Brand Name : TORICH
Model Number : GB/T 20409
Certification : ISO 9001 ISO 14001 TS 16949 EN 10204.3.1 LR KR
Place of Origin : China
MOQ : 0.5 TON
Price : negotiable
Payment Terms : L/C, D/A, D/P, T/T, Western Union, MoneyGram
Supply Ability : 60000 Tons per Year
Delivery Time : 30-40 Days
Packaging Details : In bundles in wooden box
Product name : GB/T 20409 Multi-rifled Seamless Steel Tubes for High-pressure Boiler
Keywords : Multi-rifled Seamless Steel Tubes
Material : 20G 20MnG 25MnG 12CrMoG 15CrMoG
Type : Seamless steel tube
Surface : Oiled
Usage : High-pressure Boiler
Shape : Round
Length : 8-12m
WT : 6.38-18.33mm
OD : 28.6-66.7mm
GB/T 20409 Multi-rifled Seamless Steel Tubes for High-pressure Boiler
Application:High-quality carbon structural steel, alloy structural steel cold-drawing or cold-rolled internal thread tube for boilers suitable for producing high pressure and above pressure
Size:Length--8-12m
OD--28.6-66.7mm
WT--6.38-18.33mm
Curvature--≤1.0mm/m
Surface Quality:
1.The internal and external surfaces of female threaded tubes are not allowed to have cracks, folds, knots, folds, and delaminations. 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 filling removal site should not be less than the wall thickness. The minimum allowable thickness deviation, the clearance should be rounded off
2.The shape of the thread should be kept intact. There must be no drawing, curling or collapse.
3.The inner and outer straight surfaces of internally threaded tubes (including non-sharpened core rods) shall be allowed to have a depth of not more than 4% of the minimum wall thickness and a maximum of 0.2 mm.
4.Other local imperfections that do not exceed the wall thickness to allow negative deviations are allowed to exist.
5.Oxide scales on the inner and outer surfaces of the internally threaded tube should be removed so that the thin oxide layer does not interfere with the inspection.
The grade and chemical composition of steel
Number | Brand | chemical composition(mass fraction)/ % | ||||||
C | Mn | Si | Cr | Mo | S | P | ||
1 | 20G | 0.17~0.23 | 0.35~0.65 | 0.17~0.37 | -- | -- | ≤0.020 | ≤0.025 |
2 | 20MnG | 0.17~0.23 | 0.70~1.00 | 0.17~0.37 | -- | -- | ≤0.020 | ≤0.025 |
3 | 25MnG | 0.22~0.29 | 0.7~1.00 | 0.17~0.37 | -- | -- | ≤0.020 | ≤0.025 |
4 | 12CrMoG | 0.08~0.15 | 0.40~0.70 | 0.17~0.37 | 0.40~0.70 | 0.40~0.55 | ≤0.020 | ≤0.025 |
5 | 15CrMoG | 0.12~0.18 | 0.40~0.70 | 0.17~0.37 | 0.80~1.10 | 0.40~0.55 | ≤0.020 | ≤0.025 |
Note1:Residual element content of 20G,20MnG,25MnG should satisfy: Cu≤0.20%,Cr≤0.25%,Ni≤0.25%,V≤0.08%,Mo≤0.15%;The remaining elements of other brands should satisfy: Cu≤0.20%,Ni≤0.30%. |
The size of the internal screw tubes and the allowable deviation of the thread parameters
Code | Project | “A” teeth types allowable deviation | “B” teeth types allowable deviation |
A | O.D≤38.1mm | ±0.15mm | -- |
B | O.D≤38.1mm | -- | ±0.15mm |
C | I.D of the root of the screw Thread: | ±0.15mm | ±0.15mm |
E | Minimum I.D | Negative deviation to zero | Negative deviation to zero |
F | Minimum W.T | +22% | +22% |
G | Thread tips | -- | -- |
I | Thread top width | -- | -- |
Height of thread: | ±0.3mm | ±0.18mm | |
K | Side Angle of thread. | ±15° | ±15° |
O | radius of rounded corner at the root of thread | -- | -- |
M | Thread pitch | ±3.2mm | ±3.2mm |
N | Thread lead | ±3.2mm×thread tips | ±3.2mm×thread tips |
Helix angle | Rating | Rating | |
T | Thread top width (axial) | ±1.3mm | ±1.3mm |
U | Thread top (axial) groove width | -- | -- |
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GB/T 20409 Multi - Rifled Seamless Steel Tubes For High Pressure Boiler Images |