有关螺纹、扣型的英文although not all male NPT threads can be assumed t

有关螺纹、扣型的英文
although not all male NPT threads can be assumed to be of standard length per ANSI B1-20-1,the number of male threads visible is a good indication.
(a) from ANSI B1-20-1,the correct wrench tight thread exposure is 3 1/2 threads for 1/2〝and3/4〞.NPT,if significant thread exposure is discovered the connection should be broken and inspected.
All excess of PTFE tape extruding out of the thread may indicate too much tape has been used,which will reduce thread engagement and pressure rating.

尽管不是所有的NPT公螺纹都是美国国家的标准长度B1-20-1,但上面的号码却是很好的提示,啊a,根据美国国家标准B1-20-1,半英寸和4分之3英寸螺纹的螺纹长度是3英寸半长NPT(NPT不知道是什么）,如果发现螺纹过长接套就要拆开重新检查,所有露在螺纹外面的生胶带表明胶带缠多了,会导致螺纹连接不密封,承受压力低,不一定准确,根据实际情况进行理解,
再问： National (American) Pipe Thread NPT是一种螺纹。谢谢啊！