Cutting Pipe

Cutting Pipe.-Pipe can be cut with a hacksaw, but a pipe cutter is more satisfactory and should be used, if available. The use of a pipe cutter and pipe vise is shown in Fig. 97. The cutter has a special alloy steel cutting wheel and two pressure rollers.

When measuring pipe it is necessary to allow sufficient length for thread to enter each fitting. The amount to be allowed for the thread depends on the nominal diameter, or size, of the pipe,

                                   TABLE II. 

Pipe Diameter, Inches
Nominal Diameter and Marked Size of Tap	Actual Outside	Actual Inside	Threads per Inch	Size of Tap Drill (Reamer not used)	Length Allowed for Thread, Each Fitting Inches
1/8	0.405	0.269	27	R	5/16
1/4	0.540	0.364	18	7/16	7/16
3/8	0.675	0.493	18	37/64	7/16
1/2	0.840	0.622	14	23/32	9/16
3/4	1.050	0.824	14	59/64	9/16
1	1.315	1.049	11 1/2	1 5/32	11/16
1 1/4	1.660	1.380	11 1/2	1 1/2	11/16
1 1/2	1.900	1.610	11 1/2	1 47/64	11/16
2	2.375	2.067	11 1/2	2 7/32	3/4
2 1/2	2.875	2.469	8	2 41/64	1 1/16
3	3.500	3.068	8	3 1/4	1 1/8
3 1/2	4.000	3.548	8	3 3/4	1 3/16
4	4.500	4.026	8	4 1/4	1 3/16
5	5.563	5.047	8	5 5/16	1 5/16
6	6.625	6.065	8	6 23/64

and is given in Table II. When the correct measurement has been determined, the location of the cut should be marked clearly on the pipe with a file or scriber. The pipe should be secured firmly in the pipe vise, as shown in Fig. 97, and the cutter slipped over the end. Set the cutter with the cutting wheel on the mark previously made, and then rotate the cutter around the pipe, gradually taking up on the cutting wheel, by turning the handle of the cutter, until the pipe is cut through. In order to keep the wheel tracking properly, the cutter must be kept perpendicular to the work at all times.

The operation of the pipe cutter leaves a shoulder on the outside of the end of the pipe and a burr on the inside. Always remove both. If the burr on the inside is not removed, the ragged edges will catch dirt and other solid matter and will block the flow. A pipe reamer, Fig. 98, is used for the purpose.

114. Threading Pipe.-Special dies, called pipe dies, are used to

cut pipe threads. As with bolt and screw threads, most pipe threads are cut for right-hand turning, but left-hand pipe dies are available, as some installations require a left-hand thread.

Most pipe dies can be adjusted to cut slightly different depths of threads. When an adjustable die is used, the thread is cut to about 1/2 depth at first, then the die is readjusted to finish cutting the thread to the full depth.