ASTM A193 Specification: Bolting for High Temperature / Pressure Service
The ASTM A193 specification covers alloy steel and stainless steel bolting materials which are to be used in the high temperature and high pressure services or in other demanding industrial applications. ASTM A193 standard is applicable in manufacturing ASTM A193 bolts, studs, and threaded fasteners that can be used in extreme service conditions.
ASTM A193 fasteners are commonly used in the valves, flanges, fittings, pressure vessels, and piping systems in many industries such as oil and gas, petrochemical, power generation, refineries, and chemical processing.
ASTM A193 bolts are designed to withstand mechanical strength, dimensional stability and reliability even when the temperature and the pressure are high. The ASTM A193 standard has various grades, each to address certain conditions of service of the temperature resistance, corrosion resistance, and load bearing.
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ASTM A193 Bolt & Fasteners Suppliers, Manufacturers & Exporter
Jade Alloys is a manufacturer, supplier, and exporter of specialized ASTM A193 bolts, which are used to provide high-quality bolting solutions to high-temperature and high-pressure industrial service. Our ASTM A193 fasteners are manufactured according to ASTM A193 standard and the ASTM A193 specification.
We provide full stocking of ASTM A193 bolts and studs that can be used in pressure vessel, flanges, piping systems, and fittings. All the large versions of ASTM A193 such as B7, B7M, B16, B8, and B8M are offered to satisfy various applications needs such as strength, temperature resiliency, and corrosion resistance.
By implementing strict quality control, certified raw materials, and efficient production processes, we ensure competitive global pricing while delivering fully compliant and traceable ASTM A193 bolts for critical applications worldwide.
ASTM A193 Bolt Products
ASTM A193 Bolting Grades
The ASTM A193 specification encompasses numerous grades, each with unique chemical, strength, and testing requirements tailored for specific high-pressure and high-temperature applications. Understanding these differences is crucial for proper fastener selection, as summarized below. For complete, detailed information, check out ASTM standards
| B7 |  |
Hex bolts, screws, stud bolts, double ended studs, full thread rods, full threaded studs |
| B7M |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
| B16 |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
| B8 |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
| B8M |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
| B8T |  |
Hex bolts, screws, stud bolts, double ended studs, Stud for foundation, wind energy bolts, Fasteners for wind turbines |
ASTM A193 Grade B7 Bolts and Studs
ASTM A193 Grade B7 bolts are the most commonly used ASTM A193 fasteners for industrial bolting applications. These bolts and threaded studs are manufactured from chromium-molybdenum alloy steel and are quenched and tempered to achieve high mechanical strength. Grade B7 ASTM A193 bolts are extensively used for flange connections, pressure piping, and construction assemblies. They are typically supplied in plain finish or with protective coatings such as hot-dip galvanizing, PTFE, or Xylan to enhance corrosion resistance. However, coatings may reduce maximum service temperature and must be selected carefully.
ASTM A193 Grade B8 Bolts
ASTM A193 Grade B8 bolts are threaded studs or manufactured using AISI 304 stainless steel, which is the most commonly used stainless grade in the fasteners industry. The material is an austenitic stainless steel and such an alloy needs carbide solution treatment (or solution annealing), which is a treatment that includes heating, quenching in water or fast cooling to achieve optimum inherent corrosion resistance. These B8 bolts are provided as Class 1 following this treatment. Grade B8 Class 2 bolts are subject to extra strain-hardening treatment after the solution treatment to achieve greater strength and less galling potential. These higher-strength Class 2 bolts are specially indicated as B8SH, with the symbol of the grade underlined.
ASTM A193 Grade B8M fasteners
ASTM A193 Grade B8M Class 1 fasteners are similar to Grade B8 fasteners, but made of AISI 316 stainless steel instead of being made of AISI 304. The 316 stainless molybdenum gives it better corrosion protection than 304. Fasteners in Grade B8M Class 1 must be treated using carbide solution or Class 2 is further subjected to strain-hardening processes, enhancing strength and minimizing the possibility of galling. Class 2 fasteners have a mark of B8M SH with the symbol of the grade underlined.
ASTM A193 Grade B7M bolts
ASTM A193 Grade B7M bolts are similar to Grade B7 but in a quenched and tempered, medium-carbon alloy steel. Grade B7M fasteners are manufactured to reduce strength levels and need to be subjected to 100% hardness testing on each fastener in lot. Such bolts are better resistant to chloride-induced, hydrogen stress corrosion cracking (SCC) and are frequently used in sour gas service.
ASTM A193 Grade B16 bolts
ASTM A193 Grade B16 bolts are threaded studs made out of chromium-molybdenum-vanadium alloy steel. Although their strength needs are similar to Grade B7, the inclusion of vanadium and the application of higher tempering temperatures enable Grade B16 fasteners to sustain elevated service temperatures. These are usually applied in the power generation and petrochemical sectors to boilers, turbines, and other high-temperature pressure equipment. Grade B16 does not have inherent corrosion resistance unless coated.
