall be investigated and corrected and the
retest procedures detailed in the manufacturer's quality plan shall be performed. If third party certification is
involved then the certification body shall be informed.
Table 8 — Characteristics for PVT
Characteristic
General
Wall construction (content of glass plus resin)
Pipes
α and β factors
Resistance to long-term ultimate ring deflection
Long-term failure pressure
Resistance to strain corrosion for sewer pipes
Fittings
Mechanical characteristics of fittings
Long-term chemical resistance of fittings
a b
Joint performance
Flexible joints with elastomeric sealing components
Locked socket and spigot joints with elastomeric sealing components
Wrapped and cemented joints
Bolted flange joints
a
Only the joint type most commonly used by a manufacturer may be subject to PVT. PVT covering the
joint profiles most commonly used shall be performed over a period of five years.
b
Joint types manufactured infrequently need only be subjected to PVT once every five years or when
manufactured whichever is the longer period.

Annex A
(informative)
Typical statistical methods to compare means and variances
A.1 General
When considering the possibility of combining two or more groups it is necessary to check two parameters, namely
whether the means can be considered as equal and also whether the variances can be considered as equal. For
the combination of groups to be allowed both of these parameters have to be satisfied. There may be some tests
where they are not satisfied and others where they are. Combination of groups can only be used with the tests
where these conditions are satisfied.
In addition to the consideration of modifying the grouping these procedures may be used when it is required to
verify that these properties are not significantly different between two different sets of test data.
The procedures to use to check whether x = x (where x is either the mean or the variance) are detailed in many
1 2
[6]
standard textbooks and in standards such as ISO 2854 and ISO 3494 . When using such tests the two sided test
condition should be used because one is testing that the values are neither greater nor smaller than each other, i.e.
they are equal. The typical test to compare variances is the F test though other tests are available. Similarly the
Student's t test is often used to check the equality of means though other tests are available.
Examples in A.2 can be used to evaluate software.
A.2 Example of comparison of means and variance
To calculate the mean value of a set of data use equation (A.1) and for the variance of the same set of data use
Equation (A.2).
Present equations as follows:
X
∑ i
Sample Mean: X = …(A.1)
n
Sample Variance :V =()X − X ()n −1 …(A.2)
∑ i
where
X is one individual value of the data set;
i
X is the mean of the set of data;
n is the number of data in the set;
V is the variance of the set of data.
Example
The stiffness of two sizes of pipe, each of the same nominal stiffness, SN 10000, were measured with the following
results. Is there any significance in the difference between the means?

SAMPLE 1 STIFFNESS DEVIATION = X -X (DEVIATION)

i 1
10400 -1260 1587600
11200 -460 211600
11800 140 19600
12600 940 883600
12300 640 409600
11680 20 400
10890 -770 592900
11450 -210 44100
11980 320 102400
12300 640 409600
Total 116600 0 4261400
Sample Mean X =    11660
Sample SD  σ =      688
SAMPLE 2 STIFFNESS DEVIATION = X -X (DEVIATION)

i 2
10500 -608 369664
10700 -408 166464
11300 192 36864
12100 992 984064
11600 492 242064
10890 -218 47524
10300 -808 652864
11150 42 1764
11100 -8 64
11440 332 110224
Total 111080 0 2611560
Sample Mean X =   11108
Sample SD  σ =    539
Before the means are compared using the t test the two estimates of the variance should be checked to verify that
the assumption that the two samples are drawn from the same population and hence that the two estimates of
variance are not significantly different. This is verified by means of the F test using Equation (A.3).
()largest  variance()largest SD
F = = …(A.3)
()smallest variance
()smallest SD
()688
For the data F = = 1,62929
()539
The number of degrees of freedom of the two samples is n-1 which in both cases is 10 – 1 = 9.
The calculated value of F is compared with tabulated values such as those in Table A.1. The tabulated value for
the 9 and 9 degrees of freedom is 3,18. As the calculated value is lower than this then at the 5 % level of
significance the differences between the variances is not significant and hence the two samples can be considered
to have been drawn from the same population.
Table A.1 — Distribution of variance ratio F (5 % level of significance)
...