LP Gas & Natural Gas Safety
What to do if you smell gas, gas piping installation, inspection, testing & repair; gas controls, gas regulators & LP gas tank defects
GAS LP & NATURAL GAS SAFETY HAZARDS - CONTENTS: how to find & report defects found in LP or natural gas controls, regulators, or storage tanks. How to find & report defects found in gas piping inspections.
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Gas appliance, heater, piping & control safety hazards:
Descriptions and photographs of unsafe gas piping, regulators, or controls on heating systems, indications of unsafe or improperly operating gas appliances, gas meters, and other gas installation defects.
This document also provides free sample draft home inspection report language for reporting defects in oil and gas piping at residential properties.
Immediate LP or natural gas safety hazards: if there is evidence of an LP or natural gas leak at a building, gas odors, for example, you should:
Do not do anything that is likely to cause a gas explosion, such as lighting a match, operating an electrical switch, or even using a telephone in the building
Leave the building immediately and keep a safe distance away - 100 feet or more.
Notify other building occupants of the safety concern
Contact the local gas company and/or fire department
Heating equipment which the inspector (or building occupant or manager) judges to be an immediate life safety hazard should be shut down and appropriate emergency services called.
See GAS LEAK DETECTION, LP / NG for leak detection procedures and alternatives.
General safety warning: improper installation and even improper inspection and testing methods involving natural or "LP" gas can involve
dangerous conditions and risk fire or explosion. If you smell gas you should leave the building immediately and should do so without doing anything that could create a spark such as operating a light switch or telephone.
From a safe location, call your gas company's
emergency line and/or your fire department. The text provided here is a working draft and may be incomplete or inaccurate. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
Also see How to Report Defects in Oil Piping.
NOTICE: while example report language is provided here, reproduction of this or any of our web pages or their contents at other websites
or in printed documents for sale is prohibited.
Examples of Easily-Detected Gas Leak Hazards
Gas Odors: A gas leak can be indicated by gas odor such as in the utility area near appliances or elsewhere in the building. Leave the building and call for help from a safe location.
Photo at left: coated stainless steel gas appliance connector used for appliances & heating equipment.
Watch out when moving gas appliances: older flexible tubing may be thin-wall, corroded, damaged, and easily torn or caused to leak. Shut off the gas supply before moving appliances to minimize the hazard.
Here is a list of examples of other immediate LP gas or natural gas leak safety hazards that might be detected using a TIF8800™ Combustible Gas detector or using a soap solution and bubble testing:
A gas leak in gas piping - check particularly at piping joints or in areas where there is apparent damage, corrosion, possible pin holing in the piping.
A gas leak at the gas meter equipment. Check at meter seams and at piping connections.
A gas leak at the gas control valve.
A gas leak may be found at the appliance pilot and temperature control knobs at control top.
A gas leak may be found at the center seam along the RH side of the control. (often on gas fired water heaters we can detect a very small trace leak of LP gas or natural gas at the side seams of the control; beware: volatiles in pipe dope or in valve label glue might also cause the TIF8800 to indicate that a leaking gas is present).
A gas leak may be found the gas line shutoff valve.
A gas leak may be found the appliance pilot line at the control.
You should have your plumber test/replace any suspect gas controls promptly. Replacement of a control itself should not involve significant expense. This repair should not be deferred. You should be sure that building occupants know if this or other unsafe conditions are present.
Old LP Gas Tank Leak Hazards
When inspecting old LP gas storage tanks above ground watch for corrosion, risk of rust perforation, and for leaks at control valves and fittings. Our photo below illustrates a rooftop LP gas tank installed in San Miguel de Allende, Mexico. Check the tank's date stamp and compare it with the tank ages permitted by local building codes.
Old Indoor Natural Gas Meter Hazards
Our photo below shows an older natural gas meter that is located inside of the building. This meter was originally outdoors but building expansion enclosed it. To meet current minimum gas safety codes (in New York State) the builder was required to add a vent pipe connecting the regulator (shown at left of the gas meter) to the outdoors.
The concern is that a rupture or damage inside the natural gas regulator at the meter might otherwise leak hazardous gas into the building interior. Coincidentally the meter is adjacent to a heating furnace - we would not want leaky gas to be transported through the building ductwork - increasing the hazards involved.
Abandoned or Old Gas Piping & Shutoff Hazards
When I saw this open-ended gas valve (below left) all I could say was @#$(*u&!
