ASTM A193 Bolts Manufacturer & Suppliers
Unifit Fasteners is a trusted manufacturer and international exporter of ASTM A193 alloy steel and stainless steel bolts, studs and fasteners. The ASTM A193 specifications cover alloy and stainless steel bolting materials that are applied in high temperature and pressure as well as special purpose applications.
The products are engineered with high-precision and durability and are common in the oil and gas, power generation, petrochemical and marine sectors, where high strength and reliability is of crucial importance. All products that Unifit Fasteners produces are well tested and certified as per the ASTM, ASME, and international standards of quality and can perform at its best even in the most demanding conditions.
With our wide variety of grades such as B7, B7M, B8, B8M, and B16, you can also have our personalized fastening solutions to most complicated engineering projects. We also have high production capacity and supply chain around the world, so we can guarantee standard quality and a quick turnaround time of any order.
Speak to our engineering team to find the right ASTM A193 grade for your application.
Request QuoteTable of Contents
- Scope and Applications
- Available ASTM A193 Grades at Unifit Fasteners
- Mechanical Properties of ASTM A193 Fasteners
- Chemical Composition of ASTM A193 Materials
- Recommended Nuts, Bolts & Washers Combination
- Equivalent International Standards
- Applications of ASTM A193 Fasteners
- Why Choose Unifit Fasteners
- FAQs on ASTM A193 Fasteners
Scope and Applications
The ASTM A193 standard applies to bolts, studs, nuts, and threaded rods used in:
- Boilers and heat exchangers
- Valves, flanges, and pressure vessels
- Pipelines and chemical processing units
- Power generation and refinery systems
Each grade within ASTM A193 is designed to perform under specific service conditions involving high stress, temperature, and corrosion.
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Available ASTM A193 Grades at Unifit Fasteners
| Grade | Material Type | Description / Application |
|---|---|---|
| ASTM A193 GR B7 | Alloy Steel | High tensile fasteners for high-temperature and high-pressure environments. |
| ASTM A193 GR B7M | Alloy Steel (Tempered) | Lower hardness version of B7; suitable for corrosive media. |
| ASTM A193 GR B8 / B8A | Stainless Steel 304 | Offers moderate temperature resistance and good corrosion protection. |
| ASTM A193 GR B8M CL 1 / CL 2 / B8MA | Stainless Steel 316 | Excellent corrosion and pitting resistance, ideal for marine and chemical industries. |
| ASTM A193 GR B8T / B8TA | Stainless Steel 321 | Titanium stabilized for high-temperature oxidation resistance. |
| ASTM A193 GR B8S | Stainless Steel 347 | Columbium stabilized for enhanced intergranular corrosion resistance. |
| ASTM A193 GR B16 | Cr-Mo-V Alloy Steel | Designed for turbine, boiler, and high-pressure applications. |
| ASTM A194 GR 2H / 2HM | Carbon Steel Nuts | Matches B7/B7M bolts for secure high-strength assemblies. |
| ASTM A194 GR 8 / 8A / 8M / 8MA / 8T / 8TA / 8S | Stainless Steel Nuts | Corrosion-resistant nuts for stainless steel bolts. |
| ASTM A194 GR 4 / 7 | Low Alloy Steel | For low-temperature service use. |
| F436/F436M | Hardened Steel Washer | Ensures uniform load distribution under bolts and nuts. |
| SS 304/304L / SS 316/316L / SS 321/321H / SS 347/347H | Stainless Steel | Custom fasteners in multiple grades for industry-specific needs. |
Mechanical Properties of ASTM A193 Fasteners
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Reduction of Area (%) | Hardness (HBW) |
|---|---|---|---|---|---|
| B7 | 860 min | 720 min | 16 min | 50 min | 321 max |
