Reduction in longitudinal wall-thickness variation on tubes rolled on TPA-140 longitudinal rolling mills at the Sinarskii Pipe Plant

Measurements of wall thickness along tubes rolled on the longitudinal rolling mills of the TPA-140 tube-production unit at the Sinarskii Pipe Plant showed that for thicknesses of 5.5-12 mm, the mean lengthwise wall-thickness variation is 0.4-0.8 mm. Such variation increases the mean metal content of i fin. m of sized and reduced tubing. Moreover, the thickness of the wall of the rear end of oilfield tubing often fails to satisfy the requirements of GOST 632-80 and 633-80 in regard to the parameter "thickness of the wall under the thread," even though the mean thickness (along the entire tube) does not exceed the nominal value.