ISO 16148:2016

Overview

ISO 16148:2016 specifies procedures for using acoustic emission examination (AT) with a follow-up ultrasonic examination (UT) during periodic inspection and testing of refillable seamless steel gas cylinders and tubes (water capacity up to 3 000 L) used for compressed and liquefied gases. The standard defines how acoustic emission (AE) indications are detected and located, and requires a secondary UT (shear‑wave/angle beam is the intended method) to verify and size possible flaws. Composite cylinders are excluded. Some tests involve hazardous pressurization-caution is required.

Key topics and requirements

• Scope: AT + UT follow-up for seamless steel cylinders/tubes up to 3 000 L; other secondary methods are not covered.
• AT Methods: Defines Method A (pneumatic pressurization to ≥110% normal filling pressure; typically for assemblies/bundles) and Method B (AT during hydrostatic proof pressurization to re‑test pressure on each cylinder).
• Pressurization: Test medium may be gas or liquid; AT pressures must exceed previous maximum service pressure to avoid the Kaiser effect.
• AE detection & location: Piezoelectric sensors and signal processors record AE events; at least two sensors are needed to triangulate source locations.
• UT follow-up: Shear wave (angle beam) UT immediately evaluates AE‑identified locations; use of calibration rings, distance amplitude correction (DAC) curves, and standardization procedures is required.
• Acceptance criteria: If UT reveals discontinuities exceeding specified depth/critical size limits (based on material, wall thickness, fatigue/fracture assessment), the cylinder/tube is removed from service.
• Personnel & competence: Operators must meet ISO 9712 (or equivalent, e.g., ASNT SNT‑TC‑1A) qualifications; Level I/II operators perform tests under Level III oversight.
• Equipment, calibration & safety: AT equipment specification, calibration/verification, real‑time evaluation criteria and safety precautions are covered. Some annexes provide detailed instrument settings, verification, and UT follow‑up procedures.

Applications and users

ISO 16148:2016 is used by:

• NDT and inspection companies performing periodic testing of gas cylinders and tube trailers
• Cylinder manufacturers and refurbishment/test facilities replacing hydraulic proof tests with AT/UT where permitted
• Gas suppliers, transport operators and certification bodies ensuring cylinder integrity and regulatory compliance
• Regulatory authorities and technical committees developing inspection regimes for compressed and liquefied gas containment

Keywords: ISO 16148:2016, acoustic emission (AE), AT, ultrasonic examination (UT), periodic inspection, seamless steel gas cylinders, NDT, follow‑up UT.

Related standards

Normative references include ISO 9712, ISO 5577, ISO 12716, ISO 6406, ISO/IEC 17025, EN 13477‑1/2, ASTM E1419, and ASNT SNT‑TC‑1A. These cover NDT vocabulary, personnel qualification, equipment characterization and laboratory competence.