Stud Bolts for Valves and Heat Exchangers ASTM A 193 B16

This case study focuses on large-size stud bolts for valves and heat exchangers, made from ASTM A193 B16, a special steel alloy

In the most demanding Oil & Gas applications—such as petrochemical plants, thermal power stations, and refineries—valves and heat exchangers operate under extreme temperature and pressure conditions. Fastening elements, particularly stud bolts, must ensure:

• mechanical tightness under thermal expansion and frequent load cycles
• resistance to creep and deformation at high temperatures
• metallurgical compatibility with flanges, valves, and gaskets
• thread stability and precision even after multiple assembly/disassembly cycles

Technical Features of the Stud Bolt Supplied by EFS

For a major customer in the Oil & Gas sector, EFS supplied large-diameter stud bolts with the following specifications:

• Material: ASTM A193 B16 (alloy steel for high-temperature service)
• Dimensions: Ø 2” 3/4 x 571 mm
• Threading: fine pitch 8UN with final thread recut
• Accessories: 2 nuts in ASTM A194 Gr.7

The stud bolts were used for both pressure valve assemblies and heat exchangers operating continuously above 500°C.

Why material B16 stud bolts?

The choice of ASTM A193 B16 material meets the need to operate in environments with temperatures up to 550–600°C while maintaining high mechanical strength. This alloy steel, containing chromium and molybdenum, is designed to resist creep, deformation, and oxidation at elevated temperatures.

The 8UN fine thread offers:

• increased contact surface between internal and external threads
• more stable fastening even in the presence of vibrations
• ability to apply high tightening torques without damaging the thread

The thread recut ensures perfect tolerances after heat treatments or coating processes.

The nuts in ASTM A194 Gr.7 provide metallurgical compatibility and comparable mechanical strength, minimizing the risk of critical mismatches.

Reference Standards

The supply complied with the main technical standards in the field, including:

• ASTM A193: specification for bolting materials for high-temperature and high-pressure service
• ASTM A194: nuts for critical applications made from high-strength materials
• ASME B16.34: general requirements for industrial valves
• API 6A: standard for wellhead and Christmas tree equipment in oil and gas production
• EN 10269: : selection of steels for elevated temperature service.

All stud bolts were supplied with 3.1 certification, fully traceable, and subject to dimensional and visual inspection in accordance with customer requirements.

Find out more special stud bolts and fastening systems we can provide

Sources

Standards ASTM A193