Overview
ISO 9330-1:1990 specifies the technical delivery conditions for welded steel tubes of circular cross-section made from unalloyed steel with specified room-temperature properties. Intended for pressure purposes (including transport of fluids under pressure), the standard covers manufacturing routes (ERW, SAW, fusion/butt welding), delivery conditions, required purchaser information, metallurgical and mechanical requirements, dimensions, masses, tolerances, inspection and testing, marking and protection. Certain applications permit use up to 350 °C (see annex A).
Key topics and requirements
- Scope and application: Welded tubes (tube = pipe) for pressure service; hot- or cold-finished; longitudinal or spiral welds.
- Purchaser information: Mandatory details include designation (“tube”), manufacturing process, dimensional reference (ISO 4200), outside diameter × wall thickness, length, tolerances, and inspection/testing requirements.
- Manufacturing processes: Electric resistance welding (ERW), submerged arc welding (SAW), butt/fusion welding; killed steel required (TW 320 may be semikilled); options for hot- or cold-finishing and heat treatments.
- Chemical composition: Limits are given for steel grades TW 320, TW 360, TW 410, TW 430 and TW 500 (example: TW 360 shown with C max 0.17%, Si max 0.35%, Mn 0.30–0.80%, P/S max 0.040%).
- Mechanical properties: Room-temperature tensile and yield ranges are specified by grade (examples: TW 360 tensile range ~360–500 N/mm²; TW 410 ~410–550 N/mm²; TW 500 ~500–650 N/mm²). Tests referenced include tensile, flattening, bend, drift-expanding and hydraulic tests.
- Dimensions & tolerances: Tube sizes follow ISO 4200 with defined tolerances on outside diameter, wall thickness, ovality, weld seam height and exact-length tolerances.
- Inspection & testing: Specifies visual and non‑destructive tests appropriate to welding process - ultrasonic, eddy-current, magnetic flux leakage, radiographic and hydraulic leak-tightness tests as referenced.
- Marking & protection: Requirements for marking, inspection certificates and protective measures at delivery.
Applications and users
ISO 9330-1 is used by:
- Tube manufacturers and steel mills for specifying production and delivery conditions.
- Purchasers, specifiers and procurement teams who order welded steel tubes for pressure systems.
- Design and piping engineers, pressure-vessel fabricators, pipeline contractors and quality/inspection personnel who require traceable chemical, mechanical and NDT verification for pressure-service tubing.
Related standards
Key cross-referenced standards include ISO 4200 (dimensions/masses), ISO 404 (general delivery requirements), ISO 6761 (tube end preparation), and NDT/inspection standards such as ISO 9302 / 9303 / 9304 / 9764 / 9765. Use these together with ISO 9330-1 when specifying welded steel tubes for pressure purposes.
Open preview (PDF)Welded steel tubes for pressure purposes — Technical delivery conditions — Part 1: Unalloyed steel tubes with specified room temperature properties