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ASME B18.2.3.5M B8C Hex Bolt
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Name: ASME B18.2.3.5M B8C Hex Bolt
Standard: ASME B18.2.3.5M
Material: A193 Gr. B8C
Size: M12
Lenght: 70
Surface: Natural color
Standard: ASME B18.2.3.5M
Material: A193 Gr. B8C
Size: M12
Lenght: 70
Surface: Natural color
Quantity
ASME B18.2.3.5M B8C Hex Bolt – strictly manufactured to ASME B18.2.3.5M, made of high-temperature, corrosion-resistant A193 Gr. B8C stainless steel. Size M12 × 70 mm, plain finish, ideal for critical connections in high-pressure, high-temperature service. Reliable performance, premium quality.
How does ASTM specify hexagon bolts?
ASTM itself does not govern the mechanical dimensions (across-flats width, head height, etc.); it focuses on material, mechanical properties, chemistry and test methods.
ASTM itself does not govern the mechanical dimensions (across-flats width, head height, etc.); it focuses on material, mechanical properties, chemistry and test methods.
Dimensional requirements are covered by the ASME B18 series referenced by ASME B18.2.3.5M B8C Hex Bolt—mainly ASME B18.2.1 (inch) and ASME B18.2.3.5M (metric). ASTM, in short, defines “what material” and “what strength level” the bolt shall achieve.
ASTM requirements for hex bolts can be grouped into five core areas:
1. Material & Grade
This is the heart of every ASTM standard; the chosen material fixes strength, corrosion resistance and operating environment.
This is the heart of every ASTM standard; the chosen material fixes strength, corrosion resistance and operating environment.
Carbon & alloy-steel bolts
- ASTM A307 – carbon-steel bolts for general structural joints; Grade A is the everyday commercial bolt.
- ASTM A307 – carbon-steel bolts for general structural joints; Grade A is the everyday commercial bolt.
- ASTM A325 / A325M – high-strength structural bolts for steel-frame buildings, bridges, etc.; strict chemistry and mechanical limits.
- ASTM A490 / A490M – ultra-high-strength structural bolts, stronger than A325, for the most critical joints.
- ASTM A354 – alloy-steel bolts; Grades BC and BD, with BD being the highest strength.
Stainless-steel bolts
- ASTM F593 / F594 – austenitic stainless bolts (304, 316, 316L) offering good corrosion resistance.
- ASTM F593 / F594 – austenitic stainless bolts (304, 316, 316L) offering good corrosion resistance.
- ASTM A193 / A193M – alloy-steel and stainless bolts for high-temperature pressure service. This is the standard behind ASME B18.2.3.5M B8C Hex Bolt.
Examples: A193 B7 (Cr-Mo alloy steel) is the workhorse high-temperature bolt in petro-chemical and pressure-vessel work. A193 B8 and B8C are austenitic stainless grades; B8C is “stabilised” (Ti or Nb) to resist carbide precipitation, making it weldable and suitable for higher temperatures.
Hence ASME B18.2.3.5M B8C Hex Bolt is a common choice in hot, corrosive stainless constructions.
High-temperature alloy bolts
- ASTM A453 / A453M – high-strength, high-temperature bolts such as Grade 660 (alloy A-286) used in gas turbines and jet engines.
- ASTM A453 / A453M – high-strength, high-temperature bolts such as Grade 660 (alloy A-286) used in gas turbines and jet engines.
2. Mechanical properties (property class)
The “strength label”, usually stamped on the head.
The “strength label”, usually stamped on the head.
Metric bolts use property classes 4.6, 8.8, 10.9, 12.9.
Example – an M20 bolt class 10.9:
- “10” → nominal tensile strength / 100 (10 × 100 = 1000 MPa).
- “.9” → yield-to-tensile ratio 0.9 → yield strength ≈ 900 MPa.
Relevant ASTM standards include A325M (classes 8.8 and 10.9).
- “10” → nominal tensile strength / 100 (10 × 100 = 1000 MPa).
- “.9” → yield-to-tensile ratio 0.9 → yield strength ≈ 900 MPa.
Relevant ASTM standards include A325M (classes 8.8 and 10.9).
Inch-series bolts use SAE-type grades 2, 5, 8.
Example – a Grade 8 bolt carries six radial lines; it is a high-strength alloy bolt.
Corresponding ASTM standards are A354 Grade BC (≈ SAE Grade 5) and BD (≈ SAE Grade 8).
