ISO 11666-2018 PDF

Full title and description

St ISO 11666-2018 — Non-destructive testing of welds — Ultrasonic testing — Acceptance levels. This international standard specifies ultrasonic acceptance levels for full-penetration welded joints in ferritic steels (acceptance level 2 and acceptance level 3) and guidance for applying those levels in ultrasonic examination.

Abstract

ISO 11666:2018 defines two ultrasonic acceptance levels, AL 2 and AL 3, intended to correspond to ISO 5817 quality levels B and C respectively. The document applies primarily to full penetration welded joints in ferritic steels with nominal thicknesses from 8 mm to 100 mm and is intended for use with ultrasonic testing carried out in accordance with ISO 17640. Nominal probe frequencies of 2 MHz to 5 MHz are referenced, with caveats where attenuation or resolution require other frequencies.

General information

• Status: Published — current edition (confirmed on periodic review in 2023).
• Publication date: January 2018 (Edition 2, 2018).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 25.160.40 (Welded joints and welds).
• Edition / version: Edition 2 (2018).
• Number of pages: 17 pages.

Key bibliographic and life-cycle details as published by ISO.

Scope

ISO 11666:2018 provides acceptance criteria (AL 2 and AL 3) for ultrasonic examination of full-penetration ferritic-steel welds (typically 8 mm to 100 mm thickness). It links these ultrasonic acceptance levels to the quality levels defined in ISO 5817 (B and C) and is intended to be applied where testing is performed in accordance with ISO 17640. Acceptance level for ISO 5817 quality level D is not included because ultrasonic testing is generally not required for that level. Use with other materials, weld types or thicknesses is possible but requires careful consideration of geometry, acoustic properties and achievable sensitivity.

Key topics and requirements

• Definition of two ultrasonic acceptance levels: Acceptance Level 2 (AL 2) and Acceptance Level 3 (AL 3).
• Correspondence of AL 2 and AL 3 to ISO 5817 quality levels B and C respectively.
• Applicability to full-penetration ferritic-steel welds, nominal thickness range 8 mm–100 mm (with guidance for other cases).
• Reference to test execution and assessment techniques in ISO 17640 (techniques, testing levels, assessment).
• Guidance on sensitivity setting, determination of discontinuity length, and assessment rules (including normative annexes for levels and fixed-amplitude technique).
• Probe frequency guidance—nominal probe frequencies between about 2 MHz and 5 MHz, with consideration for attenuation and resolution where needed.

Typical use and users

Used by NDT engineers, welding inspectors, third-party inspection bodies, fabricators and owners/operators in sectors where welded ferritic-steel components require ultrasonic examination for acceptance — e.g., pressure-vessel and boiler fabrication, pipeline and oil & gas fabrication, structural steelwork, shipbuilding and heavy manufacturing. The standard is applied when purchasers or specifications require ultrasonic acceptance criteria aligned with ISO 5817 quality levels. Guidance for the ultrasonic examination technique and testing level selection is provided by ISO 17640.

Related standards

Commonly referenced standards and documents: ISO 17640 — Non-destructive testing of welds — Ultrasonic testing — Techniques, testing levels and assessment (procedures and testing-level definitions used with ISO 11666); ISO 5817 — Welding — Quality levels for imperfections (provides the B/C quality level framework that AL 2/AL 3 correspond to). ISO 11666:2010 is the withdrawn predecessor to the 2018 edition.

Keywords

ultrasonic testing, UT, weld acceptance levels, AL2, AL3, ferritic steel, weld inspection, ISO 11666, ISO 17640, ISO 5817, nondestructive testing, weld quality.

FAQ

Q: What is this standard?

A: ISO 11666:2018 specifies ultrasonic acceptance levels (AL 2 and AL 3) for full-penetration welded joints in ferritic steels and gives rules for applying those acceptance levels in ultrasonic examination.

Q: What does it cover?

A: It covers acceptance criteria (levels), sensitivity-setting guidance, discontinuity-length determination and assessment rules for ultrasonic testing of full-penetration ferritic-steel welds (nominally 8–100 mm thick) and is intended to be used with ISO 17640 test procedures.

Q: Who typically uses it?

A: NDT technicians and engineers, welding inspectors, inspection bodies, fabricators and procurement/specification authors in industries requiring weld acceptance decisions (pressure equipment, pipelines, structural and heavy fabrication, shipbuilding, etc.).

Q: Is it current or superseded?

A: The 2018 edition (Edition 2) is the current published edition; it was published in January 2018 and the ISO entry indicates it was reviewed and confirmed in 2023. The 2010 edition was withdrawn and replaced by the 2018 edition.

Q: Is it part of a series?

A: Yes — ISO 11666 is part of the family of ISO standards covering non-destructive testing of welds (for example ISO 17640 for UT techniques and testing levels, and ISO 5817 for weld quality levels). It is intended to be used in conjunction with those related standards.

Q: What are the key keywords?

A: Ultrasonic testing, acceptance levels, AL 2, AL 3, weld inspection, ferritic steel, ISO 17640, ISO 5817.