InspectAPedia®   -   Search InspectApedia

Photograph of abandoned gas piping Gas Piping Defects
Identify & Report LP Gas or Natural Gas Fuel Piping Problems, Clogs, Damage

Gas piping in buildings for natural gas, LP gas, or propane distribution needs to be installed and inspected with care to avoid dangers of fire, explosion, or asphyxiation.

In this article series on gas piping we provide descriptions and photographs of unsafe gas piping, indications of unsafe or improperly operating gas appliances, gas meters, and other gas installation defects are provided.

This article series on gas piping, lighting, fixtures, and related topics provides free sample draft home inspection report language for reporting defects in oil and gas piping at residential properties.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

How to Identify & Report LP Gas or Natural Gas Fuel Piping Defects

Leaky LP gas valve (C) Daniel FriedmanSafety Warnings for Gas Leaks

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:

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.

Watch out: 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.

See also OIL TANK PIPING & PIPING DEFECTS

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.

Gas Piping Clearance Distance Requirements

Gas piping crossing electrical conduit (C) InspectApedia.com

Photo above: natural gas pipe from meter to building interior crosses an electrical conduit for the electric service entry wires. This is a permitted installation discussed at reader Q&A below on this page.

The table below summarizes reqiured clearances around gas piping.

Gas Piping Clearance Distances

Gas Piping Clearance Distances - gas service piping

Gas services will not be laid in water or sewer ditches. - PSE&G 2017

Piping shall be buried a sufficient depth or covered in a manner so as to protect the piping from physical damage.

Consideration shall be given to encasing plastic pipe and tubing with a steel sleeve when future construction or heavy surface loading is anticipated such as crossovers, sewers, etc. - PSE&G 2017

Gas piping clearance distance to water well boring

10 feet

5 feet with special precautions, see Minnesota (2008)

Gas piping clearance distance to buried water, sewer, electric lines

3 feet

Underground natural gas distribution service and mains (metallic or plastic) shall have a clearance of 3 feet when running parallel or 12 inch vertical direction when crossing from any underground facility (water, sewer, electric, etc.).

(QGCSP 3-10-05, 7.2)

EXCEPTION: Unless installed under the joint trenching agreement. - Questargas  (2015)

Gas piping clearance underground to structure

No contact, maintenance space, damage protected

1211.1.1 Clearances. Underground gas piping shall be installed with sufficient clearance from any other underground structure to avoid contact therewith, to allow maintenance, and to protect against damage from proximity to other structures.

In addition, underground plastic piping shall be installed with sufficient clearance or shall be insulated from any source of heat so as to prevent the heat from impairing the serviceability of the pipe. [NFPA54: 7.1.1] 

Gas pipe, flexible, above-grade clearance 12" to termination from below grade or under slab to above grade or slab to connector fitting. Protection from damage required for vertical runs up the building outside. - TracPipe (2016)
Gas pipe, flexible, minimum cover for direct burial (not in concrete)

4" under 4" thick exterior slab with no vehicular traffic or under a building with an interior slab

12" in trench below 2" thick concrete or equivalent

18" under 1-2 family dwelling driveways, parking lots, used only for dwelling-related purposes

23" under streets, highways, roads, alleys, driveways, parking lots - TracPipe (2016)

Gas pipe, flexible, encased in concrete concrete envelope not less than 2" thick - TracPipe (2016)

Notes to the tables above

1. Watch out: State, provincial, and/or local building code specifications for your area may vary from these example gas meter clearance distances. Consult with your local building department.

2. These gas meter clearance distance codes also pertain to building features on nearby or adjacent buildings to the building served by the gas meter.

3. Additional gas meter protection from snow cover may be required in some jurisdictions.

4. Additional gas meter protection from mechanical damage e.g. from vehicles, in form of guard posts may be required in some location & jurisdictions. Avoid guard post requirements by locating the gas meter away from areas where vehicles may enter or pass.

Gas Piping Codes, Manuals, Standards, Research

See

 

LP Gas Piping Defects & Reporting Language

Safety warnings about gas piping: Check condition of flexible gas line connections:

Watch out: for leaks in those flex-connector lines between gas line and the appliance as they are thin wall and often corrode and leak. Gas leaks are dangerous.

Caution: home inspectors and other private building inspectors do not pull out appliances to look at gas line connections, but you should do so, or have your service technician do so, in order to check condition of flexible connections for leaks and assuring that a shutoff valve is installed.

