ASTM A193 Grade B8 Fasteners Manufacturer & Supplier
Unifit Fasteners is a leading manufacturer and supplier of Grade B8 fasteners by ASTM A193 that come in a full selection of hex, stud, nuts, screws, washers, and threaded rods using quality 304/304L stainless steel. These fasteners are supplied in both solution-annealed (Class 1) and strain-hardened (Class 2) states, which make them applicable in general-purpose applications or high-pressure and high-temperature applications.
B8 fasteners have superb heat resistance, corrosion resistance, steam resistance, and aggressive chemical resistance, making them popular in chemical storage, heat exchangers, pressure piping, marine installations, dyeing systems, mine screens, and water or quarry filter systems. They are stable in temperature and vibration and should be used in both the static and heavy-duty rotating equipment.
All fasteners are handled by quality inspection and sorting systems, which guarantee the production of zero defects and dimensional accuracy. Material Test Certificates (MTC), PMI reports, and other QA/QC documents could be requested in order to be fully traced to materials and comply with the international standards.
Place your order with us, and we will offer you the best prices, test certificates and the quickest delivery services.
Request QuoteASTM A193 B8 Bolt, SS ASTM A193 Stud Bolt, A193 B8 Material, ASTM A193 B8 Fasteners, High Tensile Fasteners, ASTM A193 gr B8 Fasteners, ASTM A193 Allen Cap Screw, B8 Square Bolts, ASTM A193 B8 Washers, ASTM A193 B8 threaded rod Supplier & Exporter.
Table of Contents
- What are ASTM A193 B8 Fasteners?
- ASTM A193 Grade B8 Specification
- Send Your Enquiry
- ASTM A193 B8 Fasteners Chemical Composition
- ASTM A193 B8 Fasteners Mechanical Properties
- ASTM A193 Grade B8 Bolt Marking
- Types of ASTM A193 Grade B8 Fasteners
- ASTM A193 Grade B8 Raw Material
- Size Chart of A193 Grade B8 Stud Bolts
- Dimensions Chart of ASTM SA193 Heavy Hex Bolt (Chart 1)
- Dimensions Chart of ASTM SA193 Heavy Hex Bolt (Chart 2)
- Dimension Table of ASTM A193 B8 Hex Bolt
- Applications of ASTM A193 Grade B8 Fasteners
- FAQ’s About ASTM A193 Grade B8 fasteners
What are ASTM A193 B8 Fasteners?
SS B8 fasteners are made of 304 or 316 stainless steel, which has high reliability in environments that are subjected to heat and other corrosive media. These fasteners provide great resistance to rust, they are well weldable, and they can be easily fabricated or formed. B8 fasteners, which have been engineered as per the ASTM A193 requirements, are particularly useful in high-temperature and high-stress operations, and the fasteners do not show signs of mechanical instability or instability when their application is in high temperature and high pressure.
B8 SS Spring Washer, ASTM A193 B8 Hex Nuts, SS ASTM A193 B8 Fasteners, Heavy Hex Nuts, ASTM A193 B8 Nylon Insert Nut, ASTM A193 B8 Nuts, SS ASTM A193 B8 Washer, Heavy Hex Nuts Manufacturer & Stockist
ASTM A193 Grade B8 Specification
Understanding the official specification helps buyers select fasteners that meet exact performance standards for high‑stress applications.
| Specification | Details |
|---|---|
| Specifications | ASTM A193 / ASME SA193 |
| Length | 3mm to 200mm |
| Size | 3/6″ to 2″, M3 – M56, Custom Sizes |
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ASTM A193 B8 Fasteners Chemical Composition
ASTM A193 Grade B8 fasteners are manufactured from SS 304/304L with controlled chemical properties to ensure corrosion resistance and high-temperature strength. Below is a quick comparison of the chemical composition for A193 B7, B8, and B8M fasteners.
| Element | A193 B7 | A193 B8 | A193 B8M |
|---|---|---|---|
| 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 B8 Fasteners Mechanical Properties
ASTM A193 B8 fasteners offer dependable mechanical strength for high-pressure and high-temperature applications. The table summarizes minimum tensile strength, yield strength, elongation, and reduction of area for B7, B8, and B8M grades.
