What is this single tap and die for?

[Sylvain VAN DER WALDE]

Hello all.

The recent thread on taps and dies prompted me to look again at my (yet unused) all metric set (bought from Screwfix some time ago). To my surprise, I found the following: One single short length tap, and one die. They are marked "NPT 1/8 27". Now, I haven't the slightest idea what they are for. I'm not entirely surprised, as this set also contains a screwdriver, centre punch, thread gauge, and five stud extractors (of the l/h spiral variety). I'm guessing that they are probably used for "cleaning" damaged threads.

But on what fittings?

Answers will be gratefully received.

Sylvain.

[PeterK]

Have a look at

= US National Pipe Thread

1/8 = nominal size of pipe 27 = threads per inch

PeterK

[Roger Mills]

NPT is a pipe thread used in USA - similar to our BSP.

1/8" NPT is roughly the same size as 1/8" BSP (just under 10mm in diameter) but has 27 threads per inch compared with BSP's 28.

I have a feeling that things like engine oil pressure switches on cars had used to use NTP threads. I doubt whether they still do - more likely to be metric, these days.

[Sylvain VAN DER WALDE]

Thanks for both useful replies.

Sylvain.