ASTM A193
Grade B7 Stud Bolts
Mumbai · India
What Is ASTM A193 Grade B7 Stud Bolts
ASTM A193 is the standard specification for alloy and stainless steel bolting material for high-temperature or high-pressure service, and Grade B7 within it is by a wide margin the most commonly specified grade in that standard. It’s a chromium-molybdenum alloy steel — typically based on 4140 or 4142 chemistry — quenched and tempered to a minimum tensile strength of 125 ksi (860 MPa), giving it substantially more strength than plain carbon steel while remaining considerably less expensive than stainless or nickel alloy options.
That strength comes from the same quench-and-temper process that limits where B7 should be used. The hardness required to reach 125 ksi tensile strength also makes standard B7 susceptible to sulfide stress cracking if it’s put into H2S-containing sour service — which is exactly why the industry developed the closely related, hardness-controlled Grade B7M for that specific condition. For non-sour, general high-temperature and high-pressure flanged piping and pressure vessel bolting, though, B7 remains the practical default across refineries, petrochemical plants, and power generation facilities worldwide.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our A193 Grade B7 stud bolt range is manufactured with the same ISO 9001:2015 quality system and full mill test documentation as our related B7M, L7, and stainless stud bolt lines.
Where B7 Genuinely Earns Its Position
High Strength at Reasonable Cost
125 ksi minimum tensile strength from a widely available, cost-effective Cr-Mo alloy — the industry’s default for a reason.
Broad Temperature Range Suitability
Performs reliably from moderate sub-zero conditions through to elevated temperatures typical of refinery and process service.
Sour Service Awareness
We confirm whether your project falls under NACE MR0175 before quoting, so standard B7 isn’t supplied where B7M is actually required.
Full Mill Test Traceability
Every batch traceable by heat number with mechanical property verification confirming true B7 compliance.
Grade B7 vs B7M vs L7 vs B16
Standard B7 covers the majority of flanged joint bolting requirements, but three related grades exist for specific conditions B7 doesn’t cover well: sour service, low-temperature toughness, and elevated-temperature creep resistance. The comparison below is the one we walk through with buyers before quoting, so the correct grade matches the actual service condition.
| Property | Grade B7 | Grade B7M | Grade L7 | Grade B16 |
|---|---|---|---|---|
| Base Alloy | Cr-Mo (4140/4142 type) | Cr-Mo (4140/4142 type) | Cr-Mo, enhanced toughness | Cr-Mo-V, high-temp grade |
| Min Tensile Strength | 125 ksi (860 MPa) | 100 ksi (690 MPa) | 125 ksi (860 MPa) | 125 ksi (860 MPa) |
| Max Hardness Restriction | None specific to sour service | 235 HB / 22 HRC | None specific to sour service | None specific to sour service |
| Sour Service Qualified | No | Yes — NACE MR0175/ISO 15156 | No | No |
| Special Property | General-purpose high strength | Sulfide stress cracking resistance | Low-temperature Charpy toughness | Elevated-temperature creep resistance |
| Best Suited For | General flanged piping, non-sour | Sour gas & H2S service | Cold climate / low-temp piping | High-temperature power & steam service |
ASTM A193 B7 Product Range
B7 Stud Bolts
Standard high-strength Cr-Mo stud bolts for general flanged piping and pressure vessel joints.
Grade 2H Heavy Hex Nuts
Matching heavy hex nuts manufactured to pair correctly with B7 stud bolts per ASTM A194.
B7M Stud Bolts
Hardness-controlled version of B7 for NACE-qualified sour service applications.
L7 Stud Bolts
Enhanced low-temperature toughness variant for cold climate flanged piping service.
Grade B7 Technical Overview
Alloying Elements (4140/4142 Type)
- Chromium 0.80 – 1.10%
- Molybdenum 0.15 – 0.25%
- Carbon 0.38 – 0.48%
- Manganese 0.75 – 1.00%
- Iron Balance
Property Ranges (per ASTM A193)
- Tensile Strength 125 ksi min (860 MPa)
- Yield Strength 105 ksi min (720 MPa)
- Elongation 16% min
- Hardness Max per diameter, per spec
- Testing MTC / NABL on request
Available Dimensions
- Diameter Range 1/4″ – 4″
- Metric Equivalent M6 – M100
- Stud Length Custom to drawing
- Thread Type UNC / UNF / 8UN
- Finish As-machined / Coated on request
Application Areas
Wherever high-strength, cost-effective bolting is needed for non-sour flanged joints.
Refinery Flanged Piping
piping flange bolting
Power Generation
flanged joint fastening
Petrochemical Equipment
piping flange bolting
Non-Sour Oil & Gas
pipeline flange bolting
Pressure Vessels
ASME-code pressure equipment
Structural & Heavy Equipment
industrial flange bolting
Chemical Processing
equipment flange bolting
General Industrial Piping
flange bolting across industries
Standard Export Documentation
Prepared as standard practice for every Grade B7 shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Certificate of Conformance
Confirms the shipment matches the purchase order specification and grade in full.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
NABL Accredited Test Reports
Independent mechanical and chemical testing available on request for critical applications.
Bill of Lading
Ocean or air freight shipping document confirming carrier, mode, and consignee details.
Internationally Recognised Standards Coverage
Related Fastener Grades & Materials
ASTM A193 Grade B7M Stud Bolts
The hardness-controlled sour service variant of Grade B7, required under NACE MR0175.
View Grade B7M →ASTM A193 Grade B8 Stud Bolts
Austenitic stainless steel option where corrosion resistance matters more than raw strength.
View Grade B8 →High Tensile Bolts Specifications
Carbon and alloy steel property classes for structural and mechanical bolting.
View High Tensile Specs →Fastener Applications By Industry
A guide to matching fastener material grades to the right industry and environment.
View Applications Guide →Need Grade B7
Or a Related Variant?
Tell us your joint’s temperature, pressure, and whether H2S is present — and we’ll confirm whether B7, B7M, or L7 is the right grade. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in