Imperfections in thermoplastics welded joints - Quality levels

This document specifies quality levels for imperfections in thermoplastics welded joints that have cooled to ambient temperature and is applicable to material thickness above 2,0 mm.
Three quality levels are specified in order to permit application for a wide range of welded fabrication. They are designated by symbols B, C and D, where B is the most stringent. The quality levels refer to production quality and not to the fitness-for-purpose (see 3.2) of the manufactured product.
The quality level necessary are expected to be defined by the application standard or by the fabricator in conjunction with the user and/or other parties concerned. The level is expected to be prescribed before the start of production, preferably at the enquiry or order stage.
This document applies to the following thermoplastic materials in Table 1:
and to the following welding processes:
-   heated tool welding;
-   electrofusion socket welding;
-   hot gas welding using filler rod only;
-   extrusion welding;
-   solvent welding of pipes.

Unregelmäßigkeiten an Schweißverbindungen von thermoplastischen Kunststoffen - Qualitätsstufen

Dieses Dokument legt Qualitätsstufen für Unregelmäßigkeiten an Schweißverbindungen von thermo-plastischen Kunststoffen fest, die auf Umgebungstemperatur abgekühlt sind, und gilt für Materialdicken über 2,0 mm.
Um eine Anwendung für eine große Auswahl von Schweißerzeugnissen zu ermöglichen, sind drei Qualitäts¬stufen festgelegt. Diese sind durch Symbole B, C und D gekennzeichnet, wobei B die höchste Qualitätsstufe ist. Die Qualitätsstufen beziehen sich auf die Fertigungsqualität und nicht auf die Gebrauchstauglichkeit (siehe 3.2) des hergestellten Produkts.
Es wird davon ausgegangen, dass die für den jeweiligen Fall erforderliche Qualitätsstufe durch die Anwendungsnorm oder vom Hersteller zusammen mit dem Anwender und/oder sonstigen Parteien festgelegt wird. Es wird davon ausgegangen, dass die Qualitätsstufe vor dem Fertigungsbeginn, vorzugs-weise bei der Anfrage oder Bestellung, festgelegt wird.
Dieses Dokument gilt für die folgenden thermoplastischen Materialien in Tabelle 1:
und die folgenden Schweißverfahren:
-   Heizelementschweißen;
-   Heizwendelmuffenschweißen;
-   Warmgasschweißen, ausschließlich unter Anwendung von Schweißstab;
-   Extrusionsschweißen;
-   Quellschweißen von Rohren.

Défauts dans les assemblages soudés en thermoplastiques - Niveaux de qualité

Le présent document spécifie les niveaux de qualité pour les défauts des assemblages soudés en thermoplastiques qui ont refroidi à la température ambiante et s'applique aux matériaux présentant une épaisseur supérieure à 2,0 mm.
Trois niveaux de qualité sont spécifiés afin de permettre l'application à une large gamme d'assemblages soudés. Ils sont désignés par les symboles B, C et D, B étant le niveau le plus contraignant. Les niveaux de qualité s'appliquent à la qualité de la production et non pas à l'aptitude à l'emploi (voir 3.2) du produit fabriqué.
Le niveau de qualité nécessaire devrait être défini par la norme d'application ou par le fabricant en collaboration avec l'utilisateur et/ou d'autres parties concernées. Le niveau est supposé être prescrit avant le démarrage de la production, de préférence au moment de la consultation ou de la commande.
Le présent document s'applique aux matériaux thermoplastiques suivants dans le Tableau 1:
et aux procédés de soudage suivants :
-   soudage par outil chauffant ;
-   soudage par emboîture électrosoudable ;
-   soudage au gaz chaud avec baguette d’apport uniquement ;
-   soudage par extrusion ;
-   collage au solvant de tubes.

