ISO 9328-3:2018

Overview

ISO 9328-3:2018 - "Steel flat products for pressure purposes - Technical delivery conditions - Part 3: Weldable fine grain steels, normalized" specifies the technical delivery requirements for flat steel products intended for pressure equipment. It covers weldable fine grain steels (ferritic grain size 6 or finer per ISO 643) and applies together with the general requirements of ISO 9328-1. The standard supports ordering and supply in accordance with both European design codes and ASME-type design codes (see Annexes A and B).

Key topics and requirements

• Scope and classification: Defines steel grades and qualities (room temperature, elevated temperature, low temperature, special low temperature) and their designation rules referencing ISO 9328-1.
• Delivery condition: Default supply is normalized; untreated (+AR) delivery or simulated normalized tests are possible if agreed at order.
• Chemical composition: Cast (heat) analysis limits are in Tables A.1 and B.1; permissible deviations for product analysis are specified (Table 1). Option to agree carbon-equivalent limits.
• Mechanical properties and testing: Requirements for tensile and impact properties, including options for mid-thickness samples, longitudinal test piece verification, and elevated-temperature R values (Tables A.3–A.5, B.3–B.4).
• Weldability and HIC: Provisions for weldability statements and optional hydrogen‑induced cracking (HIC) evaluation (Annex D).
• Inspection and documentation: Specifies inspection types, sampling, marking and inspection certificates (example: Inspection certificate 3.1 per ISO 10474).
• Dimensions and tolerances, internal soundness, surface condition: Delivery requirements for manufacturing and quality control.
• Normative references: Key referenced standards include ISO 9328-1, ISO 643 (grain size), ISO 4948, ISO 10474 and EN/ASME-related guidance.

Practical applications and users

ISO 9328-3 is used where reliable, weldable flat steel products are required for pressure equipment and vessels. Typical users:

• Steel producers and plate mills specifying chemical and mechanical delivery requirements
• Pressure vessel and boiler manufacturers selecting plate material for welding and fabrication
• Fabricators and welders assessing weldability and normalized condition suitability
• Design engineers working to European or ASME-type pressure codes
• Inspection and certification bodies issuing inspection certificates and verifying compliance
• Procurement specialists placing orders for steel plates used in oil & gas, petrochemical, power generation and pressure-retaining components

Related standards

• ISO 9328-1 - General requirements for steel flat products for pressure purposes
• ISO 643 - Ferritic grain size testing
• ISO 10474 - Inspection documents and certificates
• EN 10028-3 - Harmonized data (aligned with Annex A)

Keywords: ISO 9328-3, weldable fine grain steels, normalized, pressure equipment, steel flat products, technical delivery conditions, ASME, European design codes, chemical composition, mechanical properties.