PVC explained and why your old parts don't work

ArowanaLover1902 · Mar 20, 2018

I just had a bit of problems with PVC connections and thought I'd share to help out others. PVC (thanks to capitalism) changes every once in a while, the standard (schedule 40) piping doesn't change much but the joints change incredibly. My problem was with connecting to the plumbing of an older tank that I got from craigslist. I had a PVC union piece coming down from my input to the tank. I couldn't find anyway to connect to it with anything I could get from the store. I did some researching and asked a few experts, they said it was IPS, an outdated measuring system, not even specialty stores here sell them (they were for sale online, but I didn't want to switch over to a measuring system that I can't easily get parts for, if something breaks, I need it fixed that day). I eventually had to cut out all of the IPS joints and swap them out for modern parts. It wasn't easy, but I'd advice everyone with an older plumbing system to check for IPS and either order in some backup parts or switch over to modern standards. I hope this helps anyone who is having problem pairing up PVC parts.

ihavecrabs · Mar 20, 2018

Very interesting. I have never heard of this being an issue.

How old was the tank you were working on? Good reference point in case #reefsquad gets a similar question in the future.

S-t-r-e-t-c-h · Mar 20, 2018

I hadn't heard that before, but good to know!

saltyhog · Mar 20, 2018

This a problem with unions and any other threaded fitting. I've never had an issue with slip fittings, even if they were 30+ years old.

Good heads up!

reefwiser · Mar 20, 2018

IPS PVC IPS pressure pipe is manufactured with Iron Pipe Size (IPS) diameters You can get people using all kinds of PVC on aquariums whatever they find or get for free they will use.

This size is mostly found in the construction of water systems.

ArowanaLover1902 · Mar 20, 2018

Not really sure how old it was, I never checked with the guy

Even Further · Mar 20, 2018

Your getting bad info here. IPS is NPS. IPS, iron pipe size was the early terminology for pipe, back when pipe was somewhat limited to standard wall thickness (sch.40). NPS, was adopted as newer terminology, "Nominal Pipe Size", and is to be followed by the specific schedule to properly specify. In the process pipe world, people still use "IPS" to refer to nominal pipe since it is the same. General plumbing PVC in the USA is made to NPS size, again which is the same as IPS as far as OD measurement. Your tank could have been based on tube size, which is the actual OD, or made with oddball non-standard parts. For example: 1" rigid tube measures 1" OD, 1" pipe measures 1.315" OD.

I work with piping specifications daily. I have seen people get confused between pipe and tube. The fitting dimensions and pipe sizes have not changed. Process pipe and fittings are made to well established standards. But "parts" can certainly be made outside of standards for cost or other reasons.