How Pressure Vessels Should Be Designed For Safety and Quality

October 6, 2015

Safety concerns dominate the minds of design engineers. Products are taking shape from mathematical theories, from geometry computations and metallurgical technology, but these design-centric tasks are always tied to a safety factor. The profile of the inner chamber is part of the equation, as is the thickness of the walls and the welding technique applied to the seams. Even the selection of the alloy complements this safety factor, adding mechanical strength to the outline.

A Peak Inside the Innards of Pressure Vessels

A pressure differential exists between the inside of the container and the outside world. Inside the container, the stored substance is acting on the structure in accordance with the laws of fluid dynamics. These hazardous materials, caustic fuels and toxic chemical compounds, exert stress on the structural integrity of the vessel, and it's the job of in-built safety factors to counter these dangers. International industry standards incorporate this safety factor as a percentile rating or a multiplier, thus ensuring the vessel can withstand its designed pressure rating plus an in-built safety cushion.

Coping with Transient Forces

Even though the rated pressure of the gas or fluid is established, there are a number of other issues to consider before the container can be designed. State changes occur in some fluids, a flash from a liquid state to that of a gas. Temperature changes dictate these changes, as do the capacity of the vessel. In the case of a chemical plant, the changes become more complex. Reagents and catalysts cause energetic transitions to occur in the fluid, and there's a subsequent change in the pressure differential within the container.

Reinforcing Mechanical Integrity

Having outlined the profile of the container in terms of fluid states, pressure variations, and mathematical principles, stresses are defined and it's time for the fabrication workshop to implement the production phase, to create the shell and infuse the form with its calculated safety factor. ASME regulations and international codes outline this process in more detail, illustrating the procedure with mandated guidelines. For example, MAWP (Maximum Allowable Working Pressure) is a key variable in this scenario, one that's quoted as a maximum limit for the weakest component in the system.

Micro-crystalline tests and ultrasonic weld inspections pair with the mathematically-derived structural integrity rating of the pressure vessels to form a compelling series of products. Approved for installation, the final product is mathematically designed, mechanically fabricated, and professionally inspected to ensure it conforms to and even exceeds its peak rated operating pressure (See the AS120 codes for more details on this intriguing subject).

Contact Details

Fusion - Weld Engineering Pty Ltd
ABN 98 068 987619

1865 Frankston Flinders Road,
Hastings, VIC 3915

Ph: (03) 5909 8218

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