Warning: watch out for trapped water in older boiler tubes

I was doing a pressure test on a 40-year-old fire tube boiler in a old factory outside Cleveland last month and heard a weird gurgling sound that wouldn't stop. Turned out there was a pocket of trapped water in a sagging tube that had corroded thin from the inside, nearly blew when the pressure hit 150 psi. Has anyone else run into this kind of hidden tube damage from water pooling over time?

3 comments

3 Comments

stella225d ago

We had good luck on a similar job using a flexible borescope to snake down each tube before we did any pressure testing. Found two low spots that way, one had about a quart of water sitting in it. We ended up drilling a small drain hole at the lowest point of each sagging tube to let any trapped water out before we brought pressure up. After that, we did a slow hydro test at 50 psi increments, listening for any gurgling between each step. It was tedious but saved us from a blowout like you described. Your mileage may vary depending on how accessible your tube sheet is, but that approach worked for us on a 60 year old boiler in Toledo.

max_cooper216d ago

That "gurgling sound" you mentioned is EXACTLY what I heard on a old Cleaver Brooks unit we had at a warehouse in Akron. Same situation, a low spot in the tube sheet let water pool up and it ate through the metal from the inside like acid. By the time we found it there was a pinhole leak that turned into a full rupture when we brought it up to 125 psi for a hydro test. Water shot across the boiler room like a fire hose, nearly took out a guy's leg. We ended up having to retube the whole lower section because three more tubes had the same corrosion pattern hidden under the mud drum.

felixhenderson5d ago

Man, that borescope trick is genius. I've been using a mechanics stethoscope on the tubes to hear the gurgling before pressure testing, but it's a crapshoot compared to actually seeing a pocket of water sitting there. Gonna start carrying a cheap scope on every job now.