Safety warning. Flexible soft copper piping defect example:

If flexible soft copper tubing has been used to supply municipal (natural) gas to a electric clothes dryer, hot water heater, or heating system, this is not a recommended installation and it may be prohibited by local codes - "black iron" steel piping is required in many jurisdictions.

Safety warning: Flexible ridged thin wall copper tubing defects:

If flexible "corrugated" or flexible thin-wall copper tubing been used to supply gas to a hot water heater, or heating system, this is not a recommended installation and it may be prohibited by local codes.

Technical Violation: Flexible copper LP gas line

may not be routed through walls or similar locations where it may be damaged or punctured. For these sections of routing threaded iron pipe is required. This is an usually inexpensive item to correct. You can discuss this point further with your gas supplier and your plumber.

Gas Piping Clearances from Electrical wiring & Other Building Features

See piping and gas meter clearances at

GAS METER CODES & CLEARANCE DISTANCES - clearance distances to building features, electrical piping, etc. for meters and meter piping

Code Compliance: All gas or oil piping must comply with local codes and ordinances or with the national fuel gas codes.

Copper and brass tubing (except tin lined copper) shall not be used if the gas contains more than an average of .3 grains of hydrogen sulfide per 100 standard cubic feet of gas.

Photograph of gas lighting in a pre-1900 home"Abandoned" live gas piping: Watch out: don't assume that all "old or antique gas pipes" in a building have been actually disconnected from the gas supply.

We have found "live" gas supplied in fireplaces in older homes where a gas log or heater had previously been installed and "live gas" supplied at antique gas lighting fixtures that occupants thought had been disconnected.

An example of a surprising "live" gas light is shown in our home inspection photo (left) from a New York home constructed in the 1920's.

See GAS LIGHTING, PIPES, FIXTURES

Safety: gas line loose:

At [record location of observed piping defect] you will need to provide better for the gas piping. Loose piping risks dangerous gas leaks. Even if you did not observe/smell a leak at this location when we inspected. This item should be handled as soon as possible.

*** Safety: We recommend that unused gas equipment

should be removed and that you have the unused section of gas line properly sealed by a qualified plumber or by your gas supplier. Leaky old appliances or gas lines are dangerous.

Gas Piping Installation, Inspection & Maintenance

Gas piping to meters in Camp San Maurizio, Venice Italy (C) Daniel Friedman at InspectApedia.comMAINTENANCE TIP: Openings where the gas supply pipe enters the building should be caulked to reduce possible water or insect/rodent pest entry.

Requirement for Gas Supply Piping Drip Leg or "Dirt Leg" or Sediment Trap

Our photo shows a large sediment trap included with piping bringing natural gas to four gas meters in Campo San Maurizio, Venice, Italy.

[Click to enlarge any image]

Not all jurisdictions require the installation of a drip leg or sediment trap on the natural gas supply piping at the heating appliance.

But it's good practice to always include a sediment trap on natural gas piping - at the appliance.

And in areas where the natural gas supply suffers from dirt or moisture contaminants the sediment trap is essential to permit reliable and safe gas burner operation.

The inlet gas line must have a minimum length of three (3) inches (7.6 cm) drip leg (sediment trap) installed as close to the water heater’s gas valve as possible.  (Bradford White 2011).

Reporting Common Gas Piping Defects

Natural gas water heater sediment trap or dirt leg details (C) Daniel Friedman at InspectApedia.comSafety Recommendation: the gas supply line at ... is not installed according to the manufacturer's recommendations.

Proper iron pipe plumbing with sediment trap, also called a "drip leg" (typically at least 3" long off of a "tee" at same height as the gas control) should be installed. This is an inexpensive plumbing correction and it should corrected soon to avoid moisture damage to the gas controls.

(Note that depending on the quality of the gas being delivered in some municipalities, the installation of a drip leg or dirt leg may not be required by local officials.

Safety: gas line loose: At ... better support is needed for the gas piping. Loose piping risks dangerous gas leaks.

Or: We did not observe/smell a leak at this location when we inspected, but as loose gas piping can cause dangerous gas leaks, this item should be handled as soon as possible.

Safety:We recommend that unused gas equipment be removed and that you have the unused section of gas line properly sealed by a qualified plumber or by your gas supplier. Leaky old appliances or gas lines are dangerous.

Methods for Protecting Steel Gas Piping from Corrosion

Reader Question: 8/8/14 John said:

I have a gas pipe running across the concrete floor of the garage that has gone rusty where the concrete has broken up (small area approx 6"). British Gas have inspected the pipe & told me there is no leak & I could cover it with concrete.

My question is could I use PVA & Mortar mix or would this combination react with the rusty pipe?

