Nitrogen sleeves are used to provide additional protection to key short sections of pipework, for example road crossings. Sleeves are often located in remote locations, and there are over 1200 on the NTS. A nitrogen sleeve comprises a sealed and welded steel shell around the pipeline that capable of containing line pressure and is pressurised with nitrogen to provide an inert atmosphere against corrosion on the inside of the shell. Complementary cathodic protection (CP) is also applied to the shell to protect the outside from corrosion. The integrity of the nitrogen sleeve can degrade overtime through failure of the CP system or leak of nitrogen from the sleeve. National Grid policy is therefore to monitor the pressure of nitrogen and monitor the voltage of the CP to ensure the shell and pipeline are protected from corrosion.

Benefits

Successful design, development and trial of a low maintenance combined CP and pressure remote monitoring solution for nitrogen sleeves including interface with core data systems, KPIs and specification.