Tank truck types, technical aspects and characteristics

The use of tank trucks for trucking offers a solution to various transportation issues related to the transportation of liquid cargo. There are certain peculiarities associated with the transportation of liquid cargo using tank trucks. It is a well-known fact that different types of liquid cargoes, even if they belong to the same category, require the use of different and specially adapted tank trucks. If we are talking, for example, about the transportation of different substances such as crude oil and gasoline, as well as other oil products, it is impossible to transport these substances in the same tank trucks, as there is a well-established rule about the compatibility of the previous cargoes. The same principle applies to liquid foodstuffs, including milk, molasses, butter, juice and so on.

TANKER APPLICATION

The use of tank trucks together with light semi-trailers can significantly increase the lifting capacity of the tank truck and thus reduce costs. Today there are many modifications of tank trucks specially designed for transportation of different types of liquid cargoes: light and dark oil products, chemicals, foodstuffs. Tank trucks are used more and more often, despite the somewhat higher average cost of transportation compared to conventional trucks. But their use means that there is no need for additional containers and packaging costs, plus a higher level of cargo safety during loading, transportation and unloading - while minimizing the time costs associated with these operations.

Tanks can be thermally insulated, some even have the ability to heat and cool the cargo being transported. Tanks designed to carry certain materials such as paraffin, soap or resin need to be heated to keep these products from freezing during transportation. Similarly, tanker trucks carrying perishable products are artificially cooled.

Tank trucks undergo various modifications depending on the nature of the substances being transported (inert or aggressive) and the physical condition of the liquid cargo. The composition of tank semitrailers also differs; they are specially designed for different types of cargo. Some common types of tank trucks include:

MAIN TYPES OF TANK TRUCKS

Chemical

Chemical tank trucks are designed for transportation of chemical aggressive and neutral liquids. Both neutral and aggressive products of chemical industry can be transported in tankers - for the transportation of aggressive chemicals the tanker is made of stainless steel. Thanks to the addition of molybdenum, the steel is highly resistant to corrosion, high temperatures and aggressive chemical media.

Gummed tanks are used for transportation of aggressive acid-alkali cargoes. Application of this type of tank is conditioned by lining the inner surface with mastic based on bituminous resins and other protective agents, providing reliable protection of the internal vessels of the semi-trailer-tanker from corrosion. Tanks made of composite materials such as fiberglass are also used for transportation of acid-alkali substances with aggressive corrosive properties.

Food

Tank trucks for transportation of liquid food products (food tanks) are used for transportation or temporary storage of liquid food products with density from 0.8 to 1.5 g/cm3 to points of sale and processing. Liquid food cargoes include various juices, concentrates, vegetable oils, fats, syrups, molasses, chocolate, glucose, alcoholic beverages, dairy products, etc.

Tank trucks used for transportation of liquid food products must comply with European environmental standards. This requires thorough steaming and disinfection of the inner surfaces of the flask before each loading. Such flasks are made of high quality stainless steel. To maintain the temperature of the cargo contents, food tankers have a heat-insulating layer of mineral insulation. Each tanker is equipped with filler necks for filling, disinfection and inspection of the inside of the flask. Each filler neck is closed with lids with thermal insulation, and pipelines and drain valves are protected from freezing in winter.

Gasoline tankers

Tank trucks for light oil products (gasoline tankers) are designed for transportation and temporary storage of oil products with density of 0.7 - 0.9 g/cm³ on public roads, taking into account their climatic design. These tanks are used for transportation of various types of light petroleum products such as gasoline, diesel fuel, kerosene, additives, lubricants, base oils, solvents and petrochemical raw materials.

Gasoline contains a lot of volatile, easily flammable and explosive fractions, so tank cars (gasoline tankers) are manufactured taking into account strict fire safety requirements. Tank trucks (gasoline tankers) usually have from 3 to 5 autonomous compartments, which allows to transport several types of fuel at the same time. Most often this type of tanks is made of aluminum. Gasoline tankers have different volumes from 30000 to 60000 liters. Thus, gasoline tankers differ in capacity, shape (suitcase, oval or round) and number of compartments. The right tanker shape can increase the volume of fuel transported. Separated compartments allow to deliver gasoline of different brands to gas stations at the same time.

