NC Guy
New Member
We live in an old farmhouse in Central North Carolina, with a water well that has a 6-inch casing pipe, which was probably laid as early as 1940, or possibly as late as 1950, so it's at least 70 to 80 years old [and I'm guessing more like 80].
I'm assuming the casing pipe is steel, rather than iron, but I don't know whether that's a good assumption for the era [circa 1940].
We're about to do some major work on all of our water systems, and I was wondering whether we ought to consider placing a new casing pipe at this time, because I don't want to expend all that money & sweat equity on a new system which is predicated upon having a valid casing pipe, when in reality that casing pipe might be about to collapse within the next 10 to 20 years.
The soils around here are red clay, and the water is probably at least mildly acidic [we get a little bit of blue/green staining on our porcelain sinks].
Unfortunately, I haven't been able to find much in the way of lifetime expectancy figures on casing pipes; about the best that I found was this old post at "Engineering Tips", talking about a storm water conduit:
At 1 MPY, 80 years would give only 0.080" corrosion, which shouldn't be that big of a problem.
But 16 MPY would give 16 x 80 = 1.280", which would long since have corroded out a casing pipe with a thickness of only 3/8" or 1/2".
Anyway, if anyone knows of good rules of thumb for lifetime expectancies of well casing pipes in the water wells of the Southeastern United States, then I'd love to hear from you.
Thanks so much!!!
I'm assuming the casing pipe is steel, rather than iron, but I don't know whether that's a good assumption for the era [circa 1940].
We're about to do some major work on all of our water systems, and I was wondering whether we ought to consider placing a new casing pipe at this time, because I don't want to expend all that money & sweat equity on a new system which is predicated upon having a valid casing pipe, when in reality that casing pipe might be about to collapse within the next 10 to 20 years.
The soils around here are red clay, and the water is probably at least mildly acidic [we get a little bit of blue/green staining on our porcelain sinks].
Unfortunately, I haven't been able to find much in the way of lifetime expectancy figures on casing pipes; about the best that I found was this old post at "Engineering Tips", talking about a storm water conduit:
YLWEA (Materials) - There are two considerations: internal corrosion from the storm water and external corrosion from the soil side. I have been doing a lot of work on external corrosion of buried steel piping, including bare (no coating) without C.P. on piping installed between 1915 and 1970. While the average of all the deepest pit depth measurements on all the various pipe samples works out a long term average corrosion rate of a couple MPY (1 mpy = 0.001"/year) the standard deviation is quite high (higher than the mean values). NACE RP0502 recommends using an assumed external corrosion rate of 16 mpy when no details of the soil environment are known and no prior history of corrosion performance in the specific soil is available or known. The 16 mpy is the 80% confidence level of worst pitting based on available published corrosion studies in soil (mainly work published by NBS in the early to mid 20th centuty). The 16 mpy is generally considered to be grossly conservative, but does include consideration of some very high corrosion rates for some steel samples that were buried for several years in some very corrosive soils.
https://www.eng-tips.com/viewthread.cfm?qid=92147
https://www.eng-tips.com/viewthread.cfm?qid=92147
At 1 MPY, 80 years would give only 0.080" corrosion, which shouldn't be that big of a problem.
But 16 MPY would give 16 x 80 = 1.280", which would long since have corroded out a casing pipe with a thickness of only 3/8" or 1/2".
Anyway, if anyone knows of good rules of thumb for lifetime expectancies of well casing pipes in the water wells of the Southeastern United States, then I'd love to hear from you.
Thanks so much!!!
