This pipe pinholed and started spraying. The pinhole was roughly in the middle of the 5" long section of type M pipe. You are only seeing about 3 inches, the rest I cut off. The vertical portion (that section attached to the 1/2"C x 3/4"FPT adapter) had lost material and had become very thin. The horizontal section looks ok, with no signs of loss of material.

This was the hot water outlet on a gas-fired water heater. No recirculating pump. The adapter shown is brass, not copper. The steel nipple on the water heater seems fine, with no loss of material. I don't see much of this type of erosion with Toronto city water.

The water heater was installed in 2003, as per the date on the tag on the gas pipe

What might be the cause of this erosion?



Edited 2 times.

type 'M' eroded after 11 years

type 'L' probably would have lasted 20 years

type 'K' would last 40 years

red brass about 60

Pex ?????

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I just don't think this is normal for type M. There must be a hundred thousand houses in Toronto piped the exact same way and I would be coming across a lot more of these failures if this was normal.

Perhaps stray currents? I did not think to check for stray current while I was repairing the leak.

may not be normal

my figures still stand as a basis for comparison

opinion/possible:

heater was replaced in 2003 with a slight 'repipe'
plumber got the tube from a big box store
big box stores 'occasionally' sell junk



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

type m should last a lifetime....could be a defect in the pipe/fitting

typically when I see pin holes its from recirc pumps

It is a power vented heater. Next time I am called to the house I will use an amp clamp around the pipe to see if any current is flowing when the heater is on. Perhaps the neutral is grounded at the heater control box and some of the inducer fan current is flowing through the pipe.

in Canada, as you are from Toronto, a dielectric unions need to be used on the inlet and outlet piping off the water heater to seperate dissimilar metals from making contact ie: brass/copper and steel. corrosion occured because of this, the anode rod will be gone in the water heater, eaten by the problems

I seldom see dielectric unions on water heater connections in Toronto, it is just not used. The vast majority of water heaters are hooked up the way the water heater referenced above is, with the larger/newer houses having 3/4 in copper pipe, instead of the 1/2 in.

I had not considered a used up anode rod, thanks for the suggestion.