COPPER PIPE EROSION CORROSION

[CESSNA1]

HELLO: Does anyone know of a research pare/test report/magazine artilce/ or something else that relates to the erosion corrosion rate of potable water flowing inside a damaged residential under slab copper pipe. i am trying to estimate (guess) the time required for the erosion corrosion. to wear through the damaged portion of then pipe. I realize this is a complex phenomena but I am hoping there is at least some data out there, even if it is old.

Thank you
Dave

 

[unclesyd]

If you have had a leak don't wait start with a replacement plan as soon as possible.
I don't think it is possible to predict the rates at which domestic Cu water pipe/tubing will deteriorate a specific location. There are too many variables.
Can you give a little information on your leak so you might be able to get a little better guidance for a possible time frame.

If you are using a municipal water supply I would contact the authority in charge and quiz them (the technical side) about your problems.
If your water supply is private well see if a local water authority will analyze it for you or recommend someone who can. Consult with whoever does the analysis on how to sample the water.

 

[rmw]

You are dealing with velocity and time issues with respect to the potential damaging effects of the erosion on the damaged spot.

Not knowing about the specific damage, as to how much it reduces the flow area, if you can approximate it, then do a velocity calculation, to see if it exceeds the recommended velocity limit for the tubing.

Second, what is the "on time" of the flow? Is this like most residences, where the actual flow is high during the post breakfast bathroom rush, showers, clothes washing, and then off for the rest of the time, or is it for something that is flowing all the time, like an irrigation system, etc attached to the house.

I suspect that if it is a normal residential situation, that it will be a long time before the water erodes the pipe, unless, of course, there is some sand or other abrasive material in the water.

rmw

 

[CESSNA1]

I thank both of you for your time and effort in your response. They did not however, answer the basic question.

I am looking for research papers/test reports/articles that are relative to or address the time required for erosion corrosion to wear through a damaged section of copper pipe. I am sure that, if they exist, these papers would date back 30 to 50, or more years.

Thank you
Dave

 

[EdStainless]

There are papers, some good old ones by Efird et al. Have you checked copper.org That is the CDA site.
The problem with erosion of copper in drinking water is that it is very sensitive to the shear from flow and water chemistry. The old papers have some actual shear vs metal loss curves.
Just a gut feel, I would guess that if you had a copper tubed crimped 20-30% it would shorten the life from >50 years down to <10 years.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be slowed down.

 

[YLWEA]

I have a paperback reference from "The Institute of Marine Engineers" called "Marine Engineering Practice Volume 1, Part 10 Selecting Materials for Sea Water Systems" and it does address copper pipe velocity limits in general terms, including a qualitative graph of water velocity versus "probability of premature failure from impingement". Looks like an increase from about 1.7 m/sec to 3 m/sec results in an increase of almost 3x the probability of failure (the relationship appears linear in that velocity range). At lower velocity the rate of increase is faster (steeper slope)with each incremental increase in velocity, with the probability of impingement related failure being about zero at less than about 1/2 m/sec. ASM Metals Handbook suggests that 2-3 ft/sec is a reasonable limit to impose. Perhaps that and the information above will let you get a feel for the sensitivity of the copper to velocity changes.

 

[Metalguy]

Whatever erosion rates you have for the straight sections, the downstream side of elbows and T's will wear thru a lot faster from the turb.