Stud Bolts
Manufacturer
India · Mumbai
The Engineering Case for Stud Bolts in Pressure Flanges
ASME B16.5, the primary dimensional standard governing pressure pipe flanges from ½” NPS to 24″ NPS across Classes 150 through 2500, specifies fully threaded stud bolts with two heavy hex nuts — not headed hex bolts — as the standard fastener for all pressure flange joints. This is not arbitrary: the stud bolt configuration provides fundamental engineering advantages that headed hex bolts cannot match in a pressure flange assembly.
A headed hex bolt bears on the flange face under the head and engages only part of the bolt’s total length in thread. A fully threaded stud bolt threads into both heavy hex nuts simultaneously, distributing load evenly over both nuts’ thread engagement length and eliminating the moment arm created by a hex bolt head bearing on a curved or imperfect flange face. The stud bolt configuration also allows the flange to be assembled in confined spaces by rotating the nut rather than the stud — critical in offshore, underground, and buried pipeline applications.
The most important advantage in exotic alloy service: a matched-heat stud bolt set — stud bolt and heavy hex nuts from the same ASTM-certified alloy lot — provides a single MTC that covers the complete pressure flange fastener assembly. No separate MTC for nuts, no separate PMI for studs. One document set, one traceability chain. Akbar Fasteners supplies matched-heat stud bolt sets in every exotic alloy as standard, with single MTC, PMI report, and COC covering the complete assembly.
The ASME B16.5 design intent: stud bolt length is sized so that the stud protrudes exactly one thread pitch past each nut face after assembly to the correct torque. The dimensional tables in ASME B16.5 specify the stud bolt length for every flange bore size and pressure class combination — Akbar Fasteners supplies to these exact lengths as standard, with custom lengths available within one-week lead time.
For ASME B16.5 flanges in Hastelloy C276, Hastelloy C22, Hastelloy B3, Monel K500, Monel 400, Inconel 625, Incoloy 825, stainless steel, and ASTM A193 B7 alloy steel — Akbar Fasteners Pvt. Ltd. is India’s single-source supplier for ASME B16.5 stud bolt sets in every engineering alloy, with ASME PCC-1 assembly torque documentation available on request.
Stud Bolt Types & Configurations
Fully Threaded Stud Bolts — ASME B16.5 Standard
Thread runs the complete length — the ASME B16.5 standard configuration for pressure pipe flange joints. One stud, two heavy hex nuts. Thread engages both nuts fully, providing symmetric load distribution at both flange faces. The most common exotic alloy stud bolt form for all ASME B16.5 pressure flange applications from Class 150 through 2500.
Length per ASME B16.5 Table 7 for each NPS and pressure class. Available in all exotic alloys from ASTM-certified bar stock. Matched heavy hex nuts from the same certified heat for single MTC coverage. M12–M100, lengths to 3,000mm. Custom lengths within one-week lead time.
Equal-End Double Stud Bolts — Tapped Bore Service
Equal thread length on both ends with an unthreaded plain shank in the centre — one end engages a tapped bore in the equipment body or flange, the other end takes a heavy hex nut. Used where the flange is a body stud connection (tapped hole in the equipment) rather than a through-bolt flange connection. Common in ASME B16.5 equipment nozzle connections, heat exchanger channel heads, and pressure vessel cover bolt connections in exotic alloy service.
Equal-end configuration ensures correct engagement depth in the tapped bore while providing standard nut clearance at the outer face. Available in all exotic alloys, M12–M100.
Unequal-End Double Stud Bolts — Fixed Depth Tapped Flanges
Different thread engagement lengths on each end — the shorter end is sized for engagement in a tapped flange or equipment body where engagement depth is fixed by the flange specification, the longer end provides full nut engagement. Used in ASME B16.5 flanges with integral stud boss, specialised pressure vessel equipment where one end engagement depth is constrained by the design, and reducing acid plant flanges where the equipment body tapped hole depth determines the short-end length.
Unequal-end dimensions specified per drawing or ASME equipment datasheet. Akbar Fasteners manufactures to any unequal-end dimension in all exotic alloys.
