GAS CONNETORS: AN EXPLOSIVE PROBLEM
BY HARRY J. OSTER
The uncoated flexible brass gas appliance connector, generally found in three- or four-foot lengths, has the potential to fail and cause a fire or explosion.
The U.S. Consumer Product Safety Commission estimates that since 1980 the uncoated brass flexible connector has been associated with about 40 deaths and 65 civilian injuries nationwide. No injuries or deaths were reported to be among firefighters.
However, to put this problem into a more realistic perspective, consider that within the suburban village of Spring Valley, New York, which has an estimated population of 22,000 residents and is located approximately 27 miles north of New York City, the fire inspector claims to have responded to 10 gas leaks over the past year (1996-97) that involved a faulty connector (uncoated brass, plastic epoxy-coated, or stainless steel). Two incidents were confirmed to be attributed to the uncoated brass style. One of these incidents was a serious fire that occurred in March 1997.
HISTORY
The flexible metal gas appliance connector, as described by the ASA Z21.241 standard, was originally introduced in 1942. Uncoated “corrugated” brass alloy is believed to have been the leading material used in manufacturing the connector, which continued to grow in popularity through the 1960s. Due to the noted flaws that developed, this type of gas appliance connector has not been manufactured since the mid to late 1970s. Since the level of inventory of this connector at the manufacturing, wholesale, and retail levels was not known, it cannot be estimated when the last connector of this type was sold or installed on an appliance.
One of the leading corrosion problems associated with the uncoated brass flexible connector during 1971 and 1972 was accelerated stress corrosion cracking from exposure to ammonia found in household cleaning products and, to a degree, the atmosphere.
IMPROVEMENTS TO THE CONNECTOR
Protective coating applied. In October 1973, the ANSI Z21.24 standard was revised to require that a protective coating be applied to the outside surface of the connector. The most popular coating used is the plastic “epoxy” coating, which is gray or black in color. With this improvement, the connector was also able to withstand an ANSI Z21.24 standard “torsion test” of 15 90-degree twists and a “bend test” of 30 bends without leaking or tube damage. It now offered resistance to corrosion from ammonia and many chemicals.
Methods of joining the tubing to the end piece. Another leading problem associated with the uncoated flexible brass connector was the manner in which the tubing was joined to the end piece. They separated over time.
In October 1973, the ANSI Z21.24 standard was revised to prohibit phosphorus-type materials to be used as part of the soldering or brazing compound used to join the end piece to the tube portion of the connector because it led to joint deterioration.
In September 1981, a revision to the ANSI Z21.24 standard was issued. It stated that the soldering or brazing compound used to join the end piece to the tube portion of the connector was to be able to sustain a temperature rating of not less than 1,0007F. In April 1993, the ANSI Z21.24 standard was revised. It completely disallowed soldering or brazing the end piece to the tube portion of the connector. The ends of the tube are integrally rolled out and flared.
End nut redesigned. Yet another problem associated with many of the uncoated brass and some epoxy-coated flexible connectors was that the nut on the end of the connector could inadvertently be connected to a standard tapered 12-inch piece of pipe without using a connector end fitting. This practice could, and often did, lead to gas leaks.
In August 1979, the ANSI Z21.24B standard was issued. It disallowed the use of a connector nut with standard 78-inch-14 threads per inch (tpi), which could be inadvertently connected to a regular piece of pipe. This type of connection was prone to developing a gas leak. Thus, the “Massachusetts Nut”2, an odd-sized nut with 1516-inch-16 tpi threads, was developed and is now used on the ends of the connector. This nut prevents the connector from being connected directly to a piece of pipe. Now, a “connector end fitting” must first be connected to the end of a regular piece of pipe, followed by the “Massachusetts Nut,” which is connected to the connector end fitting. This method helps to ensure a proper “transition” connection.
