Conductive (PE) system

From a technical viewpoint, EN14125 requires that, for insulating pipes, which have conductive liners, the electrical conductivity must have volume resistivity less than 10¹¹ Ω.m, or a surface resistivity less than 10 Ω. The conductive (PE) pipe passes these tests. Tests carried out on conductive (PE) pipes are performed on pipe samples as prescribed by the relevant standard but they do not take into account joints and connections. The conductive part of a conductive (PE) pipe is just a thin internal layer. The outer material and the electrofusion joints are non-conductive. Therefore, with hybrid systems, a ‘conductive insert’ must be fitted at each joint in order to ‘bridge’ the internal surfaces of the pipe each side. However, should any of these ‘bridges’ not connect or fail, the pipework system can be turned into a capacitor that can store energy in the form of an electric charge.

 

What the independent expert says:

“Any breaks in the continuity of a conductive system can produce a spark gap which must be considered as a potential ignition hazard. An intermittent connection may be good when measured after installation but may conceivably deteriorate and fail later. Spark discharges from ungrounded conductors are more hazardous than brush discharges from plastic surfaces hence the recommendation in Safety Standards to firmly bond to ground all conductive items of plant which are in or near flammable atmospheres.”

An extract from research by G L Hearn B.Sc C. Eng M.I.E.E of Wolfson Electrostatics Ltd on the electrical/electrostatic performance of conductive and non-conductive polyethylene fuel pipe.