I need to know a tap size to reduce a fitting.

by Bobby
(Colorado)

I have a compressor which needs a fitting replaced, as it has snapped off, and I have been unable to extract the broken brass threaded piece.


My best solution to this problem is to cut new threads inside of the broken piece and thread a slightly smaller piece into it as an adapter, and then convert back to the original size fitting.

My problem is that I don't know any of these sizes and abbreviations of the trade.

The original part which snapped appears to be a 1/4" MIP x 1/4" FIP.

I found that replacement piece, as well as another marked as a 1/4" OD x 1/4" FIP coupling which has slightly smaller threads on one end than the other.

It is the smaller end which I am having trouble identifying so that I may buy a tap to cut new threads to accommodate it. It's overall diameter, including threads, appears to be 7/16" with an 18 tpi thread count.

Is there an industry size designation for this so that I may order the proper size tap to install it? Thanks all.

Comments for I need to know a tap size to reduce a fitting.

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Mar 23, 2017
tap size
by: Doug in s.d.ca.

Also, bear in mind the fitting in question may be metric.

Sometimes it's not easy to tell the difference, but since you're planning to retap anyway, it may not matter.

Mar 23, 2017
FIP
by: Bill

An FIP fitting is a Female Iron Pipe size. Try googling that for dimensional information.

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