API 1104 Welding of Pipelines and Related Facilities

API 1104 is the welding code for pipelines and related facilities transporting liquids, gases, or slurries, defining procedure and welder qualification, weld inspection (RT, AUT), and acceptance criteria for cross-country and station piping.

Definition

API 1104 acceptance criteria are based on workmanship for most flaws and on engineering critical assessment (ECA, Annex A) for fatigue-critical situations. Automated UT (AUT) per Annex E is now common for pipeline girth welds, often replacing RT.

What this document is

The API standard for welding of pipelines and related facilities, containing both welding procedure and welder qualification requirements and its own radiographic and ultrasonic acceptance criteria.

How it is applied

Distinctive in that acceptance criteria live in the same document as the welding requirements, and those criteria are length-and-type based rather than the area-based approach found elsewhere. An alternative acceptance annex permits fracture-mechanics-based criteria.

The common misuse

Applying ASME Section VIII acceptance to a pipeline girth weld or vice versa. The criteria are genuinely different, and a weld can pass one and fail the other.

Where API 1104 Welding of Pipelines and Related Facilities fits in an inspection programme

A term is only useful when it connects to a decision. API 1104 Welding of Pipelines and Related Facilities appears in written procedures, in technique sheets, and in the records an owner or accreditation body reviews afterwards — which means the way it is defined in your documentation has to match the way it is applied on site. Where the two drift apart, audits find it. Atlantis writes and reviews procedures against the governing codes, trains inspection personnel to apply them, and builds the record-keeping that makes the evidence retrievable years later. Procedure development and code consulting · NDT training and certification · Ask us about your programme.

Related terms

ASME B31.4 Liquid Pipelines — ASME B31.4 is the code for transportation of liquids by pipelines, including crude oil, refined petroleum products, liquid alcohols, ammonia, and CO2, defining weld NDT requirements integrated with API 1104.
ASME B31.8 Gas Transmission and Distribution Piping — ASME B31.8 is the code for gas transmission and distribution piping systems, including pipelines and onshore station piping, defining NDT, hydrostatic testing, and integrity management for natural gas service.
Automated Ultrasonic Testing (AUT) — AUT is the use of mechanized scanners with encoded position to perform ultrasonic inspection (typically PAUT and/or TOFD) with consistent coverage, full data capture, and repeatable scan plans, widely used for pipeline girth welds.

More standard terms

ASME Section V · ASME Section VIII · ASME Section IX · ASME Section XI · ASME B31.1 Power Piping · ASME B31.3 Process Piping · API 510 Pressure Vessel Inspection Code · API 570 Piping Inspection Code · API 571 Damage Mechanisms · API 579-1 / ASME FFS-1 Fitness-for-Service

Where this comes up in practice

Terms like this one appear in three places that matter commercially: the written practice that governs how your personnel are qualified, the procedures and technique sheets that define how an examination is actually performed, and the evidence an auditor or client asks for when they want to know why an inspection was accepted. Getting the terminology right is the easy part; being able to produce the qualification record, the calibration traceability and the procedure revision that applied on the day of the inspection is the part that decides audits.

Atlantis NDT provides NDT training and certification against ASNT SNT-TC-1A and ISO 9712, ASNT Level III consulting for written practices and procedure approval, inspection management software that holds qualification, calibration and procedure-revision evidence in recoverable form, and an asset integrity platform that binds inspection results to the asset they describe. Browse the full NDT glossary or ask a Level III directly.