Pressure vessels are among the most important components in the oil and gas, petrochemical, energy, pharmaceutical, and food industries. They are designed for the storage and transport of liquids under high pressure, and even minor design flaws can lead to leaks, ruptures, or explosions.
The vessel body is one of the most important components of a pressure vessel . It bears the internal pressure of the fluid, distributes the loads, and connects other components such as nozzles, supports, and fittings. Proper design of the vessel body requires compliance with applicable standards, the selection of suitable materials, and precise wall thickness calculations.
This article discusses the design, types, construction methods, and key aspects of high-pressure vessels.
The importance of a pressure vessel body
The tank plays a crucial role in the safety and performance of the entire system :
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Internal pressure support: The housing is the main component that transfers the fluid pressure to the base.
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Pressure distribution: Through a suitable design, pressure concentrations can be reduced and the service life of the tank extended.
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Component connection: The housing serves as a contact point for lenses, attachments, mounts, controls, etc.
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Avoiding leaks and explosions: Choosing the right wall thickness and adhering to welding standards are crucial.
Housing design and components
The tank body is usually made of metal sheets and includes the following components:
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Paper:
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Sheet metal is typically made from carbon steel, alloy steel, or stainless steel.
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The plate thickness is calculated based on the design pressure, the tank radius, the material, and the welding coefficient.
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Welding:
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The panels are connected to each other by longitudinal and circumferential welds.
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The quality of the welds directly affects the strength of the vehicle structure and requires non-destructive testing (NDT).
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Lateral connection:
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Nozzles, edges and valves are mounted on the machine body.
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The connections between these components should be made using reinforcing plates to reduce stress concentrations.
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Cladding and insulation:
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The housing may contain an inner corrosion protection layer or an outer thermal insulation layer.
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These coatings not only protect the tank, but can also extend its lifespan.
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Pressure vessel type
1. Cylindrical body
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The most common type of tank is the pressure tank.
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The design is based on circumferential stress, which is the most important stress in a cylindrical tank.
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According to the thickness calculation formula in ASME Section 8:
t=P⋅RS⋅E−0.6P+Ct = \frac{P \cdot R}{S \cdot E – 0.6P} + C
Where:
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tt : Case thickness
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RR : Inner radius
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SS : Permissible stress
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EE : Welding coefficient
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CC : Corrosion resistance
2. Spherical layer
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The pressure distribution is more even in a spherical container.
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The required wall thickness is less than the wall thickness of the cylinder.
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ASME calculation formula:
t=P⋅R2S⋅E−0.2P+Ct = \frac{P \cdot R}{2S \cdot E – 0.2P} +
3. Conical bushing
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They are usually designed to connect reservoirs to lenses or to change their diameter.
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The pressures in this section are more complex and require precise calculations.
Materials used in the body
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Carbon steel: The most commonly used choice for standard storage tanks.
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Steel alloys: suitable for high pressure or high temperatures.
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Stainless steel: suitable for aggressive liquids as well as for food and pharmaceutical products.
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Special materials: In some cases, alloys are used that are corrosion-resistant and high-temperature resistant.
The choice of materials depends on the design pressure, the operating temperature and the fluid medium .
Factors that influence the design of the car body
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Compressive strength: A key factor in calculating vehicle body thickness
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Design temperature: Temperature influences the mechanical properties of materials.
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Welding efficiency: The quality of the welding directly affects the thickness of the bodywork.
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Corrosion and abrasion: A corrosion allowance is included for corrosive environments.
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Tank size and shape: The radius and length of the tank influence the thickness and type of panels.
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Reference standards: ASME, EN 13445, API 650
Methods of implementation and installation
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Precision welding: Longitudinal and circumferential welds must be carried out in accordance with standards and subjected to non-destructive testing.
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Vehicle body inspection: To ensure the quality of welds and sheet metal parts, procedures such as X-ray, ultrasonic and penetrant testing are required.
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Corrosion resistance: The inner layer and outer insulation extend the service life of the machine housing.
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Reliable connection: Pipes and valves should be fitted with reinforcement plates to reduce stress peaks.
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Mechanical stability: During assembly, the support must distribute the weight and internal pressure evenly.
Practical examples
Let us assume that a cylindrical tank is built with an internal pressure of 2 MPa, a radius of 1 m, an allowable stress of 140 MPa, a weldability coefficient of E=0.85 and a corrosion tolerance of 2 mm.
× 2 ) + 2t = − 1.2) +
The required housing thickness is therefore approximately 20 mm.
In conclusion
The vessel shell is the main component of a high-pressure vessel and therefore its most important element. The choice of materials for the shell, the calculation of the wall thickness based on pressure and temperature, the quality of the welds, and the corrosion protection measures are all crucial factors for the safety and service life of the vessel.
Valve bodies are divided into cylindrical, spherical, and conical shapes, each suited to specific applications. Compliance with applicable standards, such as ASME Part 8, and the use of non-destructive testing methods can prevent serious accidents.
Through a suitable tank design, it can withstand the internal pressure, ensure a secure connection of external components, and guarantee reliable long-term operation.