Truck Load Out
Tanker Truck Fire
The loading and unloading of tank trucks containing flammable and combustible products presents one of the most serious fire risks for production and disposal site operations. The most common interface for the charging of non-conductive and semi-conductive product is contact with metal plant equipment, including pipes, filters, pumps, and valves. A truck load-out must have proper grounding and bonding, so it doesn't become dangerously charged when an electrostatically charged liquid moves through it.
Static discharge occurs in tank truck transfer operations when other conductive objects, such as the operator, come into close proximity with a charged container. The charges on the tank truck’s container attract opposite charges to the surface of the object. This rapidly creates an electric field between their respective surfaces. The strength of this electric field can causes the “breakdown” of the air space between the container and the object, leading to static discharge. If a combustible atmosphere is present in this space, there is a high risk of ignition.
To eliminate the risk of static discharges, the NFPA and API recommend that vacuum truck operators transferring flammable and combustible product in hazardous locations must fully ground the truck prior to any other task in the transfer operation by connecting the truck to a proven ground source.
Grounding eliminates the buildup of static electricity on the tank and chassis of the tank truck. There are three key functions that must be in place before the loading/unloading operations can begin:
- Verify that the grounding clamp is connected to the ground
- Verify that the ground is bonded to the load out pipe
- Connect the grounding clamp to the tank truck chassis