ASTM A193 B7M Stud Bolt with ASTM A194 2HM Heavy Hex Nuts | NACE MR0175 Bolting
ASTM A193 Grade B7M stud bolts with ASTM A194 Grade 2HM heavy hex nuts are high-strength alloy steel fasteners specifically designed for sour service, offshore, refinery, petrochemical, and high-pressure piping applications requiring controlled hardness and NACE MR0175 compliance.
Manufactured from quenched and tempered chromium-molybdenum alloy steel (AISI 4140 / 4142), ASTM A193 B7M stud bolts provide excellent mechanical strength while maintaining reduced hardness levels to minimize the risk of sulfide stress cracking (SSC) in H₂S-containing environments.
We are a professional manufacturer and exporter of:
- ASTM A193 B7M Stud Bolts
- ASTM A194 2HM Heavy Hex Nuts
- PTFE Coated B7M Stud Bolts
- Xylan 1070 Coated Stud Bolts
- Xylan 1424 Blue Coated Stud Bolts
- NACE MR0175 Compliant Fasteners
for oil & gas, LNG, offshore, petrochemical, and pressure vessel projects worldwide.
What Is ASTM A193 B7M?
ASTM A193 Grade B7M is a modified version of ASTM A193 Grade B7 alloy steel bolting.
While both grades are manufactured from chromium-molybdenum alloy steel, B7M is specifically produced with reduced hardness and lower strength levels to satisfy NACE MR0175 and ISO 15156 requirements for sour service applications.
Compared with standard B7 fasteners, B7M offers:
- Improved resistance to sulfide stress cracking
- Controlled hardness
- Enhanced reliability in H₂S environments
- Better suitability for offshore and refinery service
ASTM A193 B7M is commonly specified for:
- Pressure vessels
- Valves
- Flanges
- Wellhead equipment
- Pipeline systems
- Refinery process units
ASTM A193 B7M Stud Bolt Specification
Download ASTM_A193_B7M_Stud_Bolts_A194_2HM_Datasheet
| Item | Description |
|---|---|
| Standard | ASTM A193 |
| Grade | B7M |
| Material | AISI 4140 / 4142 |
| Manufacturing | Quenched & Tempered |
| Thread Standard | ASME B1.1 |
| Stud Bolt Standard | ASME B18.2.1 |
| Nut Standard | ASME B18.2.2 |
| Thread Type | UNC / UNF / 8UN |
| Diameter Range | 1/4″ – 6″ |
| Metric Size | M6 – M160 |
| Certification | EN10204 3.1 / 3.2 |
ASTM A194 2HM Heavy Hex Nuts
ASTM A194 Grade 2HM heavy hex nuts are specifically designed to be used with ASTM A193 B7M stud bolts.
Mechanical Properties
| Property | Value |
|---|---|
| Proof Load | 175 ksi |
| Hardness | 248–327 HB |
| Heat Treatment | Tempered ≥ 850°F (454°C) |
The B7M / 2HM combination is widely accepted for NACE-compliant flange bolting systems.
ASTM A193 B7M Chemical Composition
| Element | Content (%) |
|---|---|
| Carbon | 0.37–0.49 |
| Manganese | 0.65–1.10 |
| Silicon | 0.15–0.35 |
| Chromium | 0.75–1.20 |
| Molybdenum | 0.15–0.25 |
| Phosphorus | ≤0.035 |
| Sulfur | ≤0.040 |
Mechanical Properties of ASTM A193 B7M
| Property | Requirement |
|---|---|
| Tensile Strength | 100 ksi (690 MPa) Min |
| Yield Strength | 75 ksi (515 MPa) Min |
| Elongation | 16% Min |
| Hardness | 235 HB Max |
| Rockwell Hardness | 99 HRB Max |
The reduced hardness requirement is the key feature distinguishing B7M from standard B7 fasteners.
Difference Between ASTM A193 B7 and ASTM A193 B7M
| Property | ASTM A193 B7 | ASTM A193 B7M |
|---|---|---|
| Tensile Strength | 125 ksi Min | 100 ksi Min |
| Hardness | 35 HRC Max | 235 HB Max |
| NACE Service | Limited | Preferred |
| H₂S Environment | Not Ideal | Recommended |
| Individual Hardness Test | No | Required |
| Nut Grade | A194 2H | A194 2HM |
Every ASTM A193 B7M stud bolt must be individually hardness tested to ensure compliance with ASTM and NACE requirements.
ASTM A193 B7M vs ASTM A320 L7M
Many EPC specifications compare ASTM A193 B7M with ASTM A320 L7M.
ASTM A193 B7M
Suitable for:
- Ambient temperature service
- High-pressure refinery systems
- Sour gas environments
ASTM A320 L7M
Suitable for:
- Low-temperature service
- Cryogenic applications
- LNG facilities
- Offshore Arctic projects
When low-temperature impact testing is required, ASTM A320 L7M is generally selected instead of B7M.
Available Surface Coatings
PTFE Coated Stud Bolts
Benefits:
- Reduced friction
- Easier installation
- Improved corrosion resistance
Xylan 1070 Coating
Suitable for:
- Offshore platforms
- Seawater environments
- Chemical processing facilities
Xylan 1424 Blue Coating
Widely used for:
- Subsea equipment
- Offshore oil & gas projects
- NORSOK applications
Available coating systems include:
- Xylan 1070
- Xylan 1424
- Xylar 2
- PTFE
- Zinc + PTFE
- Zinc Nickel + PTFE
- Cadmium + PTFE
NACE MR0175 / ISO 15156 Compliance
ASTM A193 B7M stud bolts are one of the most widely specified bolting materials for:
- Sour Gas Service
- H₂S Environments
- Offshore Platforms
- Refinery Units
- Produced Water Systems
Key requirements include:
- Controlled hardness
- Individual hardness testing
- Material traceability
- Certified heat treatment
Applications
Oil & Gas
- Pipeline flanges
- Wellhead equipment
- Manifolds
Offshore Platforms
- Topside modules
- Subsea equipment
- FPSO systems
Refineries
- Pressure vessels
- Reactors
- Heat exchangers
Petrochemical Plants
- Process piping
- Valves
- High-pressure connections
How to Order ASTM A193 B7M Stud Bolts
Example:
Stud Bolt: ASTM A193 Grade B7M
Nut: ASTM A194 Grade 2HM
Size: 1-7/8″ × 450 mm
Thread: 8UN Full Thread
Standard: ASME B18.2.1 / ASME B18.2.2
Coating: Xylan 1424 Blue PTFE
Certification: EN10204 3.1
Compliance: NACE MR0175
Related Products
- ASTM A320 L7M Stud Bolts
- ASTM A193 B7 Stud Bolts
- ASTM A194 2H Heavy Hex Nuts
- ASTM A194 2HM Heavy Hex Nuts
- Xylan Coated Fasteners
- PTFE Coated Stud Bolts
- ASTM A453 Grade 660 Stud Bolts
- Inconel 625 Stud Bolts
HOW TO ORDER OUR A193 B7M STUD BOLTS?
EXAMPLE#1,
1-7/8″-450mm STUD BOLT&NUTS, A193/A193M-B7M, FULL THREAD, 8-UN, ASME B18.2.1/B1.1 CL.2A/ A194/A194M-2HM, WITH TWO HEAVY HEX. NUTS, ASME B18.2.2/B1.1 CL.2B C/W TWO METALLIC WASHERS ASTM F436 FLAT TYPE