All that was needed for a catastrophic fire or explosion was someone ignorant of what this valve controlled to turn it in presence of a spark or flame, or to open the valve and leave it on. This natural gas line was live and could supply a virtually infinite quantity of explosive gas in the building.
Flexible Gas Appliance Connector Installation Procedures & Warnings
The manufacturer typically warns of the following safety hazards when using flexible gas connector tubing, mostly in the form of "Do Not" admonitions that we detail
at FLEXIBLE GAS CONNECTOR INSTALL.
Excerpts are below
Do not re-use flexible gas connectors, fittings and valves; they are designed for use only on original installations. The concern is that removal and re-use of a connector tubing and additional handling may damgae it, making it unsafe for re-use.
Do not use flexible gas connectors with appliances that are mounted on rollers, casters, or wheels that permit the appliance to move readily about. Flexible gas connector tubing is intended for limited movement after installatin. Repeated bending, flexing, extreme vibration, stretching, can cause metal fatigue, cracks, holes and dangerous gas leaks.
Maximum flexible gas connector tubing length is limited by code in some jurisdictions. For example in the U.S. in Massachusetts the maximum connector lenght is 36" .
What Chemicals are Used to Produce the Characteristic Odors in Natural or LP Gas?
Mercaptan gas odorant components, concentration strength, human exposure levels
Mercaptan is, according to our industry commentator J.R., a widely-recognized odorant, but only one of a number of similar-smelling products that are added to natural gas or bottled gas to assist in recognizing that a dangerous gas leak is present since natural gas alone, CH4 (Methane) is odorless.
Photo at left: an antiquated natural gas meter in the basement of a New York home.
The product added to natural gas to provide it with a characteristic odor is a mixture of tertiary butyl mercaptan, dimethyl sulfide and n-hexane.
Commonl y in the trades the gas odorant product is just called "mercaptan".
Mercaptan is added to natural gas at a rate of 0.08cc’s/1.0 m3 of natural gas.
Therefore very little mercaptan (or other gas odorant chemicals) in the gas stream.
Gas odorants are produced by Odor-Tech, a subsidiary of Arkema, by Chevron Phillips Chemical, and others. Odor Tech also produces Mercaptan Assassin ESD - an odorant-blend kit used to clean up mercaptan spills.
Critical Hazard Limits for Natural Gas or LP Gas
According to J.R., one of our industry correspondents, odorants need to be detectible in the natural gas at 1/5 the lower explosive limit (LEL), or more properly, the lower flammable limit or LFL.
So this is the amount of natural gas required in the test.
A person is exposed to very little natural gas in the air by the time they smell it.
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U.S. Energy Information Administration - eia.doe.gov/
U.S. Environmental Protection Agency - epa.gov/solar/energy-and-you/affect/natural-gas.html
At Natural Gas.Org www.naturalgas.org/environment/naturalgas.asp#emission you’ll find a table of combustion products
At geocities.com/rainforest/6847/report1.html is an interesting and detailed though not “neutral” report on the components and contaminants in the combustion of natural gas. You’ll see a long long list of emissions products, but look again – most of the contaminant levels listed are in the picograms.
apvgn.pt/documentacao/iangv_rep_part1.pdf lists the components in natural gas exhaust from vehicles
The Need Project, Manassas, VA: need.org/needpdf/infobook_activities/SecInfo/NGasS.pdf
Kroschwitz, Jacqueline I., and Mary Howe-Grant (eds.). "Gas, Natural." In Encyclopedia of Chemical Technology. 4th ed., vol. 12. New York: John Wiley and Sons, Inc., 1993.
Tussing, Arlon R., & Bob Tippee. The Natural Gas Industry: Evolution, Structure, and Economics. 2nd ed. Tulsa, OK: PennWell Publishing, 1995.
Thanks to reader E Leal for suggesting the addition of details about how to convert gas burning appliances from propane to natural gas or from natural gas to propane. 8/4/09
Thanks to reader JR for discussing LP and natural gas operating pressures and leak detection safety, October 2010.
Odor-Tech, 7591 Esler Field Road, Pineville, LA 71360, Tel: 318-767-0821
4is a subsidiary of Arkema, and has offices throughout the world. Email:
Odor-Tech products include
Spotleak® blends for natural gas odorization
Ethyl Mercaptan for propane and butane odorization
Chevron Phillips Chemical, 10001 Six Pines Drive, The Woodlands, TX 77380, Tel: 832-813-4100, 800-231-1212 (Toll free, within the US) a has offices throughout the world and produces olefins, polyolefins, aromatics, and styrenics as well as other specialty chemicals and plastics.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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