Galvanized lining for potable steel water pipe?
Galvanized lining for potable steel water pipe?
(OP)
Is it a good idea or bad idea to galvanize both the inside and outside of potable steel water pipe (2-inch size)? I know the galvanizing will over time taint the taste, but I heard the amount of chemical that leaches out into the water is not dangerous. True? Are there any health departments you know of that do not allow this? Would the piping suffer early corrosion if it was not internally lined by galvanizing?





RE: Galvanized lining for potable steel water pipe?
About health danger: Zinc is a heavy metal. That does not have to mean anything but it does not sound good for me.
RE: Galvanized lining for potable steel water pipe?
Orenda
RE: Galvanized lining for potable steel water pipe?
Galvanized piping is commonly used for building services. The extent that piping corrosion occurs depends to a large measure on the characteristics of the water.
For the most part, galvanized piping is in common use and it would be rare if enough material leached off of a pipe to create a hazard.
RE: Galvanized lining for potable steel water pipe?
RE: Galvanized lining for potable steel water pipe?
I want to clarify something that was said above, i.e. that galvanized pipe is ALWAYS inside and out. That is not true. We are seeing pipe from China that is capped at each end before it's dipped so only the exterior receives the galvanizing. So, in our case the contractor was trying to use pipe that was not galvanized on the inside (even though required) and likely from a facility that is not certified to NSF Standard 61. I point this out as a caution to others that galvanized pipe does not always mean both inside and out.
Thanks again for the input.
RE: Galvanized lining for potable steel water pipe?
While I guess all of us with any degree of experience understand the difficulties of building anything with 100% control and compliance with every law, rule and regulations out there (when we must after all in the end, "Git er' done!), and cheap prices are also a powerful incentive to many, it is my understanding per status a couple years ago (e.g. see site at http://
"NSF/ANSI Standard 61: 46 states and 11 provinces/territories have legislation, regulations or policies requiring or recommending drinking water system components to comply with NSF/ANSI Standard 61."
At some point one would almost have to think that some degree of enforcement might follow, at least to try to assure some level of reasonably substantial compliance (and to minimize risks to the Consumer).
"There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man's lawful prey." John Ruskin 1819-1900
RE: Galvanized lining for potable steel water pipe?
ANSI/NSF-61 establishes minimum health effects requirements for the chemical contaminants and impurities that are indirectly imparted to drinking water from products, components, and materials used in drinking water systems. This Standard does not establish performance, taste and odor, or microbial growth support requirements for drinking water system products, components, or materials.
Galvanized pipe must be specified to meet the ASTM A53 pipe performance standard:
http://www.astm.org/Standards/A53.htm
The ASTM A53 standard requires pipe to be hot dipped galvanized. At the present time, galvanized pipe for potable water applications is ALWAYS required to be galvanized on both the interior and the exterior.
Galvanized pipe and tube is produced by two methods; one is semi-continuous where stock lengths of tube are cleaned and passed continuously through a bath of molten zinc at 450 degrees centigrade.
The other method is continuous where strip is formed into tube from coil and the tube then passed through a bath of molten zinc at 450 degrees centigrade. This second method coats the exterior of the tube only.
Coating characteristics: The semi-continuously applied coating is a conventional galvanized coating having a coating thickness typically around 65 microns which consists largely of zinc-iron alloy layers as the free zinc layer is largely removed through air wiping during the process. The continuous tube galvanizing process produces a bright coating which is almost all free zinc with very thin alloy layers, giving the product good forming properties. Coating thickness is typically 12-25 microns on the exterior of the tube only.
General or hot dip galvanizing involves preparing work by acid pickling in batches or on jigs and then dipping the work into a bath of molten zinc.
Coating characteristics: The typical general galvanized coating ranges from 65 microns to over 300 microns depending on the steel analysis, thickness of material and immersion time in the galvanizing bath. Typical coating thickness on most general galvanized products is 80-100 microns.
The exterior coated galvanized pipe is not used for potable water applications.
http://www.idodsystems.com/galprocess.html
http://ww
Finally, this is not a good application for galvanized pipe. Your best choice for piping materials in marine applications is not galvanized pipe but a non-metallic piping system such as FRP. The joints on galvanized piping are susceptible to corrosion when the pipes are threaded. FRP has many of the properties of metallic piping, without the corrosion and can be interchanged with the metallic piping.
http://www.ameron-fpg.com/files/pdf/FP707A.pdf
http://ww
http://www.ameron-fpg.com/files/pdf/FP845A.pdf
RE: Galvanized lining for potable steel water pipe?
RE: Galvanized lining for potable steel water pipe?
RE: Galvanized lining for potable steel water pipe?
http:/
http:/
http://www.mms.gov/tarprojects/392/392.pdf
"No material or combination of materials has the answer to all the problems faced in the rugged offshore/marine environment, says McDermott's Landry — there are advantages and limitations to all groups. "Disadvantages of FRP are impact resistance, initial cost of material vs. carbon steel and some reluctance on the part of regulatory agencies. On the other hand, composites offer corrosion resistance, light weight, ease of installation, no maintenance and long service life."
http
RE: Galvanized lining for potable steel water pipe?
The article lacks details of the installation (ie. pipe material, construction method, pressure, etc.), and smacks of a typical municipal cheap political trick.
RE: Galvanized lining for potable steel water pipe?
RE: Galvanized lining for potable steel water pipe?
However, the article does not state what material (pressure rating) was specified, whether the specification was adequate for the intended use, whether the furnished material met the specification, whether the material was installed correctly, why the material was failed, yada yada yada.
In summary, it is difficult to develop a technical discussion off of a newspaper article written by a non-technical person.