Average Life of Galvanized Pipe

I cant remember the official figure but it must be about 50 years. I have seen 65 year old pipes that is almost brand new.

Where I live we have an intermittent supply of dolomite and normal water and we have 15 year old pipes that is badly rusted/scaled and even with holes. The threaded parts where it screws into sockets, tees and elbows are also erode away resulting in leaks.

Test the pH of your water, maybe the water quality is your culpret.

About cleaning - depends on the reason. Eroded pipes may not survive.

adrian, This corrosion sounds quite excessive for the pipes age. Check your system for the presents of electrical current, I had a copper system that corrosion eat holes completely though in 10 years time. The copper attached to PCV just outside the building so wasn't suitable as a ground. The electricians that wired the structure had attached 1 ground from the heating system to the copper water feed line passing by. With a volt meter I found there was 12 to 18 volts AC present when a connection was made from an outside faucet to earth. The power company checked and found the original system ground was more than adaquet. Even though I installed another 8 ft ground and attached to the copper pipe at the same point the electricians had connected their furnace ground but there was no change. The power company came back and installed 2 additional grounds and still no change. Their Engineer told me they found when two different power grids operated close to one anouther they commonly found this situation. 4 grounds on the system, 3 on one end of structure and 1 on the other, I had one engineer suspect the system was acting like a battery but I could not accept this due to it being AC verses DC. Check for current and good luck eliminating it. I know this not exactly the informtion you had asked for but this needs to be checked due to the problem at hand, without eliminating the cause of the corrosion your cleanning will be useless for eventually you will run out of pipe to clean. J.Conway .

Hello adrian,

I am not getting at you in any way OK.

But, what good would you knowing about the life of Galvanized pipe be to you. What are you going to do sue the people who made the pipe?

It sounds like you are in a 'hard' water area and the calcium naturally deposits in time. That together with the possible electrolysis from an earth point and it would easily rot through in ten years. As mentioned by Jerrell. Essentially if electrolysis is a problem the pipe becomes an Anode and gradually wear away.

That however is not your problem. Your problem is you have pipe that is no longer usable. You have no choice but to leave that where it is and fit a new pipe with a water softener as it comes into your building. Or take the old pipe in and replace doing more or less as I have said above regarding the water softener. If this is not possible because it supplies I drinking water tap or faucet in the US. In fitting the new pipe fit a reverse osmosis filter as the water enters the building. You get 5 micron or you can have a two stage system where you go through a 10 micron filter first, then on through a 5 micron filter. This twin system is better as most of the calcium get caught in the first filter, leaving the second 5mic' filter to remove anything left.

Although you will need to replace both filters regularly, you will not need to replace the finer gauge -5 mic' filter nearly as often. This can also be used outside if it is not prone to freezing. If it does freeze then it will still be better outside so that any pipe from the RO filters are are clean, and any pipe from the mains to the filters can be replaced if need be at relatively low cost. As you are replacing a short length of pipe which is easily.

Again, I meant no insult in giving this advice.

Take care and bite the bullet and fit a new pipe with the RO before the pipe enters the building or fit it just inside the building in an easily accessible place.

http://en.wikipedia.org/wiki/Reverse_osmosis#Drinking_water_purification

http://en.wikipedia.org/wiki/Electrolysis#Electrolysis_of_water

http://www.google.com/search?hl=en&q=reverse+osmosis&btnG=Google+Search

http://www.freedrinkingwater.com/parts-commercial-reverse-osmosis.htm

Good luck............

First you don't use galvanized pipe for drinking water anymore- copper or plastic. (details on galvanized at www.galvinfo.com )Life expectancy depends on several things - Zinc coating (failure defined as significant red rust) G-40 under 20yrs, G60 under 25yrs, G90 under 35 years up to G210 under 65 years. G60 to G90 most common on pre-galv. Now we have companies that mfg galv tube from pre galv coil (material galvanized on both sides so protection is on both sides). The other product by Allied & Wheatland are galvanized on the outside and primered on the inside so they rust quicker on the inside. Have seen a football bleacher being replaced after 10 years due to rusting from the inside out. Hard to say what type of tube you received. But the only houses and building I see galv pipe in are over 30 years old and have to be replaced upon sale here.

There might be a service in your area that can clean out the interior of pipe and then coat the interior of the pipe with a plastic coat. If I dig up the web site, I will pass it along for your research. It is an expensive process, but can be cost effective and less disruptive than tearing out walls to install new plumbing. Shop carefully, and verify.

"Average" life for galv pipe is based on a wide number of variables. It sounds like you are one of the unfortunates who represents the very low side of average.

http://www.americanpipelining.net/

http://curaflo.com/AboutCuraFlo.aspx

A couple of web sites for "in-place" pipe relining. I need to correct my earlier mis-statement, the coating is epoxy, not plastic.

The galvanized pipe is not proper for human water in a house anymore, now it would be copper or certain approved types of plastic pipes.

