The Perma containment piping system consists of the following components: SCLAIRPIPE HDPE core pipe, bare or pre-insulated. Threaded WEHOLITE HDPE as the outer containment pipe. PSI spacers to center the core pipe and to facilitate installation. Special heat shrinkable HDPE tubes to seal the containment pipe. HDPE containment vaults which facilitate valving, elbows, tees and monitoring equipment. PSI Link-Seals® for sealing through vault walls. The SCLAIRPIPE core pipe ends are fused together to provide a "leak-proof" transmission pipe. If the core pipe is pre-insulated, the joints would be filled using pre-formed polyurethane half shells. The joint would be covered with a heat shrink sleeve. After the core pipe is fused (or prior to fusing), the appropriate spacers are placed on the core pipe so that the outer containment pipe can be slid over the core pipe. The WEHOLITE outer containment pipe is slid over the core pipe and threaded together. A special HDPE "tube" is slid over the thread joint to provide a leak-proof low pressure containment seal. All changes in direction, valving, etc. will take place in specially-fabricated HDPE vaults. These vaults will be made from 3/4" thick HDPE. Pipes will pass through specially-installed access ports fused into the vaults. The space between the containment pipe and the access ports will be sealed using Link-Seal's® mechanical seals.