A material list line such as "BOLT;HEX;HTS;M16X50MM;GR 8.8" already carries most of what a supplier needs. These are the details worth checking before you send a list for quotation.
Bolt Grades
| Grade | Typical Use | Meaning |
|---|---|---|
| 4.6 / 4.8 | General, non-critical fixing (mild steel) | About 400 MPa tensile strength |
| 8.8 | Machinery, structures, plant: the most common high-tensile grade | About 800 MPa tensile, yield 80% of that |
| 10.9 | High-load joints and wear parts | About 1 000 MPa tensile, yield 90% of that |
Nuts Have Their Own Classes
Nuts are rated by property class, not by bolt grade. Use a class 8 nut with a grade 8.8 bolt and a class 10 nut with grade 10.9. A line asking for an "8.8 nut" usually means class 8; we quote it that way and say so on the quotation.
Stainless Steel
A2 is 304 stainless, suitable for general outdoor use. A4 is 316, with better resistance to chlorides and chemicals, and 316L is a low-carbon version for welded or more corrosive applications. Stainless fasteners are usually strength class 70 (A2-70, A4-70).
Finish
- Plain (self-colour): oiled, for indoor or painted assemblies.
- Zinc-plated / electro-galvanised: light corrosion protection.
- Hot-dip galvanised: heavy outdoor protection. The coating is thick, so galvanised nuts are tapped oversize: buy bolts and nuts as matched galvanised sets.
Locking and Washers
Nyloc nuts suit normal operating temperatures; all-metal prevailing-torque lock nuts are used where heat or vibration would defeat a nylon insert. Specify washers by type (flat, black-cut, square, spring or fender) and, for high-tensile joints, ask for hardened washers.
What to Send Us
Your material number and description, the quantity, any OEM part number, whether approved equivalents are acceptable, and any certificate you need, such as a material certificate or certificate of conformity.