B.S.P.T.

British Standard Pipe Thread


British Standard Pipe Thread is a family of standard screw thread types that has been adopted internationally for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread.


A list of 16 thread sizes are defined by the standards, ranging from 1/16 inch to 6 inch. The size was originally based on the inner diameter measured in inches of a steel tube for which the thread was intended. This often causes confusion, as people think the size refers to the outside diameter of the male thread.

Two types of threads are used:

Parallel (straight) threads, British Standard Pipe Parallel thread (BSPP)

Taper threads, British Standard Pipe Taper thread (BSPT)

Just to confuse things, often the T in BSPT refers to Thread and doesn't indicate either Taper or Parallel.

The threadform follows the British Standard Whitworth standard


The table below shows dimensions for male threads.


Thread

Threads per inch

Pitch mm

Outside Diameter mm

Outside Diameter inches

1/16 inch

28

0.907

7.723

0.304

1/8 inch

28

0.907

9.728

0.383

1/4 inch

19

1.337

13.157

0.518

3/8 inch

19

1.337

16.662

0.656

1/2 inch

14

1.814

20.995

0.825

5/8 inch

14

1.814

22.991

0.902

3/4 inch

14

1.814

26.441

1.041

1 inch

11

2.309

33.249

1.309

1¼ inch

11

2.309

41.910

1.650

1½ inch

11

2.309

47.803

1.882

2 inch

11

2.309

59.614

2.347

2½ inch

11

2.309

75.184

2.96

3 inch

11

2.309

87.884

3.46

4 inch

11

2.309

113.030

4.45

5 inch

11

2.309

138.430

5.45

6 inch

11

2.309

163.830

6.45


This is a 1/2 Inch thread, you can count 14 threads in one inch.
Example of half inch BSP thread


An end view of a 1/2 Inch male thread
End view of half inch BSP thread


As the name of the sizing does not match the actual diameter, there can be some confusion over sizing. We have shown some pictures of two of the more popular sizes along side popular UK coins.

First, a half inch thread which is similar in size to a 1 penny coin.

Half inch BSP thread shown against 1p coin


Second, a three quarter inch thread which is similar in size to a 2 pence coin :
3/4 inch BSP thread shown against 2p coin


Typical uses and sizes are :

1/4 Inch - Compressed air connections

3/8 Inch - Oil line connections

1/2 Inch - Bathroom basin and kitchen sink taps, radiator inlets, old outside tap outlets

5/8 Inch - Old outside tap outlets (very rare)

3/4 Inch - Bath taps, washing machine inlet hose connections, modern outside tap outlets

1 Inch - Domestic heating boilers and hot water cylinders

1-1/4 Inch - Wash hand basin wastes (bathroom sink)

1-1/2 Inch - Kitchen sink wastes, bath wastes, toilet syphon outlets

2-1/4 Inch - Immersion water heater elements


A selection of "Black Iron" BSP fittings :

Selection of BSP fittings


Plumbing fittings with BSP threads on ebay :

3/8 Inch BSP Brass Hose Tail Connection | British Standard Pipe Thread Fitting

£3.49
End Date: Thursday Sep-7-2017 16:14:20 BST
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1/4 Inch BSP Brass Hose Tail Connection | British Standard Pipe Thread Fitting

£2.99
End Date: Thursday Sep-7-2017 16:11:24 BST
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Chrome Plated 22mm Compression x 3/4 Inch BSP Male Adaptor Fitting

£3.95
End Date: Friday Aug-25-2017 16:03:05 BST
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Trap Extension 1-1/2 Inch BSP x 3 Inch Long | McAlpine T12A-3 MxF Trap Extender

£3.49
End Date: Sunday Sep-10-2017 16:28:43 BST
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3/4 Inch BSP Plastic Flanged Back-Nuts | British Standard Pipe Thread | 2 Pack

£1.49
End Date: Monday Sep-11-2017 17:57:42 BST
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Washing Machine Waste 1 Inch BSP Hose Nozzle / Spigot | Angled

£4.49
End Date: Wednesday Aug-23-2017 10:27:31 BST
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1/2 Inch BSP Brass Plain Plug | British Standard Pipe Thread Fitting

£1.49
End Date: Wednesday Sep-13-2017 10:58:58 BST
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15mm x 1/2 Inch BSP Service Valve | Straight | Chrome Plated Brass

