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GOST 20295-K56
keyword GOST 20295-K56 Category Steel pipe material Related products Get a quoteGOST 20295-K56 Steel Grade Submerged Arc Welded Spiral Seam Steel Pipe Chemical Composition and Mechanical Properties
1、 Chemical composition
Carbon (C): ≤ 0.18% (low-carbon design to optimize welding performance and reduce cold cracking risk).
Silicon (Si): ≤ 0.50% (deoxidation and grain refinement to improve material uniformity).
Manganese (Mn): 1.20% -1.60% (strengthens the matrix and enhances toughness, supporting high-strength requirements).
Phosphorus (P): ≤ 0.025% (strict control of impurity content to reduce cold brittleness).
Sulfur (S): ≤ 0.020% (reduces the tendency for hot cracking and improves welding stability).
Micro alloying elements (niobium Nb, vanadium V): added in small amounts to refine grain size and enhance comprehensive mechanical properties.
2、 Mechanical performance
Strength and plasticity
Yield strength (Re): ≥ 490 MPa (meets the requirements of K56 high-strength grade).
Tensile strength (Rm): 610-760 MPa (based on similar steel grades, matched with Russian standard K56 design).
Elongation (A): ≥ 18% (plastic deformation capacity of the material under high pressure environment).
Resilience requirements
Low temperature impact toughness: It is required to meet the requirement of -40 ℃ impact energy ≥ 34 J (mandatory requirement for cold and high-altitude environments according to Russian standards).
3、 Manufacturing and testing requirements
Forming process
Spiral welding: Adopting double-sided submerged arc welding (SAWH) process, the weld strength and uniformity are improved.
Tolerance control:
Outer diameter tolerance: ± 0.75% (applicable to 159-820mm specifications).
Wall thickness tolerance: ± 8% nominal wall thickness (stricter than lower steel grade standards).
Testing requirements
Non destructive testing: Ultrasonic testing (UT) and X-ray re inspection of the entire pipe section, with no defects such as porosity or slag inclusion in the weld seam.
Hydrostatic test: according to the formula
P=2ST/D test for compressive performance (S is yield strength, T is wall thickness, D is outer diameter).
4、 Application scenarios
Oil and gas transportation: suitable for high-pressure oil and natural gas long-distance pipelines and chemical equipment.
Industrial field: Used for metal structures and high-pressure pipelines in mining sites for Russian standard certification.
(Note: K56 is the high-strength grade in GOST 20295-85 standard. Specific parameters should be based on the manufacturer's technical agreement or version of the standard document.)
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