kSIST FprEN 18205:2026

• Abstract:

  This document specifies a procedure to qualify a preliminary welding procedure specification (pWPS) by welding procedure tests to produce a qualified welding procedure specification (WPS).; NOTE 1 The application of this document ensures that the qualification of the pWPS is carried out according to a uniform test procedure.; NOTE 2 The primary purpose of welding procedure qualification is to demonstrate that the joining process proposed for construction is capable of producing joints having the required mechanical properties for the intended application.; This document applies to the following thermoplastic welding processes:; — hot gas welding: round nozzle, speed, wedge;; — extrusion welding;; — heated tool welding: butt, socket, wedge;; This document applies to the welding of the following products:; — sheet; — pipe (unreinforced, solid wall only);; — fittings (unreinforced only);; — lining membrane;; This document covers the welding of the following groups of materials:; a) for sheets, pipes and fittings:; — PVC (PVC-U, PVC-C);; — PP (PP-B, PP-H, PP-R);; — PE;; — PVDF;; — ECTFE, PFA and FEP;; b) for lining membranes:; — PVC-P;; — PE;; — ECB;; — PP;; c) for pipes and fittings only:; — PA-U (PA-U 11, PA-U 12).

• Status: Not Published
• Public Enquiry End Date: 17-Sep-2025
• ICS: 25.160.10 - Welding processes
• ICS: 83.080.01 - Plastics in general
• Technical Committee: IPMA - Polimer materials and products
• Current Stage: 5020 - Formal vote (FV) (Adopted Project)
• Start Date: 23-Jul-2026
• Due Date: 10-Sep-2026
• Completion Date: 24-Jul-2026
• Ref Project: FprEN 18205 - Qualification of Welding Procedures for Plastic Materials

Overview

kSIST FprEN 18205:2026 is a comprehensive standard published by SIST, focused on the qualification of welding procedures for plastic materials. This document specifies standardized procedures for qualifying preliminary welding procedure specifications (pWPS) by carrying out welding procedure tests, ultimately providing a qualified welding procedure specification (WPS). By following this standard, organizations can ensure that welding operations for thermoplastic materials meet consistent mechanical property requirements for their specific applications.

The standard applies to a wide range of thermoplastic welding processes-such as hot gas welding (round nozzle, speed, wedge), extrusion welding, and heated tool welding (butt, socket, wedge)-and covers varied product types (sheets, pipes, fittings, and lining membranes). It ensures a uniform, reliable approach to welding procedure qualification for industries working with plastic materials.

Key Topics

• Scope of Application

  • Specifies methods for qualifying procedures for welding thermoplastics.
  • Covers various product forms, including sheets, unreinforced solid-wall pipes, fittings, and lining membranes.

• Welding Processes

  • Hot gas welding: round nozzle, speed, wedge.
  • Extrusion welding.
  • Heated tool welding: butt, socket, and wedge variants.

• Material Groups Covered

  • For sheets, pipes, and fittings: PVC-U, PVC-C, PP (PP-B, PP-H, PP-R), PE, PVDF, ECTFE, PFA, FEP.
  • For lining membranes: PVC-P, PE, ECB, PP.
  • For pipes and fittings: PA-U (PA-U 11, PA-U 12).

• Qualification Procedure

  • Details preparation and testing of welding procedure test pieces.
  • Specifies visual and destructive examination methodologies.
  • Addresses acceptance levels in accordance with referenced standards.

• Documentation

  • Outlines requirements for welding procedure qualification records (WPQR), ensuring traceability and uniformity across projects.

Applications

The kSIST FprEN 18205:2026 standard is invaluable across industries where the integrity of welded thermoplastic joints is essential for safety, performance, and regulatory compliance. Key applications include:

• Industrial Piping Systems

  • Ensures reliable joining of plastic pipes and fittings in water supply, gas distribution, or chemical processing plants.

• Construction and Infrastructure

  • Qualified welding procedures are crucial for lining membranes in containment structures, tanks, and geomembrane installations.

• Manufacturing

  • Used in the fabrication of plastic components, equipment housings, or assemblies requiring strong, consistent welded joints.

• Maintenance and Repair

  • Provides a uniform approach for validating repair welding on critical thermoplastic installations, minimizing failure risks.

• Quality Assurance

  • Enhances overall product and project quality by defining clear qualification procedures and acceptance criteria.

