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As you may or may not know, the installation of plumbing pipes and fixtures is governed by a set of rules, known as the Universal Plumbing Code (or “UPC”). The UPC rules are rarely more important than when dealing with gas lines. This is especially true for black iron gas lines.
What is a black iron pipe?
You may be familiar with “galvanized pipe for gas”. Black iron pipe is, simply put, the same thing, but without the zinc coating. The zinc coating on galvanized pipe for gas is meant to keep the pipe from corroding from contact with moisture. While it does its job pretty well, over time, it still does corrode.
Since black iron pipe does not have the zinc coating, it will corrode very quickly if exposed to water. For this reason, it cannot be used for water or waste piping. It is, however, very popular for gas piping. One reason is because it is less expensive than galvanized pipe for gas. Another is that it is easier to differentiate it from water piping when crawling around under a home.
So, can black iron be used for all gas piping?
This is where the UPC really comes into play. There are specific rules for where black iron gas pipes can be used, and where they cannot. If used in an incorrect location, it can become a very serious safety hazard.
To put it simply, black iron pipes can be used for gas under your home, in the crawl space or basement, inside the walls, or in the attic – basically where it is not exposed to earth or the elements (moisture). This is because of the lack of anti-corrosive coating.
For gas lines that must be run under ground, a special type of black pipe should be used that is coated with a special plastic material that keeps the moisture out. This is so it is easily discernible from underground water lines, and also because the plastic coating actually protects the pipe better than a galvanized coating would.
Care must be given, however, to make sure that any exposed pipe is covered by pipe-wrap glue and 10mil pipe-wrap tape. This includes the joints, and any marks in the coating from pipe wrenches, etc. The glue is important because it seals any small gaps that may be created in the taping process.
Once, the gas pipe comes up from the ground (called the “riser”), it can continue to be wrapped, but must then transition to galvanized. I am not sure why that must be. It is also allowed to use black iron if it is probably coated with a galvanized coating (which is basically a special “paint”). PG&E often does this when plumbing in their gas meters.
There are other rules for where you can and cannot run gas lines, as well as rules for the minimum sizes required to supply gas to all of your fixtures/appliances, as well as other materials that can be used, but those are topics for other articles. The most important thing that we are hoping you take away from this article is to make sure that the plumber you have working on your gas lines is an expert.
At Gogo Rooter Plumbing, we have repaired and installed hundreds of gas lines, and have become very good at it. Trust nothing less for your black iron gas lines than one of the experts at Gogo!