Figure 9-1. Loading from the bottom.
| Critical Task: | 101-519-3314 |
OVERVIEW
Following the proper procedures for loading and unloading petroleum products from rail tank cars will enable you to accurately account for the quantities delivered and issued, verify the quality of the products in transition, and prevent spills.
Lesson Description:
This lesson covers the procedures for loading and unloading rail tank cars, their maintenance, and gaging.
Terminal Learning Objective:
| Action: | The soldier will learn to supervise the operator maintenance and operation of assigned vehicles and equipment. Inspect rail cars for suitability of use; proper documentation, and security seals; loading and unloading of rail cars; and gaging of rail cars. |
| Condition: | Given subcourse QM5094. |
| Standards: | The soldier must score a minimum of 70 percent on the end of subcourse examination. |
Most countries in the world have established railway networks as a major means of transportation. Petroleum rail tank cars can provide an effective way to transport large quantities of bulk fuel efficiently. As a petroleum specialist, you are subject to worldwide assignment and may encounter rail tank cars at every duty station. It is essential that you be proficient in all aspects of rail tank car operations.
Cars are inspected for suitability of use, proper documentation, and security seals. Generally, a petroleum rail car has only one compartment; however, some have more than one compartment and can carry multi-products. Cars are manufactured from different gages of steel depending on usage and may be equipped with heaters to liquefy highly viscous product. Typically each compartment has a bottom outlet. In the U.S. 5-inch outlets are standard; overseas 4-inch outlets are standard. Each compartment has a dome through which the rail car may be loaded, unloaded, inspected, cleaned, and repaired. The dome provides room for expansion of product in the event of temperature rise and may be hinged and bolted or screwed on. The tank car is also equipped with a safety valve. The safety valve used on most tank cars consists of a poppet valve, that is spring-loaded to predetermined pressure. As pressure develops in the dome and increases to a point in excess of the pressure setting of the valve. The valve is forced off the valve seat, thereby permitting excess vapor to escape. When the pressure drops to a level equal to the valve setting, the spring closes the valve automatically.
The minimum distance from a tank car loading operation to a building should be 100 feet. A spur track or bypass should be provided for loading or unloading tank cars. Trackage should be level to maintain equal depth of product throughout the tank car compartments. Level trackage is necessary for accurate gaging of the tank and to prevent air from being trapped at one end of a tank when the tank is closed. The site should provide adequate drainage. Bond and ground the car with a minimum of four cables. Derails should be installed at the head of the siding to prevent other cars from backing into the siding during transfer operations. A metal derail is approximately 18-inches long; the forward or flat portion is about 6-inches long and the rear or wedge shaped portion, is about 12-inches long. It is attached to the top of one rail of the track. The 6-inch portion lays flat on the track and the wedge shaped portion gradually elevates to a height of about 1-foot 1/4-inch to either stop or derail the first car of a train backing into the siding. Some derails designed in a similar manner, are made of wood. Derails may also be installed at other locations to prevent cars from rolling into danger areas if the brakes are released accidentally or fail to hold. Where derails are provided, they must be set and locked or operated so that they furnish the protection intended.
Where more than one filling point is used, loading racks should be spaced to allow several cars to be loaded at one time. Each filling point should be grounded and should be equipped with bonding cables for bonding the filling point to the tank car shell and to the track. A flexible hose long enough to reach the bottom of the tank should be connected to the outlet of the loading arm. An emergency valve should be located some distance from the rack so that the line can be cut off in case of fire at the loading rack. Loading racks may be supplied with product directly from bulk storage tanks or pipelines by gravity flow or fixed or portable pumping units may be used to transfer product. A distribution manifold consisting of necessary piping and valves, extends along the loading rack and provides outlets for loading and unloading several cars at one time. Flexible hose lengths should be provided to permit loading cars through the domes. Manifolds must be grounded and equipped with cable for bonding the manifold to the track and to the tank car. A standard car mover should be provided for spotting tank cars. Electrical equipment operating in the area such as lights, switches, and motors, must be of explosion proof construction and must be in good working condition. A wooden cone-shaped plug, suitable for plugging the bottom outlet of the tank car, should be available in case of emergency. The pump assembly must be positioned a minimum of 50 feet away from rail car.
