{"id":6228,"date":"2026-09-21T08:25:22","date_gmt":"2026-09-21T05:25:22","guid":{"rendered":"https:\/\/aesinn.com\/test-ve-olcum-hizmetleri\/api-1104-boru-hatti-kaynagi-petrol-ve-gaz-iletim-hatlarinda-kaynak-nitelendirme-ve-kabul-kriterleri\/"},"modified":"2026-09-21T10:58:06","modified_gmt":"2026-09-21T07:58:06","slug":"api-1104-boru-hatti-kaynagi-petrol-ve-gaz-iletim-hatlarinda-kaynak-nitelendirme-ve-kabul-kriterleri","status":"publish","type":"page","link":"https:\/\/aesinn.com\/en\/test-ve-olcum-hizmetleri\/api-1104-boru-hatti-kaynagi-petrol-ve-gaz-iletim-hatlarinda-kaynak-nitelendirme-ve-kabul-kriterleri\/","title":{"rendered":"API 1104 Pipeline Welding: Welding Qualification and Acceptance Criteria for Oil and Gas Transmission Lines"},"content":{"rendered":"<h2 class=\"wp-block-heading\">What is API 1104 and what does it cover?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">API 1104 (Welding of Pipelines and Related Facilities) is a standard published by the American Petroleum Institute that regulates field welding of pipelines used for the transmission of oil and gas. Its scope covers the new construction and in-service repair welding of pipes and components used for pressurizing, pumping, and transporting fluids such as crude oil, petroleum products, fuel gases, carbon dioxide, and nitrogen through transmission pipelines. The focus is on cross-country pipeline circumferential seam welding, not on-site welding.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The standard is often mentioned alongside ASME B31.4 (liquid transport) and ASME B31.8 (gas transport), which provide transmission line design guidelines. When a pipeline project refers to both API 1104 and these design standards, API 1104 is the guiding principle in terms of sourcing procedures and qualifications. This content is for informational purposes only and provides a general technical framework.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>Application area: field welding of oil and gas transmission and distribution pipelines.<\/li>\n\n\n<li>Welding methods: gas melting and arc welding processes.<\/li>\n\n\n<li>Related design standards: ASME B31.4 (liquid) and ASME B31.8 (gas) transmission lines.<\/li>\n\n\n<li>Works covered: new construction welding and in-service repair welding.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How API 1104 Differs from Other Source Standards<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">To properly position API 1104, it&#039;s necessary to clearly distinguish it from similar standards. API 1104 is an American system standard specific to field welding of oil and gas transmission pipelines; it regulates circumferential seams produced in open terrain along pipelines. In contrast, ASME B31.3 deals with the design of piping within process plants and is addressed under a separate heading with an entirely different scope. The two are not the same work: one is pipeline welding along the line, the other is in-plant process piping design.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Similarly, topics such as general weld inspection (welding procedure and welder qualification for structural or pressure vessels) and ISO 5817, which defines the acceptance of defects in steel welds, are addressed under separate headings. The distinguishing feature of API 1104 is that it is pipeline-specific and includes an alternative acceptance approach based on fracture mechanics (ECA) alongside workmanship-based acceptance.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>API 1104: Field source for oil and gas transmission pipelines (pipeline, American system)<\/li>\n\n\n<li>ASME B31.3: Process in-plant piping DESIGN (different scope, separate heading)<\/li>\n\n\n<li>General source inspection (structural and pressure vessel procedure): separate heading.<\/li>\n\n\n<li>ISO 5817: Defect tolerance levels in steel welds (separate section)<\/li>\n\n\n<li>API 1104 distinguishing feature: alternative acceptance based on fracture mechanics (ECA).<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Sourcing Procedure Qualification (WPS and PQR)<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The reliability of a pipeline weld begins with the qualification of the welding procedure. The Welding Procedure Specification (WPS) is the written instruction given to the welder; it defines the range of materials, diameters, wall thicknesses, welding methods, filler metals, and parameters within which a qualified procedure is applicable. The Procedure Qualification Record (PQR) is the proof that the test weld produced using that procedure has been actually welded, tested, and meets the acceptance criteria.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Procedure characterization under API 1104 is performed by subjecting trial coupon sources to specified destructive testing. The type and number of tests vary depending on the pipe&#039;s outer diameter and wall thickness. This approach aims to measurably demonstrate that the procedure provides the expected mechanical behavior under production conditions.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>WPS: Written, periodic instructions given to the welder.<\/li>\n\n\n<li>PQR: Proof record showing that the procedure has been boiled and tested.<\/li>\n\n\n<li>Characterization is carried out using test sets that vary in diameter and wall thickness.<\/li>\n\n\n<li>Procedural qualification and welder qualification are separate steps.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Welder Qualification and Mechanical Testing<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A qualified procedure alone is not sufficient; the skill level of the welder performing that procedure must also be demonstrated. In API 1104, welder qualification is achieved by subjecting the welder&#039;s welds, produced using a qualified WPS (Waste Procedure Plan), to destructive testing in a position and feed direction representing the production job. This verifies that the welder can produce acceptable welds under field conditions.