How Deep Does Natural Gas Line Need To Be?

Contractors in Colorado are required to dig gas lines. Following these rules on your next trenching job will not only make it “gas line friendly,” but it will also save you time, money, and ensure that your project complies with the gas line installation regulations. Costly return visits, wasted man-hours, job delays, and customer frustrations can all be avoided with the right trench.

We’ve included illustrations to help illustrate the criteria for these gas line trenching regulations, so you can get the job done right the first time.

1) Call 811 for location informationthe it’s law. Keep in mind that they’re simply looking for service lines. A private locator is required to locate all private lines. 3 days are required for 811 services, not including the day you contact them before you begin digging.

  • At all riser locations, the trenches must be 24 deep and level throughout, with no rocks or debris that could damage the pipe in any way. Always use clean back-fill material for back-filling.
  • For added protection, the gas line must be put in a sleeve in specific circumstances. We ask that you notify your estimator if there will be any concrete poured or if the subterranean line will be subjected to additional weight, such as a driveway.
  • Please take additional care when back-filling a riser to ensure that it is straight and plum.

2) Let’s begin with the gas meter (see picture 1a)

How deep should a natural gas pipe be buried?

(1)All pipe, tubing, fittings, and other piping components between the tank and the first shutoff valve must be designed with a factor of safety of at least 8 based on the minimum specified tensile strength at room temperature for the full range of pressures, temperatures, and loadings to which they may be subjected.

All other pipe, tubing, fittings, and other pipeline components must be adequate for the full range of pressures, temperatures, and loads to which they may be exposed, with a factor of safety of at least four.

For plumbing systems with a working pressure more than 100 psi, underground piping must never be less than Schedule 80.

Any material utilized, including gaskets and packing, must be compatible with natural gas and the conditions in which it is used.

(2)All piping and tubing must be run as close to the source as possible, with suitable allowances for expansion, contraction, jarring, vibration, and settling.

Exterior pipe must be well supported and protected against mechanical damage, whether buried or put aboveground.

Unless otherwise protected, underground plumbing must be buried at least 18 inches below the ground’s surface.

All underground piping must be coated to prevent corrosion in accordance with Section 533(b) or an equivalent standard.

For piping below ground, zinc coatings (galvanizing) are not considered enough protection.

(3)All welded piping must be manufactured and tested in conformity with the ANSI Code for Pressure Piping, Petroleum Refinery Piping, B31.3, 1966 Edition or a similar code.

(4)All valves must be capable of withstanding the whole range of pressure and temperature that they may be exposed to.

The service ratings must be stamped or otherwise permanently marked on the valve body by the manufacturer.

Strainers, snubbers, and expansion joints, among other piping components, must be permanently marked by the manufacturer to show the service ratings.

All materials, such as valve seats, packing, gaskets, and diaphragms, must be resistant to natural gas action in the circumstances they are exposed to.

(5)It is forbidden to use the following:

(A)Valves, cocks, fittings, and other piping components made of cast iron or semisteel that do not comply with ASTM Specifications A-536-67, Grade 60-40-18; A-395-68; A-47-68, Grade 35018; and A-445-66 unless they have pressure-temperature ratings of at least 1 1/2 times the design service conditions.

Valves made of cast iron or semisteel that do not meet the three ASTM criteria specified above should not be utilized as primary stop valves.

(C)Valves with a design that allows the valve stem to be removed without disassembling the valve body or removing the entire valve bonnet.

(D)Plastic pipe, tubing, hose, and fittings, unless the Division has given written approval.

(E)Valves having valve stem packing glands that cannot be repacked under pressure unless they are separated from the vessel by another stop valve of an appropriate kind.

Service valves are exempt from this rule.

(F)Aluminum tubing for outside applications, as well as threaded aluminum connections and adapters that must be attached or removed as part of the filling or transferring operation for those connections and adapters with unique threads suitable for this service.

Compressed Natural Gas (CNG) is a type of natural gas that has been compressed.

Hose shall not be utilized in place of manifolds, pipelines, or tubing between dispensing tanks and cylinders and the loading and/or unloading hose connections, except that a segment of metallic hose not exceeding 24 inches in length may be used in each pipeline to offer flexibility where needed.