ASTM A193 Material for Grades
| Grade / Tensile Class | Material |
| A193 B7 | Chromium Molybdenum Alloy Steel, Quenched & Tempered |
| A193 B8 | AISI 304 Stainless Steel |
| A193 B8C | AISI 347 Stainless Steel |
| B8C Class 1 | AISI 347 Stainless Steel, Carbide Solution Treated |
| B8C Class 2 | AISI 347 Stainless Steel, Carbide Solution Treated & Strain Hardened |
| A193 B8T | AISI 321 Stainless Steel, Carbide Solution Tested |
| A193 B8M | AISI 316 Stainless Steel |
| B8T Class 1 | AISI 321 Stainless Steel, Carbide Solution Tested |
| B8T Class 2 | AISI 321 Stainless Steel, Carbide Solution Tested & Strain Hardened |
| A193 B16 | Chromium Molybdenum Vanadium Alloy Steel, Quenched & Tempered |
Mechanical Properties of ASTM A193 Bolts
The mechanical properties defined under the ASTM A193 specification ensure that ASTM A193 bolts can withstand extreme mechanical stress, elevated temperatures, and pressure loads during service.
This table outlines the minimum tensile strength, yield strength, elongation, and hardness requirements for each ASTM A193 grade. These mechanical property limits are mandatory to comply with the ASTM A193 standard and play a vital role in determining the fastener’s load-bearing capacity and fatigue resistance in critical applications such as flanges, pressure vessels, and piping systems.
| Grade | Size | Tensile ksi, min | Yield, ksi, min | Elong, %, min | RA % min |
|---|---|---|---|---|---|
| B7 | Up to 2-1/2 | 125 | 105 | 16 | 50 |
| 2-5/8 – 4 | 115 | 95 | 16 | 50 | |
| 4-1/8 – 7 | 100 | 75 | 18 | 50 | |
| B8 Class 1 | All | 75 | 30 | 30 | 50 |
| B8M Class 1 | All | 75 | 30 | 30 | 50 |
| B8 Class 2 | Up to 3/4 | 125 | 100 | 12 | 35 |
| 7/8 – 1 | 115 | 80 | 15 | 35 | |
| 1-1/8 – 1-1/4 | 105 | 65 | 20 | 35 | |
| 1-3/8 – 1-1/2 | 100 | 50 | 28 | 45 | |
| B8M Class 2 | Up to 3/4 | 110 | 95 | 15 | 45 |
| 7/8 – 1 | 100 | 80 | 20 | 45 | |
| 1-1/8 – 1-1/4 | 95 | 65 | 25 | 45 | |
| 1-3/8 – 1-1/2 | 90 | 50 | 30 | 45 |
ASTM A193 Material Chemical Composition
The chemical composition requirements in the ASTM A193 standard control the alloying elements that directly influence strength, corrosion resistance, heat resistance, and weldability of ASTM A193 fasteners.
This table presents the maximum and minimum allowable percentages of elements such as carbon, manganese, chromium, molybdenum, nickel, and silicon for each ASTM A193 grade. Maintaining strict chemical composition limits ensures that ASTM A193 bolts deliver consistent performance in high-temperature and pressure-critical environments.
| Element | B7 (AISI 4140) | B8 (AISI 304) | B8M (AISI 316) |
|---|---|---|---|
| Carbon | 0.37 – 0.49% | 0.08% max | 0.08% max |
| Manganese | 0.65 – 1.10% | 2.00% max | 2.00% max |
| Phosphorus, max | 0.035% | 0.045% | 0.045% |
| Sulfur, max | 0.040% | 0.030% | 0.030% |
| Silicon | 0.15 – 0.35% | 1.00% max | 1.00% max |
| Chromium | 0.75 – 1.20% | 18.0 – 20.0% | 16.0 – 18.0% |
| Nickel | 8.0 – 11.0% | 10.0 – 14.0% | |
| Molybdenum | 0.15 – 0.25% | 2.00 – 3.00% |
ASTM A193 Fasteners Heat Treatment
To be heat treated, both ASTM A193 B7 and B7M fasteners should be quenched in a liquid medium and then tempered. In the case of B7M fasteners, the last heat treatment stage is tempering only, after all machining and thread rolling operations are complete. Hardness testing and non-destructive inspection (such as ultrasonic testing) may be performed on the surface.
Unless otherwise specified, Grade B7 material may be heat-treated using furnace heating, induction heating, or electrical resistance methods.
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Request a QuoteFrequently Asked Questions About ASTM A193
The ASTM A193 specification is the international standard for high-performance bolting materials, specifically covering alloy steel and stainless steel studs and bolts. Its primary use is in demanding service conditions involving high temperatures or high pressures. Approved since 1936, this standard is heavily utilized across critical industrial sectors, most notably in petroleum and chemical construction applications, where joint integrity is essential.
ASTM A193 bolts are manufactured from various alloy and stainless steels, depending on the required grade. For example, Grade B6 bolts and rods are made from AISI 410 stainless steel which is quenched and tempered to enhance its strength. Since this is a stainless steel grade, it is frequently chosen for highly corrosive environments combined with elevated ambient temperatures.
The key difference lies in their intended application: ASTM A325 is the standard for heavy hex structural bolts primarily used in building construction, designed for shear strength. Because of this structural application, A325 bolts must always have a forged head and are manufactured in diameters from 1/2″ through 1-1/2”. In contrast, ASTM A193 covers bolts and studs designed specifically for high-pressure, high-temperature service (such as in power generation and chemical plants). A193 fasteners are commonly found securing pressure vessels, pipe flanges, and valve assemblies.
