A2 Stainless Steel (A2-70 (304)) is the most common stainless grade for indoor and general outdoor fasteners. When u-bolts are specified in this grade, the dimensions remain per Industry standard; the material determines corrosion behavior (good general corrosion resistance) and the service temperature range (approx. -200 °C to +400 °C). Both are covered below with the size table.
Why Choose A2 Stainless Steel for U-Bolts
The most common stainless grade for indoor and general outdoor fasteners. For u-bolts, this matters when good general corrosion resistance is the primary requirement.
Mechanical & Physical Properties
| Grade designation | A2-70 (304) |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C |
| Corrosion characteristic | Good general corrosion resistance |
Galvanic & Galling Considerations
Two important notes for stainless u-bolts: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.
Comparable Grades
For U-Bolts, the alternative stainless grade is A4 (316). A2 (304) suits general indoor and outdoor service; A4 (316) adds molybdenum for marine and chloride environments. Where higher strength matters more than corrosion, switch to plated alloy-steel class 8.8 or 10.9.
Sizes of U-Bolts Available in A2 Stainless Steel
| Thread size | Pitch (mm) | Inside width A (mm) | Inside height / leg length B (mm) | Pipe size ref | Thread length (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|---|
| M6 | 1.0 | 27 | 60 | 3/4 in | 25 | Industry standard | Round-bend U-bolt with 2 nuts |
| M8 | 1.25 | 34 | 75 | 1 in | 30 | Industry standard | Round-bend U-bolt with 2 nuts |
| M8 | 1.25 | 43 | 90 | 1-1/4 in | 30 | Industry standard | Round-bend U-bolt with 2 nuts |
| M10 | 1.5 | 49 | 110 | 1-1/2 in | 35 | Industry standard | Round-bend U-bolt with 2 nuts |
| M10 | 1.5 | 62 | 120 | 2 in | 35 | Industry standard | Round-bend U-bolt with 2 nuts |
| M12 | 1.75 | 77 | 140 | 2-1/2 in | 40 | Industry standard | Round-bend U-bolt with 2 nuts |
| M12 | 1.75 | 90 | 160 | 3 in | 40 | Industry standard | Round-bend U-bolt with 2 nuts |
| M16 | 2.0 | 115 | 200 | 4 in | 50 | Industry standard | Round-bend U-bolt with 2 nuts |
| M16 | 2.0 | 140 | 220 | 5 in | 50 | Industry standard | Round-bend U-bolt with 2 nuts |
| M20 | 2.5 | 168 | 260 | 6 in | 60 | Industry standard | Round-bend U-bolt with 2 nuts |