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Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
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- MERKBLATT AD 2000 W2/W7/W10
ASTM A320/A320M Grade L7 Chromium-Molybdenum Alloy Steel Bolting
Industry Standard Low-Temperature Fasteners - AISI 4140/4142 Material
ASTM A320/A320M Grade L7 stands as the most widely specified low temperature bolting grade in the industry, manufactured from AISI 4140/4142 chromium-molybdenum alloy steel. With minimum tensile strength of 125 ksi and yield strength of 105 ksi in diameters up to 2-1/2 inches, L7 delivers exceptional strength and reliability for pressure vessels, valves, and flanges. ASTM A320 Grade L7 requires mandatory Charpy impact testing at -150°F for diameters over 1/2 inch, ensuring proven performance in cryogenic and sub-zero process environments.
ASTM A320/A320M Grade L7 Stud Bolts Properties
ASTM A320/A320M Grade L7 Stud Bolts Chemical Requirements
Ferritic Steels
| Grade Symbol | Description | C | Mn | P, max | S, max | Si | Cr | Mo | |
|---|---|---|---|---|---|---|---|---|---|
| ASTM A320 L7 | Cr - Mo - B | Range,% | 0.38 - 0.48C | 0.75 - 1.00 | 0.035 | 0.04 | 0.15 - 0.35 | 0.80 - 1.10 | 0.15 - 0.25 |
| Product Variation, % Over or Under | 0.02 | 0.04 | 0.005 over | 0.005 over | 0.02 | 0.05 | 0.02 | ||
ASTM A320/A320M Grade L7 Stud Bolts Mechanical Requirements
Ferritic Steels
| Class and Grade, Diameter, in. [mm] | Heat Treatment | Minimum Tempering Temperature, °F [°C] | Tensile Strength, min, ksi [MPa] | Yield Strength, min, ksi [MPa] (0.2 % offset) | Elongation in 2 in. or 50 mm, min, % | Reduction of Area, min, % | Hardness, max |
|---|---|---|---|---|---|---|---|
| ASTM A320 L7 21/2[65] and underA | quenched and tempered | 1100 [593] | 125[860] | 105[725] | 16 | 50 | 321 HBW or 35 HRC |
ASTM A320/A320M Grade L7 Stud Bolts Requirements
| Grade | Test Temperature | CVN Specimen Section Size, mm | Min Average Impact Toughness of Three Test Specimens, ft-lbf [J] | Min Impact Value of a Single Specimen of Set of Three, ft-lbf [J] | |
|---|---|---|---|---|---|
| °F | °C | ||||
| ASTM A320 L7 | - 150 | - 101 | 10 × 7.5 | 16 [22] | 12 [16] |
| 10 × 10 | 40 [54] | 30 [41] | |||
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