Double End Stud China Suppliers

QS Fastener: Double End Stud China Suppliers

Name: Double End Stud China Suppliers
Standard: ASTM
Material: A320 L7
Size: M20
Lenght: 100 mm
Surface: Black/ PTFE/ Zinc

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The ASTM A320 L7 Double End Stud is a Cr-Mo low-temperature alloy steel fastener, manufactured to the stringent requirements of ASTM A320. It is not an aerospace aluminium alloy but a closely controlled, vacuum-degassed and calcium-treated version of AISI 4140/4142, with sulphur and phosphorus tightly limited. After quenching and tempering at a minimum of 595 °C, it achieves a hardness range of HB 235–302 (HRC 22–32), delivering a tensile strength of ≥860 MPa, yield ≥725 MPa, and elongation ≥16 % at room temperature. Its defining characteristic is exceptional low-temperature toughness: Charpy V-notch impact values average ≥27 J at –101 °C, with no single value below 20 J, ensuring that this Double End Stud resists brittle fracture even in liquid methane service.

This combination of strength and toughness offers several practical advantages. The fine-grained tempered sorbite structure with dispersed Mo₂C depresses the ductile‑to‑brittle transition to approximately –120 °C, making the stud suitable for cryogenic media such as liquid oxygen, nitrogen, ethylene, and LNG. With an 860 MPa rating, an M20 Double End Stud can sustain roughly 190 kN in tension—surpassing the equivalent room‑temperature grade A193 B7—allowing flange downsizing and valve weight reduction. Hardness kept below HRC 32 also provides intrinsic resistance to sulphide stress cracking in wet H₂S environments, while the carbon equivalent of ~0.55 % permits field welding repairs at roughly 20 % of the cost of full bolt replacement. Surface finishes range from plain black and phosphate to PTFE, hot‑dip galvanized, or Xylan coatings, accommodating both bare cryogenic use and aggressive marine atmospheres.

Real‑world applications confirm its reliability: Guangdong Dapeng LNG terminal has used M36 PTFE‑coated Double End Studs on –162 °C unloading‑arm flanges for over 15 years without a brittle failure; a Hainan refinery demethanizer saw maintenance intervals extend from 1 to 4 years after switching from stainless tie rods; silver‑plated studs served successfully on the Long‑March‑5 liquid‑oxygen filling system at –183 °C; and a North Sea FPSO project achieved 15 years of maintenance‑free service with Xylan‑coated studs, saving approximately USD 600,000 per vessel in replacement costs.

For global buyers, numerous China Suppliers now offer ASTM A320 L7 Double End Studs in stock sizes and custom lengths/finishes, with full material traceability and test reports. Sourcing from experienced China Suppliers not only ensures compliance with ASTM standards but also provides competitive lead times and cost efficiency, making these studs the default choice for pressure‑containing flanges below –101 °C. In short, the L7 Double End Stud delivers a balanced triad of low‑temperature toughness, high strength, and moderate cost—safely and economically replacing expensive nickel‑base bolting across energy, chemical, aerospace, and polar engineering sectors. Consult reputable China Suppliers for your next cryogenic or cyclic‑service project.

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