Place signs prohibiting smoking conspicuously about the area. Do not allow welding, matches, lighters, open flames of any kind, or lights, other than approved explosion proof flashlights or lanterns, within 100 feet of the transfer operation. Coal burning locomotives operating near the transfer area should be equipped with smokestacks and fire box screens. All loading and unloading equipment must be grounded and bonded. Position one CO2 or foam fire extinguisher on the ground, the other on the loading rack.
Preparation for Loading.
Sampling and Gaging Product to be Transferred. Take a sample of product that is to be transferred to the tank car and inspect visually to make sure that product has no unusual appearance. If the identity or quality of product is questionable, have the test performed to make sure that product meets specifications before starting the transfer operation. Gage the contents of supply tank and record data. Obtain a water cut from the supply tank measuring with water indicating paste. If the water layer in the tank approaches the level of the tank outlet, drain water before transferring product. Inspect pumps, hose, loading racks, pipelines, and manifolds to see that they are clean, free of any contaminating product, and in good operating condition.
Equipment preparation. When possible, use equipment exclusively for handling one product. If it is necessary to use the same equipment for handling several products, drain the equipment thoroughly of preceding product before introducing the new product into the line. See that track rails are properly bonded and grounded. Inspect cable connections to make sure that they are secure and make bare metal-to-metal contact. Position car so that there will be no unnecessary strain on hose connections. If the loading rack is to be used, position the car so that dome is opposite the filling point. Set brakes and block wheels of the tank car to prevent movement and to ensure safety of connections during loading operations. Set and lock derails, if provided. Place warning signs and fire extinguishers as required. Attach a ground wire to the shell of the tank car and to the stake and saturate the ground around the stake with water to make sure that grounding is effective. If a loading rack or tank car manifold is to be used, bond it to the tank car shell and to the loading rack.
Tank preparation. Remove the dome cover and determine whether the tank car is suitable for receiving product. Make sure that the product last carried by the tank is the same as the product that is to be transferred to the tank. If the product differs the tank must be cleaned before it is released for filling. Inspect the interior of tank for cleanliness; if there is residue on the bottom of the tank, the tank must be rejected and cleaned before it can be filled. Look for any foreign objects, such as tools, bolts, or old tank car seals that may have fallen into the tank. Objects should be removed by authorized persons. Although some objects do not contaminate the product, they may damage valves. Inspect the interior and exterior of tank to make sure that there are no holes, cracks, or loose plates. Be sure that there are no leaks in loose plates. Be sure that there are no leaks in the tank. See that the tank is properly mounted to under frame and that the tank is safe and road worthy. Inspect the dome, dome cover, and safety valve to see that they are operable and in good condition. Make sure that the vent holes in the dome cover are open and free of dirt. See that outlet chamber has not been damaged.
Tank valve inspection. Make sure that the outlet valve closes and seals properly. Place a suitable container underneath the bottom outlet chamber to catch drainage and open and close the outlet valve several times by operating the valve rod handle or hand wheel located inside dome. If valve does not close properly, the valve gasket should be replaced or the valve repaired. In an emergency, a tank car may be loaded without repairing the outlet valve; however, this condition must be reported so that persons receiving the tank will unload through the dome. In this case the car should be scheduled for repair as soon as possible. When the outlet valve is operating properly, close the valve. The drainage tub should remain underneath the outlet until the transfer operation is completed. When considered necessary, tank cars may be flushed with a small amount of the product to be loaded to remove the last traces of previous product, as well as rust and scale, from the outlet sump of the tank car. Before removing the bottom outlet cap make sure that the outlet valve is properly closed. With a tank car wrench, remove the bottom outlet cap. Allow any product trapped in outlet chamber to drain into the drainage tub. If there is any residual product in the tank, open the outlet valve and allow the product to drain into the tub. Close the outlet valve, but do not replace the outlet cap until the car is completely loaded. Dispose of any product collected in the drainage tub, and place tub in position to catch leakage.
