GB 5310 15CrMoG High Pressure Boiler Tubes
Seamless steel tubes and pipes for high pressure boiler
GB 5310 standard is applicable to steam boilers and pipeline seamless pipes for the manufacture of high pressure and above.
15CrMoG is GB 5310-95 steel grade (equivalent to 13CrMo44 of Federal Germany; corresponding to 1Cr-1 / 2Mo and 1 1 / 4cr-1 / 2mo-si steel widely used in various countries in the world). Its chromium content is higher than 12CrMo steel, so it has higher thermal strength at 500-550 ℃. When the temperature is higher than 550 ℃, the thermal strength of 15CrMoG steel is significantly reduced. When it runs at 500-550ec for a long time, it does not produce graphitization, but it will produce carbide spheroidization and redistribution of alloy elements, which all lead to the decrease of the thermal strength of steel. 15CrMoG steel has good relaxation resistance at 450 ℃. Its pipe making and welding process performance is good.
GB 5310 15CrMoG Seamless steel tubes and pipes for high pressure boiler
Maximum service temperature: it is applied to high and medium pressure boiler steam pipes, headers, superheater pipes with wall temperature of 540 ° C, forgings and elastic elements with steam parameters of 510ec.
(1)Steel smelting method
GB 5310 15CrMoG steel will be smelted by electric furnace plus furnace refining, oxygen converter plus furnace refining or electroslag remelting method.
(2)Manufacturing methods and requirements for tube blanks
The tube blank can be produced by continuous casting, die casting or hot rolling (forging).
(3)Manufacturing method of steel tube
GB 5310 15CrMoG Steel tubes shall be manufactured by hot rolling (extrusion, expansion) or cold drawing (rolling).
a) Hot rolled steel pipe, codenamed WH;
b) Cold drawn steel pipe, codenamed WC.
The steel tubes shall be delivered in a heat treated condition.
Heat treatment for GB 5310 15CrMoG High Pressure Boiler Tubes
||900 ℃～960 ℃,Normalizing；660 ℃～730 ℃,Tempering
Chemical composition of GB 5310 15CrMoG
Mechanical properties of GB 5310 15CrMoG
Allowable deviation of outer diameter and wall thickness
|Type of steel pipe
|Hot rolled tube
|Cold drawn tube
The steel pipe shall be hydraulically tested one by one, and the eddy current testing can instead of the hydraulic test.
Steel pipes with an outer diameter greater than 22 mm to 400 mm and a wall thickness not greater than 40 mm shall be subjected to a flattening test.
Steel pipes with an outer diameter greater than 400 mm or a wall
The steel pipe with an outer diameter of not more than 76 mm and a wall thickness of not more than 8 mm can be used for the flare test.
Steel pipes should be tested at low magnification. Visually visible white spots, inclusions, subcutaneous bubbles, tumbling and delamination are not allowed on the cross-section acid immersion test piece.
(6) Non-metallic inclusions
Steel pipes shall be tested for non-metallic inclusions.
The finished steel pipe should be tested for grain size.
The finished steel pipe with the grades 15CrMoG will be ferrite plus pearlite, allowing the presence of granular bainite, and no phase change critical temperature between AC1 and AC3 is allowed.
Cold drawn (rolled) finished steel pipes with an outer diameter of not more than 76 mm shall be inspected for the total decarburization layer.
The steel pipe shall be ultrasonically inspected and tested in accordance with the provisions of GB/T 5777.
The inner and outer surfaces of steel pipes do not have cracks, folds, crusting, rolling and separation. These defects shall be completely removed and the depth of defect removal shall not exceed 10% of the wall thickness. The actual outer diameter and wall thickness of the defect removal shall not be less than the minimum allowable for the outer diameter and wall thickness.
The end faces of the steel pipe should be perpendicular to the axis of the steel pipe, and the incision burrs swill be removed.
Packaging, marking and quality instructions
The packaging, marking and quality specifications of steel pipes shall comply with the provisions of GB/T 2102.
Selection principle of 15CrMoG welding material angle
E5515-b2 (heat 307) electrode is used for manual welding.
H12crmo or h15crmo welding wire is used for gas welding, and h15crmo welding wire and flux 250 are used for automatic welding.
Photos of GB 5310 15CrMoG High Pressure Boiler Tubes