£2.49
End Date: Wednesday Aug-30-2017 10:53:59 BST
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1/2 Inch BSP MxF Male x Female Brass Tap Thread Extension / Extender

£1.29
End Date: Friday Aug-25-2017 18:56:49 BST
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Washing Machine Waste 1 Inch BSP Hose Nozzle / Spigot | Straight

£4.49
End Date: Wednesday Aug-30-2017 22:21:46 BST
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1 Inch x 1 Inch x 1/2 Inch BSP Malleable Black Iron Reducing Tee

£3.99
End Date: Friday Aug-25-2017 18:11:44 BST
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3/8 Inch BSP Malleable Black Iron Socket | British Standard Pipe Thread

£1.49
End Date: Friday Aug-25-2017 17:59:37 BST
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1-1/2 Inch BSP Malleable Black Iron Socket | British Standard Pipe Thread

£4.49
End Date: Friday Aug-25-2017 17:50:06 BST
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1/4 Inch BSP Malleable Black Iron Plug | British Standard Pipe Thread Fitting

£1.49
End Date: Friday Aug-25-2017 17:44:19 BST
Buy It Now for only: £1.49
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3/8 Inch BSP Malleable Black Iron Plug | British Standard Pipe Thread Fitting

£1.49
End Date: Friday Aug-25-2017 17:43:01 BST
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1/4 Inch BSP Malleable Black Iron Hex Nipple | British Standard Pipe Thread

£1.75
End Date: Friday Aug-25-2017 17:07:44 BST
Buy It Now for only: £1.75
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3/8 Inch BSP Malleable Black Iron Elbow MxF Male x Female

£1.75
End Date: Friday Aug-25-2017 16:19:47 BST
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1/4 Inch BSP Malleable Black Iron Elbow MxF Male x Female

£1.75
End Date: Friday Aug-25-2017 16:17:33 BST
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3/8 Inch BSP Malleable Black Iron Elbow FxF Female x Female

£1.75
End Date: Friday Aug-25-2017 16:13:44 BST
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3/8 Inch BSP Malleable Black Iron Cap / Blank Nut | British Standard Pipe Thread

£1.49
End Date: Friday Aug-25-2017 16:03:11 BST
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1/8 Inch BSP Manual Air Vent | Brass Bleed Valve For Radiators + Heating Systems

£1.69
End Date: Friday Aug-25-2017 15:46:45 BST
Buy It Now for only: £1.69
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15mm Compression x 3/4 Inch BSP Male Elbow | Brass Plumbing Fitting

£3.75
End Date: Tuesday Sep-19-2017 16:59:08 BST
Buy It Now for only: £3.75
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15mm Compression x 1/4 Inch BSP Male Adaptor / Coupler | Brass Fitting

£2.49
End Date: Tuesday Sep-19-2017 16:36:15 BST
Buy It Now for only: £2.49
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15mm Compression x 3/8 Inch BSP Female Adaptor / Coupler | Brass Fitting

£1.75
End Date: Tuesday Sep-19-2017 16:32:27 BST
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15mm Compression x 3/8 Inch BSP Male Adaptor / Coupler | Brass Fitting

£2.15
End Date: Thursday Sep-14-2017 11:54:35 BST
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1/2 Inch BSP x 2 Inch Long Brass Running Nipple | British Standard Pipe Thread

£4.49
End Date: Sunday Sep-3-2017 8:44:00 BST
Buy It Now for only: £4.49
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1/2 Inch BSP Brass Running Nipple | British Standard Pipe Thread Fitting

£1.85
End Date: Saturday Sep-2-2017 11:04:58 BST
Buy It Now for only: £1.85
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3/8 Inch BSP Brass Running Nipple | British Standard Pipe Thread Fitting

£1.75
End Date: Saturday Sep-2-2017 11:02:18 BST
Buy It Now for only: £1.75
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1/8 Inch BSP Brass Running Nipple | British Standard Pipe Thread Fitting

£1.79
End Date: Saturday Sep-2-2017 10:41:58 BST
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1 Inch BSP Plastic Cap / Blank Nut and Washer | British Standard Pipe Thread

