Welding Procedure Specification

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A Welding Procedure Specification (WPS) is the formal written document describing welding procedures, which provides direction to the welder or welding operators for making sound and quality production welds as per the code requirements . 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.

Welding fabrication or sculptural process for joining materials

Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool causing fusion. Welding is distinct from lower temperature metal-joining techniques such as brazing and soldering, which do not melt the base metal.

Contents

Introduction

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

According to the American Welding Society (AWS), a WPS provides in detail the required welding variables for specific application to assure repeatability by properly trained welders. 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. For steel construction (civil engineering structures) AWS D1.1 is a widely used standard. It specifies either a pre-qualification option (chapter 3) or a qualification option (chapter 4) for approval of welding processes. [1]

American Welding Society organization

The American Welding Society (AWS) was founded in 1919 as a non-profit organization to advance the science, technology and application of welding and allied joining and cutting processes, including brazing, soldering and thermal spraying.

Repeatability or test–retest reliability is the closeness of the agreement between the results of successive measurements of the same measure carried out under the same conditions of measurement. In other words, the measurements are taken by a single person or instrument on the same item, under the same conditions, and in a short period of time. A less-than-perfect test–retest reliability causes test–retest variability. Such variability can be caused by, for example, intra-individual variability and intra-observer variability. A measurement may be said to be repeatable when this variation is smaller than a pre-determined acceptance criterion.

Welder Profession

A welder is a tradesperson who specializes in fusing materials together. The term welder refers to the operator, the machine is referred to as the welding power supply. The materials to be joined can be metals or varieties of plastic or polymer. Welders typically have to have good dexterity and attention to detail, as well as technical knowledge about the materials being joined and best practices in the field.

The American Society of Mechanical Engineers (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. [2] 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.

American Society of Mechanical Engineers Mechanical engineering professional society

The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing education, training and professional development, codes and standards, research, conferences and publications, government relations, and other forms of outreach." ASME is thus an engineering society, a standards organization, a research and development organization, an advocacy organization, a provider of training and education, and a nonprofit organization. Founded as an engineering society focused on mechanical engineering in North America, ASME is today multidisciplinary and global.

The Canadian Welding Bureau, through CSA Standards W47.1, [3] W47.2 [4] and W186, [5] specifies both a WPS and a Welding Procedure Data Sheet (WPDS) to provide direction to the welding supervisor, welders and welding operators. The WPS provides general information on the welding process and material grouping being welded, while the WPDS provides specific welding variables/parameter/conditions for the specific weldment. All WPS and WPDS must be independently reviewed and accepted by the Canadian Welding Bureau prior to use. These CSA standards also define requirements for procedure qualification testing (PQT) to support the acceptance of the WPDS. A record of the procedure qualification test and the results must be documented on a procedure qualification record (PQR). All PQTs are independently witnessed by the Canadian Welding Bureau.

Canadian Welding Bureau organization

The Canadian Welding Bureau is a certification and registration organization for companies involved in the welding of steel structures. Welders in Canada are required to be retested every two years by the Canadian Welding Bureau. The CWB Group was formed in 1947 to administer the then, new W47.1 welding standard for structural steel. The CWB has today expanded its scope well beyond the original structural steel roots and is accredited by the Standards Council of Canada as a Certification Body for the administration of CSA Standards including W47.1, W47.2, W55.3, W186, W178.1 and W48 to industries across Canada and internationally for :

In Europe, the European Committee for Standardization (CEN) has adopted the ISO standards on welding procedure qualification (ISO 15607 to ISO 15614), which replaced the former European standard EN 288. EN ISO 15607 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". [6] 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).

European Committee for Standardization standards organization

The European Committee for Standardization is a public standards organization whose mission is to foster the economy of the European Union (EU) in global trading, the welfare of European citizens and the environment by providing an efficient infrastructure to interested parties for the development, maintenance and distribution of coherent sets of standards and specifications.

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. [7]

American Petroleum Institute organization

The American Petroleum Institute (API) is the largest U.S. trade association for the oil and natural gas industry. It claims to represent about 650 corporations involved in production, refinement, distribution, and many other aspects of the petroleum industry.

WPS is of two types- Prequalified WPS(pWPS) & qualified WPS.

See also

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References

  1. AWS D1.1/D1.1M: "Structural welding code - Steel"
  2. ASME Boiler and Pressure Vessel Code section IX: "Qualification Standard for welding and brazing procedures, welders, brazers and welding and brazing operators", Article II, Section QW-200.
  3. CSA Standard W47.1: Certification of companies for the fusion welding of steel (2009)
  4. CSA Standard W47.2: Certification of companies for the fusion welding of aluminum (2011)
  5. CSA Standard W186: Welding of Reinforcing Bars in Reinforced Concrete Construction (1990)
  6. EN ISO 15607:2005 "Specification and qualification of welding procedures for metallic materials - General rules (ISO 15607:2003)"
  7. API 1104: "Welding of pipelines and related facilities", parts 3 (Definition of Terms)

List of standards