Buying Guide

NIBCO INC. WORLD HEADQUARTERS • 1516 MIDDLEBURY ST. • ELKHART, IN 46516-4740 • USA • PH: 1.800.234.0227
TECH SERVICES PH: 1.888.446.4226 • FAX: [phone] • INTERNATIONAL OFFICE PH: +1.574.295.3327 • FAX: [phone]
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AHEAD OF THE FLOW
®
Scope
The procedure presented, herein, covers threading of all IPS
Schedule 80 or heavier thermoplastic pipe. These tapered
threads are National Pipe Threads (NPT) which are cut to the
dimensions outlined in ASME B1.20.1.
Thread Dimensions
Note: Do not thread Schedule 40 pipe.
THREADING EQUIPMENT AND MATERIALS
• Pipe Dies
• Pipe Vise
• Threading ratchet or power machine
• Tapered plug
• Cutting lubricant (soap and water)
• Strap wrench
• PTFE tape
• Cutting tools
• Deburring tool
PIPE PREPARATION
Plastic pipe can be easily cut with a powersaw, circular saw,
band saw, or handsaw. For best results, use a fine-toothed
blade (16-18 teeth per inch) with little or no set (maximum 0.025
inch). A circumferential speed of about 6,000 ft./min. is suitable
for circular saws; band saw speed should be approximately
3,000 ft./min. Carbide-tipped blades are preferable when quan-
tities of pipe are to be cut. To ensure square-end cuts, a mitre
box, holddown, or jig should be used. Pipe or tubing cutters can
be used for smaller diameter pipe when the cutting wheel is
specifically designed for plastic pipe. Such a cutter is available
from the Reed Manufacturing Co. or Ridge Tool Company.
Threading Instructions for Thermoplastic Pipe
PIPE THREADS
Nominal Outside Number Normal Length Total Length: Pitch Diameter Depth of
Size Diameter of Threads Engagement of Effective End of Pipe at End of Thread
Per Inch By Hand Thread to Vanish Point Internal Thread (Max.)
D, in. C, in. A, in. B, in. E, in. in.
1/4 0.540 18 0.228 0.4018 0.5946 0.49163 0.04444
1/2 0.840 14 0.320 0.5337 0.7815 0.77843 0.05714
3/4 1.050 14 0.339 0.5457 0.7935 0.98887 0.05714
1 1.315 11
1
/2 0.400 0.6828 0.9845 1.23863 0.06957
1
1
/4 1.660 11
1
/2 0.420 0.7068 1.0085 1.58338 0.06957
1
1
/2 1.900 11
1
/2 0.420 0.7235 1.0252 1.82234 0.06957
2 2.375 11
1
/2 0.436 0.7565 1.0582 2.29627 0.06957
2
1
/2 2.875 8 0.682 1.1375 1.5712 2.76216 0.10000
3 3.500 8 0.766 1.2000 1.6337 3.38850 0.10000
4 4.500 8 0.844 1.3000 1.7337 4.38713 0.10000
THREADING DIES
Thread-cutting dies should be clean, sharp, and in good condi-
tion, and should not be used to cut materials other than plas-
tics. Dies with a 5° negative front-rake angle are recommended
when using power threading equipment and dies with a 5° to
10° negative front-rake angle are recommended when cutting
threads by hand. When cutting threads with power threading
equipment, self-opening die heads and a slight chamfer to lead
the dies will speed production.
1. Hold pipe firmly
in a pipe vise.
Protect the pipe at
the point of grip
by inserting a rub-
ber sheet or other
material between
the pipe and vise.
Revised 4/26/2019