There is no tendency for the seating surfaces of swing check valves to gall or score, because the disc meets the flat seat squarely without rubbing contact upon closing.

• 旋启式止回阀的阀座表面不存在磨损或刮伤的倾向,因为阀瓣与平面阀座相适应,不会在关闭时产生摩擦接触。