Each section must be fitted in such a way that it is shielded from mechanical harm and is easily visible for inspection.

Each section must include the manufacturer’s identification.

(1)On liquid lines between the tank and the first shutdown valve, flanged or threaded joints that have not been seal welded are forbidden.

(3)Except as provided in 536(c), piping with a diameter of 2 inches or less may be threaded, welded, or flanged (1).

(5)The plugs must be solid or bull plugs made of at least Schedule 80 seamless pipe.

(6)Threaded pipe and tubing with compression type couplings may be utilized for service temperatures of minus 20 degrees Fahrenheit or above, except as prohibited in 536(c) (2).

(7)Pipe supports for piping with a service temperature below minus 20 degrees Fahrenheit must be built to prevent support steel embrittlement by minimizing heat transfer.

(8)In low-temperature usage, bellows type expansion joints must have exterior insulation to prevent ice from accumulating on the bellows.

1.Amendment to subsections a)(1) and a)(5)(F) filed 3-29-74; effective the thirty-first day after that (Register 74, No. 13).

For a gas line, how deep should the trench be?


What kind of underground natural gas line do you use?

Underground systems must perform in tough and corrosive environments, unlike above-ground gas piping installations that require metallic piping. Underground installation of metallic pipe necessitates the use of additional, costly materials to safeguard the pipe. Polyethylene gas piping systems are designed and approved specifically for use underground. Gastite has teamed with Continental Industries, Inc. to deliver PE tubing and components that assemble in minutes to form a complete underground gas pipe system, providing a real underground gas piping solution.

Is it possible to bury both water and gas in the same trench?

  • Call for Underground Locates at least 48 hours before digging at (800) 332-2344 or 811.
  • Trenches must be at least 36 inches deep.
  • If you can’t get a 36-inch depth, call Lane Electric’s Engineering Department at 541-484-1151.
  • The following separations must be maintained if the trench is to be a common trench (shared with other utilities):
  • There should be a gap of 24 inches between the gas and electric lines.
  • Water and electric lines should be separated by 12 inches.
  • Between the sewer and power lines, there should be a gap of 24 inches.
  • Between communications and power lines, there should be 12 inches between them.
  • If the trench will only be used for power, it must be wide enough to fit the conduit, which means a 4-inch ditch-witch trench will suffice.
  • The conduit must be bedded with a minimum of 4 inches of sand if the trench is dug through hard, rocky terrain.
  • Gray Schedule 40 electrical PVC must be used for all conduits.
  • At any 90-degree curve, all primary conduit (7200V) must be 3 inches in diameter with 36-inch radius long sweeping elbows.
  • For a 200 Amp service, the secondary (120/240V) conduit must be 3 inches in diameter, with 36-inch radius long sweeping elbows at any 90 bend.
  • For a 400 Amp service, secondary (120/240V) conduit must be 3 inches in diameter, with 36-inch radius long sweeping elbows at any 90 bend. (As an example, see Exhibit A.)
  • At any 90-degree bend, street or security lighting conduit must be 1.25 inches thick with 36-inch radius long sweeping elbows.
  • In any one run of primary or secondary conduit between devices, there will be no more than 270 bends (3-90 bends or 2-90 & 2-45 bends).
  • Mandrel proofing is required for all primary conduits.
  • Details on mandreling can be found in Exhibit I.
  • All primary and secondary conduits must be left with new 2500# mule-tape. Mule-tape must be able to move freely in conduit and have enough length (10 feet or more) beyond each end to allow for conductor installation. Mule-tape is available for free at Lane Electric.
  • Specifications for transformers and primary or secondary junction boxes must be obtained from Lane Electric’s Engineering Department.
  • (Common facilities are shown in Exhibits B-G.)
  • Call Lane Electric at 541-484-1151 to schedule an inspection with the Engineering and Operations Department once the trench is dug and conduit is installed.
  • The Trench can be back-filled after the conduit and the Trench have been inspected.
  • It is not possible to install the conductor until the trench has been backfilled.

Note that no primary or secondary electric lines may be installed beneath a concrete foundation or slab.

