Question No. 1:
I have a problem
with fire hydrants corroding in an unusual manner. It seems that the outside of the bolt heads on
the fire hydrants is disappearing; that is, they just shrink away. This isnít a citywide problem but
it occurs intermittently here and there. The city Water Supervisor believes that it may be due to
voltage potential on the fire hydrants. He suggested that bonding jumpers to the water pipes in the
homes should be removed. I donít think that is the answer.
Do you know of a way that we can test the fire hydrant
and its general proximity to see if there is a problem with voltage at the hydrants? Or, do you think
that there may be another problem that is causing the bolts to disappear? This is a rather perplexing
situation that I havenít been able to get any concrete answers to. I hope that you may have some suggestions
for me or perhaps you can send me to someone that may have the answers. Thank you for any information
you may have and, keep up the good work!
Joe Stammeyer, firstname.lastname@example.org
Response No. 2:
My company has a similar problem that I would like help
with. At one of our convenience stores, the copper water piping entering the building has rapidly
corroded. The building grounding system is bonded to this copper pipe. Do you know what the cause
and cure for the problems are? My guess was that current was being impressed onto the copper pipe
causing it to corrode. I was going to suggest installing an anode bed in the ground to sacrifice itself
over the copper pipe. What do you think?
Michael Chow, MHChow@MAPLLC.com
Response No. 1:
I suggest you look into cathodic corrosion protection at
the location this occurs. I doubt the house grounds cause the corrosion. If it were, it would occur
everywhere there are houses or other buildings with that type of grounding (all buildings with power
and metal water pipes).
Response No. 2:
I think the fire marshal just got a batch of cheap fire
hydrant bolts and the heads are simply rusting away!
Earl C. Dean
Response No. 3:
Have the fire department check for dissimilar metals between the bolts and the hydrant bodies. This
sounds like a classic case of electrolysis.
Response No. 4:
As a former Chevron engineer, I can tell you that pipeline
corrosion is very complex. I suggest that you obtain a good corrosion protection manual or consult
an engineer who specializes in corrosion problems.
Response No. 5:
I donít believe grounding is any part of the problem. As
an industrial electrician, it would seem the better you are grounded the less opportunity there is
for any cathodic action. In Alaska here, we do use a ground grid under the oil tanks in our tank farms
consisting of titanium and another sacrificial anode tied in with sodium bromide bags, at an outrageous
cost. Have you contacted other fire departments around the country with a typical climate such as
yours in seeking solutions?
I have no personal experience here but would give serious
consideration to contacting the U.S. Navy about your metal corrosion problem. They must have a team
of experts in metallurgical problems. The problem may be that if dogs are relieving themselves, the
system is rich in hydrochloric acid thus creating problems.
Rocky Dippel, email@example.com
Response No. 6:
like a cathodic protection problem. Major pipelines use this method to keep their pipelines from disappearing
prematurely. I know that there must be some corrosion analysts in your area. I would contact them.
Also, see if other water utilities in the immediate area are using cathodic protection. Your problem
could be one of induction. Good luck! Corrosion problems are never easily solved.
Response No. 7:
It could be a weird case of electrolytic action, either
due to the already stated potential differences causing highly rapid oxidation, or perhaps the bolts
are of a dissimilar metal or alloy relative to the hydrant body. This alone would create metal destruction.
The services of a competent metallurgical lab are required for this one.
Allan Soifer, firstname.lastname@example.org
Response No. 8:
Disregarding bonding jumpers should not be done. One thing
you might try would be to get a special alloy bolt that will not deteriorate by electrolysis, one
that is the same strength as the steel bolt.
Charlie POPPE, Cpopinc@aol.com
Response No. 9:
My name is Ed Chavern and I teach a seminar that covers
this topic. With the correct meter, which costs about $100, the current and the source of the problem
can be detected. Donít disconnect any jumpers. This is a problem that is not too difficult to correct.
Ed Chavern, Chavernet@aol.com
Response No. 10:
I believe the problem is something else; however, one way
to test if there is voltage potential on the hydrants is to drive an independent ground rod (a short
one) about 18 inches into the soil 3 to 5 feet away. Then take a voltmeter and read AC and DC voltages
from the hydrant to the independent Ďrodí. If more than a couple of volts are measured, then some
electric circuit is not returning the current back to its source. This can be a bad connection or
an open circuit. Investigation must take place by the Utility and/or nearby electric users. If higher
voltages are detected, then underground corrosion is a strong possibility and can be very dangerous.
The problem can be cathodic or anodic. Any metal part touching the earth will deteriorate where the
current ďgets off.Ē
Ron Nelson, email@example.com
Response No. 11
I would suggest looking for a source of DC, not AC current.
The only source I could think of would be electrified trains. I worked for the Chicago Transit Authority
for 10 years. This kind of thing was a common problem in and around rail terminals. If anyone still
thinks home ground jumpers could be the problem (I doubt it myself), a piece of plastic pipe should
be inserted by the city in new water main hookups OUTSIDE the home, at least 10 feet from the building.
This will allow for the grounding properties to remain, while removing the possibility of current
flow through the pipe.
It has been my experience that if there is a problem with
AC current in a water main, it is the fault of the Power Company, who has loose neutral wires. Green
scum (copper from the pipes) can sometimes be seen in washbasins and toilets. Dimming and brightening
of lights is also a symptom.