Storage/Loading/Unloading - Tank Truck Loading
April 2, 2008

Introduction

The following procedure is applicable to the loading of tank trucks. 

The procedure is general in nature and must be adapted to the specifics of each loading facility and to the owners own procedures and rules.

Personnel

Attendance by a qualified person during the entire unloading procedure should be required.  This person must be thoroughly familiar with the hazards of sulphuric acid and all operating, emergency, safety and first aid procedures recommended for its safe handling.

Safety and Preparation

Water in large quantities should be immediately available at the unloading site to wash down any acid that may be spilled.

A safety shower is recommended along with a signal system designed to get assistance if an emergency should arise.  The signal system and safety showers should be tested routinely. 

Signs restricting access to the area should be used.

The slow attack of sulphuric acid on mild steel results in the formation of hydrogen sulphide gas which is flammable and can form explosive mixtures with air.  Smoking or other sources of ignition should not be permitted near acid tank cars, and cars fittings should never be hammered or chiseled.

Tank Truck Loading

Locating the Container

For tank trucks the driver should position the truck accurately on the unloading line.  The motor of the truck must be shut off an the brakes set.  In extremely cold weather, if the truck is left running, both tractor and trailer brakes must be dynamited.

The loading ramp can be lowered into place once the truck has been spotted and secured.

Inspect Shipping Container

Before any loading operation is commenced the truck will be chocked and thoroughly examined by the loader accompanied by the driver.  Inspect the shipping container for leaks or damage which could interfere with safe loading.

Venting

Shipping containers as received will frequently be under pressure either because of thermal expansion of the acid or slow hydrogen generation.

Carefully open the air connection valve if the truck is so equipped and vent any pressure in the container.  If there is no air connection, the safety vent should be removed.

If no venting occurs, check to make sure the air connection and valve are unobstructed.  Carefully loosen the fill hole cover bolt (do not disengage), and pry up slightly.  If any pressure is present, let it bleed off slowly until no pressure is in the tank, then open the fill hole cover.

            Caution:      All pressure must be vented before any container fittings are removed because of the danger of acid spray.  Do not remove the cap from the liquid eduction pipe until it is definitely known that all pressure has been vented from the container, and that the valve is closed (if so equipped).

Determine the Tank Contents

Ascertain the previous contents of the tank.  If truck is to be loaded with sulphuric acid, the tank must be washed if it has contained any other material.  The washing of the truck will be carried out at the tank truck transport depot.  If examination of tank interior shows not empty, the contents will be sampled and the nature of the contents determined.  If exact determination of the contents cannot be made, the tank truck will not be loaded.

If the tank is empty or the contents of the tank is sulphuric acid, then the tank truck can be loaded.

Loading System

Ensure that the loading system is ready to deliver acid to the tank truck.  The tank vent should be checked to ensure that it is open.  Ensure all valves are properly set for the loading operation.

Place the loading nozzle in hatch and chained the loading line into a secure position.

Final Check

Inspect the system to be sure and all valves are properly positioned to deliver acid.

Loading

Start the loading pump to begin loading acid into the truck.

If leaks develop or acid is spilled, promptly wash down any surface where acid has spilled with an excess of water being extremely careful to avoid getting water into the container, piping or into large accumulations of acid in holes or trenches.

While he car is loading the pump must be shut off before climbing onto the loading platform.  This is to minimize hazards to the loader due to overflowing as it is being approached.  The pump can be restarted on the platform after it has been determined there is acid required to fill the tank truck.

Termination of Loading

When the acid reaches the required outage shut off the loading pump and close valve on loading line.  Remove the loading line from the fill hole.

Sampling

If a sample of the acid is required, it should be taken after loading is complete and the loading nozzle removed from the hatch.

Sealing of Container

Close the fill hole cover tightly and replace the caps on the air connection valve and liquid eduction line.  Replace the valve covers.  Inspect the container and place proper DOT required placards on the container for the return shipment.

Wash down any acid spills from the top of the tank car and raise the loading platform.

Documentation

Obtain the necessary bills of lading signed as required and check to see that the safety data sheet and driver instruction sheet are attached.

Departing

Check that the truck for signs of leaks and ensure that the placards are in place.  If the truck is not in satisfactory condition or there is a problem the truck should not be allowed to leave until the problem is corrected