JIS G3458 alloy steel pipes

Standard is made for heat resistant pipes that are used for high temperature conveying fluid pipes for heaters and boiler tubes.

Chemical Composition:
Grade Chemical Composition %
C Si Mn P S Cr Mo
STPA 12 0.10~0.20 0.10~0.50 0.30~0.80 0.035 max. 0.035 max. 0.45~0.65
STPA 20 0.10~0.20 0.10~0.50 0.30~0.60 0.035 max. 0.035 max. 0.50~0.80 0.45~0.65
STPA 22 0.15max. 0.50 max. 0.30~0.60 0.035 max. 0.035 max. 0.80~1.25 0.45~0.65
STPA 23 0.15max. 0.50~1.00 0.30~0.60 0.030 max. 0.030 max. 1.00~1.50 0.45~0.65
STPA 24 0.15max. 0.50 max. 0.30~0.60 0.030 max. 0.030 max. 1.90~2.60 0.87~1.13
STPA 25 0.15max. 0.50 max. 0.30~0.60 0.030 max. 0.030 max. 4.00~6.00 0.45~0.65
STPA 26 0.15max. 0.25~1.00 0.30~0.60 0.030 max. 0.030 max. 8.00~10.00 0.90~1.10
Mechanical Properties:
Grade Mechanical Properties
Tensile strength Yield point or proof stress Elongation %
kgf/mm2 {N/mm2} kgf/mm2 {N/mm2} No. 11 or No.12 test piece No. 5 test piece No.4 test piece
Longitudinal Transverse Longitudinal Transverse
STPA 12 39{382}min. 21{206} min. 30 min. 25 min. 24 min. 19 min.
STPA 20 42{412}min. 21{206} min. 30 min. 25 min. 24 min. 19 min.
STPA 22 42{412}min. 21{206} min. 30 min. 25 min. 24 min. 19 min.
STPA 23 42{412}min. 21{206} min. 30 min. 25 min. 24 min. 19 min.
STPA 24 42{412}min. 21{206} min. 30 min. 25 min. 24 min. 19 min.
STPA 25 42{412}min. 21{206} min. 30 min. 25 min. 24 min. 19 min.
STPA 26 42{412}min. 21{206} min. 30 min. 25 min. 24 min. 19 min.

Packing: Bare/bundles/crates/crate protection at the both sides of tubes or as per customers’ requirements.
Painting: as requested.

The tubes shall be manufactured by seamless process, electric resistance welding process, or butt welding process, and those of other grades shall be manufactured by seamless process or electric resistance welding process. The tube shall be as manufactured or as cold-finished condition, or they shall be subjected to appropriate heat treatment.

The tubes shall be practically straight. and the two ends shall be at right angles to the axis of the tube. The tubes shall be free from defects detrimental to practical use.

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