Cutting BSPT threads with a die

Clearly I haven't seen all variations and accept my post as being too encompassing. I should have said; As far as I'm aware all the ex-main line locos I've encountered use plugs as I described.

Thank you Baldric for the helpful link.

I said right at the beginning in this discussion that I had not cut such a thread, so Jon may also be right, I was only quoting what I have read and instinctively feel is 'correct'. There are often two ways of doing things and this is clealy an example..

Thread sealing by tape or other means would I think be wise in any case

Brian

ICBW but isn't the whole purpose of the tapered thread to avoid the need for tape or other means? We're talking BSPT here not BSP.

Edited By Brian Oldford on 13/05/2015 09:23:47

Hello Brian,

ICBW?

Not an abbreviation I am familiar with I'm afraid. I favour thread sealing for the simple reason that it is easy to do when building up the joint at the start and a great deal more trouble to rectify a weep at a later stage, even though theoretically it is unneccesary.

My mechanical plumbed joints are all thus treated; apart from any other consideration they are easier to crack apart at some future date if needed.

Brian

ICBW = It Could Be Worse, according to Google

I know it as "I could be wrong"

I've made a lot of tapered threads on steel pipe, using the standard manual dies. Up to 2" dia. with a bit of scaffold pole to help. When used for water, waste water and similar fluids it was usual not to use jointing, theory is that any leak would very soon corrode up. In bad cases the old sal-ammoniac could be used, a popular leak sealer in olden times, even in steam boilers.

Sorry Gents; Jon Gibbs got what I meant. I should have been clearer in that I meant "I could be wrong".

Hi I have been a turner for oven 50 years just retired we always turned the taper first the sizes you want

for1/4 BSPT in metric small dia 12.78 to large dia13.78 length of thread 16mm Angle is 1.7899deg

3/8 BSPT is small end 16.26 large end 17.32 x 17mm long

taper both internal and external

sorry for the metric sizes but our machines were all in metric

ATB Alan