Bitumen tankers

Tank trucks for transportation of dark petroleum products (bitumen tankers, fuel oil tankers and oil tankers) are designed for transportation and short-term storage of substances such as oil, fuel oil and bitumen. These dark petroleum products are residual products of refining or natural derivatives of coal, oil and oil shale. Bitumen and fuel oil carriers are special-purpose vehicles and provide cargo heating up to 250 °C during transportation.

Various designs of bitumen trucks allow to maintain high temperature of hot bitumen during transportation, to heat it in the tank to working temperature, to pump it and take it from bitumen melting boilers and bitumen storages. Special flame tube systems, powered by diesel fuel or kerosene, provide heating of bitumen or fuel oil in the tank. The isothermal design of the tank minimizes heat losses, which, together with heating systems, allows transporting petroleum products over long distances. Inside the tank there are baffles (wave bars) to minimize hydraulic shocks during braking. Two flame pipes are attached to the breakwaters, running along the entire length of the tank, with expansion and refractory lining at the inlet, forming a furnace space. Fuel is pressurized to two stationary and one portable burner. The pump provides not only filling of the tank with bitumen, but also its circulation and drainage. Special thermal materials are used for manufacturing of bitumen trucks and their components to ensure safe transportation of specific cargo. Transportation of easily flammable cargoes at temperatures up to 230 ° C requires a special approach at all stages of transportation because of the increased danger.

Gas tank trucks

Liquefied gas tankers (gas carriers) are designed for transportation and short-term storage of gases such as propane, butane and their mixtures under pressure up to 2.3 MPa and at temperatures from -40 to +45 °C. Specialized tank trucks and semi-trailers are used for these purposes. Gas carriers have a special design with an external load-bearing shell and double vessel walls. A high level of operational safety is ensured due to the double-walled tank shell, the space between the walls of which is filled with a special non-flammable material.

Semi-trailers for liquefied gas transportation are divided into two types:

1. Refueling. These semi-trailers are designed for filling cylinders with liquefied gas into the fuel systems of motor vehicles. Their volume ranges from 12 to 31 m3. The technological unit contains a pump unit, meter, safety and shut-off valves. To control the gas level, an electronic measuring system or a mechanical level indicator are used. Liquefied gas is supplied through a filling hose and a dispensing tap into the fuel system of a car or other container.
2. Transport. These semi-trailers are equipped with a high capacity pumping unit and mechanical meters with a flow rate of 200-300 l/min. They also have bottom and safety valves and a level gauge for accurate control.

PURPOSE OF TANK TRUCKS

Tank truck for standard operating conditions

This type of tank truck has a simple metal body and is designed for transportation of liquid cargoes that do not require special conditions, at plus ambient temperature. It is also suitable for transportation of liquid petroleum products, which do not freeze due to their natural properties. In such tank trucks there are no heating and thermal insulation systems, so the temperature of the cargo is not preserved and maintained during transportation.

Isothermal tank truck

Isothermal tankers are designed to maintain the temperature of the filled cargo during transportation by using insulating materials in their construction. They minimize thermal losses of liquid cargo, which range from 1 to 3 ° C per day. Basically, such tank trucks are used for transportation of perishable food products and other goods of this segment. For example, milk in them remains cold even in the hottest weather. Isothermal tankers are also used for transportation of goods that require maintaining high temperature. The body of these tanks works on the principle of a thermos, isolating the cargo from external factors at temperatures from -30 to +40 °С. Such tanks are able to maintain the temperature of the liquid cargo for 72 hours, depending on external conditions.

Isothermal tank truck (steam heating)

This type of tank trucks combines all the properties of isothermal tank trucks and has an additional possibility of cargo heating. For example, if the temperature of the transported cargo is too low or if the cargo has thickened and become viscous during winter transportation, it may become difficult to unload it. In such cases, the thickened cargo is heated with hot steam up to 200 °C or hot water up to 80 °C.

