Updated: Feb 27, 2020
Conventional Nondestructive Testing (NDT) Methods
TECHKNOWSERV CORP. (TKS) provides conventional non-destructive (NDT) and advanced non-destructive testing services to amusement parks during the off-season and in-season. Amusement parks rides are exciting due to their speed and other fascinating entertainment features but are subjected to strong forces and cyclic fatigue. Overtime rides may develop wear, corrosion, or cracks that must be detected and corrected as early possible using conventional non-destructive and advanced non-destructive testing methods. TKS has provided non-destructive inspection (NDI) to the amusement park industry for two decades. It is important to verify the condition of amusement ride components such as axles, bogies, pivots, chassis, lap bar parts and other structural components to ensure safety and uninterrupted service during times of heavy use. The non-destructive (NDT) and inspection services offered are Visual Testing (VI), Eddy Current Testing (ET), Magnetic Particle Testing (MT), Liquid Dye Penetrant Testing (PT), Ultrasonic Testing (UT), magnetic flux leakage (MFL).
- How is the visual inspection non-destructive testing method applied to the industry? Visual inspection is the first tool in the inspection of any structure or component. Prior to any further nondestructive evaluation (NDE), a thorough visual inspection will be carried out. This inspection will reveal corrosion, damage and wear much more readily than other methods and can indicate where other investigative methods should be targeted. Over 90% of defects are found by the naked eye. Visual non-destructive testing can be assisted with borescopes, sophisticated lighting systems, and robotic crawlers. All rides are inspected visually on a daily basis.
- How is the magnetic particle inspection (MPI) non-destructive testing method applied to the industry? Magnetic particle testing is performed in accordance with ASTM E709, Standard Guide for Magnetic Particle Testing. This is arguably the most common and widely-used method of NDT in the amusement park industry after visual inspection. This non-destructive testing technique employs the nature of magnetic fields to identify potential defects. In magnetized materials, the magnetic field tends to travel within the solid material. When an applied field meets a crack or other defect, it will tend to 'jump' across the crack and exit the component. