Their thread surfaces may be rough and can cause higher-than-normal friction or even galling when making and breaking connections. Damaged or badly worn threads can also cause problems with sealing.

• 它们的螺纹表面可能是粗糙的，当进行和断开连接时，它们会引起大于正常情况的摩擦或者甚至金属表面磨损。被损坏的或严重磨损的螺纹也会引起关于密封的问题。