Is it possible to bury flexible gas lines?

Is it possible to bury it? Yes, however it must be sleeved in a non-metallic conduit that is 1/2 the diameter of the pipe. There must be no fittings in the subsurface area.

Is it possible to bury copper gas line underground?

In most circumstances, burying copper in direct contact with the soil is the best option for installing it underground. Copper has an inherent resistance to corrosion in most soils and underground conditions. While wrapping or sleeving the copper tube to offer an extra layer of protection is a good idea, it can lead to failure owing to poor sleeving or wrapping techniques. Installers should carefully assess whether sleeving or wrapping is necessary or prudent unless hostile soil conditions are present or expected. Installers should consider the following measures if they are required to ensure reliable installations and long-term system life.


When sleeving is required, it is critical that the sleeve be watertight to prevent groundwater infiltration. Failure to properly seal the sleeve might result in the collection and concentration of ground water contaminated with melting salts, fertilizers, or other chemicals near the tube surface, causing corrosion.

Sleeve sealing can be done in a variety of ways:

  • Caution. Silicon caulk the gap between the tube and the sleeve. Caulks that contain ammonia or methanol, which can outgas as they cure and, in rare situations, cause stress-cracking corrosion of the copper tube, should be avoided.
  • Caution. Use hydraulic cement to fill the gap between the tube and the sleeve. Hydraulic cement has no adverse response with copper, but it does create a highly hard connection between the sleeve and the copper tube, which can be a source of high stress as the surrounding soil expands or contracts. Work hardening and fatigue cracking of the copper tube may occur in rare situations. To avoid this, the earth at this place should be compacted properly and thoroughly during the installation process. 3.
  • Preferred. Seal the sleeve using FerncoTM or comparable electrometric clamps and electrician’s duct seal (see Figures 3 and 4). (See Figure 5). Both of these allow the tube to stretch and shrink while still maintaining a watertight seal within the sleeve.

How far can a flexible gas line be run?

Many households in the northern half of the country will have to turn on their heating systems at the beginning of October. Natural gas is one of the most cost-effective and efficient fuels for a furnace or boiler. With its benefits come questions about safety and obligations for homeowners. It is your role as a home inspector to assist in the detection of flaws that may jeopardize the safety of residents in natural gas-powered homes. We’ll go through some of the fundamentals of gas piping inspection.

The gas supply line, also known as the building line, is the plumbing that runs throughout the house. Individual appliances are served by branch lines. The branch line finishes in a drop line, which is a vertical pipe that drops down from an overhead branch line to the appliance. If it carries gas up to an appliance from a branch line below the appliance, it’s called a riser.

A sediment trap or dirt pocket, commonly referred to as a drip leg, is normally present at the appliance connection point and consists of a nipple and a cap. This pipe extension, which is normally at least 3 inches long, is designed to catch any water or foreign material that may be present in the gas before it enters the appliance. The solids and liquids fall into the pocket, which is just a gravity mechanism.

The homeowner is normally responsible for the pipework downstream of the gas meter. The gas company is normally responsible for the piping upstream of the gas meter, as well as the meter itself.

Steel, copper, and brass are the most popular materials for gas piping. In some cases, galvanized steel, copper, brass, or CSST (Corrugated Stainless Steel Tubing) can be used, but copper is prohibited by some utilities. Copper is widely used in different parts of the world. You should be aware of what is considered acceptable in your neighborhood. Black steel piping with malleable iron or steel fittings is common. In other cases, galvanized steel is also used.

Flexible connectors are allowed to be used to connect appliances to gas pipelines. A shut-off valve must be installed at the rigid piping connection. This valve must be located in the same area as the appliance.

Accessible and three or six feet long: The flexible connectors cannot pass through walls, floors, or ceilings, and they cannot be hidden. Except for gas stoves and laundry dryers, the flexible connector length is normally limited to 3 feet. 6 feet is usually allowed for these equipment. Using nipples to splice or join connectors is frequently forbidden. Flexible connectors are only allowed in some jurisdictions for gas stoves, dryers, outdoor barbecues, and other semi-portable equipment. Flexible connectors may be prohibited on gas furnaces, water heaters, space heaters, and other similar appliances. Flexible connectors are more likely to be utilized on all appliances in earthquake-prone areas because they give some protection against gas piping leakage or rupture during an earthquake. To find out what is and isn’t permitted in your area, consult your local gas code.

