As a direct manufacturer and global supplier of heat exchangers, pressure vessels, air coolers, and bundle components—including tube sheets, baffles, and channel covers — YUHONG HOLDING GROUP supply fully integrated pressure-retaining bolting assemblies.
UNS S32750 (2507) full-thread stud bolts and matching heavy hex nuts are engineered for severe corrosion environments. Designed to sustain pre-load under thermal cycling and high pressures, these continuous stud and nut sets prevent flange leakage across critical process hardware.
All fasteners are manufactured and certified in strict compliance with ASTM and ASME standards to ensure full material traceability and precise thread fitting.
Stud Bolt Standard & Grade: ASTM A1082 / A1082M Grade UNS S32750 (Super Duplex 2507)
Heavy Nut Standard & Grade: ASTM A1082 / A1082M Grade UNS S32750
Raw Material Standard: ASTM A479 / A479M UNS S32750 Bar Stock
Dimensional Standards: ASME B18.31.2 (Stud Bolts), ASME B18.2.2 (Heavy Hex Nuts)
Thread Fitting: ASME B1.1 Class 2A (Studs) / Class 2B (Nuts), UNC, UNF, or 8UN Series
Size Range: 1/2" to 2-1/2" (M12 to M64) in custom lengths with matching heavy nuts
| Test Item | Stud (ASTM A1082 S32750) | Heavy Nut (ASTM A1082 S32750) | Quality Verification Method |
|---|---|---|---|
| Tensile / Proof Load | ≥ 116 ksi (800 MPa) | Proof Load Specified per ASME B18.2.2 | ASTM E8 / Axial Proof Load Test |
| Yield Strength (0.2%) | ≥ 80 ksi (550 MPa) | N/A | ASTM E8 / Offset Method |
| Hardness Limit | ≤ 32HRC | ≤ 32HRC | ASTM E18 / Rockwell C |
| Pitting Resistance (PREN) | ≥ 42.0 | ≥ 42.0 | Chemical Heat Analysis |
These stud and heavy nut sets are specified for critical pressure boundary joints in heavy thermal hardware:
Shell and Tube Heat Exchanger Flanges: Main shell-to-tubesheet, floating head, and channel cover joints operating in high-chloride media.
Air-Cooled Heat Exchangers: Header box plug and nozzle flange bolting in marine and offshore plants.
Pressure Vessels & Process Columns: High-pressure body flanges handling wet H2S or high-salinity brines.
Matched Thermal Expansion: Supplying fully matched S32750 nuts ensures identical thermal expansion coefficients between bolt and nut, preventing pre-load loss during rapid temperature changes.
Heavy Hex Design for Load Distribution: ASME B18.2.2 Heavy Hex Nuts provide wider bearing surfaces to prevent local crushing of flange faces under high tensioning torque.
Galling Prevention & Surface Coating: Thread tolerance control combined with specialized anti-seize lubrication prevents thread galling during hydraulic tensioning.
Complete Assembly Supply: Fasteners are delivered as matched sets (1 stud + 2 heavy nuts) to simplify site installation and material tracking.
Both stud bolts and heavy hex nuts in UNS S32750 super duplex stainless steel are manufactured and certified under ASTM A1082 / A1082M. Raw material bar stock conforms to ASTM A479 UNS S32750 to ensure full chemical and mechanical integrity.
Heavy Hex Nuts have a larger width-across-flats, offering a higher load-bearing area. This reduces contact stress on the flange face or washers, supporting the extreme tensile loads required for leak-free sealing in high-pressure heat exchangers.
