In industries, there is a widespread use of numerous liquids such as chemicals and gases. Some of the chemicals and gases must be handled with immense care, and any leakage can be harmful to the workers and equipment present in the factory.
Pressure vessels are special equipment designed to hold the load, hold, and recover different kinds of liquids, gases, vapors at various pressures and most above 15 psig (gauge pressure). A common person may not feel the need to know or use a pressure vessel, but these vessels are primary equipment for several processing and manufacturing industrial tasks.
The Different Types of Pressure Vessels
Pressure vessels come in various designs to serve different commercial or industrial purposes. Pressure vessels are used in an oil refinery, food factories, chemical plants, distillation towers, high-pressure gas storage, and petrochemicals. The three commonly used pressure vessels include storage vessels, process vessels, and heat exchangers.
- Storage vessels
The storage vessel from the name means that vessels that are used to store or transport gases or liquids. The storage vessels are used for different industrial purposes and come in either horizontal or vertical variety. Storage vessels of varying sizes are made according to liquids or gases that would be stored. Carbon steel is mostly used in the manufacturing of storage vessels.
- Process vessels
The vessels used as a component in various processes are called ‘process vessels’. The process may include breaking the product, combining elements, or removing various elements. The process vessels are custom made according to a specific purpose.
- Heat exchangers
The second most commonly used vessel is the heat exchanger, which is used in food factories and chemical industries. Heat is a crucial source in the processing of different materials but can have a negative effect, which is why heat should be properly removed or reused. Heat exchangers are made from high-quality alloys to ensure smooth function and safety.
The Important Things to Consider in Manufacturing of Pressure Vessels
Due to the fragile nature of the liquids and gases, manufacturing of pressure vessels is quite a critical process and depends on the design, material selection, and construction. There are also numerous other designs and uses of pressure vessels apart from storage tanks, heat exchangers, and boilers. Each pressure vessel is designed according to specific design pressure, temperature, and operational limits. Any vessel operating outside the limits could damage the equipment and cause injuries to the workers.
The custom pressure vessel manufacturer ensures that the pressure vessels are made according to custom specifications and follow the industry standards and manufacturing codes defined by the certified engineering authorities. Steel was the primary material used to make different pressure vessels, but composite materials are also used due to advancement and changes in technology.
Mostly the pressure vessels are cylindrical, conical, and spherical in shape and a standard vessel comes with a long cylinder and two parts. Each pressure vessel’s operating temperature may differ, but the vessels perform optimally when the internal pressure is higher or lower than the air pressure.
Pressure vessels are purposefully designed to function when required pressure is achieved for the application to work. The pressure can be given directly by release gauges or valves or by transfer of heat. The common pressure levels range from 15 psi to 150,000 psi, while temperatures are high as 400 C (Centigrade). A typical pressure vessel may hold up to 75 gallons of liquid.
The Codes and Precautions of Custom Pressure Vessel
A damaged pressure vessel is highly dangerous as it can lead to gas leakage, poisonous gas leak, and fire due to inflammable gas and liquid. Due to its sensitive nature, there are numerous standards and practices on the manufacture, use, and inspection of the pressure vessel. Two of the most authentic standards are the ASME (American Society of Mechanical Engineers) Section and API (American Petroleum Institute) 510.
ASME Section VIII provides detailed information on the design, fabrication, inspection, testing, and certification of pressure vessels and part of the ASME Boiler and Pressure Vessel Code (BPVC).
API 510 is a certified inspection code that is written and published by the American Petroleum Institute (API). The code is used for in-service inspection, rating, repair, and alteration of pressure vessels.
The pressure vessels should be examined and inspected once place to perform a function and then again in 4 to 5 years of service. The inspection process can be external, internal, or both and should be done carefully and thoroughly. Certain tests and analysis are performed in the inspection, such as stress analysis, thickness evaluation, hydrostatic pressure test, surface inspection, checking the release valves of the pressure vessel, and inspecting the structural welds and joints of the pressure vessel.
Pressure vessels in most industries can be used for both heating and cooling purposes. A custom pressure can be used for either low pressure or high-pressure containment of liquids or gases. A custom pressure vessel can be made using both stainless steel and carbon steel, which is welded together in cylinders or spheres. Due to the welding process, the strength of steel is determined first then forged together. The precautions help ensure the strength of the pressure vessel used in the industrial process.
For certain processes, a special corrosion-resistant material is used made from ceramic, polymer, or metal, which withstands the vessel’s interior pressure and prevents any leaks and damage. ASME defines and implements the fabrication codes, which are then followed in the construction of the pressure vessel.
Pressure vessels are most needed and used in the oil and gas industry, where different types of oil are used at high temperatures and pressures. The pressure vessels and columns in the oil industry are usually constructed by the same manufacturer. In chemical industries, most of the chemical reactions take place inside the pressure vessel.
The range of materials that can be used in the construction of a pressure vessel includes
- Carbon steel
- High and low alloy steels
- Carbon manganese steel
- Stainless steel
- Aluminum, nickel, copper, and alloys
Apart from the materials, considerable thought is given to the material availability, toughness, performance, and durability. The material is tested at varying temperature and pressure and then used to construct a custom pressure vessel.