flange not only saves space, reduces the weight, the more important is to ensure that the joints do not leak, has good sealing performance. The reason for the reduction in the size of the compact flange is that the diameter of the seal is reduced, which will reduce the cross section of the sealing surface. Secondly, the flange gasket has been replaced by the seal ring to ensure that the sealing face matching face. This way, in order to compress the sealing surface requires only a small pressure. With the reduction of the required pressure, the size of the bolt and the required number can be reduced accordingly, so the design of a small size and light weight (compared to the traditional flange weight reduction of 80% ~ 70%) of the new products. Therefore, a relatively flat welding flange flange high-quality products, reducing the quality and space, which plays an important role for industrial use.

welding-on collar loose flange production standard: GB 
: GB/T9112-2000 (GB9113 - 1-2000 ~ GB9123? 4-2000) 
German standard: DIN2573, 2572, 2631, 2576, 2632, 2633, 2543, 2634, 2545 (PL, SO, WN, BL, TH) 
standard the Ministry of chemical industry: HG5010-52 ~ HG5028-58, HGJ44-91 ~ HGJ65-91
flange standard: HG20592-2009 (PN) HG20615-2009 (Calss) 
American Standard: ANSI B16.5 Class150, 300, 600, 900, 1500 (WN, SO, BL, TH, LJ, SW) 

Japan: JIS 5K 10K, 16K, 20K (PL, SO, BL, WN, TH, SW)