Inspections are an important part of commercial diving. Ships, oil pipelines and platforms, and underwater infrastructures like hundreds of thousands of bridges spanning bodies of water require regular routine safety checks and inspections before damage repairs are completed.
Non-destructive testing (NDT) technicians perform inspections that keep ships, bridges, planes, railroads, and all kinds of structures in the industrial world safe. Simply put, non-destructive testing is the process of inspecting structures without causing damage to the structure.
A doctor can’t determine if their patient has broken bones without an x-ray examination. Similarly, an NDT technician can’t assess if a ship hull is sound or a bridge is stable without proper inspection.
NDT inspections occur as part of routine maintenance and before repairs are completed. Most divers come in after the testing is finished to do the repair work, but a diver who is NDT certified can be placed on that job from the beginning. They can also do the routine check-ups that a non-NDT certified commercial diver could not perform.
NDT: Not just for the Commercial Diving Industry
An NDT technician will have jobs that take them both underwater and topside.
In addition to the marine industry using NDT inspections and divers for pipelines, ships, oil rigs, and steel piles, many fields utilize NDT. Some other industries where NDT is required are:
- Bridges and transportation infrastructure
- Military and civilian environments
- Automotive/motorcycle manufacturing (e.g., Harley Davidson plant)
- Structural steel construction
- Welding & fabrication
- Windfarms/wind energy (both offshore & inland)
- Environmental /conservancy inspections
- Wire rope access (e.g., ski lifts)
- Nuclear/power plants
Types of Non-Destructive Testing
In addition to having diverse applications, a variety of common NDT procedures are used to test structures while maintaining the integrity of the structure & keeping materials in production:
- Visual: Usually the first form of testing, technicians identify imperfections with the naked eye and with specific equipment such as video and digital cameras.
- Ultrasonic: Using soundwaves, technicians gauge material thickness and evaluate flaws in the material.
- Dye Penetrant: By applying dye to the surface of a structure and removing the excess, technicians can spot defects in the structure.
- Magnetic Particle: Technicians create a magnetic field then apply metal particulates which reveal possible cracks by adhering to the steel.
- Eddy Current: This type of testing uses electrical currents and magnetic fields. Defects show up as they interrupt the electric flow.
- Radiographic Testing: A somewhat familiar type of testing, RT is similar to X-rays that medical doctors use but is applied to industrial structures.
Specific elements of these procedures are taught in DIT’s stand-alone NDT courses.
NDT students practice in the classroom with the same kind of equipment that is used on NDT jobs, including:
- Transducers (probes)
- Ultrasonic gauges
- Magnetic yokes
- Britemoor & Developer—topside two-part spray used in Dye Penentrant to identify indications in steel/metal
- “My Glow”—neon powder that reacts with metal particulates to identify issues during magnetic particle testing
- Pit gauge
- Cameras (digital & video)
Prerequisites to Becoming NDT Certified
Some NDT courses at DIT have been present in the core diving program for a considerable amount of time — other stand-alone courses have been added recently.
The stand-alone NDT courses at DIT are designed for participants with various backgrounds and goals.
“The instructors are trained to communicate well with people with no previous technical background as well as those with technical or mechanical experience,” says Michelle Perrigo, DIT’s NDT courses facilitator and training administrator. “While not a requirement, students with an interest and aptitude for attention to detail, numbers, and schematics will likely enjoy NDT training and working in the NDT field.”
The requirements for enrolling in the program are simple: have a high school diploma (or equivalent). While some mathematical ability is helpful, all necessary formulas and concepts are taught in the class.
Optimum Class Sizes & Challenging Courses
Class size ranges from 3-12 students. “The maximum class size is limited to allow for each student to have plenty of hands-on equipment time and to ensure they’re understanding and mastering each day’s topics,” says Michelle.
Technicians become responsible for inspections and reports with specifications set by the government, and technicians are held accountable to the law. An inaccurate inspection or report may have legal consequences.
So, the challenge for students in NDT classes is learning the required standards and necessary terminology for writing reports. But technicians also must understand the range of permissible deviation from the standard.
“For example, there are specific limitations or variances allowable in steel that are set by engineering specs & steel fabrication standards,” explains Jeff Stiefel, a DIT instructor with commercial NDT diving expertise. “Each piece of steel and project construction will have allowable tolerances. Inspectors have to learn what those specifications are, as well as how to figure out (see/observe) what the steel is doing and properly talk about it within the acceptable reporting terminology.”
Students must learn when the standards must be strictly held to, and when there is room for deviation.
Beginning an NDT Career
In many fields, employers want workers with experience. Often as a graduate, gaining that initial experience can be difficult. However, an NDT technician has plenty of jobs to choose from after graduation.
Michelle describes the process for becoming an NDT inspector: “Students/graduates of the NDT courses start as ‘probe monkeys’ – the trainee who is allowed to collect data/information on an inspection under the direction of more senior inspectors.” As trainees gain more experience and required on-the-job training, they are given more responsibility and eventually move up to performing inspections and writing official inspection reports.
NDT technicians are not only highly sought-after, but a commercial diver who is NDT certified will most likely get a higher salary. And that’s definitely a worth-while perk.
Written by Beth Smith, Staff Writer for Water Welders.
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