If its a 1" size, it will be 11 tpi at .9091 pitch, requiring a tapping size drill of 30.75mm.
Wow that takes me back to mechie institute days!![]()
Temperature and Pressure!Could it be Female British Standard Pipe?
Together with Tapered and Parallel?
You shouldn't tell them what you want to use it for, if they can't figure that out for themselves, they shouldn't be on here giving advice.....I want to use the tapping to attach a pipe. ....
I expect the T&P valve on smaller cylinders will be a 3/4" parallel BSP tapping.
But it might be 1/2" and it just could be tapered although they are virtually only used on gas nowadays.
However, I dont have a spare one that I can check with me at the moment.
Tony
We dont change them very often and only screw them in so dont need to use a thread gauge for the job.
All "iron" threads used to be tapered but now we use copper pipes most of the time a parallel thread is more appropriate except on gas fittings.
Tapered threads are still often used on steel pipework but thats mainly for industrial work now or special applications or gas supply before the meter when plastic is not being used or for internal gas pipework before the meter. Most meters go outside now.
Tony
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