20g high pressure boiler tube.
20G high-pressure boiler tube implementation standard: GB T5310 seamless steel tube for high-pressure boiler, the product should meet the requirements of TSG D7002 pressure piping element type test rules.
20g High Pressure Boiler Tube Chemical Composition: Carbon: 017~0.23, silicon: 017~0.37, manganese: 035~0.65, Chromium: 025, molybdenum: 015, vanadium: 008, nickel: 025, Aluminum: 0015, Copper: 0020, phosphorus: not more than 0025, sulfur: not greater than 0020
20g high pressure boiler tube heat treatment system: 880 940 normalizing.
Mechanical properties: tensile strength 410 550, yield strength: 245, longitudinal elongation after fracture 24, transverse elongation after fracture 22, impact energy longitudinal 40, impact energy transverse 27,.
Product specifications: outer diameter 18 760mm, wall thickness 20~140mm.
Production mode: hot rolling, cold drawing, hot expansion. Delivery Condition: Heat Treated.
Surface. There should be no cracks, folds, scars, rolls and delamination on the inner and outer surfaces of the steel pipe. These defects should be completely removed, the depth of defect removal should not exceed 10% of the wall thickness, and the actual wall thickness at the place where the defect was removed should not be less than the minimum allowable value of the wall thickness. The allowable depth of the straight road on the inner and outer surface of the steel pipe (including non-sharp mandrel abrasion) shall comply with the following provisions.
a) Cold-drawn (rolled) steel pipe: not more than 4% of the wall thickness, and the maximum is 02 mm；
b) hot-rolled (extruded, expanded) steel pipe: not greater than 5 of the wall thickness, and the maximum is 04 mm。
After negotiation between the supply and demand parties, and indicated in the contract, 712.Straights other than 2 depth requirements. Other local deficiencies that do not exceed the allowable deviation of the wall thickness are allowed. The iron oxide scale on the inner and outer surfaces of the steel pipe should be removed, but it does not prevent the inspection of the thin oxide layer allowed to exist. If the outer diameter is greater than 300mm, the inner and outer surfaces of the steel pipe shall be delivered after overall grinding or machining. For steel pipes with an outer diameter of not less than 219 mm and a wall thickness of not less than 25 mm, when the surface defects are reworked or the surface quality is in doubt, the manufacturer should choose to use liquid penetration testing or magnetic particle testing. Liquid permeation testing or magnetic particle testing should comply with the following requirements. Liquid permeation testing should be in accordance with NB T470135. All defects that show the following should be marked with the location and removed according to the regulations: Linear Defect Display;Nonlinear defects with dimensions greater than 3 mm are displayed;- 3 or more defects arranged in rows with edge spacing less than 3mm are displayedOn a rectangular area of 100 cm, there are 5 or more dense defects in total, the long side of the rectangle is not more than 20 cm, and the defect display is taken from the most unfavorable part of the defect display. Magnetic particle testing shall comply with the provisions of GB T 15822. Defects shown by magnetic particle testing should be marked with location and removed according to regulations. Magnetic particle testing is selected by the manufacturer to use local inspection or full-length inspection of defect grinding places, and the standard specimens for local testing or full-length testing shall meet the requirements respectively.
Non-destructive testing. For the ratio of wall thickness to outer diameter is not more than 02 steel pipes should be ultrasonic tested one by one in accordance with the provisions of GB T 5777-2019, and the acceptance level should be U2.
For wall thickness to outer diameter ratio greater than 02 and less than 03. The steel pipe shall be ultrasonic tested one by one in accordance with the provisions of GB T31925-2015, and the acceptance grade shall be U2.
For the ratio of wall thickness to outer diameter is not less than 03 steel pipes, unless otherwise specified in the contract, the steel pipes shall be ultrasonic tested one by one in accordance with the provisions of GB T 5777-2019, and the acceptance level shall be U2.
When the steel pipe is delivered at the minimum wall thickness, the groove depth of the comparison sample is calculated based on the average wall thickness.
According to the requirements of the buyer, after negotiation between the supplier and the buyer, and indicated in the contract, other non-destructive testing can be added.