Our tanks are metal-based atmospheric tanks, mainly including carbon steel tank, stainless steel tank and aluminum alloy tank and each tank works with operating pressure no greater than 72 KPa and ambient operating temperature of -40 to +40 °C.
A tank body has an oval section or a round-square section (a rectangle with circular arc). The head is processed automatically by a computerized numerical control (CNC) beading machine for attractive appearance and high rigidity. The shell is made of jointed plates arranged in longitudinal joints and welded with full-automatic gas shielded welding method and the jointed plates are rolled to shape the shell as a whole, with nice-looking appearance and excellent straightness. The shell and the head are welded through the penetration butt welding method.
Inside the tank body there is a swash plate installed and in some tanks there is a longitudinal oil baffle plate installed, in order to alleviate the impact of the oil inside the tank body to the head and shell.
The upper part of the tank body is equipped with a safety frame which can ensure the safety of the user during an operation upon the tank body and can also contain the oil spilled during filling of oil, so that the spilled oil can be exported through the overflow pipe at the rear part of the tank body to avoid contamination to the outside surface of the tank.
For the sake of easy access by personnel into the tank body for repair, a manhole cover assembly is installed on the top of the tank body. The manhole cover can be completely removed by loosening the fixing bolts of the manhole cover. If the oil or gas in the tank is completely discharged and the tank presents no danger,the operating personnel can go inside the tank body. In order to make it easy to check the oil in the tank body and fill oil in the tank, the manhole cover has an oil filler cover. Rotate the hand wheel, raise the pressing beam and free the retaining ring from the hook base to open the oil filler. The user can fill oil in via an oil hose put through this oil filler.
In order to adjust the pressure differential between the interior and exterior of the tank, the manhole cover additionally has a breather valve. The air outlet valve opens when the internal pressure is 6-8 kPa greater than the external pressure and the air inlet valve opens when the internal valve is 2-3 kPa less than the external pressure, so that the interior and exterior of the tank keep constant air exchange. Usually, a tank with a small volume shall have at least one breather valve and a tank with volume greater than 12 m3 shall have two breather valves.
After a period of service of the tank body, it’s necessary to check the breather valve for operating condition.Loosen the exterior screws and remove the upper part of the breather valve. Rotate the adjusting nut at the lower part of the valve body and move the lower valve body to adjust the pressure of the air outlet valve.Rotate the adjusting nut at the upper part of the breather valve and move the valve stem to adjust the pressure of the air inlet valve. Malfunction of the vent valve is very likely to result in deformation of tank body during oil pumping.It’s recommended that the user regularly check the operating condition of the breather valve to make sure that its operating pressure is proper.
For a truck equipped with bottom loading system, the upper part of the tank body has an explosion-proof manhole cover which can prevent overflow and explosion in case of the truck tipping over. The breather valve of the explosion-proof cover is built-in to prevent liquid leakage due to damage of breather valve in case of the truck toppling. If the internal pressure of the tank reaches 21-35 KPa, the emergency release device of the
explosion-proof cover opens and discharges gas with a maximal rate of 7,000 m3/h to effectively prevent the truck from exploding.
The pipeline system comprises the setting tank and the oil drain valve at the bottom of the tank body and the pipes between them. On the outside of the oil drain valve is a male flange that has a female blanking cap.For loading/unloading of oil, connect the oil hose to the male flange and open the oil drain valve to start oil loading/unloading. After removal of the oil hose, fix the female blanking cap to the male flange immediately, to protect the mating surface of the male flange from damage and prevent the oil from leaking due to accidental valve damage.
For a truck equipped with bottom loading system, the pipeline system consists of the subsea valve,oil drain valve, reducer union for oil discharge, dust cap and the seamless steel pipe at the diameter of 4″. If the tank body is divided into several compartments, each one has a separate pipeline system.
The subsea valve is normally closed, but it is opened or closed by the pneumatic control switch during loading/unloading of oil. The oil outlet at the subsea valve has a diameter of 4″. The lower part of the subsea valve has machined cut-off groove. In case of strong impact, this valve can break off along with cut-off groove to prevent the oil from leaking.
The oil drain valve is a standard component for loading/unloading oil from the bottom and its outlet is of flat base design which can guarantee that no leakage will happen during oil loading/unloading and that oil can be loaded quickly.
The reducer union for oil discharge is used for fast discharge of oil and the slanting-downward design of the oil outlet can discharge oil more thoroughly and more quickly.
When unused, the oil drain valve is protected by the dust cap from damage to its contact surface. A sealing ring is fixed inside the dust cap to prevent oil loss due to accidental leakage at the oil drain valve.