Nepravilnosti v zvarjenih spojih plastomerov - Stopnje kakovosti

General Information

Status
Published
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
12-May-2021
Completion Date
12-May-2021

RELATIONS

Buy Standard

Standard
EN 16296:2021
English language
22 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day
Draft
prEN 16296:2020
English language
22 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day

Standards Content (sample)

SLOVENSKI STANDARD
SIST EN 16296:2021
01-julij-2021
Nadomešča:
SIST EN 16296:2014
Nepravilnosti v zvarjenih spojih plastomerov - Stopnje kakovosti
Imperfections in thermoplastics welded joints - Quality levels
Unregelmäßigkeiten an Schweißverbindungen von thermoplastischen Kunststoffen -
Bewertungsgruppen
Défauts dans les assemblages soudés en thermoplastiques - Niveaux de qualité
Ta slovenski standard je istoveten z: EN 16296:2021
ICS:
25.160.40 Varjeni spoji in vari Welded joints and welds
83.080.20 Plastomeri Thermoplastic materials
SIST EN 16296:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 16296:2021
---------------------- Page: 2 ----------------------
SIST EN 16296:2021
EN 16296
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2021
EUROPÄISCHE NORM
ICS 25.160.40 Supersedes EN 16296:2012
English Version
Imperfections in thermoplastics welded joints - Quality
levels

Défauts dans les assemblages soudés en Unregelmäßigkeiten an Schweißverbindungen von

thermoplastiques - Niveaux de qualité thermoplastischen Kunststoffen - Qualitätsstufen

This European Standard was approved by CEN on 12 April 2021.

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. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists 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-CENELEC 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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 16296:2021 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 16296:2021
EN 16296:2021 (E)
Contents Page

European foreword ............................................................................................................................................ 3

Introduction .......................................................................................................................................................... 4

1 Scope .......................................................................................................................................................... 5

2 Normative reference ............................................................................................................................ 5

3 Terms and definitions ......................................................................................................................... 6

4 Quality levels .......................................................................................................................................... 6

4.1 Classification........................................................................................................................................... 6

4.2 Choice of quality level ......................................................................................................................... 6

5 Requirements for welded joints ...................................................................................................... 7

Bibliography ....................................................................................................................................................... 22

---------------------- Page: 4 ----------------------
SIST EN 16296:2021
EN 16296:2021 (E)
European foreword

This document (EN 16296:2021) has been prepared by Technical Committee CEN/TC 249 “Plastics”, the

secretariat of which is held by NBN.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by November 2021, and conflicting national standards shall

be withdrawn at the latest by November 2021.

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

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

This document supersedes EN 16296:2012.

In comparison with the previous edition, the following technical modifications have been made:

— the PA polyamide thermoplastic material has been added in Table 1 — Thermoplastic materials;

— in Tables 3 to 8:

— the designation 1AAAA of the quality levels for “cracks” has been deleted to be consistent with

EN 14728:2019;

— the numbers and designations have been updated to be aligned with EN 14728:2019 as the texts

for the quality levels.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: 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, Republic of North

Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United

Kingdom.
---------------------- Page: 5 ----------------------
SIST EN 16296:2021
EN 16296:2021 (E)
Introduction

This document is used as a reference in the drafting of application codes and/or other application

standards. It contains a simplified selection of imperfections based on the designations and illustrations

given in EN 14728, Imperfections in thermoplastic welds — Classification.

Some imperfections according to EN 14728 have been used directly and some have been grouped

together. The basic numerical referencing system from EN 14728 has been used.

The purpose of this document is to define quality levels based on typical imperfections, which might occur

in normal fabrication. It is applicable for use within a quality system for the production of factory welded

joints. It provides three sets of dimensional values from which a selection can be made for a particular

application.

The quality levels given in this document are intended to provide basic reference data and are not

specifically related to any particular application. They refer to the types of welded joints in a fabrication

and not to the complete product or component itself. It is possible, therefore, that different quality levels

are applied to individual welded joints in the same product or component.

