L7 Stud Bolt
L7 Stud Bolt
Manufacturers:
ASTM A320 Grade L7 studs are manufactured from AISI 4140/4142 alloy steel, quenched and tempered. Dimensional specifications are governed by ASME B18.31.2. Grade markings consists of both the grade symbol "L7" and the manufacturer's identification mark on one end of each stud 3/8" diameter and larger. Manufacturer's marking may be placed on other end if insufficient space. A320 L7 all thread studs having diameters above 1" are most common in 8UN (8 threads per inch) thread pitch. A320 L7 stud bolts are intended for low temperature service. They have the same chemical and physical properties as ASTM A193 Grade B7, but must meet a Charpy impact value of 20 lb-ft at -150F to ensure satisfactory performance in low temperature services. These fasteners are commonly used for valves, flanges, fittings, and pressure vessels.
Products
Stud Flange Charts
| FLANGE | NOMINAL PIPE DIAMETER | ||||||||||
| CLASS | BOLTING | 1/2 | 3/4 | 1 | 1-1/4 | 1-1/2 | 2 | 2-1/2 | 3 | 3-1/2 | 4 |
| 150# | Number | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 8 | 8 |
| Diameter | 1/2 | 1/2 | 1/2 | 1/2 | 1/2 | 5/8 | 5/8 | 5/8 | 5/8 | 5/8 | |
| Stud Bolt Length | 2-1/4 | 2-1/2 | 2-1/2 | 2-3/4 | 2-3/4 | 3-1/4 | 3-1/2 | 3-1/2 | 3-1/2 | 3-1/2 | |
| Mach Bolt Length | 2 | 2 | 2-1/4 | 2-1/4 | 2-1/2 | 2-3/4 | 3 | 3 | 3 | 3 | |
| 300# | Number | 4 | 4 | 4 | 4 | 4 | 8 | 8 | 8 | 8 | 8 |
| Diameter | 1/2 | 5/8 | 5/8 | 5/8 | 3/4 | 5/8 | 3/4 | 3/4 | 3/4 | 3/4 | |
| Stud Bolt Length | 2-1/2 | 3 | 3 | 3-1/4 | 3-1/2 | 3-1/2 | 4 | 4-1/4 | 4-1/4 | 4-1/2 | |
| Mach Bolt Length | 2-1/4 | 2-1/2 | 2-1/2 | 2-3/4 | 3 | 3 | 3-1/4 | 3-1/2 | 3-3/4 | 3-3/4 | |
| 600# | Number | 4 | 4 | 4 | 4 | 4 | 8 | 8 | 8 | 8 | 8 |
| Diameter | 1/2 | 5/8 | 5/8 | 5/8 | 3/4 | 5/8 | 3/4 | 3/4 | 7/8 | 7/8 | |
| Stud Bolt Length | 3 | 3-1/2 | 3-1/2 | 3-3/4 | 4-1/4 | 4-1/4 | 4-3/4 | 5 | 5-1/2 | 5-3/4 | |
| 900# | Number | 4 | 4 | 4 | 4 | 4 | 8 | 8 | 8 | - | 8 |
| Diameter | 3/4 | 3/4 | 7/8 | 7/8 | 1 | 7/8 | 1 | 7/8 | - | 1-1/8 | |
| Stud Bolt Length | 4-1/4 | 4-1/2 | 5 | 5 | 5-1/2 | 5-3/4 | 6-1/4 | 5-3/4 | - | 6-3/4 | |
| 1500# | Number | 4 | 4 | 4 | 4 | 4 | 8 | 8 | 8 | - | 8 |
| Diameter | 3/4 | 3/4 | 7/8 | 7/8 | 1 | 7/8 | 1 | 1-1/8 | - | 1-1/4 | |
| Stud Bolt Length | 4-1/4 | 4-1/2 | 5 | 5 | 5-1/2 | 5-3/4 | 6-1/4 | 7 | - | 7-3/4 | |
| 2500# | Number | 4 | 4 | 4 | 4 | 4 | 8 | 8 | 8 | - | 8 |
| Diameter | 3/4 | 3/4 | 7/8 | 1 | 1-1/8 | 1 | 1-1/8 | 1-1/4 | - | 1-1/2 | |
| Stud Bolt Length | 4-3/4 | 5 | 5-1/2 | 6 | 6-3/4 | 7 | 7-3/4 | 8-3/4 | - | 10 | |
| FLANGE | NOMINAL PIPE DIAMETER | ||||||||||
| CLASS | BOLTING | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 24 |
| 150# | Number | 8 | 8 | 8 | 12 | 12 | 12 | 16 | 16 | 20 | 20 |