| Grade | Size Range | Tensile (ksi, min) | Yield (ksi, min) | Elong (%) min | RA (%) min |
|---|---|---|---|---|---|
| B7 | Up to 2-1/2 | 125 | 105 | 16 | 50 |
| B7 | 2-5/8 – 4 | 115 | 95 | 16 | 50 |
| B7 | 4-1/8 – 7 | 100 | 75 | 18 | 50 |
| B8 Class 1 | All Sizes | 75 | 30 | 30 | 50 |
| B8M Class 1 | All Sizes | 75 | 30 | 30 | 50 |
| B8 Class 2 | Up to 3/4 | 125 | 100 | 12 | 35 |
| B8 Class 2 | 7/8 – 1 | 115 | 80 | 15 | 35 |
| B8 Class 2 | 1-1/8 – 1-1/4 | 105 | 65 | 20 | 35 |
| B8 Class 2 | 1-3/8 – 1-1/2 | 100 | 50 | 28 | 45 |
| B8M Class 2 | Up to 3/4 | 110 | 95 | 15 | 45 |
| B8M Class 2 | 7/8 – 1 | 100 | 80 | 20 | 45 |
| B8M Class 2 | 1-1/8 – 1-1/4 | 95 | 65 | 25 | 45 |
| B8M Class 2 | 1-3/8 – 1-1/2 | 90 | 50 | 30 | 45 |
| Class | Heat Treatment Procedure |
|---|---|
| Class 1 | Carbide Solution Treatment |
| Class 2 | Carbide Solution Treatment & Strain Hardened |
| Class 2B | Carbide Solution Treatment & Strain Hardened |
ASTM A193 Grade B8 Bolt Marking
Recognizing proper bolt markings avoids mix‑ups and ensures you are installing the correct grade for your application.
| Marking Example | Description |
|---|---|
| UNF B8 | Manufacturer’s logo (e.g., “UNF”) + Grade marking “B8”; used for standard Class 1 |
| UNF B8 (underlined) | Manufacturer’s logo + underlined “B8”; indicates Class 2 (strain hardened) |
| Manufacturer’s Logo | Unique identifier/logo of the approved bolt manufacturer |
| B8 | Denotes A193 Grade B8 material, confirming chemical composition and performance |
Types of ASTM A193 Grade B8 Fasteners
Selecting the right type of B8 fastener can improve performance, cut downtime, and match exact installation needs.
ASTM A193 B8 Bolts
ASTM A193 B8 Structural Bolts
ASTM A193 B8 Heavy Hex Bolts
ASTM A193 B8 Hex Bolts
ASTM A193 B8 Hexagon Head Bolts
SA 193 B8 Machine Bolts
ASTM A193 Grade B8 T Bolts
ASTM A193 Gr. B8 Eye Bolt
SA 193 B8 Foundation Bolts
Alloy Steel A193 Gr B8 J Bolts
ASTM A193 B8 Button Head Bolt
SA 193 B8 Anchor Bolts
ASTM A193 B8 Long Bolts
ASTM A193 B8 Carriage Bolt
ASTM A193 B8 Elevator Bolt
ASTM A193 B8 Timber Bolts
SA 193 B8 Square Bolt
ASTM A193 B8 Metric Bolt
ASTM A193 B8 Plow Bolts
Alloy Steel Gr. B8 U Bolts
ASTM A193 B8 Flange Bolts
ASTM A193 B8 Screw
ASTM A193 B8 Socket Set Screw
ASTM A193 B8 Self Drilling Screw
ASTM A193 B8 Socket Head Cap Screw
SA 193 B8 Hex Head Screws
ASTM A193 B8 Wood Screw
ASTM A193 Gr. B8 Eye Screw
SA 193 Gr. B8 Wing Screw
ASTM A193 B8 Self Tapping Screws
ASTM A193 Gr. B8 Roofing Screw
ASTM A193 B8 Phillips Head Screw
ASTM A193 B8 Decking Screw
ASTM A193 B8 Machine Screw
ASTM A193 B8 Thumb Screw
ASTM A193 B8 Drywall Screws
SA 193 B8 Chipboard Screw
ASTM A193 B8 Metric Set Screws
Alloy Steel B8 Sems Screw
ASTM A193 B8 Thread Rolling Screw
ASTM A193 B8 Stud Bolt
ASTM A193 B8 Full Threaded Stud Bolts
SA 193 B8 Half Threaded Stud Bolts
Alloy Steel ASTM A193 B8 Threaded Rod
ASTM A193 B8 Double Ended Studs
ASTM A193 B8 Tap End Stud Bolt
Alloy Steel ASTM A193 B8 Tie Rods
Alloy Steel A193 Grade B8 Studs
SA 193 B8 Single End Stud Bolts
A193 Gr.B8 Reduced Shank Stud Bolt
A193 B8 Continuous Threaded Stud Bolt
A193 B8 Partial Threads Stud Bolt
SA193 / A193 B8 Heavy Stud Bolts
ASTM A193 Grade B8 Raw Material
Raw material quality determines the fastener’s reliability over time, making it critical for buyers aiming for long‑term service life.
