Overview
EN ISO 8493:2004 (identical to ISO 8493:1998) specifies the drift-expanding (tube expansion) test for metallic tubes. The standard defines a method to determine the ability of circular-section tubes to undergo plastic deformation by forcing a conical mandrel through a tube end until a specified outside diameter is reached. It applies to tubes with outside diameters up to 150 mm (100 mm for light metals) and wall thicknesses up to 10 mm, unless a product standard specifies otherwise.
Keywords: EN ISO 8493:2004, ISO 8493, drift-expanding test, metallic tubes, tube ductility, conical mandrel.
Key topics and requirements
- Scope: Tests tube ductility/expansion capability for circular-section tubes (limits on diameter and thickness as above).
- Test principle: Expand the tube end by driving a conical mandrel until the target maximum outside diameter or specified relative expansion (%) is achieved.
- Equipment:
- Variable-speed press or universal testing machine.
- Polished, sufficiently hard conical mandrel; preferred cone angles are 30°, 45° and 60°.
- Mandrel may include a groove for longitudinal weld flash on welded tubes.
- Test pieces:
- Length depends on mandrel angle: when angle ≤ 30° use approx. L = 2·D; when angle > 30° use approx. L = 1.5·D.
- Remaining cylindrical part after expansion must be at least 0.5·D. Ends should be perpendicular to tube axis; edges may be rounded or chamfered.
- Test conditions:
- Ambient testing: 10 °C to 35 °C; controlled testing at 23 °C ± 5 °C.
- Mandrel insertion without shock; mandrel must not rotate relative to the tube. Lubrication is permitted.
- Dispute rate limit: mandrel penetration ≤ 50 mm/min.
- Acceptance criteria:
- If product standard does not provide criteria, the test is passed if no visible cracks are observed without magnification. Slight edge cracking is not cause for rejection.
- Test report must include reference to ISO 8493, test-piece ID and dimensions, expanded maximum diameter or relative expansion, mandrel angle and the test result.
Applications and users
- Quality control and acceptance testing of steel, aluminium and other metallic tubes used in construction, hydraulic systems, heat exchangers and general engineering.
- Typical users: tube manufacturers, independent test laboratories, product standards committees, inspection and procurement engineers who need to verify tube ductility, forming performance and resistance to expansion-related cracking.
Related standards
- This European adoption EN ISO 8493:2004 supersedes EN 10234:1993.
- Prepared by ISO/TC 164 (Mechanical testing of metals) and adopted by CEN (ECISS/TC 29 - Steel tubes and fittings for steel tubes).
This summary gives practical guidance on what EN ISO 8493:2004 covers and how the drift-expanding test is specified and used in industry.
