Talk:British Standard Pipe

Odd sizes
Where do the sizes 5/8, 7/8, 1 3/4, and 2 1/4 that are currently listed in the table come from? None of the British, German, European or ISO standards that I checked mention them. If nobody can provide an authoritative source for these sizes (e.g., some national standard), I'll remove them from the table. Markus Kuhn 10:11, 3 September 2006 (UTC)
 * Now removed.

Outer pipe diameter
Could you please provide a reference for the recently added outer-diameter inch figures? An ISO or BSI document preferably. BS EN 10226 does not contain any pipe dimensions, only thread dimensions. Therefore, also the term "Pipe size" is misplaced here, the standard says "Thread size". Markus Kuhn 16:36, 5 September 2006 (UTC)

Parallel/tapered
I want to know if it's possible to screw a tapered male thread into a parallel female thread, or vice versa. Someone must know this?IMacThere4iAm 09:35, 26 October 2006 (UTC) In the article: Jointing threads: These are pipe threads for joints made pressure-tight by the mating of the threads. They always use a taper external thread, but can have either parallel or taper internal threads. This means a male BSPT (tapered) fitting will seal happily onto a female BSPP (parallel).

It is preferable to insert a tapered male fitting into a parallel female fitting. This means that thread engagement increases progressively from front to rear and sealing occurs towards the end (rear) of the male thread. If a parallel male is inserted into a tapered female, the sealing point occurs at the front (start) of the male thread, and all the threads behind it have progressively less and less engagement thus making a leak more likely. — Preceding unsigned comment added by 83.105.6.114 (talk) 12:10, 7 July 2011 (UTC)

Since the standards are indeed only: Can someone explain why very often (in Europe at least) joints are made as such:
 * ISO 7 (letter R) for mating tapered outer thread into either tapered or parallel inner thread where pressure tight joints are made on the thread itself.
 * ISO 228 (letter G) for mating parallel outer thread into parallel inner thread where pressure tight joints are not made on the thread itself.
 * Mating parallel outer thread into parallel inner thread where pressure tight joints are made on the thread itself.

Also note that ISO 7 is equivalent to the European standards EN 10226-1 and EN 10226-2. Glotty (talk) 13:03, 4 March 2020 (UTC)

Letter code
Any idea, where the letters G for parallel and R for tapered thread (as well as Rp and Rc) come from? Are these derived from some word in some language? Markus Kuhn 14:01, 10 February 2007 (UTC)

I'm not sure - we use BSPP and BSPT for _P_arrallel and _T_apered. 212.108.17.165 10:20, 2 April 2007 (UTC)

-- It's G for 'Gas', R is 'Rohr'(german for pipe), P is 'Parallel', C is Conisch (tapered) —Preceding unsigned comment added by 212.178.148.98 (talk) 14:39, 2 November 2010 (UTC)


 * I don't beleive the G could stand for gas since the G standard refers to ISO 228 which is named: "Pipe threads where pressure-tight joints are not made on the threads".  Any pipe carrying gas would want a pressure tight joint. I have not been able to find any official documentation for the origin of the G nomenclature. Dsh1001 (talk) 05:36, 12 May 2023 (UTC)

Add link
I later found the long and useful Wiki article on Screw Threads, which should be linked here. Clwydd (talk) 18:55, 21 July 2009 (UTC)


 * It is in the first sentence. Wizard191 (talk) 20:22, 21 July 2009 (UTC)

inch v. mm nomenclature
An authoritative comment should be made about the following:

Strictly speaking, BSP threads should only be referred to using the fractional inch-based numbers, eg, 3/8, 1/2, 3/4, 1, etc. Neither the word inch, nor the symbol " should be used, because no such references are used in the Standards.

In particular, the commounly accepted metric (mm) equivalents of these inch sizes, eg, 10mm, 15mm, 20mm, 25mm should not be used because again, the Standards contain no such references.

Also, the equivalent metric pipe sizes, eg DN10, DN15, DN20, DN25 (where DN means nominal diameter of the pipe) etc should not be used because again, the Standards contain no such references, and at any rate, these sizes refer to pipe sizes, not thread sizes or forms.

However, in practice, the mm sizes of 10, 15, 20, 25, etc are very commonly used, so perhaps the discussion should acknowledge this, and if so, the mm number for every thread size should be listed, and a determination made as to whether DN or mm should be quoted. My own view is that DN is preferable because this refers to the pipe size, and any given pipe size can only be threaded to the same thread size, whereas mm is an exact mm dimension but one which has no direct relationship to the thread size, eg, 1/2" is 12.7mm not 15mm, and 3/4" is 19.1mm not 20mm, etc. —Preceding unsigned comment added by Jgrahamssmith (talk • contribs) 02:51, 22 April 2010 (UTC)

Nominal size
Why isn't the nominal size given in fractions eg $3/4$? In my umpteen years of working with threaded fittings I have never seen a part advertised as 0.375 always as $3/8$. Dash sizes are seldom seen either. Dash sizing could do with an explanation, though it appears to be the nominal size expressed as sixteenths this is not stated. GraemeLeggett (talk) 15:30, 6 September 2011 (UTC)

I would like to heartily second this. I came to this page to find out details of a 1/8 BSP thread, but it's nowhere to be seen ! Has some clever-clogs decided to update everything until no-one can find anything ? Would somebody with some knowledge AND sense please put the fractional inch sizes in their proper place in the table ? Many thanks ! Darkman101 (talk) 21:03, 14 June 2012 (UTC)

Washers
Does BSP extend to a specification of washer sizes? That question was asked today at Reference_desk/Science. --Tagishsimon (talk) 01:24, 28 June 2012 (UTC)

Pipe thread sizes table needs a key
The table in British_Standard_Pipe has a number of (for me) incomprehensible initialisms. What does DM mean? BSP.PL (Rp)? The table needs a key explaining these initialisms if it is to be of use to the reader unfamiliar with the subject matter. --Tagishsimon (talk) 01:24, 28 June 2012 (UTC)

BSP alias
This needs to come up for BSP on the search. Sorry I don't know how to do that. — Preceding unsigned comment added by Nibinaear (talk • contribs) 18:40, 13 July 2016 (UTC)


 * This has been fixed over at BSP since the comment was posted. — ¾-10 05:18, 30 December 2016 (UTC)

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A Commons file used on this page or its Wikidata item has been nominated for deletion
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