AISI 304/304L stainless steel is the primary raw material for ASTM A193 Grade B8 fasteners, providing the essential corrosion resistance, mechanical strength, and durability needed for demanding applications. This material is processed by carbide solution treatment (for Class 1) or additional strain hardening (for Class 2) to deliver the specified strength properties and service performance.
304 stainless steel’s versatility and cost-effectiveness make it a preferred choice for manufacturers and buyers seeking reliable fasteners for high-temperature, high-pressure, and corrosive environments.
Size Chart of A193 Grade B8 Stud Bolts
This size chart helps select the right A193 Grade B8 Stud Bolts and ASTM A193 B8 fasteners for secure, leak-proof industrial installations.
| Hex Socket Cap Screws — Dimensional Table | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Nominal Size or Basic Screw Diameter | D Body Diameter | A Head Diameter | H Head Height | S Head Side Height (Max) | J Hex Socket Size (Nominal) | T Key Engagement | G Wall Thickness | K Chamfer or Radius (Max) | |||
| Max | Min | Max | Min | Max | Min | ||||||
| 0 | 0.0600 | 0.0600 | 0.096 | 0.091 | 0.063 | 0.057 | 0.054 | 1/16 | 0.050 | 0.025 | 0.020 |
| 1 | 0.0730 | 0.0692 | 0.110 | 0.104 | 0.073 | 0.067 | 0.064 | 5/64 | 0.063 | 0.029 | 0.020 |
| 2 | 0.0860 | 0.0822 | 0.140 | 0.134 | 0.083 | 0.077 | 0.079 | 5/64 | 0.078 | 0.034 | 0.020 |
| 3 | 0.0990 | 0.0952 | 0.161 | 0.154 | 0.093 | 0.087 | 0.089 | 3/32 | 0.094 | 0.043 | 0.020 |
| 4 | 0.1120 | 0.1082 | 0.183 | 0.176 | 0.112 | 0.101 | 0.101 | 3/32 | 0.094 | 0.057 | 0.030 |
| 5 | 0.1250 | 0.1210 | 0.205 | 0.198 | 0.122 | 0.112 | 0.112 | 1/8 | 0.125 | 0.063 | 0.030 |
| 6 | 0.1380 | 0.1340 | 0.227 | 0.218 | 0.132 | 0.121 | 0.121 | 9/64 | 0.141 | 0.069 | 0.030 |
| 8 | 0.1640 | 0.1585 | 0.270 | 0.262 | 0.158 | 0.144 | 0.144 | 5/32 | 0.156 | 0.084 | 0.030 |
| 10 | 0.1900 | 0.1840 | 0.312 | 0.300 | 0.184 | 0.170 | 0.170 | 3/16 | 0.188 | 0.095 | 0.030 |
| 1/4 | 0.2500 | 0.2438 | 0.375 | 0.363 | 0.250 | 0.238 | 0.225 | 3/16 | 0.188 | 0.120 | 0.030 |
| 5/16 | 0.3125 | 0.3057 | 0.469 | 0.455 | 0.312 | 0.298 | 0.285 | 1/4 | 0.250 | 0.159 | 0.030 |
| 3/8 | 0.3750 | 0.3678 | 0.562 | 0.547 | 0.375 | 0.360 | 0.340 | 5/16 | 0.313 | 0.182 | 0.030 |
| 7/16 | 0.4375 | 0.4299 | 0.656 | 0.639 | 0.437 | 0.420 | 0.400 | 3/8 | 0.375 | 0.210 | 0.030 |
| 1/2 | 0.5000 | 0.4920 | 0.750 | 0.731 | 0.500 | 0.480 | 0.450 | 3/8 | 0.375 | 0.243 | 0.030 |
