Patriot Bolt machines ASTM A193 Grade B5 stud bolts from certified 5 percent chromium, 1/2 percent molybdenum steel (AISI 501, UNS S50100). B5 is the bolting match for 5Cr-1/2Mo (P5 and F5) piping and flanges in hot, sulfur-bearing refinery service.
We make B5 studs to your purchase order or drawing. Every order ships with mill test reports traceable to the heat.
A193 B5 Stud Bolts at a Glance
- Specification
- ASTM A193 / ASME SA193 Grade B5
- Material
- AISI 501, 5Cr-1/2Mo steel (UNS S50100), quenched and tempered
- Strength
- 100 ksi min tensile, 80 ksi min yield (4 in and under)
- Service
- Typically up to about 1100 °F
- Matching nut
- A194 Grade 3 heavy hex
- Configurations
- Fully threaded, double-end and tap-end
Why Engineers Specify A193 B5 Stud Bolts
Hot crude, coker and hydroprocessing units carry sulfur compounds that attack ordinary alloy steel. B5 has the chromium to handle them.
- Sulfidation and scaling resistance. 4 to 6 percent chromium forms a protective oxide at refinery temperatures.
- Matches P5 piping. The stud expands and corrodes at the same rate as the 5Cr-1/2Mo flanges it clamps.
- Elevated temperature. Tempered at 1100 °F minimum and typically used up to about 1100 °F.
B5 is less common than B7 and B16, so it is often made to order.
A193 B5 Stud Bolt Specifications
A193 sets one set of B5 properties up to 4 in diameter.
| Diameter | Tensile, min | Yield (0.2%), min | Elongation, min | Reduction of area, min |
|---|---|---|---|---|
| 4 in and under | 100 ksi | 80 ksi | 16% | 50% |
The matching nut is A194 Grade 3, the 5Cr-Mo nut grade. Check your line class before substituting another nut.
A193 B5 Chemical Composition
| Element | Weight % |
|---|---|
| Carbon | 0.10 min |
| Manganese | 1.00 max |
| Phosphorus | 0.040 max |
| Sulfur | 0.030 max |
| Silicon | 1.00 max |
| Chromium | 4.0–6.0 |
| Molybdenum | 0.40–0.65 |
Limits per the current edition of the specification. The mill test report for your heat is the controlling document.
Stud Configurations
- Fully threaded studs, threaded end to end, for flange bolting where grip length varies.
- Double-end studs, threaded on both ends with an unthreaded center.
- Tap-end studs, with one end made to thread into a tapped hole.
Applications and Industries
- Refining: Crude and vacuum units, cokers, hydrotreaters and hydrocrackers. See Petrochemical & Refining.
- Fired heaters: Furnace and heater piping bolting.
- Hot Cr-Mo lines: Valve bonnets and flanges on 5Cr-1/2Mo piping.
Certification and Traceability
Patriot Bolt is ISO 9001:2015 certified. Each B5 order includes mill test reports traceable to the heat, along with a certificate of conformance to the specification on your purchase order.
Studs are marked with the grade symbol and our identification, as the specification requires.
Compare B5 with other bolting grades in our Fastener Materials Matrix.
A193 B5 Stud Bolts FAQ
What is A193 B5 made of?
B5 is AISI 501 steel with 4 to 6 percent chromium and 0.40 to 0.65 percent molybdenum, quenched and tempered.
Why use B5 instead of B7 or B16?
B5 is chosen for hot, sulfur-bearing service and to match 5Cr-1/2Mo piping. Its strength is lower than B7 or B16, so it is specified for corrosion and temperature, not maximum preload.
Which nut goes with B5?
ASTM A194 Grade 3 heavy hex nuts, the 5Cr-Mo nut grade.
Do you keep B5 studs in stock?
B5 is usually made to order. Send us the size and quantity and we will confirm material availability and lead time.
Request a Quote
Send us the stud configuration, diameter, length, thread, specification and quantity, or upload your drawing. Our team will confirm the material and lead time. Call (281) 581-0176 or request a quote.
Also in B5: A193 B5 fasteners hub · Heavy hex bolts · A194 Grade 3 nuts · All stud bolts