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Mechanical tests reveal the behavior of the weld, both from the procedure and the welder&#039;s perspective. The main destructive methods are: tensile testing (strength), bending testing (ductility and weld integrity), notch impact testing (toughness, if required), and nick-break testing. Nick-break testing allows for visual assessment of internal defects in the weld cross-section and is one of the characteristic tests of API 1104.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>Tensile test: strength of weld and base metal.<\/li>\n\n\n<li>Bending test: ductility and weld integrity (root, face, or side)<\/li>\n\n\n<li>Notch impact test: weld toughness (if required)<\/li>\n\n\n<li>Nick-break: examination of internal defects in a fractured section.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Non-destructive testing: Radiography, AUT (Automated Ultrasound), and Manual Ultrasound.<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The vast majority of production sources are evaluated using non-destructive testing. Traditionally, radiography (RT) is a commonly used method for inspecting pipeline circumferential seams and is effective in detecting non-planar defects. However, radiography is limited in reliably measuring the height (depth) of the defect along the wall.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">With the development of automated ultrasonic testing (AUT) systems, the intrawall height, length, and location (exposed, interacting with the surface, or embedded) of defects can be measured more reliably. API 1104 contains provisions for AUT, and AUT can replace or supplement radiography. Manual ultrasonic testing (UT) is also applied in certain situations. The ability to measure the intrawall height of the defect is a technical prerequisite for applying acceptance criteria based on fracture mechanics.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>Radiography (RT): a common method, limited in height measurement.<\/li>\n\n\n<li>Automated ultrasonic (AUT): powerful in height, length, and position measurement.<\/li>\n\n\n<li>Manual ultrasonography (UT): complementary for specific conditions.<\/li>\n\n\n<li>Defect height measurement is a technical prerequisite for the ECA pathway.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Two Acceptance Approaches: Workmanship and Fracture Mechanics-Based Alternative Acceptance<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The most distinctive aspect of API 1104 is that it offers two different acceptance approaches for weld defects. The first is the traditional workmanship acceptance criterion in the main body of the standard. In this approach, defects are evaluated empirically based on their type, length, width, and total accumulation over a given weld length. The workmanship criterion is designed as an indicator of good welding practice and provides a predictable acceptance framework in field application.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Secondly, there is the alternative acceptance or fitness-for-purpose approach based on fracture mechanics (ECA) under Annex A. Here, defect acceptance relies on demonstrating the actual toughness of the weld (such as notch impact or crack end opening) through test data and damage tolerance analysis performed in conjunction with stress levels. When toughness is sufficiently high and stress is within calculated safety limits, this approach may allow for defect sizes larger than the workmanship table. This approach is conditional: it must meet the additional requirements of the project specification, the AUT procedure, and the welding procedure; it is not a one-sided way out that absolves the inspector when a weld falls within a workmanship criterion.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>Acceptance of workmanship: empirical limits based on defect type, length, width, and total accumulation.<\/li>\n\n\n<li>Alternative acceptance (Annex A, ECA): fitness for purpose based on toughness testing and stress analysis.<\/li>\n\n\n<li>The ECA pathway may allow for greater defects depending on the demonstrated toughness.<\/li>\n\n\n<li>It is conditional: the project specification, AUT (Automated Procedure), and welding procedure requirements must all be met simultaneously.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Scope and Purpose of This Content<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">This content is for informational purposes only and does not include the official text of the API 1104 standard; for numerical acceptance limits, test numbers, and conditions, the current edition of the standard and the project specifications should always be used as a basis. Safe results in pipeline welding depend on the correct qualification of the procedure and welder, appropriate non-destructive testing, and the selection of acceptance criteria suitable to the project; these assessments must be carried out by a qualified engineer.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">AES is NOT a certification or accredited body; personnel and procedural certifications such as welder and WPS are the responsibility of separate accredited bodies. AES&#039;s T\u00dcRKAK accreditation is limited only to the 6.1 Electrical Installation field. Therefore, this text is not a statement of authorization for pipeline welding qualification or certification, but rather a technical informational document introducing the subject.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>The current edition of the standard and the project specifications are essential for determining numerical limits.<\/li>\n\n\n<li>The choice of acceptance approach requires competent engineering assessment.<\/li>\n\n\n<li>AES is not a certification or accredited body; personnel and procedural certification is the responsibility of separate accredited organizations.