1/4" NPT LH thread ?

[mmcmdl]

Never seen one before , but found one down the basement . What besides the obvious would you use this for ?

 

[MrWhoopee]

Rotary coupling, to prevent unscrewing?

 

[projectnut]

They're sometimes used for gas pipe fittings. When I worked constructing and updating production facilities in the LA area the local ordinances required left hand fittings for commercial gas pipe installations. I doubt they're very common since in the 40+ production facilities the company had across the country the only ones I'm aware of that used left hand fittings were in LA.

 

[benmychree]

Sometimes left hand pipe fittings were used for assembly purposes rather than using unions.

 

[eugene13]

You can use them for making in the wall repairs, so you don't need a union.

 

[JimDawson]

Normally gas pipe installations where code does not allow unions.