| B7M | 690 min | 550 min | 20 min | 50 min | 235 max |
| B8 CL 1 | 515 min | 205 min | 30 min | 50 min | 223 max |
| B8 CL 2 | 690 min | 515 min | 30 min | 50 min | 223 max |
| B8M CL 1 | 515 min | 205 min | 30 min | 50 min | 223 max |
| B8M CL 2 | 690 min | 515 min | 30 min | 50 min | 223 max |
| B16 | 860 min | 720 min | 20 min | 50 min | 321 max |
Chemical Composition of ASTM A193 Materials
| Grade | C (%) | Mn (%) | Si (%) | Cr (%) | Mo (%) | Ni (%) | Others |
|---|---|---|---|---|---|---|---|
| B7 | 0.37 max | 0.65–1.10 | 0.15–0.35 | – | 0.15–0.25 | – | – |
| B7M | 0.37 max | 0.65–1.10 | 0.15–0.35 | – | 0.15–0.25 | – | – |
| B8 / B8A | 0.08 max | 2.00 max | 1.00 max | 18.0–20.0 | – | 8.0–11.0 | – |
| B8M / B8MA | 0.08 max | 2.00 max | 1.00 max | 16.0–18.0 | 2.00–3.00 | 10.0–14.0 | – |
| B8T | 0.08 max | 2.00 max | 1.00 max | 17.0–19.0 | – | 9.0–12.0 | Ti 5×C min, 0.70 max |
| B8S | 0.08 max | 2.00 max | 1.00 max | 17.0–19.0 | – | 9.0–13.0 | Cb + Ta 10×C min, 1.10 max |
| B16 | 0.37 max | 0.65–1.10 | 0.15–0.35 | 0.40–0.60 | 0.45–0.65 | 0.40–0.60 | V 0.25–0.35 |
Recommended Nuts, Bolts & Washers Combination
| Bolting Material (ASTM A193) | Recommended Nut (ASTM A194) | Washer Specification |
|---|---|---|
| A193 B7 | A194 2H | F436 / F436M |
| A193 B7M | A194 2HM | F436 / F436M |
| A193 B8 CL 1 | A194 8 | Stainless Steel Washer |
| A193 B8 CL 2 | A194 8A | Stainless Steel Washer |
| A193 B8M CL 1 | A194 8M | Stainless Steel Washer |
| A193 B8M CL 2 | A194 8MA | Stainless Steel Washer |
| A193 B8T | A194 8T | Stainless Steel Washer |
| A193 B8S | A194 8S | Stainless Steel Washer |
| A193 B16 | A194 4 | F436 / F436M |
Equivalent International Standards
| Standard | Equivalent Specification |
|---|---|
| ASME SA193 | ASTM A193 |
| ASME SA194 | ASTM A194 |
| DIN EN ISO 3506 | Stainless Steel Fasteners |
| BS 4882 | Alloy Steel Bolts |
| JIS B1186 | Stud Bolts and Nuts |
Applications of ASTM A193 Fasteners
- Oil & Gas Industry
- Pressure Vessels and Boilers
- Heat Exchangers and Power Plants
- Petrochemical and Refinery Equipment
- Marine and Offshore Structures
- Valve and Flange Assemblies
Why Choose Unifit Fasteners
- Over two decades of manufacturing excellence
- Custom sizing, coatings, and thread configurations
- Global exports and fast delivery
- ISO & PED certified production units
- Complete traceability with mill test certification
FAQs on ASTM A193 Fasteners
What is ASTM A193?
ASTM A193 is a specification that covers alloy and stainless steel bolting materials for high-temperature and high-pressure service.
What are the key grades in ASTM A193?
Common grades include B7, B7M, B8, B8M, and B16, each suitable for different mechanical and environmental conditions.
Can ASTM A193 bolts be used in corrosive environments?
Yes, stainless steel grades like B8, B8M, and B8S provide excellent corrosion resistance in marine and chemical settings.
What does ASTM A193 mean?
ASTM A193 is a specification for alloy and stainless steel bolting materials used in high-pressure and high-temperature applications. It defines grades like B7, B8, and B16 to ensure strength, durability, and consistent performance in critical environments.
Is ASTM A193 B7 stainless steel?
No, ASTM A193 Grade B7 is not stainless steel. It is a chromium-molybdenum alloy steel known for its high strength and heat resistance but lacks the corrosion resistance of stainless steel grades like B8 or B8M.
What is the difference between ASTM A193 Grade B7 and B8?
ASTM A193 B7 is an alloy steel grade designed for strength and heat resistance, while B8 is a stainless steel grade offering excellent corrosion resistance. B7 is used in high-pressure systems, and B8 suits corrosive environments.