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ASTM A333 Grade 7
keyword ASTM A333 Grade 7 Category Steel pipe material Related products Get a quoteChemical and mechanical properties of ASTM A333 Grade 7 spiral steel pipes
1、 Chemical composition
Main elements
Carbon (C): ≤ 0.30% (low content to reduce cold brittleness and improve low-temperature toughness).
Manganese (Mn): 0.30%~1.06% (strengthens the matrix and optimizes the balance between strength and toughness).
Silicon (Si): ≥ 0.10% (auxiliary deoxidation and strength enhancement).
Phosphorus (P) and sulfur (S): both ≤ 0.025% (strictly limit impurities to reduce the risk of low-temperature embrittlement).
Alloy elements
Nickel (Ni), chromium (Cr): may be added to enhance low-temperature toughness (refer to ASTM A334 low-temperature steel pipe alloying design).
2、 Mechanical performance
Strength and plasticity
Tensile strength (Rm): ≥ 415 MPa (meets low-temperature pressure requirements).
Yield strength (Rp0.2): ≥ 240 MPa (ensuring structural stability under low temperature conditions).
Elongation rate (δ%): Longitudinal ≥ 30% (high plasticity ensures impact resistance).
Low temperature toughness
Impact energy (KV): It needs to pass the -100 ℃ Charpy impact test (applicable to extremely low temperature environments, such as liquefied natural gas transportation).
3、 Manufacturing and process requirements
Processing technology
Spiral welding process: The weld seam needs to undergo radiographic or ultrasonic testing and complete a water pressure test without defects.
Welding materials: Low hydrogen welding materials should be selected to match the properties of the base material.
Heat treatment
Normally, normalizing treatment (800 ° C~900 ° C) is required to refine the grain and improve the consistency of low-temperature performance.
4、 Application scenarios
Ultra low temperature fluid transportation: pipeline systems for media such as liquefied natural gas (LNG) and liquid nitrogen.
Chemical and energy equipment: cryogenic storage tanks, low-temperature heat exchangers, and pressure vessel pipelines.
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