ISO 3506-5:2022

Overview

ISO 3506-5:2022 - Fasteners - Mechanical properties of corrosion-resistant stainless steel fasteners - Part 5: Special fasteners (also including fasteners from nickel alloys) for high temperature applications specifies mechanical and physical requirements, designation and test methods for bolts, screws, studs and nuts made from martensitic stainless steels, precipitation‑hardening austenitic stainless steels and nickel alloys intended for use at elevated temperatures (up to 800 °C). Ambient test conditions for Clause 9 are defined as 10 °C to 35 °C, while Clause 10 contains high‑temperature test procedures. Fasteners suitable down to about −50 °C are also noted.

Key topics and technical requirements

• Scope of fasteners covered: ISO metric thread (ISO 68‑1), diameter/pitch per ISO 261/262; coarse thread M3–M39, fine thread M8×1–M39×3; thread tolerances per ISO 965‑1/‑2. Applies to full‑loadable shapes; excludes reduced‑loadability fasteners.
• Materials & manufacture: chemical composition, heat treatment and finishes for stainless steels and nickel alloys; tempering guidance for martensitic grades.
• Mechanical and physical properties: tensile strength, proof stress (0.2% offset), elongation (A), hardness and other room‑temperature properties (Clause 7–9).
• High‑temperature testing (Clause 10): high‑temperature tensile, stress‑rupture, relaxation and creep tests with reporting requirements to assess behaviour up to service temperatures.
• Testing & inspection: manufacturer, supplier and purchaser inspection, applicability of test methods, and delivery of test results (Clauses 8–10).
• Marking and labelling: manufacturer identification, fastener marking conventions and packaging information (Clause 11).
• Exclusions: does not set requirements for torque/clamp‑force properties, shear strength, fatigue, weldability or full bolted‑joint behaviour at high temperature.

Practical applications and users

ISO 3506-5:2022 is intended for:

• Design and mechanical engineers specifying fasteners for high‑temperature equipment (furnaces, boilers, turbines, heat exchangers, petrochemical and power plants).
• Fastener manufacturers and heat‑treatment shops for qualification and batch testing.
• Procurement and quality assurance teams requiring material grade, marking and test evidence.
• Test laboratories performing ambient and high‑temperature mechanical tests (tensile, stress‑rupture, creep, relaxation).

Using ISO 3506‑5 helps ensure material selection and testing are appropriate for sustained high‑temperature service, reducing risk of stress relaxation, creep and hot‑oxidation failures.

Related standards

• ISO 3506 series (Parts 1–4, 6) - related fastener grades and general rules (see ISO 3506‑6 for selection guidance).
• ISO 68‑1, ISO 261, ISO 262, ISO 965‑1/‑2 - thread forms, pitch and tolerances referenced by ISO 3506‑5.

Keywords: ISO 3506-5:2022, high temperature fasteners, stainless steel fasteners, nickel alloy fasteners, mechanical properties, tensile, creep, stress rupture, relaxation, fastener testing.