Patriot Bolt machines ASTM A193 Grade B7M fasteners for sour gas and other hydrogen sulfide service. B7M is B7 chrome-moly steel tempered to a maximum hardness of 235 HBW, with every piece hardness tested, so it meets the limits in NACE MR0175 / ISO 15156.
This page brings together the B7M fasteners we make, the B7M property limits, and how B7M compares with other alloy steel bolting grades.
A193 B7M at a Glance
- Specification
- ASTM A193 / ASME SA193 Grade B7M
- Material
- AISI 4140 / 4142, UNS G41400
- Strength
- 100 ksi min tensile, 80 ksi min yield; 235 HBW max
- Sour service
- NACE MR0175 / ISO 15156
- Matching nut
- A194 Grade 2HM
- Products
- Stud bolts, heavy hex bolts, nuts
A193 B7M Fasteners We Machine
Choose a product to see its standards and options. Every order ships with mill test reports traceable to the heat.
A193 B7M Stud BoltsFull B7M page
A194 2HM Heavy Hex NutsMatching nut
B7M Heavy Hex BoltsMade in B7MA193 B7M Mechanical Properties
| Diameter | Tensile, min | Yield (0.2%), min | Hardness, max |
|---|---|---|---|
| 4 in and under | 100 ksi | 80 ksi | 235 HBW, 100% tested |
Full chemistry is on the A193 B7M stud bolts page.
B7M vs. Other Alloy Steel Bolting Grades
| Grade | Strength (to 2-1/2 in) | Typical use |
|---|---|---|
| A193 B7M | 100 ksi / 80 ksi, 235 HBW max | Sour (H2S) service per NACE MR0175 |
| A193 B7 | 125 ksi tensile / 105 ksi yield | General flange bolting to about 800 °F |
| A320 L7 | 125 ksi / 105 ksi, impact tested at −150 °F | Low-temperature flanges to 2-1/2 in |
Compare all grades in the Fastener Materials Matrix.
A193 B7M Fastener FAQ
What makes B7M suitable for sour service?
Its hardness is limited to 235 HBW, under the 22 HRC limit in NACE MR0175, and every piece is hardness tested.
Which B7M fasteners does Patriot Bolt make?
We machine B7M stud bolts, heavy hex bolts and nuts, as well as custom parts made to your drawing.
Which nut goes with B7M?
A194 Grade 2HM, which has the same hardness limit and is also 100 percent tested.
Do B7M fasteners come with certifications?
Yes. Patriot Bolt is ISO 9001:2015 certified, and every B7M order includes mill test reports traceable to the heat and a certificate of conformance to your purchase order.
Request a Quote
Send us the product, size, specification and quantity, or upload your drawing. Call (281) 581-0176 or request a quote.