This document is directly applicable to visual examination of welds or test specimens. The need for

detection is not the subject of this document and this document does not include details of recommended

methods of detection and sizing.
---------------------- Page: 6 ----------------------
SIST EN 16296:2021
EN 16296:2021 (E)
1 Scope

This document specifies quality levels for imperfections in thermoplastics welded joints that have cooled

to ambient temperature and is applicable to material thickness above 2,0 mm.

Three quality levels are specified in order to permit application for a wide range of welded fabrication.

They are designated by symbols B, C and D, where B is the most stringent. The quality levels refer to

production quality and not to the fitness-for-purpose (see 3.2) of the manufactured product.

The quality level necessary are expected to be defined by the application standard or by the fabricator in

conjunction with the user and/or other parties concerned. The level is expected to be prescribed before

the start of production, preferably at the enquiry or order stage.
This document applies to the following thermoplastic materials in Table 1:
Table 1 — Thermoplastic materials
Abbreviation Material description
ABS Acrylonitrile-butadiene-styrene plastic
ECTFE Ethylene-chlorotrifluoroethylene copolymer
FEP Fluorinated ethylene propylene
PA-U Unplasticized polyamide
PB Polybutylene
PE Polyethylene
PFA Perfluoroalkoxy
PP-B Polypropylene block copolymer
PP-H Polypropylene homopolymer
PP-R Polypropylene random copolymer
PVC-C Chlorinated polyvinyl chloride
PVC-U Unplasticized polyvinyl chloride (rigid PVC)
PVDF Polyvinylidene fluoride
and to the following welding processes:
— heated tool welding;
— electrofusion socket welding;
— hot gas welding using filler rod only;
— extrusion welding;
— solvent welding of pipes.
2 Normative reference
There are no normative references in this document.
---------------------- Page: 7 ----------------------
SIST EN 16296:2021
EN 16296:2021 (E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
quality level

description of the qualities of a weld on the basis of type, size and number or frequency of selected

imperfections
3.2
fitness-for-purpose

ability of a product, process or service to serve a defined purpose under specific conditions

4 Quality levels
4.1 Classification

Three quality levels are defined as B, C and D in order to permit application for a wide range of welded

fabrications (see Table 2).
Table 2 — Quality levels for weld imperfections
Symbol Requirement
B Stringent
C Intermediate
D Moderate

The purpose of this document is to define quality levels based on typical imperfections, which might occur

in normal fabrications and are classified in EN 14728 [1]. It may be used within a quality system for the

production of factory welded joints. It provides three sets of dimensional values from which a selection

can be made for a particular application. The quality level necessary in each case should be defined by

the application standard or the fabricator in conjunction with the user and/or other parties concerned.

The level should be prescribed before the start of production, preferably at the enquiry or order stage.

For pressure pipe systems, it is recommended that at least level B be chosen.

For specific applications, some requirements more stringent than level B might need to be prescribed and

shall be defined between the contracting parties as quality level A.
4.2 Choice of quality level

For the choice of the quality level, the following factors, among others, shall be taken into account:

— mechanical loading (static, dynamic);
— environment (media, temperature);
— material properties (ductile, brittle);

— manufacturing conditions (workshop, construction site, welding in constrained condition);

---------------------- Page: 8 ----------------------
SIST EN 16296:2021
EN 16296:2021 (E)
— operating conditions;
— potential danger in the event of failure;
— design considerations.

Economic factors are also important and should include not only the cost of welding but also the cost of

inspection, test and repair.
5 Requirements for welded joints

Although this document includes types of imperfections relevant to the processes given in Clause 1, only

those which are applicable to the process and application in question need to be considered.

Imperfections are quoted in terms of their actual dimensions. However, their detection and evaluation

could require the use of one or more methods of non-destructive testing. It should be noted that the

detection and sizing of imperfections is dependent on the inspection methods and the extent of testing

specified in the application standard or contract.

The indication provided by non-destructive testing should not be used directly for the evaluation of

quality levels. Therefore, it needs to be supplemented by requirements for examinations, inspection and

testing.

