Common Quality Defects of Upset End of External Upset Tubing and Relevant Analysis

Summarized here in the paper are types of the common surface quality defects of upset end of the external upset tubing，including ridge，scar，end-fin，and pit as occurring on the pipe’s outer surface and inner surface circular pit，etc. Causes for such defects are analyzed. Accordingly，it is concluded that the ridge thickness could be reduced by means of decreasing the clamping force，and defects like end-fin，inner surface circular pit and outer surface scar，etc. could be eliminated via such measures as determining appropriate upsetting force，adjusting heating temperature and duration，and improving lubrication and cooling efficiencies.