Roger Mills wrote on 06/07/13 17:27:
On 06/07/2013 17:07, graham wrote:
I'm looking at buying a vacuum gauge, but they nearly all have BSPP
(male) threads - can anyone tell me how these are supposed to be sealed
when fitted to the BSPP female?
I've come across mention of copper crush washers and bonded washers, but
i've no idea if this is the standard technique.
Would the "crush washer" be sized to fit over the BSP thread, or inside
the female?

thanks,
graham.


Parallel threads normally seal on a flange and face - with a fibre or
squashable copper washer in between. Does the male thread on the gauge
have a flange?

If not, you may get away with some liquid PTFE thread sealant, but
that's not ideal.

Doesn't look like much of a flange to me - this is typical of the ones I
see: http://www.wika.co.uk/213_53_en_co.WIKA
Actually, looking at the "operating instructions" for that model it has
a little picture with the end of the BSPP thread labelled "sealing face".
So maybe a squashable washer in there?
Would htat require a special female fitting or are female BSPP threads
always a specific depth with an accurately flat bottom to the hole?