Different parts of the tank
All parts of the tank or vessel should be attached to the grounding system to ensure
electrical continuity. The utmost care must be taken to bond any metal pipes or
cables entering the structure to the tank, observing the cathodic protection system.
One special case for bonding is the floating roof tank. As the floating roof is not in
direct contact with the tank shell, high potential differences can arise under the influence
of direct or nearby lightning strikes. One recommendation is that the roof should
be electrically bonded to shoes of the seal through the most direct electrical path at
intervals not greater than 3 m on the circumference of the tank. This bonding can
be done by shunts made of stainless steel straps, but care must be taken to ensure
that they have an adequate current-carrying capacity and a suitable corrosion resistance
[14]. It is imperative that the metallic shoe stays in permanent contact with the tank
shell through the shunts. Of course, the shunts are not required when tanks do not
have a vapour space at the seal. However, it has been recognized that the shunts