GB 18248 Gas Cylinder Steel Tubes
This standard applies to the production of seamless steel pipes used in gas cylinders and accumulator housings. Primarily, it covers the manufacturing of 37Mn gas cylinder tubes, along with 30CrMo, 35CrMo, and 34CrMo4 seamless steel pipes for gas cylinder hydraulic lines.
Standard: GB 18248
Equivalent Standards: JIS G3429, EN 10297-1, ASTM A372, EN 1964-1, EN ISO 11120, ISO 11439, ISO 9809-1, JIS B8230, JIS B8241
Brands: 37Mn, 34Mn2V, 30CrMo, 35CrMo, 34CrMo4, 30CrMnSiA
Outer Diameter: 48 - 711 mm
Wall Thickness: 3.1 - 38 mm
Length: 4-12 meters
Delivery Status: As rolled, quenched and tempered, normalized plus tempered
GB 18248 outlines the dimensions, shapes, weights, technical requirements, testing methods, inspection rules, packaging, labeling, and quality certificates for seamless steel pipes used in gas cylinders and accumulator casings. It is specifically designed for the manufacturing of these types of steel pipes.
Manufacturing Process: According to GB/T 6479, pipes should be manufactured using hot rolling or cold drawing techniques.
Heat Treatment: Pipes must undergo heat treatment, where WT ≤ 30mm requires normalization followed by tempering, while WT > 30mm necessitates either quenching and tempering or normalizing plus tempering.
Inspection and Testing: Chemical composition analysis, tensile tests, flattening tests, expansion tests, impact tests, macroscopic inspections, non-metallic inclusion checks, non-destructive testing, surface inspections, and dimensional inspections are required.
Length Options: Standard lengths include 4000mm, 6000mm, 9000mm, and 12000mm. The maximum extended length can reach up to 30 meters. Additional processes such as U-bending, finning, and nailing are also available.
Surface Treatments: Options include external shot blasting to remove scale and achieve a matte finish, as well as surface polishing for further processing like fin trimming.
Chemical Composition:
| C, % | Si, % | Mn, % | P, % | S, % | Cr, % | Ni, % | Cu, % | Mo, % |
|------|-------|-------|------|------|-------|-------|-------|-------|
| 0.08-0.15 | 0.50 max | 0.40-0.60 | 0.025 max | 0.015 max | 2.00-2.50 | 0.30 max | 0.20 max | 0.90-1.13 |
Mechanical Properties:
| Tensile Strength, MPa | Yield Strength, MPa | Elongation, % | Impact (KV2)/J at 20°C |
|-----------------------|--------------------|---------------|------------------------|
| 450-600 | 280 min | 20 min | 40 (OD≥76mm & WT≥6.5mm)|
Outer Diameter and Tolerance:
Hot Rolled:
| Hot Rolled | Outside Diameter, mm | Tolerance |
|------------|----------------------|-----------|
| OD≤159 | ±1% or ±0.50mm | |
| OD>159 | +1% or +0.50mm | |
Cold Drawn:
| Cold Drawn | Outside Diameter, mm | Tolerance |
|------------|----------------------|-----------|
| OD≤30 | ±0.20mm | ±0.15mm |
| 30
50 | ±0.50% | ±0.50% |
Wall Thickness and Tolerance:
Hot Rolled:
| Hot Rolled | Outside Diameter, mm | Tolerance |
|------------|----------------------|-----------|
| OD≤159 | +12.5%/-10% or +0.50mm/-0.40mm | |
| OD>159, WT/OD≤0.05 | +15%/-10% | |
| OD>159, 0.05159, WT/OD>0.10 | ±10% | |
Cold Drawn:
| Cold Drawn | Wall Thickness, mm | Tolerance |
|------------|--------------------|-----------|
| WT≤2.0 | +12.5%/-10% | ±10% |
| WT>2.0 | ±10% | ±7.5% |
This standard ensures high-quality seamless steel pipes that meet stringent specifications for use in critical applications such as gas cylinders and accumulators.Water Filter Injection Mould
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