B620 Tanker Truck Design
B620 Tank Types
Transport Tanks - TC406
Tanks with TC 406 designation are low pressure, oval highway tanks used for the transport of most flammable liquids including gasoline, crude oil and diesel. They operate at pressures between 18 kpa (2.65 psi) and 28 kpa (4psi). These tanks cannot be loaded by vacuum. TC 406 tanks used in petroleum crude oil service may differ from units used for gasoline and other flammable liquids. There are alternate requirements for construction of TC 406 “Crude” tanks (such as alternate pressure relief devices). These units are marked “TC 406 Crude” and are to be used solely for the purposes of transporting products designated as UN1267 (PETROLEUM CRUDE OIL). These tanks may operate at a higher pressure than standard TC 406 tanks. Safety features on these tanks include rollover protection to prevent damage to manholes and vents, high strength bumpers, safety relief vents and internal baffles to minimize liquid surge and provide added strength to the barrel of the tank.
TC 406/306 Tanks for gasoline and TC 406/306 Crude Tank
diesel for crude oil only
Some TC406 tanks have more than one compartment. A “void” section often separates these compartments to prevent contamination between compartments. These voids must be open to atmosphere. There is a hole at the top and bottom of the void, which must not be plugged. The presence of a plug can indicate damage to the internal integrity of the tank. A tank found by enforcement staff with a plug will be placed out of service until the
Transport Tanks - TC407
TC 407 tanks are circular tanks often used for transporting sour crude oil. These tanks are capable of operating at pressures higher than TC 406 tanks, with Maximum Allowable Working Pressures (MAWP) starting at 172 kpa (25 psi) They are constructed to take all flammable liquids including the more volatile Packing Group I liquids, sour crude oil and some corrosives such as UN1780 - CORROSIVE LIQUIDS N.O.S (HYDROCHLORIC ACID). These tanks can be loaded by vacuum.
TC 407/412/350 tanks are vacuum trucks commonly designed with a characteristic large rear door which opens for dumping. They are generally used for cleanup of chemical or oil spills, clean out of storage tanks or hauling crude oil and water from the oil separation process at well heads. A unit dedicated to hauling crude oil may be designated as a “TC 350 Crude” tank and the certification plate on the tank would be marked accordingly. A full specification TC 350 tank must have a thermal and remote shutoff installed on all product outlet points, including mud gates, unless it is marked as a TC 350 Crude. As with TC 406 Crude tanks, only crude oil or water/oil mixtures from an oil well would be allowed in one of these units.
Transport Tanks - TC412
TC 412 tanks are circular tanks used most commonly to transport corrosive liquids. These tanks operate at pressures similar to TC 406 and 407 tanks. Some are steel with large outer stiffening rings and are often lined. The type of lining may prevent the construction of internal baffles in these units and hence they are usually long and narrow to minimize surging. Some tanks constructed to this standard are manufactured from fibreglass reinforced plastic. This type of tank is often used in dual service because it can handle both corrosive liquids and, with suitable grounding capabilities, flammable liquids such as crude oil. TC 412 tanks loaded by vacuum must have a MAWP of at least 172 kpa.
Transport Tanks - TC331
TC 331 tanks are high pressure tank designed for liquefied gases such as propane, chlorine and anhydrous ammonia. The MAWP for TC 331 tanks must be at least 690 kpa
(100psi) and can exceed 3450 kpa (500 psi). Additional features on these tanks may include off tank shutdown systems in the event of a failure during loading or offloading.
Transport Tanks - TC338
TC 338 are insulated highway tanks used for transporting cryogenic gas. These are used for cold liquefied gases such as Nitrogen. A variation on this design is the TC 341 tank, generally used for transporting non-flammable refrigerated liquefied gases (like oxygen). Both these types of tanks are designed in a similar manner to a Thermos bottle. They are engineered to keep the cold in and the heat out of the product by having a tank within a tank with a vacuum in-between to lessen heat transfer. They are not designed for high pressure service and operate at pressures of less than 1034.2 kPa (150psi). These units often periodically vent gases to maintain the pressure in the tank, especially on hot days.
Transport Tanks - TC 3AXM / 3AAXM/3T
TC 3AXM/3AAXM/3T tube trailers are specialized units that are designed to the CSA B339 Standard (Cylinders, Spheres, and Tubes for the transportation of Dangerous Goods) used for cylinders. They hold gases, which cannot be easily liquefied, such as natural gas, at very high pressure. These units are usually re-tested using acoustic methods under permits issued by Transport Canada. U.S. DOT units are allowed if they have passed inspection and testing in CSA B339.