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What you should know about welding codes and standards
What Are Welding Codes and Standards, When Are They Used, and How Are They Developed
Many aspects of the design and fabrication of welded components are governed by documents known as codes and standards. Other names used for such documents include guides, recommended practices, regulations, rules, and specifications. These documents are often specified by an end user/purchaser as a contractual agreement in order to control the characteristics of the welded fabrication that may affect its service requirements. They are also used by the manufacturer to assist in the development and implementation of their welding quality system. Many end users of welded components have developed and issued specifications that have been compiled by them to address their specific requirements. Such specifications may be limited in application and related only to that customer’s situation and requirements. National interest in areas such as public safety and reliability has promoted the development of welding codes and standards that command broader recognition both on a national and industry-specific basis. Numerous committees have been developed over the years within national engineering and technical societies that continue to evaluate the needs of industry and develop new welding codes and standards. Such committees are comprised of members who are technical experts and represent all interested parties such as manufacturers, end users, inspection authorities, and government agencies. The membership of these committees is balanced in order to prevent any one interest group from controlling the committee. On completion of a new or revised document by the specific committee, it is usually then reviewed and approved by a review committee, and if accepted, then published in the name of the applicable engineering society.
Documents that have significant influence upon public health and safety are sometimes adopted by legislative bodies or by federal regulating agencies. In those jurisdictions, such documents become law and are often referred to as Codes or Regulations.
The welding inspector should be aware of what codes or standards are applicable within their jurisdiction, understand the requirements of the relevant documents and perform their inspection accordingly.
Sources Of Codes and Standards Of Interest To The Welding Industry
The following are some of the more popular sources of welding codes and standards found in the USA.
American Welding Society (AWS) – Probably the largest producer of welding codes and standards in the USA. The AWS publishes many documents addressing the use and quality control of welding. These documents include such general subjects as Welding Definitions and Symbols, Classification of Filler Metals, Qualification and Testing, Welding Processes, Welding Applications, and Safety.
American Society of Mechanical Engineers (ASME) – This society is responsible for the development of the Boiler and Pressure Vessel Code, which contains eleven sections and covers the design, construction, and inspection of boilers and pressure vessels. ASME also produces the Code for Pressure Piping, which consists of seven sections. Each section prescribes the minimum requirements for the design, materials, fabrication, erection, testing and inspection of a particular type of piping system. Both of these documents are American National Standards.
American Petroleum Institute (API) – This institute publishes many documents relating to petroleum production, a number of which include welding requirements. The most well known is possibly API Std 1104 – Standard for Welding Pipelines and Related Facilities.
What The Welding Code and Standard Generally Provides
The specific content and requirements of a welding code or standard can vary in detail, however, there are a number of elements within these types of documents which are common and which we will examine.
The Scope and General Requirements: This is found at the beginning of the document and is important as it will normally provide a description as to the type and extent of welding fabrication for which the document was developed and intended to be used. It may also provide information relating to the limitations for the use of the document. Care should be taken to use codes and standards that are applicable for your particular application.
Design: If the document provides a section for design, it may refer the user to a secondary source of information, or it may contain minimum requirements for the design of specific welded connections.
Qualification: This section of the document will typically outline the requirements for qualification testing of welding procedure specifications (WPS) and also those requirements for qualification of welding personnel. It may provide the essential variables, these being the change limitations that govern the extent of qualification. Such variables are typically the welding process, type and thickness of base metal, filler metal type, electrical parameters, joint design, welding position, and others.
This section of the document may also provide the qualification testing requirements. Usually this is divided into welding procedure and welder performance testing requirements. Typically, it will provide the types and sizes of test samples to be welded and prepared for testing, the testing methods to be used, and the minimum acceptance criteria to be used for the evaluation of test samples.
Fabrication: This section, when included in the document, will typically provide information associated with the fabrication methods and/or workmanship standards. It may contain information and requirements on such items as base materials, welding consumable classification requirements, shielding gas quality, heat treatment requirements, preparation and care of base material, and other welding fabrication requirements.
Inspection: This section of the document will typically address the welding inspector’s qualification requirements and responsibilities, acceptance criteria for discontinuities, and requirements relating to procedures for nondestructive testing.
Opportunities For The Welding Fabricator To Improve Weld Quality And Reliability
With the move by more manufacturing organizations toward the implementation of quality management systems, such as ISO 9000, and the requirement of such systems for process control, we must consider welding as a special process and, consequently, its formal control. Welding codes and standards are often used by the welding fabricator to assist with the development of their process control system. If we consider the major elements of process control, as specified by such standards for quality systems, we will recognize those same elements as being addressed within the welding code or standard. The first requirement for process control is documented procedures defining the manner of production. For welding, this is the welding procedure specification (WPS). A second requirement is criteria for workmanship, which shall be stipulated in the clearest practical manner. For welding, this may be the code or standard acceptance criteria. A third requirement is qualification of personnel. This may be addressed by the welder performance qualification. Regardless of the manufacturer’s overall quality system, there may be opportunities available through the selection and use of an appropriate welding code or standard for welding quality and reliability improvements.