Overview
ISO 15363:2017 - Metallic materials - Tube ring hydraulic pressure test specifies a standardized hydraulic ring-expansion method to determine the hoop strength of metallic tubes. The test is typically applied to tubes with an outside diameter greater than 120 mm and an outside-diameter-to-thickness ratio of not less than 20 (d/a ≥ 20). Its objective is to ascertain the hoop stress required to produce a specified total circumferential (hoop) strain.
Keywords: ISO 15363:2017, tube ring hydraulic pressure test, hoop strength, circumferential strain, metallic tubes.
Key topics and technical requirements
- Scope and purpose: Measures hoop (circumferential) strength by unrestrained radial expansion of a tube test ring under internal hydraulic pressure.
- Test piece: Test ring machined from welded or seamless tube; edges fine-turned or ground; length commonly 76 mm with tolerance ±0.25 mm. Test pieces must be uniquely identified.
- Dimensional measurements:
- Outside diameter measured from circumference (accuracy ±1 mm).
- Wall thickness measured as the mean of eight readings around the ring (accuracy better than ±0.025 mm), excluding weld region.
- Apparatus and setup:
- Machine allowing free expansion (small gap at top platen), flexible seal to prevent pressure loss.
- Parallel platens with fine-turned or ground finish; friction minimized with lubricant or PTFE sheet.
- Measuring device for circumference change (steel tape or roller-chain extensometer).
- Measurement and recording:
- Circumferential change accuracy: ±0.25 mm.
- Pressure measurement tolerance: ±1% (calibrated at start of sequence; at least annually).
- Strain rate limited to ≤ 0.2 %/min.
- Pressure vs. circumferential-extension record used to determine pressure at the specified total strain.
- Hoop strength evaluation: The standard provides the calculation relating pressure, tube diameter and thickness to compute hoop strength at the specified circumferential strain; note the calculation is considered reliable when d/a ≥ 20 and becomes less accurate for smaller ratios.
- Annexes: Annex A covers proof and reduced-section testing options; Annex B compares symbols and harmonizes designations (including EN 10275).
Applications
- Quality control and verification of hoop strength for large-diameter metallic tubes used in pressure vessels, pipelines, boiler tubes, structural tubing and industrial piping.
- Material characterization where ring expansion better represents in-service circumferential stress than flattened tensile specimens.
- Acceptance testing where hoop strength at a specific circumferential strain is required for design qualification or supplier certification.
Who uses this standard?
- Metallurgical and mechanical test laboratories
- Tube and pipe manufacturers (seamless and welded)
- Inspection and quality assurance engineers in oil & gas, power generation, chemical and pressure-vessel industries
- Product certification bodies and materials R&D teams
Related standards
- See Annex B of ISO 15363:2017 for comparison with steel tube symbols and harmonization with EN 10275. ISO/TC 164 (Mechanical testing of metals) oversees related ductility and strength test methods.
For compliance and correct implementation, follow the detailed procedures, tolerances and reporting requirements given in ISO 15363:2017 and reference the full standard for test setup illustrations, formulae and reporting templates.
