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 Stud Bolts
Incoloy 800H stud bolts are the primary high-temperature flange-bolting choice on petrochemical and refining service to 815 deg C (1500 deg F) under ASME Section VIII Division 1 design tables. TorqBolt machines stud bolts from ASTM B408 round bar in metric range M12 to M64 and inch range 1/2 inch to 2.5 inch diameter, with lengths cut to flange callout. The stud is fully threaded both ends, with overall length controlled to the bolt schedule and chamfered ends to permit nut start. Studs ship with two heavy hex nuts (matched heavy hex nuts) and EN 10204 type 3.1 mill test certificate documenting heat number, chemistry, solution-anneal cycle, mechanical results and ASTM grain size 5 verification. Type 3.2 with Lloyds Register, DNV, BV, SGS or TUV witness is supplied on call-out for refinery and petrochemical procurement against API 660 heat-exchanger and ASME Section VIII vessel packages on hot-zone flange bolting service.
Stud Bolt Dimensions and Tolerances (ASME B16.5 + B18.2.1 Reference)
| Size designation | Across flats / OD | Head / nut height | Thread pitch | Standard reference |
|---|---|---|---|---|
| M12 (1/2 inch) | 12.0 mm OD | Full thread both ends | 1.75 mm (UNC 13 tpi) | ASME B18.2.1 / DIN 976 |
| M16 (5/8 inch) | 16.0 mm OD | Full thread both ends | 2.0 mm (UNC 11 tpi) | ASME B18.2.1 / DIN 976 |
| M20 (3/4 inch) | 20.0 mm OD | Full thread both ends | 2.5 mm (UNC 10 tpi) | ASME B18.2.1 / DIN 976 |
| M24 (7/8 inch) | 24.0 mm OD | Full thread both ends | 3.0 mm (UNC 9 tpi) | ASME B18.2.1 / DIN 976 |
| M30 (1-1/8 inch) | 30.0 mm OD | Full thread both ends | 3.5 mm (UNC 7 tpi) | ASME B18.2.1 / DIN 976 |
| M36 (1-3/8 inch) | 36.0 mm OD | Full thread both ends | 4.0 mm (UNC 6 tpi) | ASME B18.2.1 / DIN 976 |
| M42 (1-5/8 inch) | 42.0 mm OD | Full thread both ends | 4.5 mm (UNC 5.5 tpi) | ASME B18.2.1 / DIN 976 |
| M48 (1-7/8 inch) | 48.0 mm OD | Full thread both ends | 5.0 mm (UNC 5 tpi) | ASME B18.2.1 / DIN 976 |
| M56 (2-1/4 inch) | 56.0 mm OD | Full thread both ends | 5.5 mm (UNC 4.5 tpi) | ASME B18.2.1 / DIN 976 |
| M64 (2-1/2 inch) | 64.0 mm OD | Full thread both ends | 6.0 mm (UNC 4 tpi) | ASME B18.2.1 / DIN 976 |
Manufacturing Route at TorqBolt
Stud bolt manufacture from Incoloy 800H follows a fixed process sequence designed to retain the ASTM grain size 5 condition required for ASME Section VIII pressure-vessel service. The route is:
- Receive Incoloy 800H round bar to ASTM B408 with EN 10204 type 3.1 mill test certificate. PMI by X-ray fluorescence on each heat to confirm Ni 30-35, Cr 19-23, C 0.05-0.10 percent.
- Cut to overall length on horizontal bandsaw. Length tolerance per print, square-end check.
- Centerless grind shank to bar tolerance to remove mill scale and clean up surface defects.
- Thread roll on both ends in single setup. Inch threads to ASME B1.1 class 2A; metric to ISO 965 class 6g. Ring + plug gauge verification.
- Solution anneal at 1149 deg C (2100 deg F) plateau followed by rapid water quench to retain austenitic structure and ASTM grain size 5 or coarser.
- Hardness test (Brinell, 120-184 HB band) on first piece and one per batch.
- Visual + dimensional inspection 100 percent against print.
- Heat-stamp grade marking on one end: heat number, grade (800H), TorqBolt mark.
- VCI-wrap, pack with matched heavy hex nuts and dispatch with CoC + EN 10204 cert package.
