Is this a line to a private tank for oil or gas? If so to ensure the tank and plumbing are at a similar potential to the ground upon which it stands, partly for exposed conductive part into a definite extraneous, and partly as antistatic - more of a concern with LPG /propane than heavy oils.. However, if the clamp is over the plastip pipe sleeve it serves no useful purpose at all. Be aware that pipe joints with ptfe or sealing compounds can be a lot poorer connections than the pipe, and the fluids tend to be dielectrics.. If it is not a fuel line, sorry, but the installers intention is probably similar.