This question and reply were originally posted in the FAQs at CAST IRON DRAIN PIPING

Reply:

John, I'm not a corrosion expert, but I think the safest bet would be to

1. gently clean off surface rust from the gas pipe

2. spray the exposed metal surfaces with an expoxy paint

3. follow British Gas' advice permitting covering the pipe with concrete

Unprotected-steel in concrete is exposed to corrosive effects that can damage the steel or in turn the concrete.

Research Citations: corrosivity of concrete on steel pipes

These steel-in-concrete corrosivity references may be of interest. For example Biczók discusses methods for protecting steel embedded in concrete and Verbeck describes how that corrosion occurs

Contaminants in Natural Gas Piping Systems: Water, Dirt, Oil?

Oil leak at gas furnace (C) InspectApedia.com HendersonRQuestion: oil contamination at furnace blamed on natural gas supply?

We are under contract to purchase a house in Michigan.

During inspection we found oil inside the furnace.

We asked seller to have licensed HVAC come clean and inspect.

Upon executing that, HVAC pro said there is oil coming from city utility natural gas supply, shut it down immediately for repair.

Now utility company claims a new meter is the fix. We will also have all gas appliances and lines professionally cleaned inside the house.

Utility company fix seems very inadequate to us lay people. If oil gets in lines underground, won’t that continue? Wouldn’t that also suggest a gas leak? If it stops at meter, where will it go next? Should soil be tested? Isn’t this a public health concern? Whose responsibility is this?

Thanks for your time, we are grasping for answers - Anonymous by private email 23 January 2019

Reply:

Delivery of detectable oil contamination through a natural gas supply piping system and gas meter is not a problem I've encountered: the presence of significant amounts of oil in a natural gas or LP gas supply. In your case of city gas supply it'd be natural gas delivered through the gas company's piping.

Sometimes there's a problem with moisture, condensate, water in a gas supply; that water might look dirty, even oily if it picks up a small bit of oil that might be found on some iron pipe interiors or connections.

Oils are used in some natural gas distribution systems as a means of reducing corrosion.

Watch out: an unusual but possible source of oil in natural gas distribution piping systems could be PCBs used as an anti-corrosive treatment (more-likely in older systems than incurrent distribution systems) (MN PCA 2012).

PCBs are carcinogenic. If PCBs are found present in your building professional cleaning and proper disposal are required.

However in the U.S. it's unlikely to find PCBs in use in gas distribution nor in residential equipment installed after 1978.

In any event I would not expect significant levels of what is truly "oil" in the furnace combustion chamber from a gas distribution system.

The "drip leg" or "dirt leg" that (should be) installed on natural gas supply piping at the heating appliance is the normal receptacle of liquid contaminants in the gas supply and is put there specifically to prevent those contaminants from fouling the burner itself.

You should confirm that your gas supply piping includes a drip leg and your plumber should open it to drain and clean that device, taking care in handling any liquids removed as that substance would be dirty, corrosive, and possibly unsafe (with PCBs in very old heating systems).

Searching for an authoritative study citing significant oil contamination in natural gas supply systems has not - so far - indicated the appearance of oils in or at residential gas fired heating equipment. I include some research examples below.

Other possible sources of oil in (presumably the combustion chamber or at the burner of) your natural-gas fired furnace include:

I am also surprised that the repair requires a new gas meter unless there was separate evidence of gas meter defects. While ultrasonic gas meters are more-precise, most residential gas meters use a diaphragm design to measure gas flow. There is no oil contained inside the gas meter itself. (Bennett un-dated, AGA)

It would be helpful if you could show me photos of the piping at your heater as well as of the actual claimed oil-contamination.

Reader follow-up: oil leak blamed on gas odorant

I can confirm it is indeed a gas furnace, Carrier brand 100,000 BTUs. In the last two days we have worked with the utility company and they have determined that the source of the "oil" is the supply gate which is part of the gas grid itself.

They say the oil is really the odorant added at each gate into the supply.

And the way this home is situated (lower/deeper on the grid?) and due to extremely cold temps when pressure and demand is high, this would occur.

As a remedy, the utility co is installing a drip tank between the supply line and my property to collect this oil in the future.

They said this fix is used often in commercial, much less often in residential applications.

Reply:

Indeed an odorant is added to LP and to Natural gas supplies, typically Mercaptan, for safety - so that occupants may smell a dangerous gas leak.

And experts have written on removing both mercaptan contaminants and hydrogen sulfide contaminants from fluids and process streams.(Chaney 1935) and (Luna 2000).