The requirements for the quality levels in Table 2 (B, C and D) are listed as follows:

— heated tool butt welds: Table 3;
— heated tool socket welds: Table 4;
— electrofusion socket welds: Table 5;
— hot gas welds: Table 6;
— extrusion welds: Table 7;
— solvent socket welds: Table 8.

Different types of imperfection occurring simultaneously at any cross-section of the joint need special

consideration.

Any two adjacent imperfections separated by a distance less than the major dimension of the smaller

imperfection shall be considered as a single imperfection.

In certain circumstances, it is necessary to machine the completed weld. In this case, the weld shall be

examined both before and after machining.
---------------------- Page: 9 ----------------------
SIST EN 16296:2021
EN 16296:2021 (E)
Table 3 — Definition of quality levels for heated tool butt welds
Number Designations Level B Level C Level D
2BAAA Gas cavity Isolated cavities Permissible if Permissible if
permissible if diameter of diameter of
diameter ≤ 5 % largest largest
of wall thickness cavity ≤ 10 % of cavity ≤ 15 % of
wall thickness wall thickness
2CAAI Shrinkage cavity Isolated cavities Permissible if Permissible if
permissible if diameter of diameter of
diameter ≤ 5 % largest largest
of wall thickness cavity ≤ 10 % of cavity ≤ 15 % of
wall thickness wall thickness
2MAAA Surface bubble Permissible if, Permissible if, Permissible if,
when the weld when the weld when the weld
bead is removed, bead is bead is
there is no removed, there removed, there
evidence of gas is no evidence is no evidence of
cavities at the of gas cavities gas cavities at
weld interface at the weld the weld
interface interface
3AAAA Particulate inclusion Isolated and/or Isolated and/or Isolated and/or
multiple multiple multiple
inclusions inclusions inclusions
permissible if permissible if permissible if
sum of maximum sum of sum of
dimensions ≤ 5 maximum maximum
% of wall dimensions ≤ 10 dimensions ≤ 15
thickness % of wall % of wall
thickness thickness
3JAAI Parent material inclusion Not permissible Not permissible Not permissible
3KAAA Degraded polymer Not permissible Not permissible Not permissible
4BAAA Lack of fusion Not permissible Not permissible Not permissible

4QBAF Groove in upset or reinforcement Not permissible Not permissible Not permissible

if below surface if below surface if below surface
of parent of parent of parent
material material material
4WAAA Cold fusion Not permissible Not permissible Not permissible
5CAAA Incorrect weld profile Mechanical Mechanical Mechanical
testing of sample testing of testing of
welds is sample welds is sample welds is
recommended recommended recommended
Linear misalignment Permissible if Permissible if Permissible if
5EIAA
misalignment is misalignment is misalignment is
not greater than not greater than not greater than
10 % of the wall 15 % of the wall 20 % of the wall
thickness thickness thickness
---------------------- Page: 10 ----------------------
SIST EN 16296:2021
EN 16296:2021 (E)
Number Designations Level B Level C Level D
Angular misalignment Permissible if Permissible if Permissible if
5EJAA
misalignment is misalignment is misalignment is
not greater than not greater than not greater than
1,0° 1,5° 2,0°
5GAAA Irregular width To be agreed To be agreed To be agreed
between between between
contracting contracting contracting
parties parties parties
6DAAA Excessive width To be agreed To be agreed To be agreed
between between between
contracting contracting contracting
parties parties parties
Excessive asymmetry of welds Permissible if Permissible if Permissible if
6HAAA
smaller half of smaller half of smaller half of
weld bead is not weld bead is not weld bead is not
less than 70 % of less than 60 % less than 50 %
larger half of of larger half of of larger half of
weld bead at any weld bead at weld bead at
point around the any point any point
circumference around the around the
circumference circumference
6MAAA Insufficient upset material To be agreed To be agreed To be agreed
between between between
contracting contracting contracting
parties parties parties
7BAAA Thermal damage outside of Not permissible Not permissible Not permissible
welding
7VAAA Excessive toe in To be agreed To be agreed To be agreed
between between between
contracting contracting contracting
parties parties parties
9CAAA Tool mark Locally Locally Locally
permissible if the permissible if permissible if
notch depth is the notch depth the notch depth
less than 10 % of is less than is less than
the wall 10 % of the wall 15 % of the wall
thickness thickness thickness

To be agreed between contracting parties when welding materials with different melt flow rates.

