Size Deviation of SSAW Steel Pipe

Size deviation mainly in the SSAW steel pipe is straightness, roundness, aspects of uneven thickness.

In most cases, straightness tolerance for the use of spiral steel pipe under large, but the manufacturing standards for spiral pipe straightness requests, if the predetermined value is exceeded, would constitute a reason to return, and therefore, spiral pipe plant should still be noted.

Roundness tolerance will affect the use of spiral steel pipe, mainly in the group of the wrong side of the welding head. Roundness tolerance has led to the wrong side of the welded joint will not only reduce the pressure capability, but also stress concentration. When the site Group, roundness some pipe can be corrected. Outside diameter deviation and the impact on the spiral steel pipe used roundness tolerance fairly.

Non-uniform wall thickness generally easy to be ignored, and many spiral steel pipe standards are not clearly defined. If the wall thickness Uneven, it will not only result set to the wrong side of the joint, but also the secondary deformation processing (such as steel pipe manufacturing pipe) adversely affected.

Lamination Defect Control Measures of Spiral Steel Pipe

Lamination defect control measures of spiral steel pipe is following below:

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1, to improve the toughness of plastic tube
Improve the cleanliness of molten steel, to reduce the harmful inclusions; increase the proportion of the slab crystal axis, to reduce the center segregation and center porosity; the use of reasonable cooling system to avoid cracks occur within the slab; billet or rolling slab to be taken offline slow cooling process, reduce internal stress, thus ensuring the microstructure and mechanical properties of the finished tube and pipe meet the technical standards.

2, the reasonable control of the heating temperature
By measuring the thermoplastic curve, choose the best heating temperature. Note also that there is enough heating tube holding time, in order to reduce and improve plastic deformation resistance and toughness.

3, lower roll speed
Roll speed is a key parameter piercing process, the roll speed from low to high variations in the process, there is a critical stratification began the roll speed. Lower roll speed, easy to form tube bore; higher roll speed, tube and capillary easily form a layered defects. In order to eliminate delamination defects and capillary tube, roll speed should be reduced to the beginning of the critical delamination roll speed or less.