Related Standards

Complying with kSIST FprEN 18205:2026 often involves referencing additional international and European standards for testing and quality assurance, including:

• EN 12814 Series: Methods for testing welded joints of thermoplastic products (bend, tensile, peel tests).
• EN 13100-1: Visual examination of welded thermoplastic joints.
• EN 16296: Quality levels and classification of imperfections in thermoplastics welds.
• EN 13067: Qualification of welders for thermoplastics welding.
• CEN/TS 16892: Specification of welding procedures for thermoplastics.
• EN 14728: Imperfection classification for thermoplastic welds.
• EN ISO 23936-1: Guidelines for non-metallic materials in oil, gas, and energy sectors.

By integrating kSIST FprEN 18205:2026 with these related standards, organizations can establish robust, standardized welding procedure qualifications that support compliance, reliability, and high-quality outcomes in thermoplastic fabrication and construction projects.

SLOVENSKI STANDARD
oSIST prEN 18205:2025
01-september-2025
Kvalifikacija postopkov varjenja za polimerne materiale
Qualification of Welding Procedures for Plastic Materials
Qualifizierung von Schweißverfahren für Kunststoffe
Qualification des modes opératoires de soudage des matières plastiques
Ta slovenski standard je istoveten z: prEN 18205
ICS:
25.160.10 Varilni postopki in varjenje Welding processes
83.080.01 Polimerni materiali na Plastics in general
splošno
oSIST prEN 18205:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 18205:2025
oSIST prEN 18205:2025
DRAFT
EUROPEAN STANDARD
prEN 18205
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2025
ICS 25.160.10
English Version
Qualification of Welding Procedures for Plastic Materials
Qualification des modes opératoires de soudage des Qualifizierung von Schweißverfahren für Kunststoffe
matières plastiques
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, Türkiye 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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 18205:2025 E
worldwide for CEN national Members.