For mitred joints the requirements should be agreed between the contracting parties.

NOTE Some of the data in this table can also be found in DVS 2202 [2].
---------------------- Page: 11 ----------------------
SIST EN 16296:2021
EN 16296:2021 (E)
Table 4 — Definition of quality levels for heated tool socket welds
Number Designations Level B Level C Level D
2CAAA Shrinkage cavity Isolated cavities Permissible if Permissible if
permissible if diameter of diameter of
diameter ≤ 5 % of largest largest
insertion length cavity ≤ 10 % of cavity ≤ 15 % of
wall thickness wall thickness
2MAAA Surface bubble Not permissible Not permissible Not permissible
3AAAA Particulate inclusion Isolated inclusion Isolated Isolated
permissible if inclusion inclusion
maximum permissible if permissible if
dimension ≤ 5 % maximum maximum
of fusion length. dimension ≤ 10 dimension ≤ 15
% of fusion % of fusion
Multiple
length. length.
inclusions
permissible Multiple Multiple
if ≤ 25 % of fusion inclusions inclusions
length at any permissible permissible
position around if ≤ 33 % of if ≤ 40 % of
the circumference fusion length at fusion length at
any position any position
around the around the
circumference circumference
3KAAA Degraded polymer Not permissible Not permissible Not permissible
4BAAA Lack of fusion Permissible if Permissible if Permissible if
lack of lack of lack of
fusion ≤ 25 % of fusion ≤ 33 % of fusion ≤ 40 % of
fusion length at fusion length at fusion length at
any position any position any position
around the around the around the
circumference circumference circumference
4CAAA Incomplete penetration Permissible if Permissible if Permissible if
inserted length
...

SLOVENSKI STANDARD
oSIST prEN 16296:2020
01-junij-2020
Nepravilnosti v zvarjenih spojih plastomerov - Stopnje kakovosti
Imperfections in thermoplastics welded joints - Quality levels
Unregelmäßigkeiten an Schweißverbindungen von thermoplastischen Kunststoffen -
Bewertungsgruppen
Défauts dans les assemblages soudés en thermoplastiques - Niveaux de qualité
Ta slovenski standard je istoveten z: prEN 16296
ICS:
25.160.40 Varjeni spoji in vari Welded joints and welds
83.080.20 Plastomeri Thermoplastic materials
oSIST prEN 16296:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN 16296:2020
---------------------- Page: 2 ----------------------
oSIST prEN 16296:2020
DRAFT
EUROPEAN STANDARD
prEN 16296
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2020
ICS 25.160.40 Will supersede EN 16296:2012
English Version
Imperfections in thermoplastics welded joints - Quality
levels

Défauts dans les assemblages soudés en Unregelmäßigkeiten an Schweißverbindungen von

thermoplastiques - Niveaux de qualité thermoplastischen Kunststoffen - Bewertungsgruppen

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee

CEN/TC 249.

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-CENELEC

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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey 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
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16296:2020 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
oSIST prEN 16296:2020
prEN 16296:2020 (E)
Contents Page

European foreword ...................................................................................................................................................... 3

Introduction .................................................................................................................................................................... 4

1 Scope ......................................................................................................................................................................... 5

2 Normative reference ........................................................................................................................................... 5

3 Terms and definitions ......................................................................................................................................... 6

4 Quality levels .......................................................................................................................................................... 6

4.1 Classification .......................................................................................................................................................... 6

4.2 Choice of quality level ......................................................................................................................................... 6

5 Requirements for welded joints ..................................................................................................................... 7

Bibliography .................................................................................................................................................................22

---------------------- Page: 4 ----------------------
oSIST prEN 16296:2020
prEN 16296:2020 (E)
European foreword

This document (prEN 16296:2020) has been prepared by Technical Committee CEN/TC 249 “Plastics”,

the secretariat of which is held by NBN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 16296:2012.

