try this way

來源: 2019-02-28 10:33:33 [博客] [舊帖] [給我悄悄話] 本文已被閱讀:

for the steel pipe, apply this on the both ends first 

https://www.homedepot.com/p/RectorSeal-4-oz-Tru-Blu-Pipe-Thread-Sealant-with-PTFE-31630/203490732

and then wrap the male end with this

https://www.homedepot.com/p/Oatey-1-2-in-x-260-in-Yellow-PTFE-Tape-31403D/202078116