[AT] Russian Metric uses BSPP

[James Peck]

This Wikipedia articles says BSP is an international standard except in the US. That would explain their use in china.

In soft metric items that used to be in inch have the dimension converted to metric but the items stays the same size.

https://en.wikipedia.org/wiki/British_Standard_Pipe

[Dennis Johnson] <snip> Work I have done in Russia and China commonly uses BSPP threads for pipe. They are a real pain to get to seal. I developed a strong hatred of them.
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