Unlike above-grade gas piping installations that require metallic piping, underground systems need to perform in harsh and corrosive environments. Metallic pipe installed underground requires additional and costly materials to protect the pipe. Polyethylene gas piping systems are specifically engineered and certified for the underground environment. To provide a true underground gas piping solution. Risers are used to transition from below ground polyethylene pipe to above ground metallic pipe. These risers are used for both natural gas and propane gas distribution.