GB/T 3091 Dimensional Tolerances for Hot-dip Galvanized Steel Pipe
GB/T 3091 Dimensional Tolerances for Hot-dip Galvanized Steel Pipe Production
Allowed Deviations for Outer Diameter and Wall ThicknessAccording to the GB/T 3091 standard, the allowed deviations for the outer diameter and wall thickness of hot-dip galvanized steel pipes are as follows:
Outer Diameter Allowed Deviation**:
- For an outer diameter \( D \leq 48.3 \) mm, the allowed deviation is ±0.5 mm.
- For an outer diameter \( 48.3 < D \leq 273.1 \) mm, the allowed deviation is ±1% \( D \).
- For an outer diameter \( 273.1 < D \leq 508 \) mm, the allowed deviation is ±0.75% \( D \).
- For an outer diameter \( D > 508 \) mm, the allowed deviation is the smaller of ±1% \( D \) or ±10.0 mm.
-Wall Thickness Allowed Deviation:
- For wall thickness \( t \), the allowed deviation is +2.4 mm to -0.8 mm.
Length Allowed Deviation
Standard Length: The standard length of the steel pipe should be between 3000 mm and 12000 mm.
-Cut-to-Length: For straight seam high-frequency welded steel pipes, the cut-to-length deviation is +15.0 mm; for submerged arc welded steel pipes, the cut-to-length deviation is +50.0 mm.
Straightness and Roundness
- Straightness:
- For steel pipes with an outer diameter less than 114.3 mm, a reasonable degree of straightness is allowed.
- For steel pipes with an outer diameter of 114.3 mm or greater, the total straightness deviation should not exceed 0.2% of the pipe length.
- Roundness:
- For steel pipes with an outer diameter not exceeding 219.1 mm, the roundness (the difference between the maximum and minimum outer diameters measured in the same cross-section) should comply with the specifications in Table 1.
- For steel pipes with an outer diameter greater than 219.1 mm, the roundness should not exceed 80% of the outer diameter tolerance.
These dimensional tolerance requirements ensure the reliability and consistency of hot-dip galvanized steel pipes during manufacturing and use, enabling them to meet the needs of various applications.
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