The probable cause of the corrosion in the pipe is electric currents, usually you will find the electric panel bonded to the water pipes. There should be an insulating union, this may have been bridged by the rust/iron in the water.

There is also the possibility that the pipes stood unpressurized with standing water and air in the pipes.

Galvanized culverts used under driveways are not meant to be in standing water as they will rust out quickly. If the pipe is buried and the groundwater is high where the pipes are installed or if in the basement the pipe is uninsulated and there is condensation rust will attack the outside of the pipe.

If the water velocities are high enough erosion of the pipe interior can happen. This would be near bends or elbows.

If the corrosion is in the interior and in a straight length of the pipe usually it will occur under a scale accumulation, causing perforation pinholes.

I was the stock clerk in a pipefitting shop for about 5 years and this is what I saw in returned pipes and have learned as a hydro-electric power plant start-up (erection engineer in the hydro industry).

My estimate would be 30 years for galvanized pipe. That estimate comes from renovation work. From my experience degradation of efficiencies is not fully appreciated at the time of initial construction. Even Frank Lloyd Wright and his guys got galvanized pipe wrong and the Roby House concrete had to be jackhammered. Can't really beat PVC, or Copper. It does last longer. Rule is: pay now or pay later. The suggestion that you replumb while existing galvanized works at some level, is a good one.

the life depends on many factors like quality of the water, pH, flow velocity..

have a look at the links where you can find "Corrosion of Zinc and Zinc Coatings Immersed in Various Industrial and Domestic Waters".

As u can see the corrosion rate is in the range 15-150 micro m/year depending on water properties.

regarding the scale inside the pipe it depends on the type of water and chemistry, here you can find a calculator that allow you to define if your water is protective or not based on langelier index.

hope this help

V

corrosion prevention & corrosion protection

With all of the good comments will you please look at this topic -

Home | Chemical & Material Science | Chemical & Material Science | Ship Hull Preservation There may be something you can add.

Does the chlorine level in the water efect the galvanising? We have run our chlorine for our plant at about 5ppm in the past. Some of our galv pipe rusted out in under 3 years.

Short answer is yes. Chlorine is an agressive corrosive for metals.

5ppm doesn't sound like too large a level, but I know enough about water chemistry to be dangerous. I would be interested to see how others respond.

You mean chloride or chlorine gas added to the water?

the chloride has an effect on corrosion resistance of GS. 5 ppm is not so high. i think that you can use the data for fresh water corrosion linked below:

http://www.galvanizeit.org/aga/about-hot-dip-galvanizing/how-long-does-hdg-last/in-water/water-corrosion-data//#seaWater

as you can see from this ref :"the most corrosive to zinc being chloride in excess of 50 mg/L" that is 50 ppm

http://www.galvanizeit.org/aga/about-hot-dip-galvanizing/how-long-does-hdg-last/in-water

the corrosion in water is a function also of the quality of water, soft or hard.

hope this help

corrosion prevention & corrosion protection

great info, thank you

(am looking into applicability of gs for sample coolers with high chlorides - I only expect a couple of years, and stagnant conditions must be avoided - better than cs and bullet proofing with inco's (for example) is not an option)

Wesky in Alberta

Hello adrian,

You have all these various info sites and several people giving you different answers, really only 'estimates'. Because it all depends on the Ph of the water and of the external air. Which no one can know apart from you?

You needed to do something about this pipe rusting........What are you going to do? Bear in mind it is no longer the correct way to supply clean drinking water.

I cannot see this as an insurmountable problem. It cannot be said to be 'too costly' either. You have to change it before someone gets ill. You will have to replace it in the long run so why not now?

You can remove the pipe from the outside and remove any pipe inside. You can then put any Cu or plastic pipe through the same external wall hole and connect to the mains, minus the original galvanized pipe. At most it will cost a length of pipe and maybe a tap. It is hardly worth worrying over is it? If you had to pay the 'going rate' (whatever that is) for asking half a dozen qualified Engineers what they think, the job could be done in gold pipe!

So what are you doing?

Take care and good luck......................

Dear Mr.adrian,

A span of 12 years is certainly a short period. If Scaling Effect and Corrossion Effect ( indicated by RYJNER FACTOR and LANGELIAR FACTOR) is between 0.2 to 0.4, for both Factors, THE SERVICE DURATION SHOULD BE AROUND 50 Years and more.

You have not posted the details of water analysis. Yhat is required to understand the Problem.

What I understand from your posting is that scaling is very bad and brownish in colour - suggests that it will contain more Fe., which is harmful for Health.

I suggest use on-line treatment - and expenses will be relatively small than replacement of pipe once in 12 to 15 years. I have faced a similar problem, and simple on line filter/treatment has solved my problem. Pl. get the water analysed and post the details here. Then some suggestions will come from CR4 MEMBERS.

DHAYANANDHAN.S