Threads - BSP - Parallel - Tapered - BS746

Could someone please post a definition of all these different types of thread. I have searched Google and have come up with some basic, but confilicting, information.
It would also be a great addition to the FAQ.
All i have come up with;
BSP - British Standard Pipe. Parallel thread. BSPT - BSP Tapered Thread.
What is the difference between a parallel and tapered thread? How, looking at a male or female thread, would you determine this? What part of a fitting, and how, would you need to measure to determine the thread size. What size and type of thread do you get on a 15mm compression coupler? 1/2" BSP Parallel Thread? The actual thread does not measure 1/2" but the internal diameter of the 'pipe' does!
Do parallel male and female threads go together? Or is it parallel to female only?
When should and should not a fibre washer be used?
PTFE or Sealing Compound?
What is a BS746 thread?
Rich
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On 8 Jul 2003 08:26:29 -0700, in uk.d-i-y rich_ard snipped-for-privacy@yahoo.co.uk (Rich) wrote:

Here's a few starting points...
Ian Wright's "A Compilation of Thread Size Information" http://www.watchman.dsl.pipex.com/thread.html
Maryland Metrics Screw threads, overview http://mdmetric.com/fastindx/t44u.pdf
Maryland Metrics Thread Identification Chart http://mdmetric.com/tech/tic1e.htm
Brian Morgan's Screw Thread Data http://members.lycos.co.uk/A10bsa/intro.htm
John Paquay's Wood Screw Sizes and Pilot Holes http://home.insightbb.com/~jpaquay/scruchrt.html

If you give me the info you gather, I'll see what I can do.

-- Phil Addison The uk.d-i-y FAQ is at http://www.diyfaq.org.uk / Remove NOSPAM from address to reply
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