On this page 6 sections
What is 8M nuts material?
Quick answer
- Grade
- 8M
- Material
- Type 316 stainless steel
- Typical use
- A193 B8M studs
Technical summary
- Grade
- 8M
- Material
- Type 316 stainless steel
- Hardness
- 126 – 300 HBW
- Proof load
- 550 MPa (80 ksi) for heavy hex (8M)
- Dimensions
- ASME B18.2.2 heavy hex
- Certificates
- EN 10204 3.1; 3.2 on request
Where are 8M nuts used?
- A193 B8M studs
- Marine and chemical service
Selecting bolting for your joint
Bolting must suit the joint's temperature, pressure, environment and gasket. Coatings change the friction factor, so tightening torque must be recalculated. For sour service, hardness-controlled grades (B7M / 2HM) apply under NACE MR0175 / ISO 15156. See the bolting selection guide and flange types & classes.
What to include in your enquiry
- Grade and specification
- Diameter × length and thread series (UNC / 8UN / metric)
- Nuts and washers per bolt
- Coating and colour
- Quantity per size, or your flange schedule
- Certificates (3.1 / 3.2) and tests
Frequently asked questions
Which standard covers 8M?
ASTM A194 / ASME SA-194, with dimensions to the relevant ASME B18 standard.
Can the bolting be coated?
Yes: zinc, hot-dip galvanised, PTFE-based fluoropolymer or zinc-nickel coatings are available on request. Recalculate tightening torque for coated bolting.
Do you supply complete bolting sets for flange schedules?
Yes. Send your flange schedule (size, class, facing, quantity) and we will prepare the stud, nut and washer list.