Keeping downtime to a minimum is vital to downstream oil and gas operations. The oil and gas industry relies on nondestructive testing techniques to determine the lifecycle of production assets and minimizing downtime. Such techniques also play a key role in plant safety.

Inspectioneering Journal wrote that it is important for pipeline and refinery owners to have a thorough understanding of NDT and to be able to carry out the tests routinely.

“Pipeline and refinery owners should have a thorough understanding of NDT.”

Most examinations of machinery and components are mandated by various codes and standards. Being able to conduct such testing is vital to ensuring safety and continued production.

NDT-for-downstream-oil-and-gas[1]Such testing can be carried out at regular intervals to determine assets’ life cycle, during routine maintenance or when a particular component is expected to be coming to the end of its lifecycle. No matter the situation, testing and inspection are vital to plant operation.

Some of the most common NDT techniques include magnetic particle testing, ultrasonic testing, liquid penetrant testing, electromagnetic (eddy current) and radiography.

However, there are other techniques that are also important:

Remote visual inspection – Remote visual inspection uses a variety of video tools such as video probes and remote-operated cameras, and are attached to some sort of remote-operated vehicle like a robotic crawler. This technique is especially useful for spotting damage and corrosion. The three major methods, according to Inspectioneering Journal, are comparison, stereo and shadow measurements.

Magnetic flux leakage – This is similar in principle to eddy current testing because it is uses electromagnetism to detect pitting, corrosion and thinning of ferrous pipes and tubes. Magnetic flux leakage employs magnets to magnetize the item being tested. A technician can then detect flaws based on the distortions in the magnetic field.

“Acoustic emissions tests are performed on assets while they are in operation.”

Acoustic emission – When an asset is subject to a sudden change in temperature, load or pressure, there is a release of energy in the form of stress waves. These waves rise to the surface and can be recorded by sensors. According to the NDT Resource Center, acoustic emissions tests are performed on assets while they are in operation. It is particularly useful for measuring structural integrity, testing for leaks and testing the quality of welds.

Long-range ultrasonic testingLRUT is one of the fastest NDT techniques for detecting corrosion or other types of damage in pipelines. Inspectioneering Journal noted LRUT comprises a low-frequency flaw detector, pulser receiver unit, transducer rings and a computer with software that controls the testing. The transducer rings emit low-frequency waves. When the waves reach an area of the pipe where there is a change in wall thickness, they are reflected back to the transducer.

LRUT is used in a number of applications throughout the oil and gas industry. It’s useful in testing pipelines that are covered in insulation. Inspectioneering Journal noted the testing method is widely used in the field where pipelines cross roads or bodies of water. LRUT is also particularly useful when other testing methods can’t be used, such as testing buried pipelines, those at a high elevation or those that are encased in some sort of protective sleeve.

NDT techniques are vital to the downstream oil and gas industry. With these testing methods at their disposal, engineers have the tools they need to determine the structural integrity and operability of their production assets and can develop maintenance and replacement plans that keep production up and minimize downtime.