Basic design requirements for liquefied gas transport vehicles
Time:2021-10-22
Views:358
LPG tank trucks are also called LPG semi-trailers, LPG tank semi-trailers, LPG tank trailers, LPG tanker semi-trailers, etc. It refers to the single-car tanker and semi-trailer tanker with the tank fixed on the chassis of the car. It is a special vehicle used to transport liquefied gas such as propane, propylene, dimethyl ether, liquid ammonia, methylamine, acetaldehyde, etc. It is inflammable and explosive.
The liquefied gas transport vehicle is generally composed of three parts: a car (or trailer) chassis, a tank body, and an operation box. The tank is mainly composed of a circular cylinder and a head (elliptical, dish-shaped or spherical).
The industry standard for the design and implementation of liquefied gas transport vehicles in China is GB/T 19905--2005 "Liquefied Gas Transport Vehicles"; the basic standard for the calculation of the strength, stiffness and stability of the tank body, the conventional design is GB 150.1～GB 150.4-- 2011 "Pressure Vessel", the stress analysis design is JB 4732-1995 "Steel Pressure Vessel Analysis and Design"; the national regulations for the design and implementation of liquefied gas vehicles are TSG R 0005--2011 "Mobile Pressure Vessel Safety Technical Supervision Regulations" ". Units that design and manufacture liquefied gas transport vehicles shall obtain design license qualifications and manufacturing license qualifications issued by the State Administration of Quality Supervision, Inspection and Quarantine respectively. The basic requirements are as follows:
1. Tank performance: The tank is transported under the design pressure and must be absolutely safe and reliable, so that it does not leak, crack, or explode, and has good airtightness and sufficient strength. The strength of the tank should be designed to consider the equivalent pressure generated by the saturated vapor pressure of the medium in the tank, the static pressure of the liquid column, and the inertial force of the liquid.
The external pressure of the tank is checked to prevent the tank from being deformed and destabilized under the action of dynamic load. The connection between the tank support and the tank shall be subjected to the local stress analysis of the longitudinal, transverse and vertical dynamic loads; the tank shall be connected to the walking or chassis for the check calculation of the maximum inertial load.
2. Tank material: generally special steel plate for pressure vessels, such as Q345R, Q370R; the cylinder is made of steel coil welding, and the head is made by splicing and stamping or spinning.
3. Tank body inspection: The longitudinal and circumferential welded joints on the tank body shall be inspected by 100% X-ray. In addition to the 100% X-ray inspection and inspection, the butt joints on the head shall also be subjected to magnetic particle or penetration inspection; welding with the tank body Fillet joints are tested for magnetic particle or penetration; after the tank body is welded, the stress is generally relieved after welding.
Heat treatment, after the heat treatment is completed, the tank body is subjected to a hydraulic strength test of 1.3 times the design pressure. The tank body and the chassis or walking, safety accessories, pipelines, etc. are assembled into a bicycle or semi-trailer, and then the air tightness test is carried out according to the design pressure. The test is completed The rear tank is filled with 0.05-0.1MPa dry nitrogen, and the gas oxygen content in the tank does not exceed 3%.
4. Tank structure size (diameter×length): According to the carrying capacity of the chassis, it has been optimized to make the curb weight the lightest. According to GB/T 15089-2001, single-vehicle liquefied gas transport vehicles are mostly N3 vehicles (cargo vehicles with maximum design total mass> 12t); semi-trailers are mostly Type 04 vehicles (trailers with maximum design total mass> 10t) .
5. Safety accessories: TSG R 0005--2011 requires safety accessories such as safety valves, level gauges, temperature measuring devices, emergency shut-off devices, electrostatic grounding devices, and fire extinguishers to be equipped on tank trucks.
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