The use of white thread seal tape (often referred to as Teflon tape) as a connecting compound for steel gas piping is not recommended. Cutting oils on the pipe threads from the manufacturing process may hinder the tape from sealing. Yellow thread seal tape is permitted in some regions. Pipe dope is favored and may be the only option available. You might wish to double-check with the gas company. Inquire about whether any piping installations with thread seal tape of any color should be reported as a defect.

Although certain exceptions exist, most appliances should have a shut-off valve nearby.

The use of gas piping as a grounding mechanism for the electrical service is prohibited by most authorities. In many countries, however, bonding the gas piping to the electrical grounding system is required. This is often accomplished by connecting the gas pipe to the supply water piping (assuming it is grounded) near the water heater. We want to keep the gas piping at zero electrical potential by attaching it to the grounding system to prevent an electrical potential building within it that could lead to arcing, which could ignite gas.

On gas piping, the following issues are common:

  • Materials that are not appropriate
  • Inadequate assistance
  • A shut-off valve is missing.
  • Connections that are incorrect
  • Above-grade exposure of plastic pipe
  • Chimney piping and duct systems
  • Tubing made of copper that hasn’t been correctly labeled

All of these issues have the potential to result in gas leaks and explosions.

Carson Dunlop’s home inspection training program is the only certified college dedicated solely to house inspection training and is designed to ensure your success. For more information about Carson Dunlop’s home inspection training program, click here.

Is PEX suitable for gas lines?

PEX pipe is not the same as PE piping, and the two are frequently confused. Polyethylene, or PE, is a flexible plastic polymer that is ideal for piping in wells and other cold-water supply lines.

PEX stands for polyethylene that has been cross-linked. It’s made of polyethylene, a material with a stronger link between the polymer chains that make it up. PEX is now suited for both hot and cold water applications as a result of this advancement. It can also be utilized in some gas applications, depending on the building code.

PEX and PE are more flexible and have a significantly greater pressure rating than typical gas lines, thus they suit those requirements. They are, however, made of a soft material that could be damaged by nails, rodents, and other objects. As a result, in your location, either may not be permitted for use as a residential gas line. Even when the utility provider is able to install it, plumbers and homeowners are not always able to.

Why are gas lines made of black pipe?

Pipes are needed to supply water and gas to houses and businesses. Stoves, water heaters, furnaces, and other appliances run on gas. Water is both necessary and obvious. Black pipe and galvanized pipe are the two most prevalent types of steel pipe used to transport water and gas. Homeowners and even some professionals are often perplexed as to where and when to use these steel pipes.

Galvanized steel pipe has a zinc coating applied to it to make it more corrosion resistant. Galvanized pipe is mostly used to bring water to homes and structures. The zinc also helps to prevent mineral deposits from clogging the water line.

Because it is uncoated, black steel pipe differs from galvanized pipe. The black color is due to the iron oxide that formed on the surface during production. Black steel pipe’s principal function is to transport natural gas into homes and businesses. The pipe has no seams, making it a stronger and safer pipe for transporting gas. Because black steel pipe is more fire resistant than galvanized pipe, it is also utilized for fire sprinkler systems.

In summary:

  • Steel is used to make black and galvanized pipe.
  • Black pipe does not have a zinc coating, whereas galvanized pipe does.
  • Galvanized pipe is great for transporting water but not for transporting gas.
  • Because of the zinc coating, galvanized pipe is more expensive.
  • Galvanized pipe is more resistant to corrosion.

Because of the galvanized coating, you should not use galvanized pipe for gas. Galvanized steel bits will flake off over time and block your gas regulators and burner units.

If you mix galvanized and black iron, corrosion will be accelerated where they come into contact.

Is it possible to utilize plastic gas pipe above ground?

Plastic pipe, tubing, and fittings must meet ASTM D 2513, Standard Specification for Thermoplastic Gas Pressure Pipe, Tubing, and Fittings, and must be used exclusively outside underground.