However it's rather unusual for there to be so much mercaptan in the gas supply that it would appear at a residential gas furnace.

Your explanation is interesting and will probably be helpful to other readers.

Reader Follow-up:

Oil leak at gas furnace (C) InspectApedia.com HendersonRIsn't mercaptan a gas, not an oil/liquid? Hmmmm

Here are photos from the inspection, I wish I had more.

Drips were accumulated upwards of this space, on the horizontal pipe that had several outputs to the burners - sorry don't know what that part is called, but shaped kind of like an exhaust manifold in car-speak. It's all been cleaned now.

Reply:

If the source were the gas piping I would expect to see oil seepage first at the point where gas exits the metering orifices in the gas burner itself.

In your photo it looks as if the oil is outside the combustion chamber and at its entry under a blower motor but indeed you mention that the oil appears to originate at the burner. That's pretty compelling.

I am not and don't want to pretend to be smarter than your collection of onsite experts, but the location of that oil looks a bit suspicious to me.

If that were my furnace I would want to look closely at that blower motor for - lubrication fittings (present or absence) and leaks from the motor itself - to rule those in or out as an oil source.

There is also a rubber tube with a spring-clip connector - I'd want to understand the function of that component and to check the connection for leaks.

You're right that mercaptan is usually sold as a compressed gas.

See this MSDS for MERCAPTAN from Prexair Canada Inc., Mississauga ON.

However some articles I've read mention distribution of oils in the gas piping system. Possibly other oils used as anti-corrosives. By the way the principal anticorrosion treatment for gas pipelines is the use of an expoxy coating on the pipe exterior (or polyurethane coatings) as well as cathodic protection for some installations.

Mercaptan may also appear in an oil mix:

Sulfur compounds are substances of different chemical nature, from the elemental sulfur to hydrogen sulfide and mercaptan compounds, sulfides, open-chain and cyclic disulfides, and heterocyclic derivatives of thiophene, thiophane and other more complex compounds.

To date, with the exception of low molecular weight compounds, most of the sulfur compounds oils are not deciphered.

Free elemental sulfur is rarely found in crude oils. The emergence of free sulfur is associated with the decomposition of more complex sulfur compounds. - discussed

in SULFUR CONTENT of CRUDE OILS

Research on Contaminants in Natural Gas Storage & Piping Systems

 

Gas Regulator Installation, Inspection, Defects

Moved to

GAS REGULATORS & APPLIANCE / HEATER CONTROLS - home, Natural Gas regulators & appliance regulators, NG & LP

See also

GAS REGULATORS for LP TANKS - home, LPG / Propane systems

Clogged Gas Pipe Diagnosis & Repair

This topic has moved to a separate page at GAS PIPING CLOG REPAIR

 




ADVERTISEMENT





Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-05-24 - by (mod) - co-ax Internet cable wrapped on gas piping

@John,

It's certainly possible that there could be an unsafe condition such as cables that are pulling on gas piping or cable routed. so it could form an electrical short between actual electrical wiring and the gas line, but in general co-axial cables carrying TV or Internet service are not electrically live and are not particularly hazardous. It may be that you were describing sloppy work however.

This Q&A were posted originally at GAS METER CODES & CLEARANCE DISTANCES

On 2021-05-19 by John

Recently noticed Camcast cable entering mother-in-laws house wrapped around the gas line.
Is that ok ?

On 2021-05-12 - by (mod) - Rules for gas meter or gas piping clearance from electrical wire or conduit

Gas piping crossing electrical conduit (C) InspectApedia.com@Dj, thank you for the question about rules concerning gas and electric lines crossing.

A gas line is allowed to cross an electrical conduit.

If those are buried the digging around that needs to be done by hand within 2 feet to avoid risk of damage.

In any event it's your local building code compliance inspector who is the final legal authority and word on the question.

On 2021-05-12 by Dj - codes against a natural gas line crossing an electrical service conduit ?

Hello,
Are there any codes against a natural gas line crossing an electrical service conduit.
Thank You Dj

This Q&A were posted originally at GAS METER CODES & CLEARANCE DISTANCES

On 2021-04-23 - by (mod) -

@Lee Bonner,

Fair question, Lee.

The local building code or plumbing inspector is the final legal authority on questions of gas meter clearance distance,

but that said, I expect most inspectors will simply measure the distance from the closest edge of the electrical panel to the closest edge of any gas meter comoponent.

That avoids arguing about gas meter vent fumes and ignition risks. I hate to get into splitting hairs over an argument like this, particularly because I know from experience that, god forbid, a catastrophe happens later - like a building fire or explosion, nobody is going to continue to say that the original installation that measured gas meter clearance distance in a way that was "convenient" was acceptable. Certainly not the plaintiff attorneys.

