U-Bolt Bending in 3D

Order it by what it has to fit

Pipe sizes are nominal: NPS 2 pipe is 2.375 in. across the outside and NPS 4 is 4.500 in. A round U-bolt is sized from the outside diameter, with the width taken between the legs and the length from the end of a leg to the inside of the bend. Some makers measure to the centre of the bend or between leg centres, so a drawing settles it.

Bending stretches the outside of the bend and squeezes the inside. ASTM F1554, the specification for bent anchor bolts, asks for a bend free of cracks at 10× magnification that keeps at least 90% of the rod's cross-section. ASME B18.31.5 covers bent bolts in inch sizes, with tables for U-bolts of different bends; the threads are Unified threads to ASME B1.1.

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Width between the legs and length from the end of a leg to the inside of the bend: IFI-136, now ASME B18.31.5. NPS 2 pipe, 2.375 in. outside diameter: ASME B36.10M; the round former's radius is half of it. Rolled threads need the rod to turn between the dies, so they go on while it is straight: two dies turning the same way drive the rod the other way, and the thread grows out of rod about the pitch diameter (ASTM F1554 Table 4). Bend requirements: ASTM F1554. The part is drawn as a 3/8-16 UNC U-bolt for NPS 2 pipe with 3/8 heavy hex nuts (ASME B18.2.2 proportions); the square bend has an inside radius twice the rod, the usual minimum. The saw, rolling machine, bender, gauge and plate are generic, the leg and thread lengths are for the drawing only, the cut is time-lapsed and the rolling and the bend are slowed down.