Now here is why bonding and grounding falls well short of being all the precautions we need when transferring NON-CONDUCTIVE FLAMMABLE LIQUIDS. Bonding and grounding takes into account that we are equalizing the energy levels between the containers and therefore the static will not be released to the differently charged container. This works when it is DONE properly when we are transferring conductive flammables. However, there is one MAJOR misunderstanding with bonding and grounding.
In the paint, coatings, and adhesives industry there is a fairly common practice to put down floor coverings to help make cleanup easier. Many times the covering is cardboard or industrial paper that is taped to the floor. An operator is filling a tote. The tote is sitting on this cardboard or paper, which is acting as an INSULATOR and is preventing the tote from being grounded. But not to worry, the operator attaches the “bonding” cable to the tote so that now the vessel and the tote are “bonded” thus equalizing the charges in the vessels. So everything is safe?
Well what happens when the operator walks up to the tote to disconnect the hose connection? The operator is wearing static dissipative boots as he/she should be. They are not on the cardboard/paper and thus they are grounded AND they are more than likely at a DIFFERENT charge than the tote that is insulated from the “ground” they are standing on. Do we have a potential problem? YES we do. Bottom line, we should ensure that BOTH containers are grounded, as well as bonded together. Having an insulator in an area where we transfer non-conductive flammable liquids is a VERY BAD IDEA.
Keep in mind that painting a floor, floor covered in dust, operator standing on a pallet, etc. all act as an insulator from their “ground”. I have even seen a potential for sparking with an operator standing on an upper floor of a processing building and the vessel being grounded on the ground level and the operator being at a considerable different charge, even though he/she were wearing static dissipative boots. Epoxy floor paint was found to be the insulator.
Have you ever seen a metal plate built into the floor right in front of the manway of a vessel? It is there to allow the operator to stand on the plate so that he/she will be at the same charge as the vessel, as BOTH the operator and the vessel are using the exact same ground and therefore they are EQUAL in CHARGE. However, if we damage the concrete, paint the metal plate, metal plate is coated with a buildup of “gunk” or powders, or the operator is not standing on it.
Bonding and Grounding is a MUST when transferring any flammable liquids, but when we are transferring non-conductive there is MORE TO DO.