Another material introduced. In March 1972, stainless steel flexible gas connectors, which are silver in color, were introduced into the marketplace by a small but growing company based out of Pennsylvania. However, it wasn`t until about July 1987 that this type of connector began to be mass-produced by a larger manufacturer, which, in turn, made a large usage impact on the market. The leading advantages of the stainless-steel flexible gas connectors over the plastic epoxy-coated connector include the following:
–They can be used outdoors or places where appliances are subject to vibration during normal use, such as a pulse air furnace.
–This connector was also able to withstand an ANSI Z21.24 standard “torsion test” of 15 90-degree twists and a “bend test” of 30 bends without leaking or tube damage.
–The stainless-steel connector also offers superior resistance to corrosion from air pollution, petroleum products, ammonia, fatty oils and grease, most household chemicals, and liquid petroleum and natural gases that have a high sulfur content.
WHICH CONNECTOR IS BEST?
Obviously, the uncoated brass connector should not be used based on its history. This leaves the epoxy-coated and stainless-steel connectors. Which one is better, I believe, largely depends on the intended application. However, safety is the main issue. Although I have not personally observed any, I have been told that both types still may have occasional flaws due to quality-control problems.
Epoxy connectors. These connectors have been known to have “holiday errors” (little blemishes in the coating that expose the bare corrugations) and “epoxy overspray at the flare seat,” which could cause internal electrical arcing.
Stainless-steel connector. This type of connector has been known to have small openings develop anywhere along its seam. Why? Because stainless steel is a harder material than brass, it must be rolled and welded rather than extruded in one piece, as in the case of brass. There has also been a problem at the flared ends, where a fold (ridge or bump) from the fusion inert gas welding process can remain on the flared seat because the material`s hardness makes it difficult or impossible for a leakproof joint to be made.
In general, all of these problems should be detected during the multistage testing process prior to shipment from the factory or during the initial field installation of the connector and therefore are generally corrected immediately to alleviate severe consequences. The constant vigilance of the ANSI subcommittee helps to encourage the gas connector industry to produce safer products. The gas connectors of today are far superior to those produced in the past.
OPERATIONAL CONSIDERATIONS
The following safe operating guidelines should be followed when responding to the scene of a gas leak, even if an uncoated brass flexible gas connector is not involved.
Avoid moving the appliance. The slightest movement of the appliance, for whatever reason, can cause a connector of this type to fail and possibly cause a serious gas leak, fire, or explosion. Move the appliance only after you are sure you have located the gas shutoff valve for the appliance and perceive that you can shut it with little or no difficulty. You may also want to consider posting a member at the meter or main shutoff valve in case the individual appliance valve fails to operate.
As a rule of thumb, appliance and building meter gas shutoff valves or gas cocks require only that you to turn the handle a quarter turn to close. Also note that these valves are of the noncontinuous rotational design. Therefore, if you encounter severe resistance, try turning the valve in the opposite direction. The older type of ground seat valves require a tool (pliers or the fork end of a halligan, for example) to turn the valve handle. However, with the new stainless ball designed type of valve, you can turn the valve handle with relative ease using your hand.
Open any windows or doors in the affected area(s) quickly. EXCEPTION: For a structure other than a one-family home, close–but do not lock or latch–the door leading into the public hallway. This practice will help to keep the gas fumes from entering the public hallway and will maintain easy access into the affected area for a representative from the utility company or other firefighters.
Do not use anything that could create a spark in the immediate area of the suspected gas leak. This includes using communication equipment, a doorbell, a light switch, a phone, and so on. Note: The “ripe” ignition ratio for natural gas to air in a given area is between four and 15 percent. If conditions are below four percent, the ratio is too lean; if it is above 15 percent, the ratio is too rich to readily ignite. However, it`s important to note that a dangerous condition still exists until the source of the leak is controlled. This is especially true when a higher ratio starts to drop down into the “ripe” ratio (via venting an area) on the way down to the final 0 percent ratio.
