GB/T 19793 Small Diameter Thick Wall Welded Pipe / Tube Q235 Q195 SPCC SPHC
GB/T 19793 small diameter Thick-wall welded pipe/tube Q235 Q195 SPCC SPHC
Typical fields of application are in:
Automobile and motorcycle Shock Absorber Pipe
Hydraulic-cylinder Pipe
Mechanical steel pipes for auto and motor parts
Gas Spring pipe
motor casing pipe etc
size:length--2~12m WT--2~4.5mm OD--16~50mm
material:Q235 Q195 SPCC SPHC
Production process: ordinary high-frequency welded pipe
Advantages: small diameter and thick wall
Surface Quality:The internal and external surfaces of the steel tube are not allowed to have cracks, scabs, folds, delaminations, laps, and burns. Allows for scribes, scratches, misalignment of welds, burns, oxide scales, and external burr removal traces that are not more than a negative wall thickness deviation
Inspection items:
chemical composition
Tensile test
Ultrasonic examination
Eddy current flaw detection
Bending test
Flattening test
Permissible Tolerance of Outer Diameter and Wall Thickness (mm)
| Type of steel Tube | Dimension of steel tube | Permissible tolerance | ||
| Average class | High class | |||
| Hot-rolled (extruded and expanded) tube | Outer diameter D | All | ±1% (min.+/-0.50) | - |
| Wall thickness | All | +15%/-12.5% (min.+4.5/-4.0) | - | |
| Cold-drawn (cold-rolled) tube | Outer diameter D | 6~10 | ±0.2 | ±0.15 |
| >10~30 | ±0.40 | ±0.20 | ||
| >30~50 | ±0.45 | ±0.30 | ||
| >50 | ±1% | ±0.8% | ||
| Wall thickness | <1 | ±0.15 | ±0.12 | |
| >1~3 | +15% -10% | +12.5% -10% | ||
| >3 | +12.5% -10% | ±10% | ||
| Note: For hot-expanded tubes with outer diameter>35mm,the permissible tolerance of wall thickness is±18%. | ||||
Longitudinal Mechanical Properties of Steel Tubes
| NO. | Steel Grade | Tensile Strength(Mpa) | Yield point(Mpa) | Elongation after breaking(%) | |
| s<16 | s>16 | ||||
| Not less than | |||||
| 1 | 10 | 335~475 | 205 | 195 | 24 |
| 2 | 20 | 410~550 | 245 | 235 | 20 |
| 3 | Q295 | 430~610 | 295 | 285 | 22 |
| 4 | Q345 | 490~665 | 325 | 315 | 21 |
Permissible deviations of the product analysis from the specified limits
| Element | Limiting values for cast analysis | Permissible deviatioon of the product analysis in % by mass |
| C | ≤0.22 | +0.02 |
| Si | ≤0.55 | +0.05 |
| Mn | ≤1.60 | +0.10 |
| P | ≤0.025 | +0.005 |
| S | ≤0.015 | +0.003 |
| Al | ≥0.025 | -0.005 |
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