Pitted pipes

JohnStarcher

A client sent this to me. We are going to be installing a new high efficiency boiler later this year. His current system is hot water w/ fintube baseboard, 80% cast iron boiler with a vent damper. City water. Does this look like electrolysis? Any ideas on what to do about it? I'm thinking we need to replace it all. This pipe was located in an attic run - under 12" of insulation.

ratio

Is it just discoloration, or can you feel it when you run your finger across it? if it's on the outside of the pipe, it got to be something around the pipe. Maybe some contaminates in the itchy, like something got spilled in it.

JUGHNE

Mouse Pee??

There is a reason you don't use copper and brass in hog confinement barns.

HomerJSmith

Sand the discoloration with emery cloth and examine the pipe to see if it is topical. I would expect boiler water all over the place if the pipe were leaking. The green is copper sulfate, more than likely. Look for an acidic environment. If the whole piping system is similarly pitted, it may be a manufacturing defect.

If it is actually a pinhole in the pipe, replace the pipe, look for the quality of the water in the system as to acidity. Look for electrical current in the water because of impurities in the water. If you have a water quality problem go to DI or distilled water mixed with spring water to a TDS of 20ppm.

EBEBRATT-Ed

To me it looks like it starting from the outside. I would suspect moisture combining with something in the insulation.

Why is their an un insulated pipe in an attic? Is it a vented attic??

Take some sand cloth and sand the pipe. If it looks ok insulate it with armaflex

Larry Weingarten

Hi, I see small green circles in the center of the discolored areas. If those stay when you sand it, I'd worry about it pinholing. Maybe cut out a section and replace it with new copper, then slice the cut out piece lengthwise. If pitting is happening, you'll see it inside of the pipe.

Yours, Larry

hot_rod

It does look like an attack from the outside.

Check over at the CDA website, they have volumes of info on copper tube failures and causes.

Zman

How lineal are the pinholes?
This pipe had holes like that. I believe it was a combination of impurities in the original extrusion, domestic hot water and high velocity.

Mark Eatherton

The pits on the outside probably have tubercles on the inside. They are common in systems that use Alum as a coagulant for water treatment. Alum is derived from aluminum. Wherever a molecule of alum touches the copper, it starts a corrosion cell. If the water treatment company is following and maintaining a good Langlier Index (induced hardness) it's usually not a problem. Detroit switched water sources, and wasn't maintaining the Langlier Index, hence all the protective patina disappeared from inside the pipes, and exposed users to lead, rust and legionella. Washington D.C. had this problem a few years back.

Also known as cold water pitting.

ME

Zman

When you cut it out, please send a picture of the inside. Inquiring minds...

psb75

Rodents love, LOVE fiberglass. I'm positing rodent urine.

JohnStarcher

Thanks for the feedback, guys. I visited the home yesterday and took a look. The pitting seems to be confined to a lone 6' section of pipe. All of the copper piping up and downstream appears to be fine. I lightly sanded the tubing at one of the pit-marks, and it looks like the tube wall itself is compromised.

To answer Ed's question above, this is a second floor zone in a two-story home. The piping travels up into an area behind a knee wall to feed two rooms of baseboard heat and a hallway. The pipe is covered by about a foot of blown-in fiberglass.

I think we may have found an answer - the homeowner told me yesterday that the original homeowner experienced a freeze-up many years ago in this exact area. There was a burst pipe, and lots of leakage. My theory is that the pitting was caused by electrical current due to nearby can-lights that were REALLY wet. We are going to replace the damaged section of pipe with some hePex when we change out the boiler this summer and redo a bunch of radiation - upgrading to panel rads in the main living area. Assuming we don't find any other pitted piping in the system, I'm putting this one in the "solved" pile, at least for now.

NY_Rob

If it's just confined to that one area, why not replace w/copper?

Much less flow through 3/4" PEX vs. 3/4" copper.

JohnStarcher

Because Pex will be more resistant to bursting should there ever be conditions in the future where freezing could occur - long term power outage, etc. Flow is not really an issue - it's a relatively small zone, so I see no issues with a minimal flow reduction due to pex tubing vs copper

Charlie from wmass

I'm working on piping just like this today I will post pictures of the inside of what I remove. I was always under the understanding it was from the chlorine in the water. I only come across this on City water sources

EBEBRATT-Ed

I have done a little research on copper with pin holes in it which is probably a different but similar problem.

My former boss had that problem at his house in the cold city water line would get pin holes in L copper. The problem was too much flux left inside the pipe.

The clue? The HW domestic was ok, same pipe, same plumber, same solder and flux, same age. The hw would wash the lux away

HomerJSmith

That's why I always use water soluble flux.

Zman

@Erin Holohan Haskell

This is such a great subject.

As far as I know, there is no central database anywhere that documents what types of pipe deterioration is occurring under what conditions.

I wonder if there would be a way for folks to be able to contribute photos and descriptions into a central file for everyone to share. If you see pipe damage similar to damage you are seeing on a job, you could read account of others and perhaps reach out to them for advise.

The best thing about Heating Help is the way the collective intelligence of the group (and occasionally the lack there of ) brings everyone to a higher level of expertise.

Charlie from wmass

That green line would be oriented as the bottom of the pipe.

Erin Holohan Haskell

Zman said:

@Erin Holohan Haskell

This is such a great subject.

As far as I know, there is no central database anywhere that documents what types of pipe deterioration is occurring under what conditions.

I wonder if there would be a way for folks to be able to contribute photos and descriptions into a central file for everyone to share. If you see pipe damage similar to damage you are seeing on a job, you could read account of others and perhaps reach out to them for advise.

The best thing about Heating Help is the way the collective intelligence of the group (and occasionally the lack there of ) brings everyone to a higher level of expertise.

@Zman, that's an excellent point. I've made a new category on The Wall called Pipe Deterioration for these issues.

Zman

@Erin Holohan Haskell
Thank You,
I will start digging through pictures.

Erin Holohan Haskell

Zman said:

@Erin Holohan Haskell
Thank You,
I will start digging through pictures.

Great. Thanks!

Leonard

Fiberglass insulation usually comes in large batts. All those small bits of fiberglass looks like a mouse tried to make nesting. And associated very corrosive mouse urine (ammonia). Mice urine is VERY corrosive and destructive in generator control boxes to the contacts and all metals copper/brass/steel/aluminum, even without a dissimilar metal touching it.

hot_rod

Zman said:

@Erin Holohan Haskell

This is such a great subject.

As far as I know, there is no central database anywhere that documents what types of pipe deterioration is occurring under what conditions.

I wonder if there would be a way for folks to be able to contribute photos and descriptions into a central file for everyone to share. If you see pipe damage similar to damage you are seeing on a job, you could read account of others and perhaps reach out to them for advise.

The best thing about Heating Help is the way the collective intelligence of the group (and occasionally the lack there of ) brings everyone to a higher level of expertise.

Actually the Copper Development Association back in NY has a huge data base of copper information. Most of it is free at their website, I have purchased some of their manuals over the years. Lots of info and pics on water pipe problems and caused. And the statue of liberty

https://www.copper.org

Click on Resources and Education buttons

https://www.copper.org

Erin Holohan Haskell

Thanks, @hot rod!