Sch. 40 pipe pitting off the equalizer after 4 months

MilanD

This one came off a tee at the bottom of equalizer (last pic for location). It was put in new last January when the failed section was replaced. At any rate, anyone else seen this kind of damage after 4-5 months? The eaten up threads were under the cap, at the end of the dead-leg.

I took it off to wand the boiler and cleaned it before putting it back only to discover this. Replaced it with sch. 80.

What can be the cause of this? I'm thinking the vortex from condensate pump is right above it and must be at least adding to it, combined with Chinesium? Weld line running down on inside catching flow and adding to vortex? I wash all new nipples and threads in dawn detergent before installing to cut down on oils, so I noticed this Fergusson supplied nipple had a very tall one inside the whole length of it. I usually try to put those welds facing up, but can't be certain where this one was.

As I said, I put a sch. 80 on there and my plan is to throttle down one of the isolation valves from the feeder, to slow down the flow rate of condensate. I think I read somewhere they should be throttled down to begin with. Will this create issues above normal wear and tare on the motor? Any other issues to worry about?

Thanks!
Milan

EBEBRATT-Ed

Something is going on and it doesn't look good. I would make sure to have a water meter on the make-up water and also check the chlorides and PH. Something has got to be wrong with the water quality.

Is the system using a ton of MU water?

MilanD

Since the fix, and this being installed new, no new water aside from regular blowdown makeup. This is also the only one nipple with this pitting, below water line, dead leg of the equalizer return. All else looks fine. I did monitor pH during last season and it's in 9+ range. I'm sure chlorides were high as it's city water with 60+ chlorides and 170-180 tds. After wanding, I mixed 23 gals of distilled and 13 gals of city and added steamaster, just this Friday and brought to boil to get o2 out. I'll add more steamaster tabs and test pH and chlorides. I may need to add lye to raise pH if steamaster doesn't do it, and sulfite for O2 scavenging if needed. Didn't get to testing water yet after the new fill, but water should be better in terms of chlorides and tds, for sure. And, from now on, all new make up will be distilled, with monitoring of pH, tds, chlorides and sulfites, adding stesmaster, lye, and sodium sulfite if needed.

Fred

@MilanD , If I had wet returns that looked like that after only six months, I'd be really, REALLY concerned about what caused that and what is happening inside the boiler. It's not a matter of Schedule 40 or Schedule 80 pipe, one is just thicker walled and may take 9 or 12 months to eat through instead of 6 months. I'm just sayin.

MilanD

Thanks @Fred. I'm going to check water quality. New fill this fall is as explained.

Curious thing is it is ONLY that one 3" nipple, at the dead end as the equalizer goes down to a tee, one side goes back into the boiler, and the other into that dead end 3" and a cap - pic 4 in 1st post. Cap is fine. That's why I'm wondering if it has to do with a combo of large weld ridge inside the length of the nipple and the swirling or vortex of flow from the feeder motor and equalizer. You know how copper line can pitt inside a water line if saulder runs through and into the pipe creating an obstruction inside the flow, and running water creates a small vortex around it that eats the tube from inside.

Fred

@MilanD , IDK. You've got five turns out of that pump to get to that stub and on top of that, you're going from a 3/4" supply into a 1.5" pipe. It would seem to me that a vortex is not likely and, if you had that kind of force, you'd see some thinning on the back wall of that Tee that the 3/4" pipe ties into. I suppose it could have been a defective nipple. If I were sure that is the only place that sees damage, I think I would have left the nipple off and put a plug into that tee.

MilanD

Thanks again @Fred. I think I just may do the plug next time I need to drain the boiler. I think I'll look at the chemistry next week and see where we are.