Welding Procedure Specification
Encyclopedia
A Welding Procedure Specification (WPS) is a formal document describing welding
Welding
Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...

 procedures. The purpose of the document is to guide welders to the accepted procedures so that repeatable and trusted welding techniques are used. A WPS is developed for each material alloy and for each welding type used. Specific codes and/or engineering societies are often the driving force behind the development of a company's WPS. A WPS is supported by a Procedure Qualification Record (PQR or WPQR). A PQR is a record of a test weld performed and tested (more rigorously) to ensure that the procedure will produce a good weld. Individual welders are certified with a qualification test documented in a Welder Qualification Test Record (WQTR) that shows they have the understanding and demonstrated ability to work within the specified WPS.

Introduction

The following are definitions for WPS and PQR found in various codes and standards:

According to the American Welding Society
American Welding Society
The American Welding Society is a nonprofit organization dedicated to advancing the science, technology, and application of welding and allied joining and cutting processes, including brazing, soldering, and thermal spraying...

 (AWS), a WPS provides in detail the required welding variables for specific application to assure repeatability
Repeatability
Repeatability or test-retest reliability is the variation in measurements if they would have been taken by a single person or instrument on the same item and under the same conditions. A less-than-perfect test-retest reliability causes test-retest variability. Such variability can be caused by, for...

 by properly trained welder
Welder
A welder is a tradesman who specializes in welding materials together. The materials to be joined can be metals or varieties of plastic or polymer...

s. The AWS defines welding PQR as a record of welding variables used to produce an acceptable test weldment and the results of tests conducted on the weldment to qualify a Welding Procedure Specification.

The American Society of Mechanical Engineers
American Society of Mechanical Engineers
The American Society of Mechanical Engineers is a professional body, specifically an engineering society, focused on mechanical engineering....

 (ASME) similarly defines a WPS as a written document that provides direction to the welder or welding operator for making production welds in accordance with Code requirements. ASME also defines welding PQR as a record of variables recorded during the welding of the test coupon. The record also contains the test results of the tested specimens.

In Europe, the European Committee for Standardization
European Committee for Standardization
The European Committee for Standardization or Comité Européen de Normalisation , is a non-profit organisation whose mission is to foster the European economy in global trading, the welfare of European citizens and the environment by providing an efficient infrastructure to interested parties for...

(CEN) has adopted the ISO standards on welding procedure qualification (ISO 15607 to ISO 15614) and on welder qualification (ISO 9606), with the exception of qualification for steel welders, where a new version of the old European EN 287-1 standard still applies. EN ISO 15706 defines a WPS as "A document that has been qualified by one of the methods described in clause 6 and provides the required variables of the welding procedure to ensure repeatability during production welding". The same standard defines a Welding Procedure Qualification Record (WPQR) as "Record comprising all necessary data needed for qualification of a preliminary welding procedure specification". In addition to the standard WPS qualification procedure specified in ISO 15614, the ISO 156xx series of standards provides also for alternative WPS approval methods. These include: Tested welding consumables (ISO 15610), Previous welding experience (ISO 15611), Standard welding procedure (ISO 15612) and Preproduction welding test (ISO 15613).

In the oil and gas pipeline sector, the American Petroleum Institute API 1104 standard is used almost exclusively worldwide. API 1104 accepts the definitions of the American Welding Society code AWS A3.0.

List of standards

  • ASME Boiler and Pressure Vessel Code section IX: "Qualification Standard for welding and brazing procedures, welders, brazers and welding and brazing operators"
  • EN ISO 15607: "Specification and qualification of welding procedures for metallic materials - General rules (ISO 15607:2003)"
  • EN ISO 15609: "Specification and qualification of welding procedures for metallic materials - Welding procedure specification (ISO 15609)", five parts.
  • EN ISO 15614: "Specification and qualification of welding procedures for metallic materials - Welding procedure test (ISO 15614)", 13 parts.
  • EN ISO 9606: "Qualification test of welders — Fusion welding (ISO 9606)" four parts
  • EN 287-1:2004 "Qualification test of welders — Fusion welding — Part 1: Steels"
  • API 1104: "Welding of pipelines and related facilities", parts 5 (procedures) & 6 (welders)
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