ISO 9330-6:1997

Overview

ISO 9330-6:1997 - "Welded steel tubes for pressure purposes - Technical delivery conditions - Part 6: Longitudinally welded austenitic stainless steel tubes" - defines technical delivery requirements for longitudinally welded, circular-section austenitic stainless steel tubes used for pressure and corrosion-resisting service at room, low and elevated temperatures. It is a partial revision of ISO 2604-5:1978 and covers manufacturing, heat treatment, metallurgical requirements, inspection, testing, marking and documentation for tubes intended for pressure vessels, chemical plants, steam-generating equipment and interconnecting pipework.

Key topics and technical requirements

• Scope and exclusions: Applies to circular (and by agreement non-circular) longitudinally welded austenitic stainless steel tubes for pressure purposes. Excludes oilfield casing/tubing/linepipe and general gas/water/sewage distribution pipes.
• Purchaser information: Orders must specify tube dimensions (OD × wall), length, steel grade, test category, inspection type and reference to ISO 9330-6:1997.
• Manufacturing: Tubes are made from bent skelp or plate and longitudinally fusion-welded (with or without filler metal). Filler metal must be compatible; welds may be bead conditioned. Cold finishing and cold working options are addressed for smaller diameters.
• Heat treatment / delivery conditions: Solution-treated or hot-finished conditions are defined; types of condition include “as welded”, “cold finished” and “bead conditioned”.
• Metallurgical properties: Heat analysis and product analysis limits for chemical composition are specified; mechanical properties are required at room, low and elevated temperatures (including proof stress values). Annexes provide stress-rupture data and typical low-temperature impact behavior.
• Inspection & testing: Requirements include tensile, Charpy (ISO 148), flattening/drift/expanding tests, hydraulic leak tests and non-destructive testing (ultrasonic, eddy-current, electromagnetic and radiographic methods per referenced ISO standards).
• Marking, protection & documentation: Prescribes marking, protective treatment and inspection certificates (e.g., ISO 10474 document types).

Applications

• Manufacture and procurement of pressure-bearing austenitic stainless steel tubes for:
  • Pressure vessels and boilers
  • Heat exchangers and chemical process plants
  • Steam-generating equipment and interconnecting pipework
• Basis for specifying tube supply conditions, testing and documentation to meet safety, quality and regulatory needs.

Who should use this standard

• Tube manufacturers and fabricators
• Procurement and quality managers specifying technical delivery conditions
• Pressure-vessel and chemical plant designers and engineers
• Inspection, testing and certification bodies

Related standards

Relevant normative references include ISO 1127, ISO 1129, ISO 5252, ISO 6892, ISO 9302/9303/9304, ISO 10474 and ISO 14284, which govern dimensions, tolerances, mechanical tests and non-destructive inspection methods.

Keywords: ISO 9330-6:1997, longitudinally welded austenitic stainless steel tubes, technical delivery conditions, pressure purposes, tube inspection and testing, heat treatment, pressure vessel tubes.