API RP 577-2020 PDF

Full title and description

API RP 577 — Welding Processes, Inspection, and Metallurgy. This Recommended Practice provides guidance for welding processes, welder and procedure qualification, metallurgical effects of welding, and inspection and nondestructive examination methods as applied to fabrication and repair of refinery, petrochemical, and related plant equipment and piping.

Abstract

API RP 577 (Third Edition, 2020) is intended to support the API authorized inspector and other inspection, metallurgy and welding personnel by describing common welding processes, welding procedure and welder qualification relationships (including ASME Section IX), metallurgical considerations (effects of welding, PWHT, hydrogen control, material compatibility), typical weld discontinuities, and recommended inspection and NDE practices used in the petroleum and chemical industries. The document is used as a reference for inspection tasks associated with API 510, 570 and 653 programs.

General information

• Status: Third edition (2020); current edition amended by Errata 1 (issued September 2025).
• Publication date: October 1, 2020 (Third edition).
• Publisher: American Petroleum Institute (API).
• ICS / categories: Petroleum and related technologies (75.180); Metallurgy — testing and metallurgy (77.000 / 77.040). (Representative ICS groupings for welding/metallurgy standards.)
• Edition / version: 3rd edition (2020).
• Number of pages: Approximately 194 pages (commonly listed as 194–195 pages depending on publisher reprints).

Scope

Provides guidance to API authorized inspectors and other responsible parties on welding inspection and metallurgical considerations encountered during fabrication, erection and repair of refinery, petrochemical and related industry equipment and piping. Topics include selection and control of welding processes, filler metals and consumables, welding procedure specification (WPS) and procedure qualification records (PQR), welder performance qualification, preheat/postweld heat treatment, control of hydrogen and residual stresses, evaluation of weld discontinuities, and selection and application of nondestructive examination methods appropriate to industry practice.

Key topics and requirements

• Overview of common welding processes used in industry and their advantages/limitations (SMAW, GMAW, GTAW, SAW, FCAW, and others).
• Welding procedure and welder qualification principles and their relationship to ASME Section IX.
• Metallurgical effects of welding: HAZ characteristics, PWHT, hydrogen control, weldability of various alloys, and failure mechanisms.
• Inspection responsibilities for the API authorized inspector, including visual inspection, acceptance criteria, and typical defect identification.
• Nondestructive examination (NDE) methods applied to welds (VT, PT, MT, UT, RT, PMI/positive material identification) and guidance on their use.
• Material and consumable selection, control of filler metals, and reference to material verification practices (e.g., API 578).
• Recommended practices for welding repairs, overlay, and fabrication-specific issues in refinery/petrochemical service.

Typical use and users

Primary users are API authorized inspectors and inspectors preparing for API 577 certification, welding engineers, metallurgists, QA/QC and fabrication supervisors, plant inspectors working under API 510/570/653 programs, and training organizations delivering welding inspection and metallurgy courses. The RP is also used as a reference for developing inspection plans and for training toward industry certifications.

Related standards

Commonly referenced standards and codes include: ASME Section IX (welding qualifications), ASME Section V (NDE), ASME Section VIII and ASME B31.3 (pressure equipment and piping), API RP 578 (material verification), API RP 582, API RP 572, API RP 574, API 510/570/653 inspection documents, and relevant AWS and ISO welding standards. These documents are frequently cited in API RP 577 and used alongside it.

Keywords

welding, weld inspection, metallurgy, PWHT, welder qualification, welding procedure specification (WPS), nondestructive examination (NDE), API inspector, refinery, petrochemical, filler metal, welding discontinuities, material verification.

FAQ

Q: What is this standard?

A: API RP 577 is an API Recommended Practice titled "Welding Processes, Inspection, and Metallurgy" that provides guidance for welding inspection and metallurgical considerations in refinery, petrochemical and related industries.

Q: What does it cover?

A: It covers welding processes, welding procedure and welder qualification principles (links to ASME Section IX), metallurgical effects of welding (HAZ, PWHT, hydrogen control), inspection techniques, common discontinuities and appropriate NDE methods, and guidance for repairs and materials/consumables selection.

Q: Who typically uses it?

A: API authorized inspectors, welding engineers, metallurgists, QA/QC personnel, fabricators, training providers, and individuals preparing for API 577 certification or working under API 510/570/653 inspection programs.

Q: Is it current or superseded?

A: The most recent edition is the Third Edition published October 2020; it was issued with an Errata 1 in September 2025. Users should confirm they have the 2020 third edition and note the 2025 errata when applying the RP.

Q: Is it part of a series?

A: API RP 577 is part of API's family of inspection and mechanical integrity documents and is commonly used together with API 510, API 570, API 653 and related RPs (e.g., API RP 572, RP 574, RP 578) and ASME code documents.

Q: What are the key keywords?

A: Welding, inspection, metallurgy, PWHT, WPS, welder qualification, nondestructive examination, API inspector, filler metals, material verification.