Look at this shit. I hate it.
ISO 7 is the international standard for sizes of pipe fittings. Here are some things that are wrong with it:
- The nominal size of these pipes is measured in eighths of an inch. What the fuck is "1⅛ inch". In this house we speak metric
- These are absolutely nothing like a nice Renard series of sizes
- They aren't even the actual size of anything! Your nominal "1 inch pipe" is 1.1928 inches on the inside and 1.3090 inches on the outside!
- I'm sorry does that say eleven threads per inch what are you even doing
- Because of the fact that everything is in fucked-up numbers of inches, you'd think we get to blame Americans for it. But North America doesn't even use this standard
I don't even get the opportunity to snarkily say "well I guess this is how they do things over at @NIST" because it isn't. North America uses ANSI's National Pipe Thread instead.
It would be hilarious if the ANSI standard used metric, but, no, they just use different fucked-up numbers of inches.
This sewage pipe of a standard is also known as British Standard Pipe. It's using "imperial" measurements and reminding us which empire is responsible for them being called that. For some reason, which I suspect involves politics or maybe just bribery, the ISO decided to take what the Brits were doing and make it the worldwide standard for how to put pipes together.
Germany and Austria had a different, metric standard called Panzergewinde (DIN 40430) but it's been replaced by the ISO one now.
So that's how we arrive at the pessimal state of the whole world having to measure pipes in inches, yet not even ending up compatible with the country that actually likes using inches.