4.Oil & gas recovery system
A truck capable of loading at the bottom has oil & gas recovery system, oil & gas recovery joint, reducer union for venting, side plate valve, dust cap and the seamless steel pipe at the diameter of 4″. During loading/unloading of oil of a truck, gas recovery is achieved in a fully closed environment. For oil loading, the oil and gas are recovered via the oil depot connected recovery pipe connected to the oil depot; for oil unloading,the oil and gas in the oil tank at the petrol station are recovered via the recovery pipe into the truck.
The oil & gas recovery valves are installed on the upper part of the tank body and each compartment has one oil & gas recovery valve. This valve is normally closed and is open during loading/unloading of oil.The side plate valve is installed in the oil & gas recovery pipeline on the top of the tank and is normally open. During loading/unloading of oil, when the oil & gas recovery system is connected to the oil depot or the oil & gas recovery pipe at the petrol station, the side plate valve is closed. During loading/unloading of oil, if the oil & gas recovery system is not connected to any external oil & gas recovery equipment, the side plate valve remains open to keep the internal pressure and external pressure of the tank balanced and prevent any danger.
The oil & gas recovery joint is fixed at the end of the oil & gas recovery pipe and is a fast-connection structure which makes easy connection to the oil depot or the oil & gas recovery equipment at a petrol station.The valve body is equipped with a pneumatic interlocking valve that is interlocked with the side plate vent valve.
The reducer union for venting, with outlet diameter of 3″, is supposed to be installed at the oil & gas recovery joint when the oil & gas recovery equipment of the truck is connected to that of the petrol station.
The dust cap is installed at the oil & gas recovery joint to protect the contact surface from any damage.
A truck capable of loading at the bottom has an anti-overflow system which consists of the anti-overflow probe rod, connector socket and grounding bolt etc. During oil loading, if the oil level in the tank reaches the probe point of the anti-overflow probe rod, the signal from the probe rod discontinues and the oil loading control system of the oil depot stops working.
If there are multiple tank compartments, each compartment has one anti-overflow probe rod which is installed at the manhole cover of that compartment.The connector socket is installed in the control box where it can be easily connected to the anti-overflow plug of the oil depot.
The grounding bolts are fixed on the frame. When the anti-overflow plug of the oil depot is connected to the connector socket of the truck, the static electricity generated in the truck can be connected to the electrostatic circuit of the oil depot.
6.Air circuit control system
A truck capable of loading at the bottom has an air circuit control system that consists of air cylinder,reducing valve, emergency control valve, three-way joint of air circuit, oil & gas recovery joint control valve,combination switch,etc.
When the air circuit system is operating, the high-pressure air in the air cylinder is adjusted to 0.6 MPa by the reducing valve. Connect the emergency control valve at the rear of the tank body, so that the air circuit can be cut off to shut off the subsea valves of the compartments in case of emergency.
From the emergency control valve, the air passes through the three-way joint of air circuit. One air circuit is connected to the pneumatic interlocking valve of oil & air recovery joint and then connected to the side plate valve at the top of the tank body. Opening and closing of the side plate valve are controlled by the pneumatic interlocking valve of oil & gas recovery joint.
The air circuit is connected to the combination switch and is then connected by the switch of each compartment to the oil & gas recovery valve on the top of the tank body and to the subsea valve of that compartment.
Engage the master switch of the combination switch and then engage the control switches of the compartments successively or simultaneously, to load or unload oil at the bottom of each compartment separately or simultaneously.
The guardrail is installed on the top of the tank body and is usually placed down. During an operation on the top of the tank, the guardrail stands upright to protect the personnel operating on the top of the tank body.
8.Static electricity conducting device
In order to keep trucks safe during transportation and prevent fire caused by static electricity, an ESD chain is fixed at the tail of every tank. One end of the ESD chain is connected to the tank body and the other touches the ground, so that the electrostatic charge generated during travel of the truck is transferred to the earth,therefore the ESD chain shall never leave the ground during operation of the truck. If the ESD chain has shortened due to friction, the fixing bolts at the rear of the frame can be loosened to extend the ESD chain; if the ESD chain is no longer extendable, it shall be replaced with a new one in time.
The static electricity conducting disks made of copper are installed at conspicuous positions at two sides of the tank body, one at each side. During loading/unloading of oil, draw the ground wire of the oil depot or petrol station to the truck and fix the clamp to the static electricity conducting plate.
Trucks capable of loading at the bottom and refueling trucks additionally have static electricity conducting disks which shall be connected to the grounding device of the oil depot or petrol station during loading/unloading of oil. A static electricity conducting disk has a grounding bar which is inserted into the ground when oil is being loaded/unloaded at a location where no grounding device is available and which is secured by a static electricity conducting disk clamp.
Every truck produced by our company has 2 oil hoses that are placed respectively in the hose chambers at two sides of the tank body and are used for loading/unloading of oil.