GB/T 20409 Multi - Rifled Seamless Steel Tubes For High Pressure Boiler
Brand Name:TORICH
Certification:ISO 9001 ISO 14001 TS 16949 EN 10204.3.1 LR KR
Model Number:GB/T 20409
Minimum Order Quantity:0.5 TON
Delivery Time:30-40 Days
Payment Terms:L/C, D/A, D/P, T/T, Western Union, MoneyGram
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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
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