API Screw Thread Gages

BTC Screw Threads for American Petroleum Institute-API

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Buttress Thread Casing (BTC) API SPEC 5B
Working Ring or Working Plug
Size (in Inches)	T.P.I. (Threads per Inch)	T.P.F. (Taper per Foot)
4-1/2	5	3/4
5	5	3/4
5-1/2	5	3/4
6-5/8	5	3/4
7	5	3/4
7-5/8	5	3/4
8-5/8	5	3/4
9-5/8	5	3/4
10-3/4	5	3/4
11-3/4	5	3/4
13-3/8	5	3/4
16	5	1
18-5/8	5	1
20	5	1

 

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Original Posting: 08/24/2011
Last Revision: 6/11/2012
Error corrections in or comments about the above data can be sent to: office@gagecrib.com