Once the appliance or meter(s) is turned off, do not turn it back on! Leave this task for the responsible party, which may be the utility company, a building superintendent, or a plumbing contractor.
Consider immediately shutting down the gas meter on the outside of the building on your arrival on the scene if there is a strong odor of gas, an explosion, or a fire, especially if the meter is readily visible. n
Endnotes
1. Prior to October 1969, ANSI was known as USASI (United States of American Standard Institute) and as ASA (American Standard Association) before August 1966.
2. “Massachusetts Nut” is a local term used to describe a new fitting for gas connectors developed by the ANSI Z21.24 subcommittee in the early 1980s. This new fitting could not be directly connected to a standard IPS tapered pipe thread. It`s believed that Massachusetts was the first state to recognize that the previous adapter, which could be connected directly to a standard IPS tapered pipe thread, could become vulnerable to gas leaks. Consequently, its use was disallowed.
Disclaimer: The information and views expressed in this article are meant for informational purposes only and are based on the actual field experiences and research performed by the author. The material does not necessarily reflect the views of other firefighters, plumbers, gas associations, or manufacturers of gas connectors. Obtain legal and safety advice before attempting to act on any of the above information or applying it in the field.
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(Top left) An old uncoated brass connector with corrosion. Note the charring underneath the wood cabinet. This connector was involved in the March 1997 fire in Spring Valley, New York. (Photo courtesy of the Office of the Spring Valley Fire Inspector.) (Top right) An epoxy-coated brass connector (ID band date: 1976) with the old (78 inch-14) nut that could be connected to a 12-inch IPS nipple. (Bottom left) A stainless-steel connector (ID band date: 1987) in use with a pulse-type furnace. (Bottom right) Uncoated connector with corrosion and old nut; bottom, other side of the same connector with corrosion and two end fittings put together somehow–a good location for a gas leak to develop. (Photos by author.)
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(Top) The connector on the left (ID band date: 1987), with new-style 1516-inch ends, has an overspray of epoxy on the flare seat. At right is the other end of the connector after it was manually “burnished” to remove the overspray. (Bottom) Products currently available for use with adapters include (top) an epoxy connector (ID band date: 1995) and (bottom) a stainless steel connector (ID band date: 1997).
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An uncoated brass flexible appliance connector on a dryer. The red ring indicates the connector was made in 1969, the same year the house was built. The dryer is believed to be at least 10 years old. Deficiencies that could lead to a gas leak, fire, or explosion include the tight turn at the neck of the connector where it passes up through the floor and the use of a nonapproved adapter (black nut) to connect the dryer at the adapter of the flex line. The gas shutoff is in an accessible area in the basement.
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(Top) A tool (here, pliers, but others, such as a halligan, may also be used) is needed to turn the old-style appliance gas cock. (Bottom) The new type one-quarter turn gas cock can be operated by hand.
Safety Tips To Pass On To
Homeowners who Smell gas Or
Suspect They Have A Natural Gas Leak
The following guidelines may be used in your department`s public education program:
Use a neighbor`s phone or a cellular phone (outside the home) to call your utility`s gas emergency department, or dial 911.
Stay outside the building. Do not reenter your home until you are told to do so by a representative from the utility company or the fire department.
Open any windows or doors in the affected areas as you quickly exit the building. Exception: Other than for a one-family home, close–but do not lock–the door leading to the public hallway. This practice will help to keep the gas fumes from entering the public hallway and maintain easy access into the affected area for a representative from the utility company or members of the fire department.
Do not use anything that could make a spark in the immediate area of the suspected gas leak, such as a phone, light switch, doorbell, or stove. Do not start a vehicle, strike a match, or initiate any action that might produce a spark. n
HARRY J. OSTER has been a career firefighter with the City of New York (NY) Fire Department for more than 10 years and is assigned to Ladder 49 in the South Bronx. He has an associate`s degree in fire protection technology and a master plumber`s license in Rockland County, New York.