Loading Product. Tank cars should be loaded through the bottom outlet (Figure 9-1) whenever possible to prevent vapor loss, reduce the generation of static electricity, and protect the fuel against contamination from outside sources. To bottom load a tank car proceed as follows. Locate and ground a pumping assembly at least 50 feet away from the tank car. Make sure that the supply container is properly grounded and vented. Connect the hose lines and take care to prevent hose connections from lying on the ground or from becoming otherwise contaminated. Station a man on the windward side of the dome to signal when the full mark is reached. Before starting the pump, open the appropriate valves to avoid pumping against a closed system. Start the pump and observe safety precautions. When the transfer operation is halted for any reason, disconnect the pump discharge hose. When the level of product in the tank car is near the full mark of the bench mark, signal the pump operator to reduce the pump speed and be alert to stop the pump. When using a loading rack or other system that provides a control valve, reduce the flow of product into the tank by partially closing the valve. If the tank does not have a full mark, load the tank until the product reaches the top of the shell. When the product reaches the full mark or top of shell shut down the pump, close all valves, and disconnect the pump discharge hose.
Figure 9-1. Loading from the bottom.
Top Loading. Top loading is done only in emergency situations when bottom loading is not possible and is accomplished by inserting the end of the loading hose or drop tube through the dome of the tank until it almost touches the bottom of the tank (Figure 9-2). If the hose or drop tube does not extend far enough into the tank, the product splashes, causes undue loss of product through vaporization, and creates a potential fire hazard. Make sure that there is no unnecessary strain on the hose, which could cause the hose to move or come out of the tank during the transfer. Before starting the pump, open the appropriate valves to avoid pumping against a closed system. When all connections are secure and the necessary valves are open, start the pump. When product starts to flow into the tank, observe the bottom outlet to see if there is any leakage. If leakage is apparent, stop the pump and attempt to seat the bottom outlet valve by turning the valve rod handle in a clockwise direction. If the leak cannot be stopped, discontinue loading operations, recover product from the tank, and clear the area of spilled product. Follow safety precautions as given for bottom loading above.
Figure 9-2. Loading from the dome.
Follow-Up Procedures. After loading the car follow-up procedures are performed. Allow product to stand for 15 minutes so that suspended water or sediment can settle. Gage and sample contents of tank. Take the temperature of product, correct volume to 60 degrees F, and record data. Retain sample for reference until car has been delivered. If tank contains any water or sediment, drain it from the tank, and again load product until the tank is full. After daily closing gages are taken, compare total storage tank issue with total quantities loaded on tank cars. Report excessive loss to the proper authority. When a tank car is full of product, replace bottom outlet, cap, and close and lock the dome cover. Place an identification seal on the dome cover; it must be an approved seal, one which cannot be removed without being destroyed. The receiver is assured that the car has not been tampered with if the seal is in place. Record the seal marking on all shipping papers. Remove the drainage tub from under the bottom outlet and discard any product that is in the tub. If the car has DANGEROUS-EMPTY placards, remove them and replace them with FLAMMABLE placards. Some placards bear the two signs; they only need to be reversed. Disconnect grounding wire from tank car; remove derails, if provided; and remove TANK CAR CONNECTED signs. Release brakes and remove car from transfer area.
Equipment Preparation. Inspect the unloading equipment such as pumps, hose, loading racks, pipelines, and manifolds to see that they are clean, free of any contaminating product, and in good operating condition. When possible, use equipment exclusively for handling one product. If it is necessary to use the same equipment for handling several products, drain the equipment thoroughly of preceding product before introducing the new product into the line. If product in the tank car is to be transferred to cans, drums, tank trucks, or semitrailers inspect the containers or vehicle and make sure that they are clean and in good condition. If the product in the tank car is to be transferred to storage tanks, make sure that the tanks are clean and suitable for receiving the assigned product. If the tanks are not clean, they must be freed of vapors and cleaned before receiving product.
Sampling and Gaging Receiving Tank. When a receiving tank already contains product, gage and sample the contents of tank. Take the temperature of the product, correct volume to 60 degrees Fahrenheit, and record data. Make sure that there is enough space (outage) in tank to receive product. Inspect the sample visually to make sure the product in the receiving tank is the same as product in the tank car. If there is any doubt as to the identity or quality of the product, have the test performed to verify correct grade and quality before mixing new product with it. Drain water from the tank before starting transfer. Gage tank again and record the data. Make sure that the receiving container and tank car are properly grounded and vented.
