Copper Fuel Gas Piping
Julius Ballanco, PE
Copper tubing has seen resurgence in its use for fuel gas piping systems. Not that everyone stopped using copper tubing for these systems. After all, one of the most popular piping materials for LP gas systems is copper tubing. My friends in northern Virginia always praise the use of copper tubing in their 2 psi gas systems. They can run smaller tubing since the pressure is much higher.
Copper tubing is also quite popular in natural gas piping systems when connecting outdoor barbecue grills and gas lights. But copper never caught on as a popular piping material for natural gas systems inside a building (with the exception in pockets of areas in the country).
The copper tubing industry, however, decided to launch a new effort - about a year and a half ago - promoting the use of copper tubing in fuel gas piping systems. Part of the reason for promoting copper tubing is related to the increased use of corrugated stainless-steel tubing (CSST).
In many ways, this philosophy is very appropriate. Unlike steel pipe, the flexibility of CSST makes it easier to install. The tubing also can be installed in tight locations without much trouble.
Installing copper tubing is similar to CSST. You can install flexible copper tubing much faster and easier than steel pipe. It is strong metallic tubing, just like CSST.
Similar to CSST, copper tubing penetrations in wood studs and joists must be protected with safety plates. The plates are designed to prevent an errant nail from puncturing the gas piping. Most plumbing or fuel gas codes require the safety plate to be a minimum of 18 gauge.
Another code requirement applicable to both CSST and copper tubing is that the tubing must be marked as gas piping to avoid misidentifying the piping system. One copper tubing manufacturer has been producing lined copper tubing that continuously marks the tubing as gas piping. For other copper tubing, labels can be applied to the tubing.
Some in the industry may be old enough to remember when the gas industry questioned the use of copper tubing. There was concern that hydrogen sulfide in the gas could have an adverse chemical reaction with the copper tubing, resulting in premature failure. The last thing you want is the premature failure of gas piping. The consequences are normally devastating.
Today, federal regulations limit the amount of contaminants in natural gas. Hydrogen sulfide must be below a level that will adversely affect copper tubing.
One of the advantages that CSST had over copper tubing was the joining method. CSST mechanical fittings are quick and easy to install. Most contractors are accustomed to soldering copper tubing. However, soldering of tubing and fittings for fuel gas piping systems is illegal. The fittings must be brazed. This adds time, cost and skill to the installation.
Another method of joining copper tubing is with approved mechanical fittings. However, for gas piping systems, most of those fittings are for small-diameter copper tubing. You don't find many of the mechanical gas fittings in 1-inch, 1 1/4-inch and 1 1/2-inch sizes. You could always use flare fittings, but again, flaring large-diameter copper tubing is no simple task.
New Joining SystemWhat I believe will revolutionize the copper tubing industry for fuel gas systems is the new joining system being introduced. Well, it is not new, but it is for gas piping systems. The new “system” is copper press fittings.
One of the copper press fitting systems just received approval (and listing) for the use of its fittings in fuel gas piping systems. With a listed mechanical joint, the fittings are approved for use by the National Fuel Gas Code, the International Fuel Gas Code and the Uniform Plumbing Code. Press fittings have been extremely popular for water piping, hydronics piping and steam systems.
But the fuel gas press connect fittings are not the same as the water piping press fittings. If you are experienced with press connect fittings, you probably are asking, “How can you use a system that has an elastomeric o-ring in fuel gas piping?”
While the o-ring is strong and durable, a gas piping system pipe joint needs to stay intact during a fire situation. If the o-ring melts in a fire, the fuel gas will leak, causing a larger fire.
Well, the press connect fittings for fuel gas piping are different than the water fittings. The gas fittings use a high-temperature o-ring that can withstand temperatures in excess of 800 degrees F. Hence, the press connect joint can withstand the temperatures experienced in a fire condition without allowing a leak.
The manufacturer has used a yellow marking on the outside of the fitting to distinguish the gas fittings from the water fittings. Basically, the difference in the two fittings is the o-ring. Thus, the same joining tool and jaws can be used for both the gas fittings and the water fittings. The joint can be made in four seconds with the plug-in tool and seven seconds with the battery tool.
With the advent of press connect fittings for copper fuel gas piping, copper tubing may be considered more often for natural gas piping inside a building. The speed of installing CSST will be matched by the speed of installing copper tubing. Of course, black steel pipe will continue to lag behind, requiring the most time to install.
It is interesting to note that, within a short period of time, copper press fittings have gained acceptance for water distribution systems; hydronics and steam piping systems; have been listed for both wet and dry automatic fire sprinkler systems; and now have been approved for fuel gas piping installations.
If you have not already tried press connect fittings for copper tubing, you may want to seriously consider it now. There is a trend moving in that direction. As for using copper tubing in fuel gas piping, again, something to seriously consider.