Manufacturing ball-type head, the the GB dome head http://www.hebftc2.com/ telephone 0317-8210122, for the phone 13722724665 ball head which method to calculate the figure of a head schematic diagram CD, AB said closure head straight edge, ED, FB parts of the small arc EF represents a big arc. The head longitudinally welded patchwork for Class A welds. JB/T4730.2-2005 standard specifies testing level for the AB grade longitudinal stitching weld K ≤ 1.03. This is detailed data.