Loading and unloading liquid bulk tankers pose unique operational and safety challenges. Workers must take added precautions when handling flammable and/or combustible materials to avoid potentially catastrophic consequences. In this article, we will review the procedures for safely loading and unloading bulk liquid tankers.
What are Tanker Trucks?
A tanker truck, or fuel truck, is a vehicle that is designed to carry liquids or gases on roadways. Tanker trucks have evolved greatly since Standard Oil started using them more than 100 years ago. Today, there are many different types of tanker trucks that vary greatly in size and their intended use. That being said, most tankers have a cylinder shape as it offers many benefits. The tank’s rounded corners do not require the level of reinforcement that a container with straight sides and corners does, making it more stable. Moreover, the design helps to prevent liquid surge and makes it easier to extract liquids, leaving less product in the tank and reducing contamination for the next load.
In the U.S., large tanker trucks have capacities that range from 5,500 to 11,600 gallons. They are used to transport highly flammable substances such as gasoline, natural gas, and industrial chemicals. But they are also used to transport many different types of liquid goods such as molasses, milk, and wine. When transporting substances that are intended for human consumption, food grade or insulated tankers need to be used to keep products safe and sanitary during transport. Tanker trucks that utilize compartments can carry a variety of substances at once.
Smaller tanker trucks typically have a capacity of fewer than 3,000 gallons and primarily transport liquid cargo within the community. For example, vacuum trucks are equipped with empty septic tanks to collect waste.
Tanker Truck Loading and Unloading
Tanker truck loading and unloading procedures can vary depending on the substances that are being transported. For instance, some chemicals require the use of pumps while others require compressors. There are, however, just two ways to load tanker trucks – top loading and bottom loading. Top loading involves attaching a hose to the manhole located on the top of the tanker. Bottom loading utilizes valves and fittings loaded underneath the tanker trailer.
Of the two loading methods, bottom loading tends to be safer for fuel products. The reason is that top loading can agitate the fuel which can lead to both vapor and static buildup. This is especially dangerous since neither are visible and a single spark can produce a catastrophic explosion. Bottom loading, however, does not agitate fuel as much making it the preferred loading and unloading option.
Tanker Truck Loading Procedures
Again, tanker truck loading procedures can vary depending on the nature of the substance(s) being transported. The following procedures apply to situations where inflammable bulk liquids are being loaded from storage tanks into tanker trucks.
Before loading liquids into the tanker, it is important to do a thorough inspection. Ensure that all equipment is in working order and that there are no leaks. If you detect any odor stop what you are doing and try to identify and remedy the issue. Make sure that the trailer is the right one to transport that particular chemical. Check inside the tanker trailer compartments and make sure that they are empty to avoid contamination. If the chemical that you are transporting is hazardous, ensure that the trailer has all required labels.
Once you have completed your preloading inspection, you can begin the loading process which consists of the following steps:
- Park the trailer in the designated loading area and ensure that the drop tube is positioned vertically into the tank as far down as possible to reduce agitation.
- Turn the engine off and ensure that all electrical devices are off to reduce the likelihood of sparks.
- When filing, mixing, blending, or transferring flammable and/or combustible materials, it is crucial to utilize a truck grounding system. The truck ground system allows built-up static charges to flow into the ground to avoid a dangerous spark that could ignite the chemicals.
- If you are loading a compartmentalized tanker, check to see if all compartment valves are closed. The only compartment that should be open is the one that is being filled. The others should remain closed.
- If using a meter stop, set it to the desired amount to prevent overfilling and spills, leaving adequate room for thermal expansion.
- Open the loading valve to start the flow. When loading flammable or combustible chemicals it is important to start slowly – less than 120 gallons per minute for the first 6 inches of a compartment. Slow loading helps to minimize static buildup. Stay alert and remain near the truck until loading is complete.
- When loading is complete, close the loading valve. Leave the drop tube in the tank for several minutes to ensure that it is completely drained. Once empty, remove the drop tube and close the dome cover.
- If you are loading multiple compartments, follows these steps to load each one.
- Disconnect the truck grounding system.
- Conduct a post-loading inspection. Walk around the truck and ensure that all equipment has been disconnected and that there are no obstructions near the truck. Drive the truck away from the loading spot and report any issues to your supervisor in accordance with company policies and procedures.
Tanker Truck Unloading Procedures
Like the loading process, tanker truck unloading procedures depend on the materials being transported. The following are some general steps for unloading bulk liquids into a storage tank. Note that it is up to the carrier to know all applicable procedures and requirements for a particular chemical.
- Position the tanker in the designated unloading location.
- Turn off the engine and all electrical equipment in the truck.
- Inspect the truck, tank, and unloading equipment. Ensure that there are no hazards or obstructions in the unloading area.
- Mark off a perimeter to ensure that no one accidentally enters the unloading area.
- Make sure that the storage tank contains the same substance that you are unloading and that the tank can accommodate all the materials that you are delivering.
- Connect the truck grounding system.
- Uncap the discharge connection and attach the unloading hose.
- Ensure that all receiving valves are closed.
- Attach the discharge hose to the correct receiving line and storage tank.
- If the chemicals you are unloading are prone to releasing vapor, utilize a vapor recovery system.
- Open the internal safety valves for no more than 2 of the tank compartments that are being unloaded.
- Open the discharge valve slowly to ensure that there are no leaks.
- Remain alert and near the truck, constantly checking for leaks, overfills, and other potential issues throughout the unloading process.
- Close all the valves that were opened prior to unloading. Drain residual products from the hoses and fittings into the storage tank. Return them to the appropriate locations.
- Close all caps and manholes.
- Disconnect the truck grounding system.
- Complete all required paperwork.
- Conduct a final inspection of the truck and unloading area to ensure that there are no obstructions or other issues.
- Remove the truck from the unloading area.
Conclusion
Loading and unloading tanker trucks can be incredibly dangerous without the property equipment and safety solutions. SafeRack is the leading supplier of OSHA-compliant safety access solutions in North America. We offer many innovative solutions that can help keep workers safe and productive while loading and unloading tanker trucks.
Workers typically need to climb on top of tanks to open a hatch or compressed air valve. Our tanker truck loading platforms with access gangways allow workers to safely and efficiently access the tops and bottoms of tankers. This eliminates the need to climb on top of tankers and significantly reduces the likelihood of slip and falls. Top loading arms and bottom loading arms offer fluid level sensors, vapor recovery, and grounding and metering.
Our aluminum awnings and canopies are cost-effective solutions that keep workers and materials safe from the elements while loading and unloading truck tankers. SafeRack also offers truck grounding and monitoring systems and spill containment solutions. Our experienced engineers can fully integrate any solution into your existing application and processes. Contact our dedicated team today to learn more about our industry-leading safety solutions.
