Sunday, September 25

Short Overview of The Fabrication of Pressure Vessels

Pressure vessels are enclosed containers that hold liquids, gases, or vapours at a pressure either higher or lower than the ambient pressure. These vessels are used in numerous industries such as oil and gas, chemical, petrochemical, and more. 

Pressure vessels such as reactors, separators, or flash drums are specially designed to operate within certain temperature and pressure limits. As pressure vessel manufacturing companies in India design, fabricate, and test these vessels, they should adhere to set standards and regulation codes. Here’s a short overview of the process to understand more about pressure vessel fabrication.

Safety requirements

Heavy engineering companies adhere to safety standard codes and regulations set by the American Society of Mechanical Engineers (ASME). These standards detail the rules and regulations to follow while designing and fabricating pressure vessels to guarantee their safety, functional value, and durability. 

These ASME rules and requirements stipulate the requirements applicable to the design, fabrication, inspection, testing, and certification of pressure vessels depending on the pressure rating, materials used, and type of vessel. Different sections of the code show specifications for handling different vessels. For instance, ASME Section VIII Division 2 has specifications on how to build pressure vessels operating at internal pressures above 600 PSIG, but less than 10000 PSIG. Section II contains material specifications. 

Aside from sticking to the code, you also have to factor in your client’s specifications, but they should adhere to the code. 

Pressure vessel welding and fabrication

Section VIII, which governs pressure vessel manufacture, consists of three divisions. 

  • Division I – covers vessels operating at an internal or external pressure above 15 PSIG, but lower than 600 PSIG. 
  • Division II – covers vessels operating at an internal or external pressure above 600 PSIG, but lower than 10000 PSIG.
  • Division III – covers vessels operating at an internal or external pressure above 10000 PSIG.

These divisions contain mandatory and alternative rules for the construction and welding of pressure vessel parts.  

The process

The first step to assembling pressure vessels is selecting the raw materials you need for the plates, piping, structural shapes, forgings, wires, welding rods, and more. Next, cut and burn the raw material as per the specifications, then machine the speciality parts if needed. Once this is done, assemble and weld the vessel, but cool the weld and sandblast it before applying primer and paint. 

After fabricating the vessels, you have to test them to ensure they can withstand the pressure and won’t leak. Section V of the ASME code dictates the requirements and methods to use for the nondestructive examination of pressure vessels. It details the pressure vessel manufacturer’s responsibilities, duties of qualified inspectors, and qualification requirements for personnel, inspection, and vessel examination.  

There are numerous types of pressure vessels depending on their purpose or geometry. But despite this vast range, the design and fabrication process is nearly identical. Heavy engineering companies in India and knowledgeable personnel must adhere to stipulated rules and standards to ensure safety, functionality, and durability. This way, they do not harm the users and the surrounding environment. 

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