Stud Bolt Sizes Stocked and Lead Times
| Diameter range | Length range | Stock status | Lead time |
|---|---|---|---|
| M12 - M24 / 1/2 inch - 7/8 inch | 50 mm - 500 mm | Stock + ex-stock | 7 working days |
| M27 - M36 / 1 inch - 1-3/8 inch | 75 mm - 600 mm | Made-to-order from bar | 10 to 14 working days |
| M42 - M48 / 1-5/8 inch - 1-7/8 inch | 100 mm - 750 mm | Made-to-order, large bar | 3 to 4 weeks |
| M56 - M64 / 2-1/4 inch - 2-1/2 inch | 150 mm - 1000 mm | Made-to-order, forged blank | 5 to 6 weeks |
Inspection and Heat Marking
EN 10204 type 3.1 mill test certificate is the default deliverable. Type 3.2 with third-party witness is supplied on call-out. The certificate package documents the full stud bolt traceability chain:
- Heat number stamped on one end of every stud, traceable to ASTM B408 bar melt.
- Chemistry analysis showing Ni 30-35, Cr 19-23, C 0.05-0.10, Al+Ti 0.30-1.20 (800H window).
- Solution-anneal cycle log: 1149 deg C plateau, hold time, rapid water quench.
- Tensile result >= 450 MPa, 0.2 percent proof >= 170 MPa, elongation A5 >= 30 percent.
- ASTM E112 grain-size etch verification showing grain size 5 or coarser.
- Hardness band 120-184 HB on first piece and one per batch.
- Thread ring + plug gauge verification logged.
- Visual inspection for surface defects, thread damage and dimensional callouts.
Typical Service Conditions
Stud bolts are the dominant fastener form on hot-zone flange joints. Typical service conditions are:
- Ethylene cracker tube radiant-section pigtail flange bolting, 850 deg C tube-skin temperature.
- Reformer pigtail outlet flanges between catalyst tubes and outlet headers.
- Heat exchanger tubesheet stud bolting on hydrocracker and coker units.
- ASME Section VIII pressure vessel flange bolting above 540 deg C.
- Steam superheater final-stage flange bolting on fossil and waste-heat boilers.
- Refractory-anchor stud welding to vessel walls in hydrocarbon-cracking furnaces.
Incoloy 800H Alloy Considerations on This Fastener Form
Companion Fasteners and Related Pages
- Heavy Hex Nuts: matched nuts for stud bolt assemblies, ASME B18.2.2.
- Tap End Studs: alternative when one end is permanently installed.
- Double End Studs: both ends threaded with plain centre section.
- Threaded Rod: cut-to-length variant for field assembly.
- Heavy Hex Bolts: head-and-shank alternative when a captive head is required.
Frequently Asked Questions
Q. Are Incoloy 800H stud bolts qualified to ASME B16.5 flange bolting?
Yes. ASME B16.5 specifies the bolting hole pattern, stud length and nut size for each pipe class and flange size. TorqBolt machines Incoloy 800H studs to the B16.5 length-and-diameter schedule, with stud length controlled to flange standoff plus nut height plus chamfer allowance.
Q. Do you supply matched two-nut sets on every stud?
Yes. Default delivery is one stud plus two heavy hex nuts of the same heat batch. Single-nut delivery or alternative nut grades are supplied on PO call-out.
Q. What torque value should be used on Incoloy 800H stud bolts?
Torque values depend on joint geometry, gasket type and lubrication condition. TorqBolt supplies torque guidance on request; the controlling document is the customer flange-management procedure. Nickel-base anti-seize is recommended on threads to prevent galling at elevated temperature.
Q. Are Incoloy 800H studs available with ACME or buttress threads?
Yes on call-out. Standard supply is UNC (inch) or coarse metric (M-series). Fine-pitch threads (UNF, UN8, ACME, buttress) are machined on PO call-out from the same B408 bar stock.
Q. Can studs be supplied with through-hardness verification on every piece?
Yes on call-out. Standard practice is hardness on first piece and one per batch. 100 percent hardness can be added at extra inspection cost; results logged on the EN 10204 certificate.
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