Steam or water is supplied from an external source through special pipes located in the inner circuit of the semi-trailer. Heated steam is supplied from steam units and universal air heaters. The presence of a steam jacket in the tank truck and a steam generator at the unloading point are the most important conditions that ensure fast and high-quality unloading of the most viscous types of liquid cargoes.

Isothermal tank truck with autonomous heating

Isothermal tank truck with autonomous heating is a type of vehicle equipped with special equipment (webasta) designed to maintain a constant temperature of the transported liquid cargo. The complete set of such specialized equipment includes a full set of devices that ensure the maintenance of the specified temperature of the cargo during transportation. This includes a heat generator (vebasta) and a system of heat conducting channels laid inside the tank container. Isothermal tank trucks are equipped with a special autonomous heating system, which operates independently of the tractor engine. The principle of operation of this system is that the coolant (most often tosol) is heated to the required temperature and circulates through special internal channels of the semi-trailer-tanker. The autonomous heating system is able to maintain the required temperature for the cargo, regulated by pre-set parameters of the relay-controller. Thus, in conditions of winter transportation the isothermal tank truck with autonomous heating provides a number of advantages aimed at preserving stability and safety of transported liquid cargoes during their seasonal transportation.

Tank truck for transportation of dangerous goods

Transportation of hazardous liquid cargoes in tank trucks represents a significant part of the sphere of liquid cargo transportation by road. This type of cargo includes such hazardous materials as oil and petroleum products, liquefied gases, acids, alkalis, solvents, alcohols, resins, polymers, hazardous waste and other chemical liquids with dangerous properties. Safety of dangerous goods transportation is to ensure protection of life and health of people, safety of their property, environment, as well as objects and means of transport from potential hazards associated with the transportation of such hazardous materials.

A tank designed for transportation of hazardous liquid cargoes is a means for transportation of chemical industry products, including both light and aggressive substances. When transporting corrosive chemicals, stainless steel is often used to manufacture the tanker flask, which are additionally gummed on the interior surfaces of the semi-trailer.

Gummed tanks are used for transportation and temporary storage of aggressive acids or alkalis. The inner surface of the tank intended for transportation of acids and alkalis is coated with mastic based on bitumen resins and other protective agents that provide reliable protection against corrosion of the internal surfaces of the semi-trailer. All pipelines, shut-off valves and elements in contact with the transported chemical substance are also subjected to gumming.

Transportation of dangerous goods by road requires special attention to the technical condition of special vehicles. The fuel tank should be separated from the battery and the transported cargo by protective partitions. Electrical wiring must be insulated with corrosion-resistant, seamless material, and the vehicle must be grounded to protect against static discharges. A vehicle carrying dangerous goods must be marked with decals indicating the type of dangerous goods. A vehicle carrying dangerous goods may only be driven by a driver who has an ADR certificate and medical control, and who has at least 3 years of experience in driving such a vehicle.

Today, dangerous goods include thousands of substances included in the list of hazardous substances and subject to national and international regulations for the transportation of dangerous goods.

CLASSIFICATION OF TANK TRUCKS

Tank trucks are categorized into the following types according to various criteria:

1. By type of base chassis: tank truck, tank trailer, tank semi-trailer;
2. By type of cargo transported: for liquid, gaseous, powdery, loose and semi-liquid cargoes;
3. By hazard class:

• For liquefied and compressed gases and pressurized dissolved gases;
• for flammable liquids, substances and materials;

1. By tank capacity: small, medium and large capacity;
2. By type of technological equipment for product unloading: gravity unloading, mechanical unloading, pneumatic unloading, unloading with pumps (pump).

Tank truck equipment

Tank truck equipment allows to perform the following operations:

- Tanker filling;

- Unloading from the tank by pump or gravity (gravity);

- Pumping the cargo from dispensing and receiving hoses into the tank/tank;

- Pumping cargo from one tank to another tank, bypassing the tank.