£3.75
End Date: Saturday Sep-2-2017 9:57:03 BST
Buy It Now for only: £3.75
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1-1/2 Inch BSP Alloy Flanged Back-nut | Kitchen Sink Waste Size

£1.99
End Date: Saturday Sep-2-2017 8:32:54 BST
Buy It Now for only: £1.99
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1-1/4 Inch BSP Alloy Flanged Back-nut | Bathroom Wash Hand Basin Waste Size

£1.99
End Date: Saturday Sep-2-2017 8:31:29 BST
Buy It Now for only: £1.99
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1/2 Inch BSP Lever Ball Valve | FxF Isolation Valve With Yellow Handle

£6.49
End Date: Saturday Sep-16-2017 22:24:57 BST
Buy It Now for only: £6.49
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1 Inch BSP Brass Elbow MxF Male x Female | British Standard Pipe Thread

£7.49
End Date: Tuesday Sep-19-2017 13:28:36 BST
Buy It Now for only: £7.49
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1/8 Inch BSP Brass Hex Nipple | British Standard Pipe Thread Fitting

£1.35
End Date: Tuesday Aug-29-2017 17:53:31 BST
Buy It Now for only: £1.35
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3/8 Inch BSP Brass Flanged Back-nut | British Standard Pipe Thread Fitting

£1.79
End Date: Monday Aug-28-2017 10:21:47 BST
Buy It Now for only: £1.79
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1-1/2 Inch BSP Plastic Flanged Back-nut | Kitchen Sink Waste Size

£1.45
End Date: Monday Aug-28-2017 10:19:06 BST
Buy It Now for only: £1.45
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3/4 Inch BSP Brass Flanged Back-nut | British Standard Pipe Thread Fitting

£1.25
End Date: Monday Aug-28-2017 10:19:03 BST
Buy It Now for only: £1.25
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1/8 Inch BSP Brass Elbow FxF Female x Female | British Standard Pipe Thread

£3.24
End Date: Sunday Aug-27-2017 10:10:17 BST
Buy It Now for only: £3.24
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3/4 Inch x 1/2 Inch BSP Brass Hex Reducing Bush | British Standard Pipe Thread

£1.37
End Date: Saturday Aug-26-2017 22:15:18 BST
Buy It Now for only: £1.37
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2 Inch BSP Brass Cap / Blank Nut | British Standard Pipe Thread Fitting

£8.49
End Date: Saturday Aug-26-2017 15:55:19 BST
Buy It Now for only: £8.49
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1-1/4 Inch BSP Plastic Flanged Back-nut | Bathroom Wash Hand Basin Waste Size

£1.45
End Date: Saturday Aug-26-2017 15:55:12 BST
Buy It Now for only: £1.45
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1/4 Inch BSP Brass Elbow FxF Female x Female | British Standard Pipe Thread

£2.99
End Date: Saturday Aug-26-2017 15:49:45 BST
Buy It Now for only: £2.99
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1/8 Inch Brass Flanged Plugs | BSP - British Standard Pipe Thread | 2 Pack

£2.54
End Date: Saturday Aug-26-2017 15:43:49 BST
Buy It Now for only: £2.54
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1/2 Inch BSP Chrome Plated Brass Cap / Blank Nut

£3.79
End Date: Saturday Aug-26-2017 15:43:29 BST
Buy It Now for only: £3.79
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1/2 Inch BSP Brass Socket | British Standard Pipe Thread Fitting

£2.19
End Date: Saturday Aug-26-2017 13:19:28 BST
Buy It Now for only: £2.19
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1 Inch BSP Brass Socket | British Standard Pipe Thread Fitting

£4.49
End Date: Saturday Aug-26-2017 13:19:26 BST
Buy It Now for only: £4.49
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3/8 Inch BSP Brass Socket | British Standard Pipe Thread Fitting

£1.64
End Date: Saturday Aug-26-2017 13:19:21 BST
Buy It Now for only: £1.64
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3/8 Inch BSP Brass Elbow FxF Female x Female | British Standard Pipe Thread

£2.46
End Date: Saturday Aug-26-2017 13:19:14 BST
Buy It Now for only: £2.46
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1/2 Inch BSP Malleable Black Iron Cap / Blank Nut | British Standard Pipe Thread

£1.49
End Date: Saturday Aug-26-2017 13:08:09 BST
Buy It Now for only: £1.49
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