Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Incoloy 800H U-Bolts
Incoloy 800H U-bolts are U-shaped pipe-clamp fasteners machined from ASTM B408 round bar for high-temperature pipe-support, hanger and clamp applications on petrochemical, refinery and steam-cycle service to 815 deg C (1500 deg F). The U-bolt is cold-bent into a U profile sized to the pipe outside diameter (OD), with both legs threaded for nut engagement through a saddle plate. TorqBolt manufactures U-bolts for pipe sizes NPS 1/2 inch through NPS 24 inch (metric DN 15 through DN 600), with leg lengths cut to support geometry. Standard rod diameter range is M10 to M30 (3/8 inch to 1-1/4 inch). The U-bolt profile is bent on a controlled radius matching the pipe OD plus insulation allowance, with both leg ends threaded to the same length and chamfered for nut start. Every U-bolt ships with EN 10204 type 3.1 mill test certificate documenting heat number, ASTM B408 chemistry, solution-anneal cycle and ASTM grain size 5 verification (cold-bent areas verified post-anneal).
U-Bolt Dimensions (Per Pipe Schedule)
| Size designation | Across flats / OD | Head / nut height | Thread pitch | Standard reference |
|---|---|---|---|---|
| NPS 1/2 inch (DN 15) | Rod M10 (3/8 inch) | Bend ID 21 mm + insulation; leg length per print | 1.5 mm (16 tpi UNC) | Per pipe support print |
| NPS 1 inch (DN 25) | Rod M12 (1/2 inch) | Bend ID 33 mm + insulation; leg length per print | 1.75 mm (13 tpi UNC) | Per pipe support print |
| NPS 2 inch (DN 50) | Rod M16 (5/8 inch) | Bend ID 60 mm + insulation; leg length per print | 2.0 mm (11 tpi UNC) | Per pipe support print |
| NPS 4 inch (DN 100) | Rod M20 (3/4 inch) | Bend ID 114 mm + insulation; leg length per print | 2.5 mm (10 tpi UNC) | Per pipe support print |
| NPS 6 inch (DN 150) | Rod M20 (3/4 inch) | Bend ID 168 mm + insulation; leg length per print | 2.5 mm (10 tpi UNC) | Per pipe support print |
| NPS 8 inch (DN 200) | Rod M24 (7/8 inch) | Bend ID 219 mm + insulation; leg length per print | 3.0 mm (9 tpi UNC) | Per pipe support print |
| NPS 12 inch (DN 300) | Rod M24 (7/8 inch) | Bend ID 324 mm + insulation; leg length per print | 3.0 mm (9 tpi UNC) | Per pipe support print |
| NPS 16 inch (DN 400) | Rod M30 (1-1/8 inch) | Bend ID 406 mm + insulation; leg length per print | 3.5 mm (7 tpi UNC) | Per pipe support print |
| NPS 24 inch (DN 600) | Rod M30 (1-1/8 inch) | Bend ID 610 mm + insulation; leg length per print | 3.5 mm (7 tpi UNC) | Per pipe support print |
Manufacturing Route at TorqBolt
U-bolt manufacture is a controlled cold-bend operation followed by thread roll on both leg ends and post-bend solution anneal to restore ASTM grain size 5:
- Receive Incoloy 800H bar to ASTM B408; PMI verification.
- Cut bar to developed length per print (straight length + bend allowance for both leg arcs).
- Cold-bend on hydraulic bender to pipe OD plus insulation allowance; controlled radius and symmetric leg geometry.
- Thread roll both leg ends to equal length: class 2A UNC inch or class 6g metric.
- Solution anneal at 1149 deg C plateau followed by rapid quench (mandatory after cold-bend); ASTM grain size 5 verified post-anneal.
- Hardness band 120-184 HB on first piece and one per batch.
- Visual + dimensional + PMI inspection 100 percent.
- Verify symmetric leg geometry: both legs within 0.5 mm of design length.
- Heat-stamp grade marking on one leg; pack with saddle plate and matched nuts + washers per print.
U-Bolt Sizes Stocked and Lead Times
| Diameter range | Length range | Stock status | Lead time |
|---|---|---|---|
| NPS 1/2 inch - NPS 4 inch | Per pipe schedule | Made-to-order from stock bar | 10 to 14 working days |
| NPS 6 inch - NPS 12 inch | Per pipe schedule | Made-to-order from stock bar | 14 to 21 working days |
| NPS 14 inch - NPS 24 inch | Per pipe schedule | Made-to-order, large bar | 3 to 5 weeks |
| Above NPS 24 inch | Per print | Forged or fabricated | 5 to 7 weeks |
Inspection and Heat Marking
U-bolt specific inspections cover bend geometry, symmetric leg length, post-bend grain size and thread compliance:
- Bend inner-diameter verified per print (pipe OD plus insulation allowance).
- Bend radius and bend angle verified symmetric on both legs.
- Leg length verified equal both sides to print.
- Thread engagement on both legs verified with ring + plug gauges.
- Hardness band 120-184 HB after post-bend solution anneal.
- ASTM E112 grain-size etch verification including cold-bent crown area.
- PMI by X-ray fluorescence on first piece and one per batch.
- Heat number stamped on one leg for traceability.
Typical Service Conditions
U-bolts are specified for pipe-support, hanger and clamp applications on hot-zone process lines where carbon-steel U-bolts would oxidize or relax:
- Ethylene cracker transfer-line pipe-support clamping.
- Reformer pigtail support-clip and guide-clamp fastening.
- Steam superheater tube-bank guide-bracket clamping.
- Heat exchanger shell-saddle clamping on hot-zone piping.
- Furnace component burner-line and pilot-line clamping.
- Pressure-vessel external-line guide clamping above 540 deg C.
Incoloy 800H Alloy Considerations on This Fastener Form
Companion Fasteners and Related Pages
- Anchor Bolts: structural foundation-anchor alternative.
- Hex Nuts: matched DIN 934 nuts for U-bolt assemblies.
- Heavy Hex Nuts: heavy-pattern nut for high-load U-bolts.
- Washers: saddle and flat washers for U-bolt fixing.
- Threaded Rod: cut-to-length alternative for hanger rod construction.
Frequently Asked Questions
Q. Are U-bolts manufactured to a specific dimensional standard?
No single dimensional standard covers U-bolts industry-wide. TorqBolt manufactures per project pipe-support drawing, with bend ID sized to pipe OD plus insulation allowance and leg length per support geometry. MSS SP-58 and MSS SP-69 cover pipe-hanger materials and types but do not dimension U-bolts directly.
Q. Is post-bend solution anneal mandatory?
Yes. Cold-bending Incoloy 800H locks residual strain into the crown of the U; sustained service above 540 deg C will relax the residual strain and may cause cracking. Post-bend solution anneal at 1149 deg C restores ASTM grain size 5 and removes residual cold-work.
Q. Can U-bolts be supplied with insulation pad or cushion?
U-bolts are supplied bare metal. Insulation pads (calcium-silicate, ceramic-fibre) are a separate insulation-contractor scope and not part of the U-bolt package.
Q. Are saddle plates supplied with U-bolt sets?
Yes on PO call-out. Carbon-steel or stainless-steel saddle plates with drilled hole pattern matching the U-bolt leg spacing are supplied on request.
Q. What is the maximum pipe size?
Standard supply is NPS 1/2 inch through NPS 24 inch. Above NPS 24 inch, U-bolt construction shifts to fabricated half-clamps or full-circle clamps and is supplied to print on PO call-out.
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