Earthing Issue

follow local regulation. Follow international standards, if local authority refer to so. There nothing essential. All are good practice or regulatory requirements only.

Thank you!

The USA rule is to bond anything that may become energized. So if you had a pipe in the very top of a building, it would be unlikely that it could become energized. Someone has to make the decision if the device could be a problem. If there are no electrical facilities in the area of the pipe rack structures, then I would not think grounding is necessary. Remember the local code requirements must be followed.

Codes for example BS7430 require that all metal structures in a plant should be essentially grounded, this includes re-bars in the foundation as well.

Two separate electrical grounding systems if exist in a plant are to be bonded together for an equipotential bonding.

An isolated chimney at the top can get opposite charge from the clouds in an event of thunderstorm, Electrostatic buildup can occour due to friction, stray magnetic fields can induce voltage in structure elements, In soil, mineral salts when combine with sub-soil water form a week electrolyte to generate fraction of a volt.

Most important to you is to follow the design.