I wanted to warn all my fellow plumbers. While most of you may know better maybe I can help a few. The company I work for just completed 3-2 story schools. A bathroom and island sink in each classroom. 200 fixtures in all. To save money the higher ups at the shop put their heads together and figured they’d save money by using poly tubing on the finish. It was done in the heat of the summer when many fire hydrants where open and water pressure was under 20lbs some days. I had a few of the shop rockets stop in on Saturday to give me a hand. Until one day we had a blowout! The poly tubing blew out of the poly ferrure. It was tighened but I found out that if more than one thread can be seen on the compression joint it probably isn’t tight enough.I personally had to go back over every sink. A mixing valve and filter in each room also. I suffered 12 ruined ceiling tiles. Nothing compared to what happened the other 2 schools before they where gone over. Not to brag but it was a near perfect job except for this mishap that luckily was caught quick. But nearly ruined a year of hard work.