NDT Standards Comparison: ASME vs ASTM vs ISO vs EN

A comprehensive comparison of the major NDT codes and standards used globally — ASME Section V, ASTM, ISO, EN, AWS, and API — organised by method, application, country, and acceptance criteria. The governing principle: the construction code determines the NDE standard. Equipment built to ASME Section VIII uses ASME Section V for NDE; PED equipment in Europe uses EN/ISO standards; pipeline girth welds follow API 1104; structural steel follows AWS D1.1. Always identify the construction code first.

ASME Section V — Nondestructive Examination

The most widely referenced NDE code in oil & gas, petrochemical, and power generation. Key articles: Article 1 (general requirements), Article 2 (radiographic), Articles 4–5 (ultrasonic, welds and materials), Article 6 (penetrant), Article 7 (magnetic particle), Article 8 (eddy current), Article 9 (visual), Article 10 (leak testing), Articles 12–13 (acoustic emission), Article 23 (adopted SE standards), plus Appendix IV (phased array UT) and Appendix IX (TOFD). Acceptance criteria live in the referencing code — e.g., ASME Section VIII UW-51/52.

ASTM Standards by Method

ASTM standards define the detailed "how"; ASME Section V adopts them as SE standards and tells you what to examine and when.

ISO and EN Standards

Key ISO NDT standards include ISO 17640 (UT of welds), ISO 10863 (TOFD), ISO 13588 (automated PAUT), ISO 3452-1 (PT), ISO 9934-1 (MT), ISO 5579 and ISO 17636 (RT), ISO 11666 (UT acceptance levels), and ISO 9712 (personnel certification). European EN standards — mandatory under the Pressure Equipment Directive — include EN 12668 (UT equipment), EN 12062 (NDE of welds), EN 13018 (VT), and EN 13480 (metallic piping); many are now harmonised as "EN ISO" documents identical to their ISO counterparts.

AWS and API Codes

AWS: D1.1 Structural Welding Code — Steel (NDE in Part C, acceptance in Tables 6.1/6.2), D1.5 Bridge Welding (more stringent, UT per Annex K), D1.6 stainless, D1.8 seismic supplement, D17.1 aerospace. API: API 510 (in-service pressure vessels), API 570 (piping), API 653 (storage tanks), API 1104 (pipeline welding NDE), API RP 580/581 (risk-based inspection), and API 579-1/ASME FFS-1 (fitness-for-service) — see the API inspector guide.

Which Standard Applies? By Application & Country

By country: the USA runs ASME/API/AWS/ASTM with ASNT SNT-TC-1A or ACCP; the UK uses BS EN with PCN and CSWIP; Germany and France use DIN/NF EN with ISO 9712 bodies; Saudi Arabia and the UAE apply ASME/API plus Aramco/ADNOC standards accepting ASNT, ISO 9712, and PCN; India combines ASME with IBR; Australia uses AS/NZS with AINDT; Canada CSA with CGSB.

Acceptance Criteria Comparison

Cracks are rejectable under ASME VIII, AWS D1.1, and EN 13445 alike. Lack of fusion is rejected by ASME VIII and AWS D1.1 but API 1104 permits limited lengths. Porosity and slag are accepted within tabulated per-code limits, and undercut is commonly limited to about 1/32 inch. Nuclear codes are the most stringent, then aerospace; EN/ISO systems use quality levels B (strictest) through D. To select: identify the construction code, check the project specification, confirm the regulatory framework (PED, NR-13, IBR), determine whether in-service codes such as API 510/570/653 now govern, and verify the matching certification scheme.

Frequently Asked Questions

Which NDT standard applies to pressure vessel weld inspection?

In the USA: ASME Section V procedures with acceptance criteria from ASME Section VIII (new construction) or API 510 (in-service). In Europe: EN 13445 referencing EN/ISO method standards and ISO 5817 quality levels. The project construction code decides.

What is the difference between ASME Section V and ASTM standards?

ASME Section V is the code framework specifying what NDE to perform and when; ASTM standards are individual test-method documents describing how — many adopted into Section V as SE standards (e.g., E164 becomes SE-164).

Are EN and ISO NDT standards the same?

Increasingly yes: documents prefixed "EN ISO" are identical to the ISO version. Standards carrying only the "EN" prefix may include European-specific PED-driven content. The trend is full harmonisation.

Which standard applies to pipeline NDT?

API 1104 governs girth weld NDE for oil & gas pipelines in the USA and most international projects, using ASME Section V procedures with API 1104 acceptance criteria; Europe uses EN 12732.

Which acceptance criteria are the most stringent?

Nuclear codes (ASME Section III, RCC-M), then aerospace (NAS-410/Nadcap). Among industrial codes, ASME VIII is stricter than API 1104; AWS D1.1 sits between; EN/ISO quality level B is the strictest of its tiers.

How do I know which standard to use on my project?

Follow the chain: construction code, project specification, regulatory framework, in-service inspection codes, and personnel certification scheme. When in doubt, Atlantis NDT Level III consultants provide standard selection, procedure development, and compliance reviews across ASME, API, AWS, ISO, and EN.

Atlantis NDT Products & Services

Atlantis NDT supports inspection organisations end to end: NDT inspection management software — Atlantis ERP for work orders, certification tracking and audit-ready records; a digital twin platform for asset integrity that overlays inspection history on a navigable 3D model; modern NDT reporting software; NDT training & certification backed by a 96% first-attempt pass rate and ASNT Level III authorship; ASNT Level III consulting; and 3D laser scanning services. Affordable. Accessible. Fully customizable. Book a free consultation — pricing varies by region and scope, and we return a tailored quote within 24 hours.