Page 366 - BOLA Catalogue

Determination – Thread Types
Choosing a suitable fitting, screw cap or multiple distributor with the correct thread type and size is not as easy as it might seem with regards to the multitude of thread types.
On the following pages we have summarized the most common threads that we use at BOLA for our fittings, screw caps and multiple distributors.
Please use a sliding calliper for the determination of a thread type. Use
it for the determination of the thread O. D. and the thread pitch. The
pitch is the distance from one thread crest to the other as shown on our schematic drawings. Now the thread type can be determined by comparing the original thread with our figures. Once you have found a similar type, the actual thread size is identified by comparing the measured dimensions (thread O. D. and pitch) with the typical dimensions stated in the related chart.
Of course we will help you if you should still have problems in determi- ning your thread. Just send us a sample or counterpiece, we will be glad to help you with your choice.
NPT (National Pipe Taper) Thread,
American Pipe Thread or BSP (British Standard Pipe) Thread Easy recognisable by its tapered outer and inner diameter which is self sealing. Therefore, NPT threads are also known as “sealing thread” or “tightly threaded connection”.
Example:
NPT 3/8" – O. D. = 16,6 mm
Pitch
18 turns at1"=1,41mm
TECHNICAL INFORMATION
Thread
Type
O. D.
mm
Pitch
mm
NPT
1/8"
9,9
27 turns at 1" = 0,94
NPT
1/4"
13,2
18 turns at 1" = 1,41
NPT
3/8"
16,6
18 turns at 1" = 1,41
NPT
1/2"
20,6
14 turns at 1" = 1,81
NPT
3/4"
26,0
14 turns at 1" = 1,81
NPT
1"
32,5
11,5 turns at 1" = 2,21
By the way: BOLA offers custom manufacture. From 1 piece. Hotline +49 (0) 93 46-92 86-0
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