About Polyethylene Gas Pipe
Polyethylene (PE) Gas Pipe offers a convenient, cost-effective and approved method of running outdoor underground gas lines from meters and propane tanks to indoor gas system and variety of outdoor gas-fired equipment, including hot tubs, grills, infrared gas heaters and many others. At present, it accounts for over 90% of all gas pipe installed in the US.
With over 50 years in service, PE gas pipe has proven to be a reliable product for handling gas distribution, with excellent resistance to both varying soil conditions and the constituents in the gas itself.
Decoding SDR, IPS, CTS, MDPE and HDPE
At present, there’s a multitude of PE gas pipe types, sizes and dimensional standards, which can be confusing, especially when selecting a compatible fitting system.
SDR (Standard Dimension Ratio) is a standard attribute of all plastic pipes, indicating the relation of pipes’ outside diameter (OD) pipe to its’ wall thickness. SDR = OD / Wall Thickness. The most common SDR for yellow PE underground gas pipe is SDR-11 and it is the size we offer at PexUniverse
IPS (Iron Pipe Size) and CTS (Copper Tube Size) indicate which dimensional standard PE pipe uses. Majority of PE gas pipe on the market is IPS size and it the size we sell
. IPS is also the same dimensional standard used for black gas pipe, making it easier to cross-reference between the two.
HDPE (High Density Polyethylene) and MDPE (Medium Density Polyethylene) refers to a grade/type of polyethylene with the major distinction between the two being flexibility (stress-cracking) and pressure resistance (tensile strength). MDPE, being more flexible, is the material of choice for the underground gas piping applications, and it is the type we sell at PexUniverse.
HDPE pipe is less common is the gas industry and usually is intended for non-residential applications with high pressures (up to 125 psi). MDPE gas pipe is yellow in color, while HDPE pipe can be black, black with yellow stripe or black with a yellow outmost layer.
Types of fittings and connection systems for PE gas pipe
All types of fittings used for PE pipe fall into (2) distinct categories - mechanical fittings and fusion fittings.
Mechanical fittings are most common for low-volume installations, including residential and light commercial projects with pipe size not exceeding 2". They include:
- Compression-style PE pipe fittings - work in a manner similar to most compression type fittings in the plumbing & heating industry. They utilize a compression ring, ferrule and nut to create a leak-proof connection. PE gas pipe fittings we sell are compression style. Compression PE gas pipe fittings are reusable and economically-priced, making them a popular choice.
- Con-Stab ID Seal® fittings are push-to-connect style fittings, which work in a manner similar to SharkBite®, where pipe is inserted in the fitting and is held inside by a retainer ring, while sealing O-rings prevent gas leakage. Con-stab gas fittings are the easiest to install, but also cost significantly more that the compression counterpart, are non-reusable and require chamfering.
Fusion connections are less common in the residential market and are primarily intended for larger pipe sizes, such as 3" IPS and above. They utilize special equipment & tools and require special training. There’s a variety of PE fusion connection techniques, including:
- Butt fusion (incl. saddle fusion) - applies heat to the butt of the pipe and the fitting assembly, fusing them together.
- Socket fusion - heat is applied both to the fitting and the pipe surface (separately), until both reach desired temperature and start melting. Afterwards, the pipe is inserted into the fitting and both are held together until cooled off.
- Electrofusion (EF) – utilizes electricity to fuse the fitting (made of conductive material) and the pipe together.
Frequently Asked Questions
Q: What are PE gas pipe risers used for?
A: Anodeless risers (or meter risers) are used to create a 90-degree transition from PE underground gas pipe to above-ground metal pipe - most commonly for connecting to gas meters, tanks, etc. Transition fittings (straight stub-outs) are used for a similar purpose in below-grade installation. Some risers come with a fitting (coupling) pre-installed, while others have a standard PE to metal transition.
Q: What is tracer wire used for?
A: Tracer wire is laid alongside the PE pipe to provide easy means of detection of an underground gas line and prevent accidental damage during excavation. It is required by federal code. Yellow is the designated tracer wire color for underground gas lines and 14 AWG (gauge) is the standard thickness for open trench installations (some localities may require 12 AWG). HDPE insulation jacket thickness requirement is usually 30 mil. The wire core requirements may also vary, where some require low-carbon steel core with copper cladding, others may accept standard copper core.
Q: Does mag-detectable tape replace the tracer wire?
A: Magnetic-detectable tape is usually used in addition to the tracer wire, especially where the latter is buried alongside the underground gas pipe instead of at the top. While local codes and installation requirements may vary, the tape generally does not replace the tracer wire and is used only as a supplementary identification and location safety measure. Yellow or yellow striped is the APWA designed color for gas lines and 5.0 mil is the standard thickness. Width of the tape usually determines the burial depth, being 6-9" for 2" wide tape, 9-12" for 3", 12-15" for 4", etc.
Q: Can PE gas pipe be exposed to sunlight?
A: While pipe can be exposed to sunlight for a short duration of time prior to installation, it is not UV-rated and must always be buried underground.
Q: Is polyethylene gas pipe suitable DIY installation?
A: No. It must be installed only by a licensed and trained professional.