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Grade 20G Seamless Steel Boiler Pipe is applicable to seamless tubes for making steam boiler whose pressure is high or higher and seamless tubes used as pipelines.
20G seamless steel pipe is a high-quality carbon structural steel, boiler material, the carbon content of 0.17-0.24%, tensile strength of 410Mpa, yield point 230-250Mpa. Is our main production of steel, we can provide 20G Seamless pipe with high quality and competitive price. Here to introduce you to our 20G seamless pipe basic chemical properties and mechanical properties.
UT(Ultrasonic examination), AR(As Hot Rolled only), TMCP(Thermal Mechanical Control Processing), N(Normalized), Q+T(Quenched and Tempered),Z Direction Test(Z15,Z25,Z35), Charpy V-Notch Impact Test, The Third Party Test (such as SGS Test), Coated or Shot Blasting and Painting.Additional Condition GB5310 20G20G seamless steel pipe is a high-quality carbon structural steel, boiler material, the carbon content of 0.17-0.24%, tensile strength of 410Mpa, yield point 230-250Mpa. Is our main production of steel, we can provide 20G Seamless pipe with high quality and competitive price.
Standard:GB 5310
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.
Manufacturing methods
(1)Steel smelting method
GB 5310 20G 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 20G Steel tubes shall be manufactured by hot rolling (extrusion, expansion) or cold drawing (rolling).
Chemical composition of GB 5310 20G
| Grade | Chemical Composition(%) | ||||||||||
| C | Si | Mn | Cr | Mo | V | Ni | Altot | Cu | P | ||
| Max | |||||||||||
| 20G | 0.17~0.23 | 0.17~0.37 | 0.35~0.65 | ≤0.25 | ≤0.15 | ≤0.08 | ≤0.25 | ≤0.015 | ≤0.20 | 0.025 | |
| Steel Pipe | Tensile properties | Impact energy(Akv),J | Hardness | |||||||
| Tensile strength (MPa) |
Yield Strength (MPa) |
Elongation % |
Portrait | Landscape | A | B | C | |||
| HBW | HV | HRC | ||||||||
| Portrait | Landscape | |||||||||
| Max | Min | |||||||||
| 20G | 410~550 | 245 | 24 | 22 | 40 | 27 | - | - | - | |
| 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% | - |
Main production process (main inspection process) of hot rolled seamless steel pipe:
Preparation and inspection of tube blank → heating of tube blank → perforation → Rolling of tube → reheating of tube in waste → fixing (reducing) diameter → heat treatment → straightening of finished pipe → finishing → inspection (non-destructive, physical and chemical, table inspection) → storage.
Boiler steel pipe Application:
GB5310 20G seamless steel pipes are mainly used for pressure vessels, machinery, pipe fittings, oil and chemical industry.Boiler tubing is used in these industries:
Steam Boilers
Power Generation
Fossil Fuel Plants
Electric Power Plants
Industrial Processing Plants
Cogeneration Facilities
Internal defect control of small-diameter high-pressure boiler pipe
Hardness testing methods of high-pressure GB5310 20G boiler steel pipe
Characteristics of boiler pipe
Heat boiler seamless extrusion technology
Low and medium pressure boiler pipe
GB 5310- 2008 standard is applicable to seamless tubes for making steam boiler whose pressure is high or higher and seamless tubes used as pipelines.
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 GB 5310 20G steel pipe of high-quality carbon structural steel shall be ferrite plus pearlite, and no superheated structure shall be allowed;
(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.
According to customer,on-time delivery. We hold large inventories of products in a large of variety of grade.We use wooden pallet packaging, which can effectively prevent the corrosion of sea water.
Q:How do you control quality?
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