oSIST prEN 18205:2025
prEN 18205:2025(E)
Contents Page
European Foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 6
3 Terms and definitions . 7
4 Preliminary welding procedure specification . 7
5 Welding procedure test . 7
6 Test piece . 7
6.1 Welding of test pieces . 7
6.2 Shape and dimensions of test pieces and test specimens . 7
7 Examination and testing . 12
7.1 Type and extent of testing . 12
7.1.1 Visual examination . 12
7.1.2 Destructive testing. 12
7.2 Welding procedure qualification record (WPQR) . 12
7.3 Acceptance levels . 13
7.3.1 Visual examination . 13
7.3.2 Destructive testing. 13
7.3.3 Re-testing . 14
8 Range of qualification . 14
8.1 General . 14
8.2 Related to the organization responsible for welding . 14
8.3 Related to the parent material . 14
8.4 Related to material thickness. 15
8.5 Related to welding process . 15
8.6 Related to welding position . 15
8.7 Related to type of joint . 16
8.8 Related to the quality level . 16
8.9 Specific to process . 16
8.9.1 Hot gas welding . 16
8.9.2 Extrusion welding . 16
8.9.3 Heated tool butt welding . 17
8.9.4 Heated tool socket welding . 18
8.9.5 Heated tool wedge welding . 18
8.9.6 Hot gas wedge welding . 19
Annex A (informative) Welding procedure qualification record (WPQR) - Hot gas welding . 20
oSIST prEN 18205:2025
prEN 18205:2025 (E)
European Foreword
This document (prEN 18205:2025) has been prepared by Technical Committee CEN/TC 249 “Plastics”,
the secretariat of which is held by SIS.
This document is currently submitted to the CEN Enquiry.
oSIST prEN 18205:2025
prEN 18205:2025(E)
Introduction
This document covers the principles to be observed in the qualification testing of welding procedures for
thermoplastic materials.
oSIST prEN 18205:2025
prEN 18205:2025 (E)
1 Scope
This document specifies a procedure to qualify a preliminary welding procedure specification (pWPS) by
welding procedure tests to produce a qualified welding procedure specification (WPS).
NOTE 1 The application of this document ensures that the qualification of the pWPS is carried out according to
a uniform test procedure.
NOTE 2 The primary purpose of welding procedure qualification is to demonstrate that the joining process
proposed for construction is capable of producing joints having the required mechanical properties for the intended
application.
This document applies to the following thermoplastic welding processes:
— hot gas welding: round nozzle, speed, wedge;
— extrusion welding;
— heated tool welding: butt, socket, wedge;
This document applies to the welding of the following products:
— sheet
— pipe (unreinforced, solid wall only);
— fittings (unreinforced only);
— lining membrane;
This document covers the welding of the following groups of materials:
a) for sheets, pipes and fittings:
— PVC (including all kinds of PVC-U, PVC-C) and ABS;
— PP;
— PE;
— PVDF;
— ECTFE, PFA and FEP;
b) for lining membranes:
— PVC-P;
— PE;
— ECB;
— PP;
c) for pipes and fittings only:
— PA-U 11 and PA-U 12.
oSIST prEN 18205:2025
prEN 18205:2025(E)
2 Normative references
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 12814-1, Testing of welded joints of thermoplastics semi-finished products - Part 1: Bend test
EN 12814-2, Testing of welded joints of thermoplastics semi-finished products - Part 2: Tensile test
EN 12814-4, Testing of welded joints of thermoplastics semi-finished products - Part 4: Peel test
EN 12814-7, Testing of welded joints of thermoplastics semi-finished products - Part 7: Tensile test with
waisted test specimens
EN 12814-8, Testing of welded joints of thermoplastics semi-finished products - Part 8: Requirements
EN 13100-1, Non destructive testing of welded joints of thermoplastics semi-finished products - Part 1:
Visual examination
EN 14728, Imperfections in thermoplastic welds - Classification
EN 16296, Imperfections in thermoplastics welded joints - Quality levels
EN 13067, Plastics welding personnel - Qualification of welders - Thermoplastics welded assemblies
CEN/TS 16892, Plastics - Welding of thermoplastics - Specification of welding procedures
EN ISO 23936-1, Oil and gas industries including lower carbon energy - Non-metallic materials in contact
with media related to oil and gas production - Part 1: Thermoplastics (ISO 23936-1)
ISO/TR 20118, Plastics – Guidance on fire characteristics and fire performance of PVC materials used in
building applications
ISO/TR 25901-1, Welding and allied processes — Vocabulary — Part 1: General terms
ISO 13953, Polyethylene (PE) pipes and fittings — Determination of the tensile strength and failure mode
of test pieces from a butt-fused joint
oSIST prEN 18205:2025
prEN 18205:2025 (E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 13067, ISO 23936-1,
ISO/TR 20118, ISO/TR 25901-1 and the following apply.
ISO and IEC maintain terminoloy databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
standard welding procedure specification
sWPS
welding procedure specification that contains acceptable welding variables based on standard industry
practice and is specified in national or international standards or specifications
4 Preliminary welding procedure specification
The preliminary welding procedure specification shall be prepared in accordance with CEN/TS 16892.
5 Welding procedure test
The welding and testing of test pieces shall be in accordance with Clauses 6 and 7.
6 Test piece
6.1 Welding of test pieces
Preparation and welding of the test pieces shall be carried out in accordance with the pWPS.
6.2 Shape and dimensions of test pieces and test specimens
The dimensions of the test piece and the number of test specimens to be cut from the test piece are
specified in Figures 1 to 7.
The shapes, dimensions and conditioning of the test specimens are specified in the relevant test
standards.
Cutting the test specimens shall be carried out without significant damage to the welds and their heat
affected zones.
oSIST prEN 18205:2025
prEN 18205:2025(E)
Minimum dimensions in millimetres

Key
1 discard
2 6 bend test specimens cut from within this area
Figure 1 — Test piece for a butt weld on sheet (for bend test specimens)
oSIST prEN 18205:2025
prEN 18205:2025 (E)
Key
1 4 test specimens, 1 in each location (x1, x2, y1, y2)
l ≥ 350 or 2 dn, whichever is longer
Figure 2 — Test piece for a butt weld on pipe (for bend or tensile test specimens)
Minimum dimensions in millimetres

Key
1 discard
2 5 tensile test specimens cut from within this area
3 tensile test specimens (for reference)
Figure 3 —Test piece for a butt weld on sheet (for tensile test specimens)
oSIST prEN 18205:2025
prEN 18205:2025(E)
Key
1 socket
2 pipe
l ≥ 5 dn
Figure 4 — Test piece for a socket weld
Minimum dimensions in millimetres

a) Test piece for lining membranes b) Lap seam without testing channel
Key
1 discard
2 5 peel test specimens cut from within this area
3 welding zone
Figure 5 — Test piece for lining membranes - Lap seam without testing channel
oSIST prEN 18205:2025
prEN 18205:2025 (E)
Minimum dimensions in millimetres

a) Test piece for lining membranes b) Lap seam with testing channel
Key
1 discard
2 5 peel test specimens cut from within this area
3 welding
...