In a process plant, how the metal structure is earthed?

Answer 1

Jeffery S is correct but there are some differences in how some engineers do it.

Some ground each piece of equipment and structure while others only ground some items and depend on the interconnecting piping to ground the rest of the system.

I believe grounding each piece of equipment and each structure is a better way to assure that all items are always grounded. In the case of steel pipe racks, there should be multiple grounds in case some portion is isolated during maintenance.

Answer 2

Some are not properly "grounded". The main columns of the structure should have conductors attached to them permanently and either attached to the reinforcing steel of the foundation or electrodes driven into the ground. I have send them use copper conductors "cad welded" to the structure and to the reinforcement steel of the piers.

I don't have the expertise to design a proper grounding system but I can tell you it requires a knowledge of soil conditions. The ground system has to insure the entire structure is grounded at zero potential.

Answer 3

I assume by "earthed" you mean grounded. This is typically done through the use of ground wires attached to the metal and then attached to a grounding rod or grid burried around the structure.