ASTM Fasteners
ASTM A193 B7 Studs, Hex Bolts, Nuts & Threaded Rods Supplier
High-Strength Alloy Steel Fasteners for High-Temperature, High-Pressure, and Critical Engineering Services
Product Overview
Kuldevi Forge & Fittings is a premier manufacturer and stockist of high-strength **ASTM Fasteners** in India. Specializing in **ASTM A193 Grade B7 Bolts**, **Studs**, and **Threaded Rods**, we supply complete bolting kits with matching heavy hex nuts and washers to major petroleum refineries, chemical processing plants, pressure vessels, and pipeline projects.
ASTM A193 Grade B7 is a standard specification for chromium-molybdenum alloy steel bolting material. It is quenched and tempered to achieve high tensile and yield strengths, making it the industry standard for securing high-pressure pipeline flanges, valve assemblies, and high-temperature equipment under extreme stress.
Our manufacturing capabilities cover a complete range of heavy hex bolts, fully-threaded studs, and continuous threaded rods conforming to standard dimensions (ASME B18.2.1 / B18.2.2). We also supply **ASME SA193 Grade B7M Bolts**, which are specifically heat-treated to a lower hardness limit (99 HRB or 22 HRC max) to provide resistance against sulfide stress cracking (SSC) in sour gas (H2S) service environments.
Mechanical Properties (ASTM A193 B7)
| Steel Grade | Size / Diameter (inches) | Tensile Strength (KSI, min) | Yield Strength 0.2% Offset (KSI, min) | Elongation in 4D (%, min) | Reduction of Area (%, min) | Hardness (Max HBW) | Hardness (Max HRC) |
|---|---|---|---|---|---|---|---|
| B7 Bolts & Studs | Up to 2-1/2" | 125 | 105 | 16 | 50 | 321 HBW | 35 HRC |
| 2-5/8" to 4" | 115 | 95 | 16 | 50 | |||
| 4-1/8" to 7" | 100 | 75 | 18 | 50 |
Chemical Composition (AISI 4140)
| Element | B7 Alloy Steel Range |
|---|---|
| Carbon | 0.38 - 0.48% |
| Manganese | 0.75 - 1.00% |
| Phosphorus (max) | 0.035% |
| Sulfur (max) | 0.040% |
| Silicon | 0.15 - 0.35% |
| Chromium | 0.80 - 1.10% |
| Molybdenum | 0.15 - 0.25% |
| Nickel | Trace / Optional |
Recommended Hardware
Recommended matching nuts and washers according to standard structural bolting codes.
| Bolt Grade | Matching Nut Grade | Matching Washer |
|---|---|---|
| B7 | ASTM A194 Grade 2H Heavy Hex Nuts | ASTM F436 Hardened Washers |
| B7M | ASTM A194 Grade 2HM Heavy Hex Nuts | ASTM F436 Hardened Washers |
Tightening Torque Chart (ASTM A193 B7)
Target tightening torque values in foot-pounds (ft-lbs) based on clamp load load levels.
| Bolt Size | Threads Per Inch (TPI) | Proof Load (lbs) | Clamp Load (lbs) | Torque (ft lbs) [Galv + Wax] | Torque (ft lbs) [Galv] | Torque (ft lbs) [Plain] |
|---|---|---|---|---|---|---|
| 1/4" | 20 | 3,350 | 2,513 | 5 | 13 | 10 |
| 5/16" | 18 | 5,500 | 4,125 | 11 | 27 | 21 |
| 3/8" | 16 | 8,150 | 6,113 | 19 | 48 | 38 |
| 7/16" | 14 | 11,150 | 8,363 | 30 | 76 | 61 |
| 1/2" | 13 | 14,900 | 11,175 | 47 | 116 | 93 |
| 9/16" | 12 | 19,100 | 14,325 | 67 | 168 | 134 |
| 5/8" | 11 | 23,750 | 17,813 | 93 | 232 | 186 |
| 3/4" | 10 | 35,050 | 26,288 | 164 | 411 | 329 |
| 7/8" | 9 | 48,500 | 36,375 | 265 | 663 | 530 |
| 1" | 8 | 63,650 | 47,738 | 398 | 995 | 796 |
Heavy Hex Bolts Dimensions (ASME B18.2.1)
All dimensions in inches (in)
| Nominal Size (D) | Body Diameter (D) | Across Flats (F) | Across Corners (C) | Head Height (H) | Thread Length (T) | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| MAX | MIN | MAX | MIN | MAX | MIN | MAX | MIN | < 6" Length | > 6" Length | |
| 1/2" | 0.515 | 0.482 | 0.875 | 0.850 | 1.010 | 0.969 | 0.364 | 0.302 | 1.25 | 1.50 |
| 5/8" | 0.642 | 0.605 | 1.062 | 1.031 | 1.227 | 1.175 | 0.444 | 0.378 | 1.50 | 1.75 |
| 3/4" | 0.768 | 0.729 | 1.250 | 1.212 | 1.443 | 1.383 | 0.524 | 0.455 | 1.75 | 2.00 |
| 7/8" | 0.895 | 0.852 | 1.438 | 1.394 | 1.660 | 1.589 | 0.604 | 0.531 | 2.00 | 2.25 |
| 1" | 1.022 | 0.976 | 1.625 | 1.575 | 1.876 | 1.796 | 0.684 | 0.608 | 2.25 | 2.50 |
Metric Hex Bolts Dimension Standard (conforming to DIN 931/933)
All dimensions in millimeters (mm)
| Nominal Size (D) | Body Diameter | Head Thickness (H) | Across Flats (F) | Across Corners (C) | ||||
|---|---|---|---|---|---|---|---|---|
| MAX | MIN | MAX | MIN | MAX | MIN | MAX | 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 | 7.24 | 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 |