U-Bolts manufactured in Grade 8.8 Steel (class 8.8) are dimensioned to Industry standard. The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose Grade 8.8 Steel for U-Bolts
The workhorse medium-carbon alloy grade for structural joints. For u-bolts, this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | class 8.8 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | up to approx. +300 °C |
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
Corrosion Behavior in Service
Carbon and alloy steel u-bolts require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.
Comparable Grades
For U-Bolts, class 10.9 or 12.9 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.
Sizes of U-Bolts Available in Grade 8.8 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 |