British Standard Pipe

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British Standard Pipe (BSP) is a set of technical standards for screw threads that has been adopted internationally for interconnecting and sealing pipes and fittings by mating an external (male) thread with an internal (female) thread. It has been adopted as standard in plumbing and pipe fitting, except in North America, where NPT and related threads are used.



BSPP fitting BSPP Male Straight Thread.png
BSPP fitting

Two types of threads are distinguished:

BSPT Pipe Threads. Colder BSPT Threads.png
BSPT Pipe Threads.

These can be combined into two types of joints:

Jointing threads
These are pipe threads where pressure-tightness is made through the mating of two threads together. They always use a taper male thread, but can have either parallel or taper female threads. (In Europe, taper female pipe threads are not commonly used.)
Longscrew threads
These are parallel pipe threads used where a pressure-tight joint is achieved by the compression of a soft material (such as an o-ring seal or a washer) between the end face of the male thread and a socket or nipple face, with the tightening of a backnut.

Thread form

The thread form follows the British Standard Whitworth standard:

Pipe thread sizes

At least 41 thread sizes have been defined, ranging from 116 to 18, although of these only 15 are included in ISO 7 and 24 in ISO 228. [3] [4] [5] [6] The size number was originally based on the inner diameter (measured in inches) of a steel tube for which the thread was intended, but contemporary pipes tend to use thinner walls to save material, and thus have an inner diameter larger than this nominal size. In the modern standard metric version, it is simply a size number, where listed diameter size is the major outer diameter of the external thread. For a taper thread, it is the diameter at the "gauge length" (plus/minus one thread pitch) from the small end of the thread. The taper is 1:16, meaning that for each 16 units of measurement increase in the distance from the end, the diameter increases by 1 unit of measurement.

Tapping drill
R 95%G 80%
1 18112.3091.492037.8971.375634.9390.409110.435.135.5
1 14112.3091.650041.9101.533538.9521212.739.139.5
1 38112.3091.745044.3231.628541.3651212.741.542.0
1 12112.3091.882047.8031.765644.8451212.745.045.4
1 58112.3092.082052.8831.965649.9265815.950.150.5
1 34112.3092.116053.7461.999550.7885815.950.951.4
1 78112.3092.244056.9982.127654.0415815.954.254.6
2 14112.3092.587065.7102.470662.752111617.562.963.3
2 12112.3092.960075.1842.843572.226111617.572.472.8
2 34112.3093.210081.5343.093578.576131620.678.779.2
3 14112.3093.700093.9803.583591.0227822.291.291.6
3 12112.3093.9500100.3303.833597.3727822.297.598.0
3 34112.3094.2000106.6804.0835103.7227822.2103.9104.3
4 12112.3094.9500125.7304.8335122.772125.4122.9123.4
5112.3095.4500138.4305.3335135.4721 1828.6135.6136.1
5 12112.3095.9500151.1305.8335148.1721 1828.6148.3148.8
6112.3096.4500163.8306.3335160.8721 1828.6161.0161.5
7102.5407.4500189.2307.3220185.9791 3834.9186.1186.6
8102.5408.4500214.6308.3220211.3791 1238.1211.5212.0
9102.5409.4500240.0309.3220236.7791 1238.1236.9237.4
10102.54010.4500265.43010.3220262.1791 5841.3262.3262.8
1183.17511.4500290.83011.2900286.7661 5841.3287.0287.6
1283.17512.4500316.23012.2900312.1661 5841.3312.4313.0
1383.17513.6800347.47213.5200343.4081 5841.3343.6344.2
1483.17514.6800372.87214.5200368.8081 3444.5369.0369.6
1583.17515.6800398.27215.5200394.2081 3444.5394.4395.0
1683.17516.6800423.67216.5200419.6081 7847.6419.8420.4

These standard pipe threads are formally referred to by the following sequence of blocks:

Threads are normally right-hand. For left-hand threads, the letters, LH, are appended.

Example: Pipe thread EN 10226 Rp 2 12

The terminology for the use of G and R originated from Germany (G for gas, as it was originally designed for use on gas pipes; R for rohr, meaning pipe.)

Pipe and fastener dimensions

G / R
Typ. nut
Corresponding pipe
3822 or 231017.22.3
1 14533242.43.2
1 12574048.33.2
2 126576.13.6

ISO 7 (Pressure Tight threads)

The standard ISO 7 - Pipe threads where pressure-tight joints are made on the threads consists of the following parts:

ISO 228 (Non Pressure Tight Threads)

The standard ISO 228 - Pipe threads where pressure-tight joints are not made on the threads consists of the following parts:

See also

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  2. "Archived copy" (PDF). Archived from the original (PDF) on 2013-10-07. Retrieved 2013-12-27.CS1 maint: archived copy as title (link)
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  6. "BSP Thread data". Retrieved 2016-07-15.