The most important countermeasure that must be taken to prevent an electrostatic hazard is to bond all metal objects together. Bonding eliminates the risk of discharges between metal objects, which can be very energetic and dangerous.
On ships, bonding to earth is effectively accomplished by connecting metallic objects to the metal structure of the ship, which is naturally earthed through the sea.
Some examples of objects which might be electrically insulated in hazardous situations and which must therefore be bonded are:
- Ship shore hose couplings and flanges if more than one length of non-conducting hose or pipe is used in a string.
- Portable tank cleaning machines.
- Conducting manual ullaging and sampling equipment.
- The float of a permanently fitted ullage device if it lacks an earthing path through the metal tape.
Certain objects may be insulated during tanker operations, for example:
- A metal object such as a can floating in a static accumulating liquid.
- A loose metal object while it is falling in a tank during washing operations.
Every effort should be made to ensure that such objects are removed from the tank, since there is evidently no possibility of deliberately bonding them. This necessitates careful inspection of tanks, particularly after shipyard repairs.
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