Understanding the Criticality of Borescope and NDE Inspections

Natural gas is the second most heavily consumed energy source in the United States, and the United States was the largest producer of natural gas in 2016, extracting almost 750 billion cubic meters of natural gas. Natural gas is the driving force for turbines across the country, fueling aircraft, trains, ships, electrical generators, pumps, compressors, and more.

There are two types of land-based gas turbines: heavy frame engines and aeroderivative engines. The three primary modules in these gas turbines are compressor, combustion, and turbine. Gas turbines operate at a much higher temperature than steam turbines, operating at approximately 2,000 degrees Fahrenheit.

A Combined Cycle Gas Turbine (CCGT) plant can achieve a thermal efficiency of around 62% in base-load operation, in contrast to a single cycle steam power plant, which is limited to efficiencies of around 35% to 42%. So how do you know if a turbine is achieving the appropriate thermal efficiency and operating levels?

Gas turbine inspection and steam turbine testing are important to test for not only efficiency in a running turbine but also in the quality of the machinery. One type of inspection that achieves this is a borescope inspection.

In breaking down the terminology, a borescope is just that: “bores” and “scopes” out the parts and operation of the turbine. A borescope is an optical tool used to scope out those hard to reach and not visible areas of the turbine. It is inserted into the turbine without destroying the parts or operation process. Borescopes are used to inspect the condition, parts for quality and security (or safe retrieval and removal in the event of a parts change). A borescope inspection can assist in regular maintenance on a turbine to ensure maximum service life capacity of the turbine.

There are a few different types of methods that can be used in a borescope inspection. The most common type of borescope inspection uses a videoscope. A videoscope uses a small video camera/detection device at the end of a borescope to detect possible wear and tear and potential problems without having to take the turbine apart completely. Because this uses video camera technology, it can also utilize recording to pull the video up for future reference, while also saving time and money of having to go through the entire process again in the event of maintenance time or a mechanical problem.

Borescope inspections are important to the industrial side of equipment maintenance and efficiency. Turbine and power generation providers have a lot to consider when looking for the right company or contractor to complete a borescope inspection.

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