GB/T 5310 Seamless Steel Tubes
12Cr1MoVG High Pressure Seamless Boiler Tubes
GB 5310 12Cr1MoVG High Pressure Seamless Boiler Tubes
Short Description:
GB/T 5310 12Cr1MoVG alloy steel seamless steel pipe is mainly used for boiler superheater, reheater and other heating surface piping systems with metal wall temperature not exceeding 580°C.
12Cr1MoVG is a Cr-Mo-V low alloy heat-resistant steel introduced from the Soviet Union in the 1950s and 1960s. Vanadium is an element that reduces the y-phase region. When dissolved in y-fe, it will inhibit the transformation of ADI to pearlite, which is beneficial to the formation of ADI. The total amount of alloy in 12Cr1MoVG steel is only one half of that of 2.25Cr-1Mo steel, but the endurance strength (580 ° C) is 1.4 times of that of 2.25Cr-1Mo steel. Similar steel grades widely used abroad include ASTM a405 p24 in the United States, bs3604 in the United Kingdom, DIN 13crmov42 in Germany, etc.
GB 5310 12Cr1MoVG High Pressure Boiler Tubes Quick Details
Manufacture:Seamless process ,Hot-finished or Cold-finished
Wall thickness(WT): 2.8 mm——150 mm.
Outer diameter (OD): 23 mm——1500 mm
Length: 6M or specified length as required.
Ends: Plain End, Beveled End, Threaded
Additional Info
Surface: Tubes will be varnished (Outside only) to prevent rust.
Marking: Standard + Steel Grade + Size + Heat No + Lot No
Package: Bundles (hexagonal), Wooden Boxes, Crates (steel/wooden) or as required
Manufacturing methods
(1)Steel smelting method
GB 5310 12Cr1MoVG 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).
Forging and rolling: the initial forging temperature is 1180-1145 ℃, and the final forging temperature is greater than 850 ℃. After forging, stack cooling is required.
(3)Manufacturing method of steel tube
GB 5310 12Cr1MoVG Steel tubes shall be manufactured by hot rolling (extrusion, expansion) or cold drawing (rolling).
Classification, code
a) Hot rolled steel pipe, codenamed WH;
b) Cold drawn steel pipe, codenamed WC.
Delivery status
The steel tubes shall be delivered in a heat treated condition.
Heat treatment for GB 5310 12Cr1MoVG High Pressure Boiler Tubes
| Grade | Heat treatment |
| 12Cr1MoVG | 980 ℃～1 020 ℃,Normalizing，980 °C ~ 1 020 °C normalizing, when the wall thickness is greater than 30 mm, forced cooling; 720 °C ~ 760 °C tempering. |
Chemical composition of GB 5310 12Cr1MoVG
| Grade | Chemical Composition(%) | |||||||||
| C | Si | Mn | Cr | Mo | V | Ni | Cu | P | S | |
| Max | ||||||||||
| 12Cr1MoVG | 0.08～0.15 | 0.17～0.37 | 0.40～0.70 | 0.90～1.20 | 0.25～0.35 | 0.15～0.30 | ≤0.30 | ≤0.20 | 0.025 | 0.020 |
Mechanical properties of GB 5310 12Cr1MoVG
| Steel Pipe | Tensile properties | Impact energy(Akv)，J | ||||
| Tensile strength (MPa) | Yield Strength (MPa) | Elongation % | Portrait | Landscape | ||
| Portrait | Landscape | |||||
| Max | ||||||
| 12Cr1MoVG | 470～640 | 255 | 21 | 19 | 40 | 27 |
The annual oxidation corrosion rate of 12Cr1MoVG steel in hot air is 0.042-0.050 mm / year at 580 ° C and 0.129-0.220 mm / year at 600 ° C.
Welding process
Allowable deviation of outer diameter and wall thickness
| Type of steel pipe | Outer diameter(mm) | Tolerance | |||
| ordinary | advanced | ||||
| Hot rolled tube | OD | ≤50 | ±0.40 | ±0.30 | |
| ＞50～≤325 | WT≤35 | ±0.75% | ±0.5% | ||
| WT＞35 | ±1% | ±0.75% | |||
| ＞325 | ±1% | ±0.75% | |||
| WT | ≤4.0 | ±0.4 | ±0.3 | ||
| ＞4.0～≤20 | ±10% | ±7.5% | |||
| ＞20 | OD＜219 | ±10% | ±7.5% | ||
| OD≥219 | +12.5% -10% | ±10% | |||
| Cold drawn tube | OD | ≤25.4 | ±0.15 | — |
| ＞25.4～≤40 | ±0.20 | — | ||
| ＞40～≤50 | ±0.25 | — | ||
| ＞50～≤60 | ±0.30 | — | ||
| ＞60 | ±0.5% | — | ||
| WT | ≤2.8 | ±0.2 | — | |
| ＞2.8 | ±7.5% | — |
Testings
(1)Hydraulic test
The steel pipe shall be hydraulically tested one by one, and the eddy current testing can instead of the hydraulic test.
(2)Flattening 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.
(3)Bending test
Steel pipes with an outer diameter greater than 400 mm or a wall
(4)Flaring test
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.
(5)Low-power 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.
(7)grain size
The finished steel pipe should be tested for grain size.
(8)Microstructure
The finished steel pipe with the grades 15MoG will be ferrite plus pearlite, allowing the presence of granular bainite, and no phase change critical temperature between AC1 and AC3 is allowed.
Complete phase change product (such as yellow bar martensite); the finished steel pipe of grade 12Cr1MoVG allows the presence of sorbite;
(9)Decarburization layer
Cold drawn (rolled) finished steel pipes with an outer diameter of not more than 76 mm shall be inspected for the total decarburization layer.
(10)Non-destructive testing
The steel pipe shall be ultrasonically inspected and tested in accordance with the provisions of GB/T 5777.
Surface quality
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.
End shape
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.
Application