| 9/16 | 0.5625 | 0.5540 | 0.844 | 0.823 | 0.562 | 0.540 | 0.510 | 7/16 | 0.438 | 0.270 | 0.030 |
| 5/8 | 0.6250 | 0.6160 | 0.938 | 0.915 | 0.625 | 0.600 | 0.570 | 1/2 | 0.500 | 0.300 | 0.030 |
| 3/4 | 0.7500 | 0.7405 | 1.125 | 1.098 | 0.750 | 0.720 | 0.675 | 9/16 | 0.563 | 0.333 | 0.030 |
| 7/8 | 0.8750 | 0.8650 | 1.312 | 1.281 | 0.875 | 0.840 | 0.760 | 5/8 | 0.625 | 0.380 | 0.030 |
| 1 | 1.0000 | 0.9886 | 1.500 | 1.479 | 1.000 | 0.988 | 0.900 | 3/4 | 0.750 | 0.495 | 0.030 |
Dimensions Chart of ASTM SA193 Heavy Hex Bolt
This chart provides precise measurements for ASTM A193 B8 fasteners and heavy hex bolts, helping buyers choose the perfect fit for high-pressure and structural applications. Correct dimensions ensure proper installation, strength, and long-term reliability in critical assemblies.
| Diameter (D) | Body Diameter (D) | Across the Flats (F) | Across the Corners ⌀ | Head Height (H) | Thread Lengths (T) | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| MAX | MIN | MAX | MIN | MAX | MIN | MAX | MIN | < 6" | > 6" | |
| 1/2 | 0.515 | 0.482 | 0.875 | 0.85 | 1.01 | 0.969 | 0.364 | 0.302 | 1.25 | 1.5 |
| 5/8 | 0.642 | 0.605 | 1.062 | 1.031 | 1.227 | 1.175 | 0.444 | 0.378 | 1.5 | 1.75 |
| 3/4 | 0.768 | 0.729 | 1.25 | 1.212 | 1.443 | 1.383 | 0.524 | 0.455 | 1.75 | 2 |
| 7/8 | 0.895 | 0.852 | 1.438 | 1.394 | 1.66 | 1.589 | 0.604 | 0.531 | 2 | 2.25 |
| 1 | 1.022 | 0.976 | 1.625 | 1.575 | 1.876 | 1.796 | 0.7 | 0.591 | 2.25 | 2.5 |
| 1 1/8 | 1.149 | 1.098 | 1.812 | 1.756 | 2.093 | 2.002 | 0.78 | 0.658 | 2.5 | 2.75 |
| 1 1/4 | 1.277 | 1.223 | 2 | 1.938 | 2.309 | 2.209 | 0.876 | 0.749 | 2.75 | 3 |
| 1 3/8 | 1.404 | 1.345 | 2.188 | 2.119 | 2.526 | 2.416 | 0.94 | 0.81 | 3 | 3.25 |
| 1 1/2 | 1.531 | 1.47 | 2.375 | 2.3 | 2.742 | 2.622 | 1.036 | 0.902 | 3.25 | 3.5 |
| 1 3/4 | 1.785 | 1.716 | 2.75 | 2.662 | 3.175 | 3.035 | 1.196 | 1.054 | 3.75 | 4 |
| 2 | 2.039 | 1.964 | 3.125 | 3.025 | 3.608 | 3.449 | 1.388 | 1.175 | 4.25 | 4.5 |
| 2 1/4 | 2.305 | 2.214 | 3.5 | 3.388 | 4.041 | 3.862 | 1.548 | 1.327 | 4.75 | 5 |
| 2 1/2 | 2.559 | 2.461 | 3.875 | 3.75 | 4.474 | 4.275 | 1.708 | 1.479 | 5.25 | 5.5 |
| 2 3/4 | 2.827 | 2.711 | 4.25 | 4.112 | 4.907 | 4.688 | 1.869 | 1.632 | 5.75 | 6 |
| 3 | 3.081 | 2.961 | 4.625 | 4.475 | 5.34 | 5.102 | 2.06 | 1.815 | 6.25 | 6.5 |
Dimensions Chart of ASTM SA193 Heavy Hex Bolt
Correct dimensions guide buyers toward bolts that achieve perfect fit and structural compatibility.
