DIN 3570 U-Bolt Equivalent: Dimensions, ASME B18.31.5 and Replacement Checks
DIN 3570 specifies round steel U-bolts used to secure pipes, tubes or round bars to a bracket, frame or support. It is a pipe-support fastener, not a general straight structural bolt.
What identifies a DIN 3570 U-bolt?
Thread size alone is not enough. A correct replacement must match:
- pipe or tube outside diameter;
- inside width and leg spacing;
- rod diameter and bend radius;
- overall height and threaded-leg length;
- metric thread pitch;
- material, strength requirement and coating.
An M12 thread can still be the wrong U-bolt if the inside width or bend does not fit the actual pipe.
DIN 3570 and international references
| Reference | Relationship | Direct replacement? |
|---|---|---|
| DIN 3570 | Original pipe U-bolt product standard | Yes, when specified |
| ASME B18.31.5 | Related bent-bolt/U-bolt standard | No, verify complete geometry |
| ISO | Companion thread, property or coating references | No single product equivalent |
| UNI / JIS | No confirmed one-to-one product equivalent | No |
ASME B18.31.5 covers several bent-bolt configurations. It may perform the same function, but thread system, pipe clearance, leg spacing, bend radius, nuts and washers can differ. Treat it as a functional counterpart, not a dimensional conversion.
Application and support design
The usual assembly may include a U-bolt, nuts, washers, a bracket and pipe lining. DIN 3570 does not define the complete support design, locking method, insulation or thermal movement requirement. For expanding pipes, specify whether the clamp must restrain the pipe or permit controlled sliding.
Material and surface treatment
DIN 3570 identifies the product geometry, not one universal material or load rating. Specify carbon/alloy steel or stainless steel, required strength, plain or zinc-plated finish, hot-dip galvanizing, passivation and any test or corrosion requirements separately.
Replacement checklist
Before accepting an ASME, generic metric, UNI or JIS U-bolt, compare pipe outside diameter, inside width, leg spacing, height, bend radius, threaded length, pitch, material, coating, nut/washer requirements and supplier drawing. Same thread ≠ same U-bolt.
Final recommendation
DIN 3570 has no confirmed one-to-one ISO, UNI or JIS product equivalent. ASME B18.31.5 is the most useful international functional reference, but the complete pipe-support geometry must be matched before approval.
