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Selecting and Measuring Pipe & Fittings

How to Measure Threaded Pipe and Fittings

0 118

14

12

34

38

Place the outside edge of the pipe or fitting on the “0” line. The line on the opposite edge gives the pipe size.

Align the top of the threads on one wall (not the wall itself) with the “0” line. The line that aligns with the top of the threads on the opposite side gives the pipe size.

0 118

116

14

12

34 11

4 112 22 1

2 33 12

38

0 118 14 12 3438

0 118

116

14

12

34 11

4 112 22 1

2 33 12

38

Have you ever tried to order fittings, pipe, nipples, or valves and had difficulty determining the size? If so, you’re not alone. Even experienced maintenance people are sometimes confused by the industry’s terminology and method of sizing. Before joining a pipe with a fitting or valve, you need to know the pipe size, thread style, and thread type—the pipe sizes must be the same and the thread types must be compatible in order for two components to fit properly.

When we provide the size of a pipe or fitting in our catalog, we will call it a pipe size or a thread size.

Pipe size, which is the most common, is not an actual measured size, but rather an industry designation. When people refer to pipe size, they sometimes call it IPS or nominal size. You can determine pipe size by using the sizing guides at the bottom of this page. You can also use a sizing gauge or kit sold separately below.

Thread size is the actual measured diameter of the threads. The most common connections that have a thread size are UN/UNF and metric threads; for these, you can use a ruler to measure the threads.

There are two thread styles: tapered and straight. Tapered threads, which are the most common

type, have a slight taper toward the end of the fitting. When threads are mated and tightened together, they hold the fitting in place and seal the connection.

Straight (parallel) threads maintain the same diameter along their entire length. They’re used for mechanical joining and serve one purpose—to hold a fit-ting in place. Straight threads require a seal to make a tight connection.

Pipe Basics

Pipe Size and Thread Size Thread Style

How To Measure Pipe and Fittings with Male (External) Threads

How To Measure Fittings with Female (Internal) Threads

To measure larger pipe and fittings up to pipe size 8, go to mcmaster.com and search for 4464KAC.

5887T1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $8.13

Quickly measure your pipe and fittings. This plastic gauge measures male and fe-male threads in NPT and BSPT pipe sizes 1/8, 1/4, 3/8, 1/2, 3/4, 1, 11/4, 11/2, and 2. It includes two metal gauges for measuring NPT and BSPT thread pitch.

Accurately determine the size of your pipe and fittings with one of these kits. For more gauges, see pages 2259-2261.Pipe Size Measuring Gauges and Kits

Kits include Type 304 stainless steel 90° elbows that have male threads on one end and female threads on the other end.

You’ll get four gauges that measure the pitch of BSPT, BSPP, metric, NPT, and UN/UNF threads; a caliper; and an instruction manual. The gauges and caliper are metal. Furnished in a folding plastic case.

7863K1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $54.33

Pipe Size Kits

Pipe Size Measuring Gauges Thread Pitch Measuring Kits

6-Piece Kit

No. of Pieces For Pipe Sizes NPT Kits BSPT Kits6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1/8, 1/4, 3/8, 1/2, 3/4, 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7843K5 . . . . . . . $19.80 7843K7 . . . . . . . $21.409 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1/8, 1/4, 3/8, 1/2, 3/4, 1, 11/4, 11/2, 2. . . . . . . . . . . . . . . . . . . . . . . . . 7843K6 . . . . . . . 56.89 7843K8 . . . . . . . 61.44