DIP sewerline coating
DIP sewerline coating
(OP)
quick survey - which is the better interior lining for ductile iron pipe sewerlines, epoxy or mortar?
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RE: DIP sewerline coating
Just a guess, but for gravity sewers where H2S gas is likely to be present, along with other aggressive chemicals, a cement mortar lining would seem to offer little protection.
RE: DIP sewerline coating
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: DIP sewerline coating
RE: DIP sewerline coating
Epoxy lining for DIP sewer use is the standard for every utility I am aware of (about 15).
As usual, RWF7437 is correct. A cement mortar lining offers no protection due to the H2S.
I've also run into the DIP only restriction. I don't understand it, because PVC is appropriate for sanitary sewer use in most situations.
RE: DIP sewerline coating
RE: DIP sewerline coating
I have the following:
1) Provide linings to a minimum thickness of 40 mils. Lining shall be Ceramic epoxy, "Protecto 401" by U.S. Pipe.
RE: DIP sewerline coating
RE: DIP sewerline coating
RE: DIP sewerline coating
It is true that if there are some specific conditions in gravity or pressure sewer applications (these are not necessarily omnipresent conditions, they involve many factors/variables, and these variables are now pretty well-discussed in many authoritative ASCE, WEF, and EPA etc. publications) that result in continuing biological/biogenic conversion of H2S gas to extremely low pH sulfuric acid, this can be aggressive to a great many materials, including even good quality cement mortar linings and iron. Among the design considerations that are reportedly involved in evaluating such conditions e.g. according to ASCE MOP #'s 60 and/or 69 are high wastewater temperature, high sewage concentration (or lack of dilution), "very slow" flow velocities, waste solids intermittingly agitated, in effect sort of aged sewage in very large, long trunk lines, high concomitant H2S concentrations, and also must have areas/head space etc. that are non-full for extended period of time etc. It is also true that e.g. extremely acidic chemical/industrial waste discharges might also have direct effect, though in that case one would think e.g. most on the bottom side of the sewer, but I suspect such discharges are now discharges largely prohibited (into modern municipal systems) by regulatory organizations such as EPA or state etc. agencies.
Where per Engineering analyses such very aggressive conditions (as the biological conversion of H2S to very low pH sulfuric acid etc.) might occur, I believe the linings now most frequently applied to DIP are types of quite high-build epoxies such as "ceramic epoxy" (as can be searched from many portals, including previous responses).
RE: DIP sewerline coating
Here is our local standard for sanitary piping.
See pages 10 through 12 for epoxy lined specification section with ASTM references.
RE: DIP sewerline coating
RE: DIP sewerline coating
RE: DIP sewerline coating
RE: DIP sewerline coating
RE: DIP sewerline coating
You are correct in thinking that the sewer must go septic (oxygen deficient or anaerobic) but if the source of the H2S is another intercepting sewer, the size is not an issue, all sixes will corrode, unless they flow full and are kept full.