Bursting at the seams

Just before leaving on vacation last week, I ran into one of my neighbors on the way back from the mailbox. He's a retired Canadian gentleman who bought the house 2 doors down, and he had recently had troubles with his pool, you know eh? Seems while he was back up near Calgary, his pool piping burst.

This is Schedule 40 PVC, 2 inch diameter. It has a 200 psi operating pressure, and burst pressure of nearly 1000 psi. The photo shows the "T" that comes directly out of the pump. the left side does to the pool water features, the right side goes to the filter, similar to my pool piping, same installation and design. The ONLY pipe that is NOT swelled and at rupture, is the diagonal one just prior to the pump inlet flange. That's insane!

A 1.5HP Hayward pool pump, just like I have, generates 20 to 30 psi max on a 2 inch discharge line - I monitor mine on the pressure gauge on the top of my filter housing. My Canadian neighbor's pump was running at 25psi, the day after he replaced the ruptured pipes (filters not yet back-washed). I suspected chemical attack (it ruptured on a day when it was 90F ambient, 10% RH) by a inept pool contractor, but PVC is inert to both strong acid and strong base attack. Our common neighbor across the street uses PVC stirring rods & piping in the strong sodium hydroxide he mixes for the farm he manages in SW Phoenix and he said it never embrittles, even at 120F.

I've never seen such a small pool circulating pump generate such extreme pressures. It's not a single glued joint that failed, it's multiple fittings immediately adjacent to the discharge. Surprising, and impressive.