High-Strength Stud Bolts & Nuts for Critical Service
Realbolt Engineering Industries supplies SA 193 B7, B7M, B8, B8M, B8 CL2 and SA 320 L7, L7M bolting for refineries, power plants, pipelines and pressure equipment.
- 40+Years of experience
- 50,000+Products in stock
- ISO 90012015 certified
See How We Make Your Bolting
Machining, threading and inspection under one roof. Tap any photo or the video to view it larger.
ASTM A193 and A320 bolting grades we supply
Alloy steel, stainless steel and low-temperature grades, available as stud bolts, hex bolts and with matching A194 nuts.
Grade B7
Cr-Mo alloy steel (AISI 4140/4142), quenched and tempered
The most widely used grade for high-temperature and high-pressure flanges, valves and pressure vessels.
Matching nut: A194 Gr. 2H
Grade B7M
Cr-Mo alloy steel, controlled lower hardness
For sour service (H2S) where hard bolts risk cracking. Softer than B7.
Matching nut: A194 Gr. 2HM
Grade L7
Cr-Mo alloy steel, impact tested
For low-temperature service such as cryogenic lines and cold-climate pipelines. Note: L7 belongs to A320, not A193.
Matching nut: A194 Gr. 4 / 7
Grade L7M
Cr-Mo alloy steel, impact tested, lower hardness
Low-temperature plus sour service combination. Belongs to A320.
Matching nut: A194 Gr. 7M
Grade B8 (Class 1)
Stainless steel AISI 304, carbide solution treated
Good general corrosion resistance. Lower strength than alloy steel grades.
Matching nut: A194 Gr. 8
Grade B8M (Class 1)
Stainless steel AISI 316, carbide solution treated
Better resistance to chlorides and chemicals than B8. Common in marine and process plants.
Matching nut: A194 Gr. 8M
Grade B8 CL2
Stainless steel AISI 304, strain hardened (Class 2)
Higher strength than Class 1 through strain hardening. Strength varies with bolt diameter.
Matching nut: A194 Gr. 8
SA is the ASME designation of the same material as A, so SA 193 B7 and A193 B7 are the same grade.
Our Products
Minimum Mechanical Properties
Quick reference for the grades we supply. Always confirm against the current edition of the standard and your purchase order.
| Grade | Standard | Size | Tensile (ksi, min) | Yield (ksi, min) | Elongation (pct, min) | Reduction of area (pct, min) | Hardness (max) |
|---|---|---|---|---|---|---|---|
| B7 | A193 | Up to 2.5 in | 125 | 105 | 16 | 50 | 321 HBW / 35 HRC |
| B7 | A193 | 2.625 to 4 in | 115 | 95 | 16 | 50 | 321 HBW / 35 HRC |
| B7 | A193 | 4.125 to 7 in | 100 | 75 | 18 | 50 | 321 HBW / 35 HRC |
| B7M | A193 | Per standard | 100 | 80 | 18 | 50 | 235 HBW / 99 HRB |
| L7 | A320 | Up to 2.5 in | 125 | 105 | 16 | 50 | 321 HBW / 35 HRC |
| L7M | A320 | Per standard | 100 | 80 | 18 | 50 | 235 HBW / 99 HRB |
| B8 Class 1 | A193 | All | 75 | 30 | 30 | 50 | 223 HBW / 96 HRB |
| B8M Class 1 | A193 | All | 75 | 30 | 30 | 50 | 223 HBW / 96 HRB |
| B8 Class 2 | A193 | Up to 0.75 in | 125 | 100 | 12 | 35 | 321 HBW / 35 HRC |
Values are for quick reference only and are not a substitute for the official ASTM standard. HBW is Brinell hardness. HRC and HRB are Rockwell C and B hardness.
Bolting You Can Trace and Trust
Precision fasteners for every application, backed by documentation and stock.
ISO 9001:2015 Certified
A certified quality management system behind every order.
Test Certificates
Mill test certificates so you can verify grade, chemistry and mechanical properties.
Inspection and Traceability
Material checks and heat-number traceability from stock to dispatch.
Large Ready Stock
Over 50,000 products in stock, covering bolts, nuts, studs, threaded rods and washers.
Custom Sizes
Stud bolts cut to your length and thread specification, with matching A194 nuts.
Fast Quotations
Send your grade, size and quantity and get a quotation quickly.
Where A193 and A320 Bolting Is Used
Our bolting goes into equipment where joints must hold under heat, pressure, cold or corrosion.
Oil and Gas
Flanged joints, wellheads, separators and refineries.
Petrochemical
Reactors, heat exchangers and process piping.
Power Plants
Boilers, turbines and steam lines.
Pipelines
Pipe flanges, valves and pump connections.
Water Treatment and Desalination
Stainless B8 / B8M bolting for corrosive service.
Wind Energy
Tower, foundation and flange bolting for turbine installations.
Frequently Asked Questions
They describe the same material. "SA" is the ASME designation. Many buyers accept either, but check what your purchase order asks for.
No. L7 and L7M are grades of ASTM A320 (SA 320), the specification for low-temperature bolting. B7, B7M, B8, B8M and B8 Class 2 are A193 grades.
B7M has a controlled lower hardness and is used in sour (H2S) service where harder bolts can crack. B7 is stronger and suits general high-temperature, high-pressure service.
B8 is stainless 304 and B8M is stainless 316, which resists chlorides better. Class 2 means the stainless steel is strain hardened, giving higher strength than Class 1, with strength depending on diameter.
Typically A194 nuts: 2H with B7, 2HM with B7M, Gr. 4 or 7 with L7, Gr. 7M with L7M, Gr. 8 with B8 and Gr. 8M with B8M. See the Specifications section for the full pairing table.
Yes, mill test certificates can be supplied with the shipment. Mention any certificate or third-party inspection requirement in your enquiry.
Contact
Mumbai, Maharashtra 400004
Plot No. 1, Golani Naka, Waliv,
Vasai (E) 401208