In comparison with the previous edition, the following technical modifications have been made:

— the PA polyamide thermoplastic material has been added in Table 1- Thermoplastic materials;

— in the Tables 3 to 8:

— the designation 1AAAA of the quality levels for "cracks" has been deleted to be consistent with

EN 14728:2019;

— the numbers and designations have been updated to be aligned with EN 14728:2019 as the texts

for the quality levels.
---------------------- Page: 5 ----------------------
oSIST prEN 16296:2020
prEN 16296:2020 (E)
Introduction

This document should be used as a reference in drafting of application codes and/or other application

standards. It contains a simplified selection of imperfections based on the designations given in

EN 14728, Imperfections in thermoplastic welds — Classification.

Some imperfections according to EN 14728 have been used directly and some have been grouped

together. The basic numerical referencing system from EN 14728 has been used.

The purpose of this document is to define quality levels based on typical imperfections, which might occur

in normal fabrication. It may be used within a quality system for the production of factory welded joints.

It provides three sets of dimensional values from which a selection can be made for a particular

application. The quality level necessary in each case should be defined by the application standard or the

fabricator in conjunction with the user and/or other parties concerned. The level should be prescribed

before the start of production, preferably at the enquiry or order stage.

The quality levels given in this document are intended to provide basic reference data and are not

specifically related to any particular application. They refer to the types of welded joints in a fabrication

and not to the complete product or component itself. It is possible, therefore, that different quality levels

are applied to individual welded joints in the same product or component.

The choice of quality level for any application should take account of design considerations, subsequent

processing, mode of stressing (e.g. static, dynamic), service conditions (e.g. pressure, temperature,

environment) and consequences of failure. Economic factors are also important and should include not

only the cost of welding but also of inspection, test and repair.

Although this document includes types of imperfections relevant to the processes given in Clause 1, only

those which are applicable to the process and application in question need to be considered.

Imperfections are quoted in terms of their actual dimensions. However, their detection and evaluation

may require the use of one or more methods of non-destructive testing. It should be noted that the

detection and sizing of imperfections is dependent on the inspection methods and the extent of testing

specified in the application standard or contract.
The need for detection is not the subject of this document.

This document is directly applicable to visual examination of welds or test specimens. It does not include

details of recommended methods of detection and sizing. The indication provided by non-destructive

testing should not be used directly for the evaluation of quality levels. Therefore, it needs to be

supplemented by requirements for examinations, inspection and testing.
---------------------- Page: 6 ----------------------
oSIST prEN 16296:2020
prEN 16296:2020 (E)
1 Scope

This document provides quality levels for imperfections in thermoplastics welded joints. It applies to

material thickness above 2,0 mm.

Three quality levels are given in order to permit application for a wide range of welded fabrication. They

are designated by symbols B, C and D, where B is the most stringent. The quality levels refer to production

quality and not to the fitness-for-purpose (see 3.2) of the manufactured product.

This document applies to the following thermoplastic materials in Table 1:
Table 1 — Thermoplastic materials
Abbreviation Material description
ABS Acrylonitrile-butadiene-styrene plastic
ECTFE Ethylene-chlorotrifluoroethylene copolymer
FEP Fluorinated ethylene propylene
PA-U Unplasticized Polyamide
PB Polybutylene
PE Polyethylene
PFA Perfluoroalkoxy
PP-B Polypropylene block copolymer
PP-H Polypropylene homopolymer
PP-R Polypropylene random copolymer
PVC-C Chlorinated polyvinyl chloride
PVC-U Unplasticized polyvinyl chloride (rigid PVC)
PVDF Polyvinylidene fluoride
and to the following welding processes:
— heated tool welding;
— electrofusion welding;
— hot gas welding using filler rod only;
— extrusion welding;
— solvent welding of pipes.
2 Normative reference