| Diameter (D) | Body Diameter (D) | Across the Flats (F) | Across the Corners ⌀ | Head Height (H) | Thread Lengths (T) | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| MAX | MIN | MAX | MIN | MAX | MIN | MAX | MIN | < 6" | > 6" | |
| 1/2 | 0.515 | 0.482 | 0.875 | 0.85 | 1.01 | 0.969 | 0.364 | 0.302 | 1.25 | 1.5 |
| 5/8 | 0.642 | 0.605 | 1.062 | 1.031 | 1.227 | 1.175 | 0.444 | 0.378 | 1.5 | 1.75 |
| 3/4 | 0.768 | 0.729 | 1.25 | 1.212 | 1.443 | 1.383 | 0.524 | 0.455 | 1.75 | 2 |
| 7/8 | 0.895 | 0.852 | 1.438 | 1.394 | 1.66 | 1.589 | 0.604 | 0.531 | 2 | 2.25 |
| 1 | 1.022 | 0.976 | 1.625 | 1.575 | 1.876 | 1.796 | 0.7 | 0.591 | 2.25 | 2.5 |
| 1 1/8 | 1.149 | 1.098 | 1.812 | 1.756 | 2.093 | 2.002 | 0.78 | 0.658 | 2.5 | 2.75 |
| 1 1/4 | 1.277 | 1.223 | 2 | 1.938 | 2.309 | 2.209 | 0.876 | 0.749 | 2.75 | 3 |
| 1 3/8 | 1.404 | 1.345 | 2.188 | 2.119 | 2.526 | 2.416 | 0.94 | 0.81 | 3 | 3.25 |
| 1 1/2 | 1.531 | 1.47 | 2.375 | 2.3 | 2.742 | 2.622 | 1.036 | 0.902 | 3.25 | 3.5 |
| 1 3/4 | 1.785 | 1.716 | 2.75 | 2.662 | 3.175 | 3.035 | 1.196 | 1.054 | 3.75 | 4 |
| 2 | 2.039 | 1.964 | 3.125 | 3.025 | 3.608 | 3.449 | 1.388 | 1.175 | 4.25 | 4.5 |
| 2 1/4 | 2.305 | 2.214 | 3.5 | 3.388 | 4.041 | 3.862 | 1.548 | 1.327 | 4.75 | 5 |
| 2 1/2 | 2.559 | 2.461 | 3.875 | 3.75 | 4.474 | 4.275 | 1.708 | 1.479 | 5.25 | 5.5 |
| 2 3/4 | 2.827 | 2.711 | 4.25 | 4.112 | 4.907 | 4.688 | 1.869 | 1.632 | 5.75 | 6 |
| 3 | 3.081 | 2.961 | 4.625 | 4.475 | 5.34 | 5.102 | 2.06 | 1.815 | 6.25 | 6.5 |
Dimension Table of ASTM A193 B8 Hex Bolt
Dimension details allow buyers to plan installations with precision and avoid compatibility issues.
