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Weld Inspection and Non-Destructive Testing of Pressure Equipment

14 June 2020

Pressure equipment are specifically constructed to adhere to an existing standard of design and construction. During the designing process, the design thickness is possible to decrease in size than the actual fabricated pressure equipment. That why there is a design corrosion allowance in the base metal. Such features will not be properly assessed with weld inspection and non-destructive testing of pressure equipment. Below is an overview of such.

Weld Inspection Basics

During a weld inspection, the inspector thoroughly considers the operating conditions of the pressure equipment. Aside from that, they take note of the inspection history so that they can look if the material for construction of the pressure equipment is within quality standards. They also take note of the reasons for failure in case they notice something that is off with the pressure equipment. They are able to do so by spotting the location of the damaged area through visual inspection and evaluation. Afterwards, they had to re-evaluate the need for repairs through design calculations. From such an evaluation they had to come up with the necessary repair methods for pressure retaining parts. This gives way to the preparation of preparation of repair procedures and replacement of major components.

The entire weld inspection consist of the thorough data collection of operating parameters as well as the inspection history. These information includes a detailed list of internal inspection reports, materials of construction, observable behaviour with the process fluid, welding techniques used during construction, design consideration and others. Having these important details dictates whether or not the pressure equipment is usable or in need of repair. The proper documentation of selected material of construction and the fabrication procedures, welding procedures as well as inspection and certification by the competent inspection authorities during fabrication stage are indeed helpful for the actual weld inspection.

Non-Destructive Testing

Similarly, non-destructive testing (NDT) aids the quality assessment of pressure equipment. Since it relates to the identification of defects, imperfections and discontinuities of the pressure equipment that might negatively affect its function, the information that surfaces during this particular testing is deemed essential to anyone involved in pressure equipment manufacturing and operations. During a non-destructive testing, defects originating from design, processing, fabrication and service conditions are observed. Once these defects are spotted, improvements in the pressure equipment are made to ensure that it is working and reliable. Of course, defects are also categorised as detrimental or non-detrimental in pressure equipment’s function.

NDT methods vary in complexity. It can be as simple as a visual inspection wherein you can easily spot visible defects through magnetic methods. If there are defects that are more serious in nature then there is a need to make use of ultrasonic or radiography methods such as optical inspection, dye penetrant testing, magnetic particle testing,  eddy  current  testing,  radiography  testing,  and ultrasonic testing.

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