| Diameter | 3/4 | 3/4 | 3/4 | 7/8 | 7/8 | 1 | 1 | 1-1/8 | 1-1/8 | 1-1/4 | |
| Stud Bolt Length | 3-3/4 | 4 | 4-1/4 | 4-1/2 | 4-3/4 | 5-1/4 | 5-1/4 | 5-3/4 | 6-1/4 | 6-3/4 | |
| Mach Bolt Length | 3-1/4 | 3-1/4 | 3-1/2 | 4 | 4 | 4-1/2 | 4-1/2 | 5 | 5-1/2 | 6 | |
| 300# | Number | 8 | 12 | 12 | 16 | 16 | 20 | 20 | 24 | 24 | 24 |
| Diameter | 3/4 | 3/4 | 7/8 | 1 | 1-1/8 | 1-1/8 | 1-1/4 | 1-1/4 | 1-1/4 | 1-1/2 | |
| Stud Bolt Length | 4-3/4 | 4-3/4 | 5-1/2 | 6-1/4 | 6-3/4 | 7 | 7-1/2 | 7-3/4 | 8 | 9 | |
| Mach Bolt Length | 4-1/4 | 4-1/4 | 4-3/4 | 5-1/2 | 5-3/4 | 6-1/4 | 6-1/2 | 6-3/4 | 7-1/4 | 8 | |
| 600# | Number | 8 | 12 | 12 | 16 | 20 | 20 | 20 | 20 | 24 | 24 |
| Diameter | 1 | 1 | 1-1/8 | 1-1/4 | 1-1/4 | 1-3/8 | 1-1/2 | 1-5/8 | 1-5/8 | 1-7/8 | |
| Stud Bolt Length | 6-1/2 | 6-3/4 | 7-1/2 | 8-1/2 | 8-3/4 | 9-1/4 | 10 | 10-3/4 | 11-1/4 | 13 | |
| 900# | Number | 8 | 12 | 12 | 16 | 20 | 20 | 20 | 20 | 20 | 20 |
| Diameter | 1-1/4 | 1-1/8 | 1-3/8 | 1-3/8 | 1-3/8 | 1-1/2 | 1-5/8 | 1-7/8 | 2 | 2-1/2 | |
| Stud Bolt Length | 7-1/2 | 7-1/2 | 8-3/4 | 9-1/4 | 10 | 10-3/4 | 11-1/4 | 12-3/4 | 13-3/4 | 17-1/4 | |
| 1500# | Number | 8 | 12 | 12 | 12 | 16 | 16 | 16 | 16 | 16 | 16 |
| Diameter | 1-1/2 | 1-3/8 | 1-5/8 | 1-7/8 | 2 | 2-1/4 | 2-1/2 | 2-3/4 | 3 | 3-1/2 | |
| Stud Bolt Length | 9-3/4 | 10-1/4 | 11-1/2 | 13-1/4 | 14-3/4 | 16 | 17-1/2 | 19-1/2 | 21-1/4 | 24-1/4 | |
| 2500# | Number | 8 | 8 | 12 | 12 | 12 | - | - | - | - | - |
| Diameter | 1-3/4 | 2 | 2 | 2-1/2 | 2-3/4 | - | - | - | - | - | |
| Stud Bolt Length | 11-3/4 | 13-1/2 | 15 | 19-1/4 | 21-1/4 | - | - | - | - | - | |
- All dimensions are in inches.
Governing Standards
| ASTM A320 | Covers alloy steel bolting materials and bolting components for pressure vessels, valves, flanges, and fittings for low-temperature service. |
| ASME B18.31.2 | Covers the complete dimensional and general data for continuous thread, flange studs (stud bolts), and double-end inch-dimensioned studs. |
| ASME B1.1 UNC & UNF Class 2A | Specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads. |
Grade L7 Material Marking
Mechanical Properties
| Alloy Steel, Quenched & Tempered | Per ASTM A320/A320M-15a | |||||
| Diameter | Tempering Temperature |
Tensile Strength |
Yield Strength, 0.2% offset |
Elongation in 4D |
Reduction of Area |
Hardness |
| Min | Min ksi | Min ksi | Min % | Min % | Max | |
| 2 1/2" and under | 1100F | 125 | 105 | 16 | 50 | 321 HBW or 35 HRC |
Chemical Properties
| Per ASTM A320/A320M-15a | |||||||
| Grade | Carbon | Manganese | Phosphorus | Sulfur | Silicon | Chromium | Molybdenum |
| % by weight | % by weight | % by weight | % by weight | % by weight | % by weight | % by weight | |
| L7 | 0.38-0.48 | 0.75-1.00 | 0.035 max | 0.040 max | 0.15-0.35 | 0.80-1.10 | 0.15-0.25 |