<\/li>\n\n\n<li>AES accreditation is limited to the 6.1 Electrical Installation field only.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Related Services<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li><a href=\"https:\/\/aesinn.com\/en\/test-ve-olcum-hizmetleri\/asme-b31-3-proses-boru-tesisati-tasarim-imalat-muayene-ve-test-kodunun-bilgilendirici-rehberi\/\">ASME B31.3 Process Piping Design and Manufacturing Code<\/a><\/li>\n\n\n<li><a href=\"https:\/\/aesinn.com\/en\/test-ve-olcum-hizmetleri\/kaynak-muayenesi-ve-kaynakci-wps-yeterlilik-degerlendirmesi-aws-d1-1-asme-bpvc-section-ix-ve-ts-en-iso-9606\/\">Welding Inspection and Welder \/ WPS Qualification Assessment<\/a><\/li>\n\n\n<li><a href=\"https:\/\/aesinn.com\/en\/test-ve-olcum-hizmetleri\/iso-5817-ergitme-kaynakli-baglantilarda-kusur-kabul-seviyeleri-b-c-d-kalite-seviyeleri\/\">ISO 5817 Steel Welding Defect Acceptance Levels (B \/ C \/ D)<\/a><\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Frequently Asked Questions<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">What tasks does API 1104 cover?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">It covers the field welding of pipelines and related components used for the transmission of oil and gas; it regulates gas melting and arc welding processes for new construction and in-service repair welding of pipelines carrying fluids such as crude oil, petroleum products, fuel gases, carbon dioxide, and nitrogen.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Are API 1104 and ASME B31.3 the same thing?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">No. API 1104 is the American system standard regulating field welding of oil and gas transmission pipelines; ASME B31.3 is a different, comprehensive, separate standard dealing with the design of piping within process plants. ASME B31.4 and B31.8 are also mentioned in relation to pipeline design.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between WPS and PQR?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">WPS is a written instruction given to the welder and defines the material, diameter, thickness, and parameter range for which the procedure is valid. PQR is a proof record documenting that the test weld produced using that procedure has been welded, tested, and meets the acceptance criteria.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What are the two acceptance approaches for API 1104?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Firstly, there is the traditional workmanship acceptance criterion in the main body; it evaluates defects empirically based on type, length, width, and total accumulation. Secondly, there is the alternative acceptance based on fracture mechanics (ECA) under Annex A; it relies on demonstrated toughness and stress analysis and may allow for larger defects depending on the conditions.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What inspection methods are used in pipeline welding?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Non-destructive testing utilizes radiography, automated ultrasonic testing (AUT), and manual ultrasonic testing (UT). Destructive testing includes tensile, bending, notch impact, and nick-break tests. AUT is a technical prerequisite for alternative acceptance methods because it can measure the intrawall height of the defect.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Does AES provide pipeline welder or WPS certification?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">No. AES is not a certification or accredited body; personnel and procedural certifications such as welder and WPS certifications are the responsibility of separate accredited organizations. AES&#039;s T\u00dcRKAK accreditation is limited only to the 6.1 Electrical Installation field. This content is for informational purposes only.<\/p>","protected":false},"excerpt":{"rendered":"<p>API 1104, petrol ve gaz iletim boru hatlar\u0131n\u0131n saha kayna\u011f\u0131n\u0131 d\u00fczenleyen Amerikan standard\u0131d\u0131r; geleneksel i\u015f\u00e7ilik kabul kriterlerinin yan\u0131nda k\u0131r\u0131lma mekani\u011fi tabanl\u0131 alternatif kabul (ECA) yakla\u015f\u0131m\u0131yla ay\u0131rt edilir.<\/p>","protected":false},"author":1,"featured_media":6231,"parent":2518,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_kad_blocks_custom_css":".transparent-header.content-title-style-hide .content-area{padding-top:140px;}@media (max-width:767px){.transparent-header.content-title-style-hide .content-area{padding-top:90px;}}","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","slim_seo":{"title":"API 1104 Pipeline Welding Guide","description":"API 1104: Acceptance criteria for field welding, welder qualification, non-destructive testing, and fracture mechanics for oil and gas transmission pipelines."},"_pplb_hide_from_list":false,"footnotes":""},"class_list":["post-6228","page","type-page","status-publish","has-post-thumbnail","hentry"],"acf":[],"taxonomy_info":[],"featured_image_src_large":["https:\/\/aesinn.com\/wp-content\/uploads\/api1104-aes-kart-1024x1024.png",1024,1024,true],"author_info":{"display_name":"Emre Metin","author_link":"https:\/\/aesinn.com\/en\/author\/yonetim\/"},"comment_info":"","_hostinger_reach_plugin_has_subscription_block":false,"_hostinger_reach_plugin_is_elementor":false,"_links":{"self":[{"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages\/6228","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/comments?post=6228"}],"version-history":[{"count":2,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages\/6228\/revisions"}],"predecessor-version":[{"id":6237,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages\/6228\/revisions\/6237"}],"up":[{"embeddable":true,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages\/2518"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/media\/6231"}],"wp:attachment":[{"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/media?parent=6228"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}