Gas piping blockages or clogs in buildings for natural gas, LP gas, or propane:

How to find and clear or de-clog a blocked natural gas or LP gas pipe or gas line to an appliance or to a gas light.

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.

Page top photo: we lit this antique wall mounted gas jet to prove that, to everyone's shock, the gas lines in the walls of this old New York home were still connected and "live".

Clogged Gas Pipe Diagnosis & Repair

Question: how do I un-clog the gas line to an outdoor gas lamp?

2017/04/22 Bill

How to unclog a natural gas line to my outside lamp.

This question and answer were posted originally

at OIL LINE CLOGGING FIX

Above/left, an image of an outdoor gas light in Moenchbruch, Germany, Wikipedia 2017 cited atReferences or Citations

Reply:

For un-clogging a natural gas or LP gas pipe we start with some questions and include a safety warning.

First: anyone, even an expert, must be sure that the gas supply is turned OFF before fooling with gas piping at all.

What is the gas pipe material and diameter? If it's black iron pipe 1/2" or larger you or your plumber may be able to run a 1/4" diameter drain auger through the piping run.

Smaller gas lines such as 3/8" or 1/2" flexible copper tubing or flexible stainless steel tubing are sometimes cleared by pushing a wire through the piping but at least with flexible tubing I'd prefer to use a smooth flexible plastic probe since scoring the interior of thin walled gas piping may cause damage or even a future point of corrosion and leakage.

But I'd be wary of ANY de clogging effort if the clog is due to rust, debris, or insects.

That's because any debris remaining in the gas line risks clogging a gas orifice or control - making the gas light unreliable or even possibly unsafe.

For an outdoor gas light or appliance whose gas supply line is buried, water leaking into the gas line can cause a blockage or can cause corrosion that blocks the line. Just 4" of water pressure can be enough to block a natural gas line.

Water in a gas pipe is almost certainly from a leak, not from "condensation" as the water content of LP or natural gas is very low.

Our image above illustrates a gas line riser intended for use with plastic gas piping. Produced by RW Lyall the Lyco® flexible riser seals and protects the plastic gas pipe where it enters or exits the ground. That's a common point at which water enters a buried gas line.

Below is an example of CSST, flexible corrugated stainless steel tubing used in some gas piping installations and described in detail at GAS PIPING, FLEXIBLE CSST.

Watch out: If you find water in the gas line and it's corroded and/or the leak is not an obvious one easily repaired, that gas line should be replaced as it is unsafe, risking not just a gas appliance that doesn't work but also a gas explosion.

Your plumber may have or have access to a small-diameter pipe borescope that would permit inspection of the pipe interior. That would be worthwhile if you want to investigate the possibility of being able to avoid having to simply replace the line.

Plumbers often replace outdoor gas piping with continuous, waterproof, flexible polyethylene gas piping with risers at the pipe entry and exit points to keep water out of the system.

Producers of PVC or polyethylene gas piping and its connecting fittings include Dormont, DriscoPlex, GasTite, Endot, Pro-Flex, Lyall Lyco, Yellowpipe, and others.

Your plumber will find these at both plumbing suppliers and at building supply outlets such as Home Depot and Lowes.

So find out what has caused the clogged gas pipe. And replace the line if it contains water, rust, corrosion debris.

Research on clogged gas piping

• Enbin, Liu, Li Changjun, Peng Shanbi, and Zhang Hongbing. "Detection Technology for Pipeline Plugging Based on Barotropic Wave Method." Natural Gas Industry 26, no. 4 (2006): 112.
• NAESB, NATURAL GAS SPECIFICATIONS SHEET [PDF] North American Energy Standards Board, original source: naesb [dot] org/pdf2/wgq_bps100605w2 [dot] pdf
• Ng, Heng-Joo, and Donald B. Robinson. "Hydrate formation in systems containing methane, ethane, propane, carbon dioxide or hydrogen sulfide in the presence of methanol." Fluid Phase Equilibria 21, no. 1-2 (1985): 145-155.
  Abstract:
  Experimental measurements have been made on the initial hydrate formation temperatures and pressures in systems containing methane, ethane, propane, carbon dioxide or hydrogen sulfide in the presence of methanol solutions.
  
