What is ISO 3506‑2 about?
ISO 3506‑2 is the second in a six-part series of international standards on the mechanical and physical properties of stainless steel fasteners. BS EN ISO 3506‑2 specifies the mechanical and physical properties of nuts, with coarse pitch thread and fine pitch thread, made of corrosion-resistant stainless steel.
ISO 3506-2 specifies property classes about austenitic, martensitic, ferritic and duplex steel grades for nuts and applies to nuts of any shape with:
- ISO metric thread in accordance with ISO 68-1
- Diameter/pitch combinations in accordance with ISO 261 and ISO 262
- Coarse pitch thread M5 to M39, and fine pitch thread M8×1 to M39×3
- Thread tolerances in accordance with ISO 965-1 and ISO 965-2
- Specified property classes, including proof load
- Different nut styles: thin nuts, regular nuts and high nuts
- A minimum nut height m ≥ 0,45D
- A minimum outside diameter or width across flats s ≥ 1,45D and able to mate with bolts, screws and studs with property classes in accordance with ISO 3506-1
Who is BS EN ISO 3506‑2 for?
BS EN ISO 3506‑2 on properties of stainless steel fasteners is relevant to:
- Manufacturers and distributors of stainless steel fasteners
- Structural and consulting engineers
- Construction and civil engineering contractors and larger sub-contractors
- Test houses and laboratories
- Industries associated with oil and gas production and distribution
Why should you use BS EN ISO 3506‑2?
BS EN ISO 3506‑2 specifies the mechanical and physical properties of nuts with coarse pitch thread and fine pitch thread, made of corrosion-resistant stainless steels and when tested at the ambient temperature range of 10 °C to 35 °C.
Together with BS EN ISO 3506-1:2020 and BS ISO 3506-6:2020 it provides additional advice and guidance for most applications where these products will be required.
There are other standards which deal specifically with specialized areas such as oil and gas but this considerably revised document provides an excellent foundation for any assessment.
What’s changed since the last update?
BS EN ISO 3506‑2:2020 supersedes EN ISO 3506-2:2009. The main changes compared to the previous edition are as follows:
- Duplex (austenitic-ferritic) stainless steels for property classes 70, 80 and 100 have been added
- Property class 100 for austenitic stainless steel grades as well as grade A8 have been added
- Information for nut styles has been added
- Design of stainless steel bolt and nut assemblies, and design principles of stainless steel nuts have been added
- Finish has been improved
- Calculated proof load values and rounding rules have been added
- Requirements and guidance for inspection procedures have been added
- Thread dimensions of the test mandrel for proof load have been added
- Operational temperature ranges have been clarified
- Test methods for proof load and hardness have been improved
- Nut marking and labelling especially for thin nuts with reduced loadability have been addedDuplex (austenitic-ferritic) stainless steels for property classes 70, 80 and 100 have been added
