过去的老式法兰,大部分密封靠橡胶板或石棉纸垫。这些垫经过大压力拧紧后,垫子向管道部位挤压,有的使管径变小,液流不畅通,有的天长日久,逐渐老化,残渣被压力油冲到阀内,使阀心卡死,造成很大的危险。 In the past, the old flanges were mostly sealed with rubber sheets or asbestos paper pads. After these pads have been tightened with great pressure, the cushions will be squeezed toward the pipe parts, some will make the pipe diameter smaller and the liquid flow will not be smooth, and some will last for a long time and will gradually age. The residue will be pressed into the valve by pressure oil, Cause great danger.