The choice of technological equipment for tank trucks depends on several factors, such as: operations to be performed, features of the vehicle chassis on which this equipment will be installed. The equipment options are many. All tank trucks are usually equipped with breathing valves to regulate excessive pressure (pressure relief valves). They are also equipped with drainage systems, liquid level indicators, special chemical-resistant hoses and fire extinguishing equipment. Many tankers are equipped with mechanically driven compressors or pumps. Transverse breakwaters are installed inside the semi-trailers to mitigate vibrations and prevent rocking during the transportation of liquid cargo. Depending on seasonal transportation conditions, tank trucks can be equipped with thermal insulation to protect cargo from external temperature changes. Additionally, they can have built-in pumping equipment, cargo heating systems and other functions.

Equipment of tank trucks for transportation of liquid raw materials:

- Filler neck;

- Valve for pressure regulation/relief;

- Pump for liquid transfer;

- Compressor;

- Piping system;

- Temperature control device;

- Instruments for temperature control and measurement;

- Fire extinguishing equipment.

Types of tank trucks

- Tank trucks for transportation of light oil products (gasoline carrier, oil carrier);

- Tank trucks for transportation of dark oil products (bitumen carrier, fuel oil carrier, oil carrier);

- Tank trucks for transportation of chemical liquids (acid carrier, alkaline carrier);

- Tank trucks for transportation of food liquids (water carrier, milk carrier, treacle carrier, oil carrier);

- Tank trucks for transportation of gases (gas carrier, propane carrier, methane carrier, ammonia carrier, etc.);

- Tank trucks for transportation of bulk goods (mukovoz, fodder carrier, silo carrier, cement carrier, etc.).

Varieties of cross-sectional shape of tank cars:

• Tanks with cylindrical shape have a circular cross-section;
• Tanks with elliptical shape have an oval cross-section;
• Tanks with a trapezoidal shape have a cross-section resembling a suitcase.

What materials are used to make tanker trucks?

The choice of material for the manufacture of tractor tanks is important. Usually for this purpose, structural, thin sheet, alloy or stainless steel, as well as durable aluminum alloys, as well as composite materials are used. Each of these options has its own advantages. In this area, tank trucks fall into three main categories:

• Stainless steel tanks;
• Aluminum tanks;
• Tanks made of composite materials.

Stainless steel tanker

The thickness of stainless steel is 3 mm, which allows to transport gasoline or diesel fuel in a standard set of 4 sections with a capacity of 34,000 liters, with the empty weight of the semi-trailer of 6,500 kilograms. Stainless steel tanks are significantly lighter than trailers made of structural (black) steel, and have greater strength and reliability compared to fuel tanks made of aluminum. This material is used in the manufacture of equipment for food and chemical plants, for the production, transportation and storage of milk and by-products, wine, beer and other beverages, as well as kitchen and tableware.

Tank truck made of aluminum

The fuel tanker is made of a modern material - alloyed aluminum. The use of this material ensures that the tanker is light in weight. The standard configuration, 5 sections, 36000 liters and a weight of 5700 kilograms. At the same time the strength is maintained and the level of environmental safety is increased. Aluminum alloy tank truck walls are much thicker than their steel counterparts, usually reaching 6 mm. Compared to steel, aluminum has the following advantages:

- Less weight;

- Resistance to both internal and external metal corrosion;

- Wear resistance and long service life;

- Ability to retain ductility at extremely low temperatures.

Fiberglass composite tank

A tanker with a composite tank allows the transportation of aggressive and corrosive liquids. Fiberglass is a composite material consisting mainly of fiberglass filler and polymer matrix, which combines the filler into a single structure. Tanks made of composite materials are designed for temporary storage and transportation of various types of liquids, including chemically aggressive media, acids, alkalis, petroleum products and others. The used 10 mm thick fiberglass based on polyester and vinylester resins is resistant to many aggressive liquids. Fiberglass is a structural material that can withstand various types of loads, including shocks and vibrations. It is insoluble and not subject to melting, has high chemical resistance, low moisture absorption and environmental friendliness. The shape of the tank is cylindrical with internal stiffening elements, such as wave cutters, which increase the reliability of the entire tank structure and prevent the occurrence of water hammer. Advantages of fiberglass tank semitrailers include high specific mechanical strength, resistance to aggressive media, ease of repair and possibility of on-site work, as well as resistance to biofouling and ultraviolet radiation.