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 14728, Imperfections in thermoplastic welds — Classification
---------------------- Page: 7 ----------------------
oSIST prEN 16296:2020
prEN 16296:2020 (E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
quality level

description of the qualities of a weld on the basis of type and size of selected imperfections

3.2
fitness-for-purpose

ability of a product, process or service to serve a defined purpose under specific conditions

4 Quality levels
4.1 Classification

Three quality levels are defined as B, C and D in order to permit application for a wide range of welded

fabrications (see Table 2).
Table 2 — Quality levels for weld imperfections
Symbol Requirement
B Stringent
C Intermediate
D Moderate

The purpose of this document is to define quality levels based on typical imperfections, which might occur

in normal fabrications and are classified in EN 14728. It may be used within a quality system for the

production of factory welded joints. It provides three sets of dimensional values from which a selection

can be made for a particular application. The quality level necessary in each case should be defined by

the application standard or the fabricator in conjunction with the user and/or other parties concerned.

The level should be prescribed before the start of production, preferably at the enquiry or order stage.

For pressure pipe systems, it is recommended that at least level B be chosen.

For specific applications, additional requirements not covered by this standard may need to be

prescribed. These additional requirements shall be defined as quality level A.
4.2 Choice of quality level

For the choice of the quality level, the following factors, among others, shall be taken into account:

— mechanical loading (static, dynamic);
— environment (media, temperature);
— material properties (ductile, brittle);
---------------------- Page: 8 ----------------------
oSIST prEN 16296:2020
prEN 16296:2020 (E)

— manufacturing conditions (workshop, construction site, welding in constrained condition);

— operating conditions;
— potential danger in the vent of failure.
5 Requirements for welded joints

The requirements for the above mentioned quality levels (B, C and D) are listed as follows:

— heated tool butt welds: Table 3;
— heated tool socket welds: Table 4;
— electrofusion socket welds: Table 5;
— hot gas welds: Table 6;
— extrusion welds: Table 7;
— solvent socket welds : Table 8.

Different types of imperfection occurring simultaneously at any cross-section of the joint may need

special consideration and advice should be sought from the product manufacturer.

Any two adjacent imperfections separated by a distance smaller than the major dimension of the smaller

imperfection shall be considered as a single imperfection.

In certain circumstances, it is necessary to machine the completed weld. In this case, the weld shall be

examined both before and after machining.
---------------------- Page: 9 ----------------------
oSIST prEN 16296:2020
prEN 16296:2020 (E)
Table 3 — Definition of quality levels for heated tool butt welds
Number Designations Level B Level C Level D

2BAAA Gas cavity inside of fusion zone Isolated cavities Permissible if Permissible if

permissible if diameter of diameter of
diameter ≤ 5 % largest cavity largest cavity
of wall thickness ≤ 10 % of wall ≤ 15 % of wall
thickness thickness
2CAAI Shrinkage cavity Isolated cavities Permissible if Permissible if
permissible if diameter of diameter of
diameter ≤ 5 % largest cavity largest cavity
of wall thickness ≤ 10 % of wall ≤ 15 % of wall
thickness thickness
2MAAA Surface bubble Permissible if, Permissible if, Permissible if,
when the weld when the weld when the weld
bead is removed, bead is bead is
there is no removed, there removed, there
evidence of gas is no evidence is no evidence of
cavities at the of gas cavities gas cavities at
weld interface at the weld the weld
interface interface
3AAAA Particulate inclusion Isolated inclusion Isolated and Isolated and
permissible if rows of rows of
maximum inclusions inclusions
dimension ≤ 5 % permissible if permissible if
of wall thickness maximum maximum
dimension dimension
≤ 10 % of wall ≤ 15 % of wall
thickness thickness
3JAAI Parent material inclusion Not permissible Not permissible Not permissible
3KAAA Degraded polymer Not permissible Not permissible Not permissible
4BAAA Lack of fusion Not permissible Not permissible Not permissible