Metric Double-End Studs — DIN 939 / DIN 938
DIN 939 (long-threaded end) and DIN 938 (short-threaded end) metric double-end studs for European chemical plant, acid synthesis facilities, and DIN-flanged equipment where ASME B16.5 is not specified. One end engages the tapped bore (engagement depth = 1× or 1.25× diameter for DIN 938 and DIN 939 respectively), the other end takes a DIN 934 or ISO 4032 hex nut. Used in European EPC projects specifying DIN flanges rather than ASME B16.5 for chemical process, acid plant, and reducing acid service.
DIN 939/938 studs available in all exotic alloys from same ASTM certified bar as fully threaded stud bolts. M12–M100.
Stud Bolt Lengths — ASME B16.5 NPS 4″ Representative
Representative ASME B16.5 stud bolt dimensions for NPS 4″ flange. All six pressure classes, M20–M36 depending on class. Full tables for all NPS and all alloys on request to sales@akbarfasteners.in.
| ASME Class | Design Pressure | Stud Dia (NPS 4″) | Stud Length (mm) | No. Studs | Nut Standard | Alloys Available |
|---|---|---|---|---|---|---|
| ASME B16.5 FULLY THREADED STUD BOLT SETS · NPS 4″ · ALL EXOTIC ALLOYS · MATCHED NUTS FROM SAME HEAT | ||||||
| Class 150 | ~15 Bar | M20 | 120 mm | 8 | B18.2.2 HH | C276 · C22 · B3 · SS 316L · B7 |
| Class 300 | ~52 Bar | M24 | 185 mm | 8 | B18.2.2 HH | C276 · C22 · B3 · K500 · SS |
| Class 600 | ~103 Bar | M24 | 215 mm | 8 | B18.2.2 HH | C276 · C22 · B3 · K500 · SS |
| Class 900 | ~155 Bar | M24 | 250 mm | 8 | B18.2.2 HH | C276 · C22 · K500 · B7 |
| Class 1500 | ~258 Bar | M30 | 350 mm | 8 | B18.2.2 HH | C276 · C22 · K500 · B7 |
| Class 2500 | ~430 Bar | M36 | 480 mm | 8 | B18.2.2 HH | C276 · C22 · K500 · B7 |
All lengths in mm. Inch-thread per ASME B16.5 Table 7 also available. Full tables for all NPS — sales@akbarfasteners.in
All Alloys for ASME B16.5 Stud Bolts
Every exotic and engineering alloy available as ASME B16.5 stud bolt sets from Akbar Fasteners Pvt. Ltd., Mumbai. Click any card for the alloy-specific stud bolt page with composition data, ASME pressure class tables, and matched nut information.
Hastelloy C276
Hastelloy C22
Hastelloy B3
Hastelloy B2
Monel K500
Monel 400
Inconel 625
Incoloy 825 / 925
Nickel 200 / 201
SS 316L / 904L / Duplex 2205
ASTM A193 B7 / B7M
Inconel 718
Stud Bolt Applications
ASME B16.5 pressure flanged connections in chemical, petrochemical, offshore, power, and process industries — wherever a bolted pipe flange joint must withstand pressure, temperature, and corrosive service simultaneously.
Chemical Processing
corrosive service stud sets
Oil & Gas
NACE sour service stud sets
Offshore Platforms
Class 900/1500 FPSO flanges
FGD Systems
FGD duct stud bolt sets
Power Generation
condenser seawater flanges
Desalination
brine circuit stud bolt sets
Pharmaceutical
GMP process stud bolt sets
LNG / Petrochemical
Class 600–2500 stud sets
Stud Bolt Standards Coverage
Same ISO 9001:2015 certified quality system for stud bolts in all alloys — from ASTM A193 B7 carbon steel through Hastelloy B3 exotic alloy. Full heat traceability.
Complete Documentation Package
Heat & Lot Traceable
Conformance
100% Lots Verified
Tensile · Hardness
TÜV · BV · Lloyds
Need ASME B16.5 Stud Bolts
in Any Alloy?
Alloy · ASME class · NPS · quantity · documentation. Akbar Fasteners Pvt. Ltd. responds within 24 hours with full pricing, lead time, and MTC documentation list.
Export: +91 8696 32 4646 · Support: +91 800 9315 333 · export@akbarfasteners.in