ISO 11363-2:2017

Overview

ISO 11363-2:2017 specifies the types, dimensions and principles of use for inspection gauges used with the 17E and 25E taper threads defined in ISO 11363-1. The standard describes plain and threaded plug and ring gauges (single‑part and two‑part), gives dimensional tables and tolerances, and explains how to use gauges to accept or reject cylinder neck and valve stem threads. Annex A provides worked examples for calculating large‑end thread gauge dimensions; Annex B highlights limitations of the gauging system.

Key topics and technical requirements

• Thread form: British Standard Whitworth (BSW) profile with a 55° thread angle.
• Handedness: right‑hand thread.
• Taper: nominal taper ratio 3/25, taper angle 6° 52′, taper slope 12%.
• Pitch: nominal pitch 1.814 mm.
• Gauge types: single‑part and two‑part plug gauges (for cylinder neck/internal threads) and ring gauges (for valve stem/external threads); plain and threaded variants; dedicated check gauges for verifying inspection gauges.
• Dimensional control: standardized gauge dimensions and tight tolerances are specified (e.g., lengths and inspection‑gauge diameters specified to ±0.01 mm); the standard also defines tolerances and verification procedures for plug and ring gauges.
• Use and acceptance criteria: methods for fitting plain and threaded gauges, and criteria for accept/reject decisions (e.g., position of the cylinder neck plane relative to gauge test surfaces).
• Verification & identification: procedures for verification of inspection and check gauges and marking/identification requirements.

Practical applications

ISO 11363-2:2017 is practical guidance for:

• Quality control and incoming inspection of gas cylinders and fittings.
• Manufacturing and calibration of inspection gauges (plug and ring gauges) for 17E/25E threads.
• Acceptance testing during cylinder production, valve assembly, repair and refurbishment.
• Test labs and certification bodies implementing thread gauging procedures. Key benefits include consistent interchangeability between cylinder necks and valve stems, defined acceptance criteria, and reduced risk of leaks or improper valve fit due to thread mismatch.

Who should use this standard

• Cylinder manufacturers and assemblers
• Valve and fitting manufacturers
• Quality, inspection and calibration engineers
• Test laboratories, service centers and regulatory inspectors
• Gauge manufacturers and suppliers

Related standards

• ISO 11363-1 - Gas cylinders - 17E and 25E taper threads - Part 1: Specifications (primary normative reference for thread geometry and nominal sizes).

For definitive dimensional tables, tolerances, verification methods and worked examples consult the full ISO 11363-2:2017 document from ISO.