ASME B18.2.3.5M B8C Hex Bolt belongs to the stainless high-temperature class and is intended for corrosion- and heat-resistant duties.
ASME B18.2.3.5M B8C Hex Bolt belongs to the stainless high-temperature class and is intended for corrosion- and heat-resistant duties.
3. Dimensions & tolerances
Although dimensions are set by ASME B18, ASTM standards incorporate those limits by reference.
Although dimensions are set by ASME B18, ASTM standards incorporate those limits by reference.
Example: ASTM A325 states that bolts shall conform to ASME B18.2.1 or B18.2.3.5M.
Likewise, ASME B18.2.3.5M B8C Hex Bolt must meet the geometry and tolerance tables of that standard.
4. Identification marking
ASTM requires the head to be clearly stamped with:
- Manufacturer’s ID (logo or symbol).
ASTM requires the head to be clearly stamped with:
- Manufacturer’s ID (logo or symbol).
- Material / grade symbol: “A325”, “8”, “B7”, etc.
Example: a bolt marked “B7” indicates ASTM A193, Cr-Mo alloy steel, for high-temperature service.
Example: a bolt marked “B7” indicates ASTM A193, Cr-Mo alloy steel, for high-temperature service.
ASME B18.2.3.5M B8C Hex Bolt will normally be marked “B8C” to show its material class.
5. Testing & inspection
ASTM mandates tests to guarantee quality:
- Tensile test – proof load, tensile strength, yield strength, elongation.
ASTM mandates tests to guarantee quality:
- Tensile test – proof load, tensile strength, yield strength, elongation.
- Hardness – Brinell, Rockwell or Vickers.
- Impact test – for low-temperature bolts (e.g. A320 L7) toughness is required.
- Chemical analysis – to verify heat composition.
- Wedge load test – to verify head-to-shank integrity.
ASME B18.2.3.5M B8C Hex Bolt must pass these tests before shipment to ensure reliability in hot, corrosive environments.
Buying guide
When ordering ASTM hex bolts, always state the following four items to create a complete technical description:
When ordering ASTM hex bolts, always state the following four items to create a complete technical description:
1. Standard & grade – choose the correct ASTM standard and grade for the duty.
- General structure: ASTM A307
- High-strength steelwork: ASTM A325 / A490
- High T / High P (petro-chemical): ASTM A193 B7 / B8 / B8C → i.e. ASME B18.2.3.5M B8C Hex Bolt
- Corrosive service: ASTM F593 304 / 316
- High-strength steelwork: ASTM A325 / A490
- High T / High P (petro-chemical): ASTM A193 B7 / B8 / B8C → i.e. ASME B18.2.3.5M B8C Hex Bolt
- Corrosive service: ASTM F593 304 / 316
2. Dimensional standard & size – quote the ASME B18 standard (B18.2.1 or ASME B18.2.3.5M B8C Hex Bolt) and the exact size.
Example: ASME B18.2.3.5M M12 × 70 mm
Example: ASME B18.2.3.5M M12 × 70 mm
3. Property class – select the required strength class (e.g. 10.9 or Grade 8).
For stainless high-temperature duty, ASME B18.2.3.5M B8C Hex Bolt is the logical choice.
For stainless high-temperature duty, ASME B18.2.3.5M B8C Hex Bolt is the logical choice.
4. Surface finish – choose according to corrosion resistance and friction requirements.
Options: hot-dip galvanised, dacromet, phosphated, plain, etc.
Options: hot-dip galvanised, dacromet, phosphated, plain, etc.
ASME B18.2.3.5M B8C Hex Bolt is normally supplied plain or pick-and-passivated to enhance corrosion resistance.
Complete purchase description example:
“Supply bolt: ASTM A193 Gr. B8C, size ASME B18.2.3.5M B8C Hex Bolt M12 × 70 mm, strength class equivalent to 10.9, finish plain (natural).”
“Supply bolt: ASTM A193 Gr. B8C, size ASME B18.2.3.5M B8C Hex Bolt M12 × 70 mm, strength class equivalent to 10.9, finish plain (natural).”
A systematic statement like this ensures that the bolts you receive match every project requirement—dimension, material and performance—avoiding safety risks and costly replacements.
For elevated temperature, corrosive or critical joints, selecting ASME B18.2.3.5M B8C Hex Bolt is a key step in keeping the system safe and reliable.
Should you need drawings, mill certificates or supplier recommendations for ASME B18.2.3.5M B8C Hex Bolt, please feel free to ask.
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