4QBAF Groove in upset or reinforcement Not permissible Not permissible Not permissible

if below surface if below surface if below surface
of parent of parent of parent
material material material
4WAAA Cold fusion Not permissible Not permissible Not permissible
5CAAA Deviation of the specified shape Mechanical Mechanical Mechanical
of the weld bead testing of sample testing of testing of
welds is sample welds is sample welds is
recommended recommended recommended
5EIAA Linear misalignment Permissible if Permissible if Permissible if
misalignment is misalignment is misalignment is
not greater than not greater than not greater than
10 % of the wall 15 % of the wall 20 % of the wall
thickness thickness thickness
---------------------- Page: 10 ----------------------
oSIST prEN 16296:2020
prEN 16296:2020 (E)
Number Designations Level B Level C Level D
5EJAA Angular misalignment Permissible if Permissible if Permissible if
misalignment is misalignment is misalignment is
not greater than not greater than not greater than
1,0° 1,5° 2,0°
5GAAA Irregular width To be agreed To be agreed To be agreed
between between between
contracting contracting contracting
parties parties parties
6DAAA Excessive width To be agreed To be agreed To be agreed
between between between
contracting contracting contracting
parties parties parties
6HAAA Excessive asymmetry of welds Permissible if Permissible if Permissible if
smaller half of smaller half of smaller half of
weld bead is not weld bead is not weld bead is not
less than 70 % of less than 60 % less than 50 %
larger half of of larger half of of larger half of
weld bead at any weld bead at weld bead at
point around the any point any point
circumference around the around the
circumference circumference
6MAAA Insufficient upset material To be agreed To be agreed To be agreed
between between between
contracting contracting contracting
parties parties parties
7BAAA Thermal damage outside of Not permissible Not permissible Not permissible
welding
7VAAA Excessive toe in To be agreed To be agreed To be agreed
between between between
contracting contracting contracting
parties parties parties
9CAAA Tool mark Locally Locally Locally
permissible if the permissible if permissible if
notch depth is the notch depth the notch depth
less than 10 % of is less than is less than
the wall 10 % of the wall 15 % of the wall
thickness thickness thickness

To be agreed between contracting parties when welding materials with different MFRs.

For mitred joints the requirements should be agreed between the contracting parties.

NOTE Some of the data in this table can also be found in DVS 2202 [1].
---------------------- Page: 11 ----------------------
oSIST prEN 16296:2020
prEN 16296:2020 (E)
Table 4 — Definition of quality levels for heated tool socket welds
Number Designations Level B Level C Level D
2CAAA Shrinkage cavity Isolated cavities Permissible if Permissible if
permissible if diameter of diameter of
diameter ≤ 5 % of largest cavity largest cavity
insertion length ≤ 10 % of wall ≤ 15 % of wall
thickness thickness
2MAAA Surface bubble Not permissible Not permissible Not permissible
3AAAA Particulate inclusion Isolated inclusion Isolated Isolated
permissible if inclusion inclusion
maximum permissible if permissible if
dimension ≤ 5 % maximum maximum
of fusion length. dimension dimension
≤ 10 % of fusion ≤ 15 % of fusion
Multiple
length. length.
inclusions
permissible if Multiple Multiple
≤ 25 % of fusion inclusions inclusions
length at any permissible if permissible if
position around ≤ 33 % of fusion ≤ 40 % of fusion
the circumference length at any length at any
position around position around
the the
circumference circumference
3KAAA Degraded polymer Not permissible Not permissible Not permissible
4BAAA Lack of fusion Permissible if Permissible if Permissible if
lack of fusion lack of fusion lack of fusion
≤ 25 % of fusion ≤ 33 % of fusion ≤ 40 % of fusion
length at any length at any length at any
position around position around position around
the circumference the the
circumference circumference
4CAAA Incomplete penetration Permissible if Permissible
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.