ASTM A193 Grade B16 Fasteners Manufacturer & Exporter

What Is ASTM A193 Grade B16?

ASTM A193 Grade B16 is the specification for chromium-molybdenum-vanadium (Cr-Mo-V) alloy steel bolting used in high-temperature, high-pressure service: bolts, studs, nuts, and screws for power plants, refineries, and chemical processing. It is a close relative of the far more common Grade B7. Both start from a 4140-type chromium-molybdenum steel, quenched and tempered. The difference is vanadium, plus a higher tempering temperature, and that difference is entirely about heat.

Below roughly 400 degrees C, B7 and B16 behave much alike and B7's lower cost usually wins. Above it, they diverge sharply. Vanadium stabilises the steel's microstructure against creep, the slow time-dependent deformation that, in a bolt, shows up as stress relaxation: the fastener gradually sheds the preload holding the joint tight. A relaxed bolt means a decompressed gasket, and a decompressed gasket means a leak. B16 is specified precisely where that failure mode is unacceptable, and it holds usable strength up to about 590 degrees C (1100 degrees F).

Send Your Enquiry

Key Properties of ASTM A193 B16 Fasteners

• Cr-Mo-V chemistry, chromium for hardenability and oxidation resistance, molybdenum for high-temperature strength, and vanadium for the creep resistance that defines the grade.
• Stress-relaxation resistance, the practical advantage over B7: B16 holds bolt preload at temperatures where B7 would creep and let the joint leak.
• High strength, 860 MPa (125 ksi) minimum tensile and 725 MPa (105 ksi) minimum yield in the common diameter range, with strength tapering in larger diameters (full table below).
• Quenched and tempered, heat treated with a higher tempering temperature than B7, which is what locks in the elevated-temperature stability.
• Matched nuts required, pair B16 with ASTM A194 Grade 7 nuts (Grade 16 for the very hottest service), never standard 2H, so the nut's temperature capability matches the bolt.

Applications of ASTM A193 B16 Fasteners

B16's high-temperature creep resistance sends it to the hottest bolted joints in heavy industry, the applications where B7 would relax and leak:

• Steam turbines and boilers, the signature B16 application, holding preload through thermal cycling.
• Power generation, nuclear, thermal, and hydroelectric plant, turbine and pressure-part bolting.
• Petrochemical and refining, hot flanged joints on reactors, columns, and high-temperature piping.
• Pressure vessels and valves, flanged closures where sustained clamping force at temperature is critical.
• Oil and gas, onshore and offshore high-temperature process equipment.
• Heavy engineering and steel plants, furnace-area and high-temperature mill equipment.

Manufactured in India, Supplied Worldwide

Unifit Fastener manufactures ASTM A193 B16 fasteners in India and exports to high-temperature process industries worldwide, across the Middle East, Southeast Asia, Europe, North America, and Africa. Every order ships with EN 10204 3.1 mill test certification, PMI on request, and full heat-number traceability, with export documentation and third-party inspection handled in-house. For a price or custom quote, send your size, quantity, and specification.

Request a Quote

Send your grade, size, quantity, and standard, or your drawing for custom B16 fasteners, and we will confirm availability, certification, and lead time for domestic supply or export.