Pipeline inspection is critical in ensuring that pipeline issues are noticed and fixed before they become major issues. As we know, pipelines play an important role in the gas and oil transporting market. It is crucial to ensure the good performance and integrity of pipelines in real practice. Apart from a strict manufacturing process, a professional and thorough inspection is also an important factor in the performance of the pipeline. Let us get to know some inspection methods.
Nondestructive testing (NDT)
Nondestructive testing is also known as NDT. It is a widely used method in the inspection of the pipeline. This is a process of inspecting, testing and evaluating the characteristics and quality of the material without causing damage to the pipeline. It also doesn’t affect the regular work of the pipeline. This means that after non-destructive testing, the part can be put into use. NDT makes use of changes in sound, heat and magnets that are caused by abnormal inner structure and flaws to inspect the external and internal defects of the material.
The commonly known inspection methods of nondestructive testing are ultrasonic testing, visual testing, hydrostatic testing and radiographic testing.
A hydrostatic test is a method of inspection used by pipeline inspectors to reduce any risk of flaws in the pipeline that might threaten the ability to withstand the system’s maximum operating pressure. Hydrostatic testing inspects the pipeline’s integrity by filling in the pipe with a liquid that is non-compressible to increase the levels of pressure above the normal pressure to see if there exists any defect. It can either be done on pipes before being put into service or it can be done on existing pipes already in use.
What you should notice in hydrostatic testing
There are certain rules you should follow if you want to carry out hydrostatic testing. First, it is important to understand that testing with air is not recommended as it is very dangerous. This means that the first step is to release the air in the pipe. During the testing process, all the vents and valves should be shut down to observe whether there is a loss of pressure. It is important to perform a hydrostatic test after the hot work has been done to the pipeline, including heat treatment and welding.
Ultrasonic testing (UT)
Ultrasonic testing (UT) enjoyed a wide application in the detection of flaws and quality control of the manufacturing and metallurgy industry. It can also be used to precisely inspect, detect and diagnose the flaws in the material.
During this test, the ultrasonic transducer machine connected to a special diagnostic machine is placed on the pipeline being inspected. Sound waves at a high frequency can directly travel through the metallic material. In case the sound comes in contact with a defect, with a different acoustic object, some of the waves reflect to the original sending unit. Inspectors can therefore see the result in the form of signals on the display. By analyzing the reflection during pipeline inspection, inspectors can test and locate the crack or any other hidden defects.