  The methanol solutions were varied from 5 to 20% by weight. The temperature range for hydrate formation was from about −10 to 17°C and the pressure range from 0.8 to 20 MPa.
  
  The results were compared with predictions made using the Hammerschmidt equation.
  
  Reasonably good agreement was found for the aqueous liquid—hydrate—gas region but poor agreement was found in the aqueous liquid—hydrate-former liquid—hydrate region.
  Excerpt:
  It was pointed out by Ham- merschmidt (1939) that gas hydrates were the cause of blocked natural gas pipelines.
• Rogers, Rudy, Guochang Zhang, Jennifer Dearman, and Charles Woods. "Investigations into surfactant/gas hydrate relationship." Journal of Petroleum Science and Engineering 56, no. 1 (2007): 82-88.
• Stoll, Robert D., and George M. Bryan. "Physical properties of sediments containing gas hydrates." Journal of Geophysical Research: Solid Earth 84, no. B4 (1979): 1629-1634.
• Tsochatzidis, Nikolaos A., and Konstantinos E. Maroulis. "Methods help remove black powder from gas pipelines." Oil and gas journal 105, no. 10 (2007): 52.
  Excerpt:
  Clogging of instrumentation and valves. ... As a result, other gas filtration devices along DEPA's system clogged regularly and had to be replaced.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

What caused my LP gas line to clog?

Liquid gas pipe line clogged what cause On 2021-04-16 by Yuvaraj

Answer by (mod) -

@Yuvaraj,

Common causes of gas line clogging include debris from rust or moisture that condenses as water in the gas line; in a freezing climate water can also freeze in a line.

Watch out: when burying an LPG line between tank and a destination, such as an outdoor generator, take care to keep the buried lines as short as possible; condensation accumluating in dips in gas piping can cause the piping to become blocked by water or even to be damaged by freezing.

I think my RV's LPG line is clogged. How can I tell?

I believe I have a gas plug in my rv lpg line. Is there a way to check it out? On 2021-04-04 by Steve

Suggestions by (mod) -

@Steve,

Your plumber would start by checking that there is gas supply, that the gas regulator is working, and if those seem OK she might look for blockages that are easily accessed by insects (like at a gas pilot), and for piping that might invite rust, debris, condensate that are not properly trapped.

If your gas piping is for LPG and there could be water or condensate in the lines the piping could be water-blocked, or in a freezing-climate, even ice-clogged.

Beyond that you'd need to shut off and disconnect the gas lines at the source and destination and try air pressure to see if there's flow.

Take a look at OIL LINE CLOGGING FIX https://inspectapedia.com/oiltanks/Oil_Line_Clog.php where we describe a CO2 cartridge oil line clog blast-out method that might work on some gas piping systems.

If the gas piping is clogged by corrosive rust flakes (in iron piping) or by "black dust" (corrosive oxides left by H2S in the gas supply) the pipes may need to be blown clean or in the worst case, replace.

Watch out: after working on your LPG gas piping be sure every connection and section is checked for leaks, lest you have a fire or explosion.

Interesting research on gas line clogging:

Zarinabadi, Soroush, and Amir Samimi. Problems of hydrate formation in oil and gas pipes deal. [PDF] Australian journal of basic and applied science 5 (2011): 741-745.

Natural Gas line under my slab seems clog, I need help.

I have a unit that on a flat slab which has been empty for three week. Before this gas was flowing through the pipes to my water heater, stove, wall heater & outlet for washer and dryer.

Gas Company informed me that they left gas on as a courtesy for the new tenant.

However I had my plumber replace the old water heater with a new one due to leaking.

Now gas line is plugged.Meter for gas is open. Please help; On 2019-06-10 by Anonymous

Reply by (mod) -

Watch out: The safe thing to do would be to turn off the gas supply at the point of entry. You're going to need to have a plumber remove rusted or clogged gas piping or if possible clean some of those sections.

It's also possible that a drip leg or dirt line was forgotten and the piping arrangement. I don't know I can only guess because I can't see your installation.

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