As a 14-year veteran of the fire service and a former HVAC contractor, building construction is a big part of the reason I enjoy the fire service so much. I take every opportunity to read and study the subject. This morning, I received the weekly newsletter and found the article “Plastic Fuel Gas Pipe” by Greg Havel. (Fire Engineering e-Newsletter, 12/12/07). I usually enjoy his articles, but I have some questions regarding this one. I have installed many gas lines in my time and never installed the PEX he refers to in his article. I did research on this today before responding and have raised a few feathers doing so. One manufacturer has asked for all my findings on this matter, since it feels it may need to do damage control for its product. PEX is not an approved material for installation of gas piping anywhere or in any code with which the manufacturer is familiar. The article has two photos. The first photo is not PEX or CPVC. It is the same material featured in the second photo–corrugated stainless steel tubing (CSST). It is flexible tubing with a layer of polyethylene plastic covering it…
Gregory Havel responds: The gas pipe in both photos in the “Construction Concerns” Web site article is Gastite brand, as noted by the reader. As stated in the next-to-last paragraph of the article, this gas pipe is “corrugated stainless-steel tubing covered with ultraviolet-resistant polyethylene, and uses special fittings to connect to threaded metal pipe.” An Internet search for “corrugated stainless steel gas pipe” will provide a link to www.gastite.com, and other manufacturers’ Web sites, with extensive information on materials, fittings, and installations. I included these photos and descriptions in the article, because this kind of tubing is often assumed to be all-plastic because of its plastic jacket. Sometimes, things aren’t what they appear to be.
The fittings in Photo 2 connecting the tubing to the copper pipe are by the same manufacturer and have been approved for gas service. The “compression” fittings used to join the copper pipe sections are also approved for gas service (a different type of O-ring than for water), and are installed with a hydraulic crimping tool. The installation in Photo 2 is in compliance with Wisconsin’s plumbing code; it passed state and local plan review and local and state inspections (including air-pressure testing) during construction.
The installation in Photo 2 is mostly underground, as noted by the reader. The plastic-coated, stainless-steel gas pipe runs from a gas valve manifold in a mechanical equipment room down through the concrete floor and into the soil, where it is protected by PVC pipe. It runs some distance in the PVC pipe in the soil under the floor until it and the PVC pipe are brought above the concrete floor in the science lab in the photo.
In the same building, similar installations serve second-floor science labs. The plastic-coated, stainless-steel gas pipe runs through the soil under the floor and up inside the concrete-block wall inside a PVC pipe until it is brought into the room, where it is connected to copper pipe for distribution to the work stations along the wall.
Photo 1 is from a strip mall under construction. The plastic-coated stainless-steel gas pipes run from a valve manifold in the mechanical equipment room, up inside a steel-stud framed wall, through the wood roof trusses; they are connected to black steel gas pipe before they pass through the roof to supply roof-top heating units.
Perhaps it would have been better if there had been separate articles for all-plastic types of gas pipe and for the plastic-coated stainless-steel.
This is in reference to Greg Havel’s article on plastic gas pipe. The tubing shown is not PEX or CPVC. It is better known as Flextite or Gastite (brand names). Both are flexible, stainless tubing, possibly seamless with a rubber jacket.
Also, I question the installation shown (rigid compression fittings and the use of copper). This may go against UPC codes, or it is at least an uncommon piping practice. I believe PVC is used for underground services only. I might be wrong, but perhaps there should be more research.
Endicott (NY) Fire Department
Gregory Havel responds: The second point in the letter is covered in my response above.
Regarding approvals on plastic gas pipe without the inner corrugated stainless steel liner is concerned, at the time I wrote the article several months ago and last month before the article was sent to www.fireengineering.com, the Internet search for “plastic gas pipe” listed Gastite and other brands of corrugated stainless steel tubing with plastic jacket, as well as CPVC and PEX. One of the trade association Web sites also listed these materials as approved for natural gas. This Internet search today brings up Gastite and CSST, as well as polyethylene and other materials for underground gas distribution pipe, but not CPVC or PEX. The trade association Web site no longer lists CPVC or PEX as approved for natural gas. The ultraviolet-resistant polyethylene used to jacket the CSST may be PEX (cross-linked polyethylene), since one way to provide ultraviolet resistance is to cross-link the polymer molecules.
It does not surprise me that the results of Internet searches change, since the search engines continually refine their software. It also does not surprise me that information on Web sites can change, since a Web site has none of the permanence of the printed word. Yet, most of my requests for information on materials, products, or technology result in referrals to manufacturer, trade association, or consensus standards Web sites. Even consensus standards like ASTM International and National Fire Protection Association, and the model building codes, change as a result of their scheduled review and revision. Even Occupational Safety and Health Administration regulations change, despite the common perception that that agency is an immovable object.
About eight years ago, I saw orange plastic tubing from a coil (not CSST) being installed in a small commercial building to connect gas valves in a mechanical equipment room with rooftop heating units. It had the American Gas Association (AGA) stamp on it, and the pipe fitter said this material was specified by the architect and approved by the building inspector. I do not recall the manufacturer. This installation was covered by gypsum board walls and ceilings. At the time, I assumed that this was a proper installation of a legitimate material. Today, I am wondering if it was code-compliant at the time, if it was installed under a state or other authority exception to a code, or if the wrong material was used in the wrong place.
A few years ago, this building’s new owner extensively remodeled before moving in. The orange plastic gas pipe inside the walls and ceilings was replaced with black steel pipe with threaded fittings, run up the outside of the back wall and across the roof, the architect’s preference.
Since I live and work mostly in southeast Wisconsin, I am most familiar with the materials, methods, and codes that apply here. I welcome hearing (and learning) from others from outside this area, where other materials and methods might be more common and other code requirements may apply.
|Gregory Havel is a member of the Town of Burlington (WI) Fire Department; retired deputy chief and training officer; and a 30-year veteran of the fire service. He is a Wisconsin-certified fire instructor II and fire officer II, an adjunct instructor in fire service programs at Gateway Technical College, and safety director for Scherrer Construction Co., Inc. He has a bachelor’s degree from St. Norbert College. He has more than 30 years of experience in facilities management and building construction.|