| Nominal Size (D) | Body Diameter | Head Thickness ASTM A193 | Across ASTM A193 The Flats | Across ASTM A193 Corners | ||||
|---|---|---|---|---|---|---|---|---|
| D (MAX) | D (MIN) | H (MAX) | H (MIN) | F (MAX) | F (MIN) | C (MAX) | C (MIN) | |
| m10 | 10.00 | 9.78 | 6.63 | 6.17 | 17.00 | 15.73 | 18.48 | 17.77 |
| m12 | 12.00 | 11.73 | 7.76 | 4.24 | 19.00 | 17.73 | 20.78 | 20.03 |
| m14 | 14.00 | 13.73 | 9.09 | 8.51 | 22.00 | 20.67 | 24.25 | 23.35 |
| m16 | 16.00 | 15.73 | 10.32 | 9.68 | 24.00 | 23.67 | 27.71 | 26.75 |
| m20 | 20.00 | 19.67 | 12.88 | 12.12 | 30.00 | 29.16 | 34.64 | 32.95 |
| m24 | 24.00 | 23.67 | 15.44 | 14.56 | 36.00 | 35.00 | 41.57 | 39.55 |
| m30 | 30.00 | 29.67 | 19.48 | 17.92 | 46.00 | 45.00 | 53.12 | 50.85 |
| m36 | 36.00 | 35.61 | 23.38 | 21.63 | 55.00 | 53.80 | 63.51 | 60.79 |
| m42 | 42.00 | 41.38 | 26.97 | 25.03 | 65.00 | 62.90 | 75.06 | 71.71 |
| m48 | 48.00 | 47.38 | 31.07 | 28.93 | 75.00 | 72.60 | 86.60 | 82.76 |
| m56 | 56.00 | 55.26 | 36.20 | 33.80 | 85.00 | 82.20 | 98.15 | 93.71 |
| m64 | 64.00 | 63.26 | 41.32 | 38.68 | 95.00 | 91.80 | 109.70 | 104.65 |
| m72 | 72.00 | 71.26 | 46.45 | 43.55 | 105.00 | 101.40 | 121.24 | 115.60 |
| m80 | 80.00 | 79.26 | 51.58 | 48.42 | 115.00 | 111.00 | 132.72 | 126.54 |
| m90 | 90.00 | 89.13 | 57.74 | 54.26 | 130.00 | 125.50 | 150.11 | 143.67 |
| m100 | 90.00 | 99.13 | 63.90 | 60.10 | 145.00 | 140.00 | 167.43 | 159.60 |
Applications of ASTM A193 Grade B8 Fasteners
ASTM A193 B8 fasteners are widely used where reliable strength, corrosion resistance and high-temperature capability are essential. Some key applications include:
Chemical Processing & Petrochemical Plants
- Oil & Gas Refineries: Ideal for heat exchangers, boilers, valves, separators and high-pressure flanged joints exposed to steam, hydrocarbon media and corrosive fluids.
- Power Generation & Boilers: Suitable for high-temperature bolting in turbines, steam lines, condensers, and pressure vessels.
- Pharmaceutical & Food Industry: Used in hygienic equipment, filtration systems and machinery where contamination-free, rust-free fastening is required.
- Marine & Offshore Structures: Performs reliably in seawater, moisture and chloride environments, preventing corrosion and galling.
- Water Treatment & Desalination Plants: Applied in pumps, pipelines, filtration units and high-pressure RO systems.
- Pulp & Paper Mills: Used in digesters, bleaching units and chemical-filled processing areas.
- Construction & Structural Fabrication: For stainless steel structures, supports, industrial frameworks and machinery installation.
FAQ’s About ASTM A193 Grade B8 fasteners
What are ASTM A193 Grade B8 fasteners?
ASTM A193 Grade B8 fasteners are made from 304/304L or similar stainless steel and are engineered to withstand high temperatures, pressure, corrosion and chemical attack — ideal for industrial service.
Where are ASTM A193 Grade B8 fasteners commonly used?
These ASTM A193 Grade B8 fasteners are widely used in applications such as boilers, pressure vessels, heat exchangers, pipelines, offshore platforms, chemical processing plants, and marine environments.
What is the difference between Class 1 and Class 2 in B8 fasteners?
ASTM A193 Grade B8 Class 1 (solution annealed) fasteners have moderate strength and good ductility suitable for general service. Class 2 (strain hardened) fasteners exhibit higher tensile and yield strength for critical high-pressure applications.