Kidde Fire Protection 400 Series, Design, Installation, Operation, And Maintenance Manual

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Installation
July 2018 4-24 06-237518-001
4-9.5 Installation of Pipes
4-9.5.1 Cutting
The required length of pipe is measured and marked on the pipe. The pipe is cut at 90° with a
cutting machine. After cutting, the pipe end shall be reamed and all burrs removed and all
cutting oil shall be removed from both inside and outside of the pipe.
4-9.5.2 NPT/BSPT – Threading
Threads on all pipe and fittings must be tapered threads conforming to ANSI Specification
B-20.1. or ISO/IEC Guide 7. Joint compound, tape or thread lubricant must be applied only to
the male threads of the joint excluding the first two threads.
Threads shall be cut to the full cutting length as specified in Table 4-14 and Table 4-15 using
a pipe-threading machine. After threading, the pipe shall be cleaned to remove excess cutting
oil and any other particulates.
After the thread has been cut it is recommended that the crest and root of the thread is
truncated (shortened) a minimum of 0.033 x p (pitch of thread) in order to ease adherence of
the packing material.
Note: When assembling NPT threads a distance between the two parts will always be visible.
Table 4-14. NPT Thread Length
Pipe Diameter
Length of NPT-
Thread
Effective Length of
NPT-Thread
Free Length of
NPT- Thread
1/2" 14.50 mm 13.56 mm 0.94 mm
3/4" 16.00 mm 13.86 mm 2.14 mm
1" 19.00 mm 17.34 mm 1.66 mm
1 1/4" 20.50 mm 17.95 mm 2.55 mm
1 1/2" 20.50 mm 18.38 mm 2.12 mm
2" 22.00 mm 19.20 mm 2.80 mm
2 1/2" 31.00 mm 29.00 mm 3.00 mm
3" 33.50 mm 30.48 mm 3.02 mm
Table 4-15. BSPT Thread Length
Pipe Diameter
Length of BSPT-
Thread (mm)
Effective Length of
BSPT-Thread (mm)
Free Length of
BSPT- thread
1/2" 14.50 13.0 1.50 mm
3/4" 16.00 15.0 1.00 mm
1" 19.00 17.0 2.00 mm
1 1/4" 20.50 19.0 1.50 mm
1 1/2" 20.50 19.0 1.50 mm
2" 22.00 20.0 2.00 mm
2 1/2" 31.00 27.0 4.00 mm
3" 33.50 30.0 3.50 mm