We should, perhaps, start every one of these worrisome queries as "Dear InspectAPedia.com and Gentlemen/Women of the Jury: ..."

 

On 2020-04-14 - by (mod) - For the last 7-10 days I have smelled the odor of exhaust fumes in my apartment

Beatriz

Let's start with the most important basic safety steps.

Be sure that you have working fire and smoke detectors installed and tested.

I know that you think this is not a smell of gas fuel such as propane or natural gas. That's a critical distinction to make because of the explosion hazard.

The smell of what you describe is not something that I can safely and reliably diagnosed by text. However it occurs to me from your description that there could have been a spill of heating oil or diesel fuel in or near the building. Do you know if you were building or an immediately adjacent building is using heating oil or do you know if it's the case that the only fuels being used are propane or natural gas?

It's also possible that the order that you're smelling a sewer gas from the plumbing problems such as bad venting or a sewage leak nearby.

It may be diagnostic to determine if you can improve big odor condition by ventilating with fresh air.

Keep in mind that sewer gas to is potentially explosive.

Because there are life safety concerns involved you certainly should notify the building owner and if conditions continue or get worse you may need to ask for help from Emergency Services. I agree that you don't want to do that if it's not necessary.

On 2020-04-14 by beatriz

For the last 7-10 days I have smelled the odor of exhaust fumes in my apartment. I believe the neighbor who lives directly above me call smell it as well. I saw him at the back of the building 3 days ago looking at the pipes. To be clear, this is not the smell of clean, natural gas. This is the smell of fumes, like burned off fuel almost like exhaust from a diesel engine. It smells like I live in an auto garage and someone has closed all the windows with the engine on.

And it's not coming from a local garage or cars on the street because someone would have to be running their car engine 20 hours a day. We are on corona virus lock down and there are only a few cars on the street. It's like constant fumes. That's why I assumed it was coming from an appliance that runs for 20 out of 24 hours of the day.

We have a gas stove but do not use it. If the fumes were coming from our gas range shouldn't I be able to smell the fumes all the time when I'm in my kitchen? I woke up Monday morning and noticed that the smell had almost dissipated entirely.

I did not turn on any appliances at all because I was on the internet all morning and I use my microwave mainly for eating. About 4-5 hours later, the smell came back. I'm assuming that its coming from a neighbor's apartment and whenever they turn on their problematic appliance, the fumes start. I have a gas wall heater but have not used it for 3 years and the pilot light is not even lit because I use electric floor heaters. This started about 10 days ago when it got cooler in California and I assumed that the upstairs neighbor was using their Williams gas wall heater.

I lurked about our Williams wall heater because I believe that both of our heaters are installed on the same wall and use the same ventilation pipe but there is no odor in that area. Is there anything else it could be in the apartment?

The only 2 items in the apartment that use gas are the stove and the wall heater. I don't think the fumes are affecting any other apartment other than mine and the one directly above me. If it was a broken or rusted vent pipe from the heater, shouldn't I smell fumes in the area of the heater? If anyone can help please help me.

On 2020-03-04 by Anonymous - exposed propane pipes on a building in Panama

Dan

You need first to decide if the LP pipe is absolutely safe since if it's badly corroded or damaged it's a leak risk such that just painting it would be dangerous.

What tiles popped: Ceiling, floor? Over gas piping? Due to exfoliating rust? If so the pipe may need replacement.

On 2020-03-03 by dan

we live in a ten story building in Panama,, some tiles popped up and there is an exposed propane pipe rusted,, how to repair, prime and cover.?.
thanks

On 2019-11-28 by (mod) - most common gas piping defects

OPINION: gas leaks due to:

1. improperly selected or installed fittings or connections

2. mechanically-damaged gas piping

3. corroded gas piping

All leading to leaks

On 2019-11-28 by Anonymous

What is the common faults gas pipework?


...

Continue reading  at GAS PIPING CLOG REPAIR or select a topic from the closely-related articles below,Replace with (MAYBE - CHECK EACH ONE) or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see GAS PIPING DEFECT FAQs - questions & answers posted originally at this page.

Or see these

Recommended Articles

Suggested citation for this web page

GAS PIPING CLEARANCES, CODES & DEFECTS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to GAS APPLIANCES, PIPING, CONTROLS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification
when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Comment Form is loading comments...

Citations & References

In addition to any citations in the article above, a full list is available on request.



ADVERTISEMENT