Non Destructive Inspection

Posted by Csiscan NZ on April 19th, 2021

Non Destructive Testing (NDT) or <a href="https://csiscan.nz/">Non-Destructive Inspection</a> as it's also known as a collection of techniques that allow the testing of materials without having to damage or interfere with the material in any way.
In practice, Non-Destructive Inspection allows various industries to check the condition of equipment such as boilers, tubes, pipes, heat exchangers, etc. Without degrading it and if necessary, without taking systems offline or interfering with finely calibrated equipment.

NDT is used throughout many different industries including chemical, petroleum, power, bulk storage & offshore, amongst many more. Typically <a href="https://kidscorner.co.nz/auckland/directory/concrete-structure-investigations-ltd">Non Destructive Inspection</a> services are used as part of a written scheme of examination, which ensures regular tests are performed on equipment to maintain safety and prevent failures.

In practice the level of Non-Destructive Inspection carried out in different industries varies widely, and it's not uncommon for testing to only be performed when a failure occurs.
Recently a job involved being called out to inspect tube leaks occurring within the client's main condenser, the tubes were not due to be replaced for a couple of years and had forced the unit offline on multiple occasions. The leaks could not be isolated to one area, so a full inspection was ordered to assess the situation and plug the leaks.

The situation was remedied and the condenser remained online without incident until the next scheduled shutdown. Situations like these can be avoided, and whether this was the case above or not, regular inspections can keep units online and prevent loss of revenue from reduced capacity, as well as ensure the safety of everyone operating in the area.

Inspection of plants usually involves several different methods to fully assess flaws. Ultrasonic is often used to sure up tests performed via other methods for example. This helps save time and money by using cheaper, quicker techniques to get an idea of where the flaws are, before investigating them more thoroughly.

Some of the most common techniques used include;

LFET - Low-Frequency Electromagnetic Technique originally developed to inspect tank floors, scanners have been developed for most applications.

RFET - Remote Field Electromagnetic Technique, designed to quickly and accurately inspect ferrous tubing from inside.

ECT - Eddy Current Technique developed to test nonferrous metals, though expanded to also include ferrous metals via mag wave technology.

BFET - Balanced Field Electromagnetic Technique, used as an alternative to eddy current and is much faster than other methods such as dye penetrant and magnetic particle, this can be used virtually anywhere cracking is an issue.

Ultrasonic Inspection - Often used for thickness measurements, or to sure up readings via other methods.