Tank Car Inspection. Compare car number and seal number with numbers on shipping papers to see that the car to be unloaded is at the right destination. Examine the seals and locks carefully for evidence of tampering. If cars arrive with broken seals or locks, notify the proper authority. If it is absolutely necessary that the car be released because of a shortage of tank cars, transfer the contents into a separate container, but do not use the product for any purpose until tested samples have been approved. Shortage of product should be made a matter of record. Pry seals loose and remove the dome cover. In hot weather extremely high pressures may develop in tank cars if the safety valve is not functioning. When time permits, relieve pressure by permitting the car to cool overnight. If pressure is released by venting, large quantities of product are lost through vaporization creating potential fire hazard. Inspect the tank car for leaks through the shell and bottom outlet. If the car shows evidence of leaking, schedule the car for immediate unloading. Place containers in position to catch leaking product.
Sampling and Gaging Tank Car. Gage and sample the contents of the tank car, and examine the sample for appearance and color. Take temperature of the product, correct the volume to 60 degrees Fahrenheit, and record the data. Remove any water present in the tank by draining water slowly through the bottom outlet. If water is removed, gage the contents again, correct volume to 60 degrees Fahrenheit, and record data. Examine a sample of the product visually to make sure that the product is of proper grade. Fuel having a cloudy or decidedly "off color" appearance should be suspected of having some contamination. Any questionable product should be thoroughly tested to make sure that it meets specifications before it is unloaded.
Tank Car Valve Inspection. If the car is to be unloaded through the bottom outlet; make sure that the outlet chamber is in good condition and that the outlet valve is operating properly. The valve may become inoperable in cold weather because water in the tank is likely to settle and freeze around the outlet valve. To free frozen valves, apply steam jet, hot water, or hot cloths to the outlet chamber. When authorized a hot air duct tent heater, or a slave kit may be used by trained personnel to thaw the outlet. If time permits, allow the valve to thaw during the warm part of the day.
Unloading Tank Car.
Dome Unloading. To unload the tank car through the dome locate the pump at least 50 feet from the tank car and ground the pump. Place a drainage tub under the bottom outlet to catch any drainage. Insert the end of the unloading hose through the tank dome until it almost touches the bottom of the tank. Keep the hose below the surface of the product until the tank is completely unloaded. Connect the pump discharge line to the inlet of the receiving container. Place the dome cover over the manhole so that the cover rests against the hose and allows ample space for venting. Follow pumping procedures described above. When the tank car is almost empty, manipulate the hose so that all product is drawn from the car. If possible, remove the bottom outlet cap and drain product from the outlet chamber into the tub.
Follow-Up Procedures. Make sure that the tank car is completely empty. Gage and sample the contents of the receiving tank, correct volume to 60 degrees Fahrenheit, and record the data. Compare the quantity of product delivered to the receiving tank with quantity taken from the tank car. Report excessive loss to the proper authority. Allow ample time for any suspended water and sediment to settle in the receiving tank, drain the water, gage the contents again, and record data. Close the bottom outlet valve. Remove the unloading hose from the tank car. If a wooden block is used to hold the dome cover open, be sure that the block does not fall into the tank car. Disconnect the tank car adapter, and replace the outlet cap; tighten the cap with a tank car wrench. Close and lock the dome cover; remove the drainage tub and discard any product in the tub. If the car has FLAMMABLE placards, remove and replace them with DANGEROUS-EMPTY placards. Disconnect grounding wire from the tank car; remove derails, if provided; and remove TANK CAR CONNECTED signs. Release the brakes and remove the car from the transfer area. Notify the proper authority that the unloaded tank car is ready for removal and is being returned empty, free for load. Report any defective car to the property authority.
The two most common reasons for cleaning tank cars are contamination and change of product. Prior to beginning cleaning operations, appropriate safety measures must be taken. These include bonding and grounding the car and placement of safety signs and fire extinguishers. Clean uncoated tanks by steaming for one hour. If sludge remains, continue steaming until clean. On tank cars with multiple compartments clean one compartment at a time. Allow the tank(s) to cool then check with explosimeter. Remove residual sludge and steam again with cleaning solvent. Allow the tank to cool then dry with lint-free rags.
Never clean coated tanks with steam. Use air ejector or air eductor to vapor free the tank, check with explosimeter, then remove sludge. Scrub the tank with solvent, rinse with warm water and dry with lint-free rags.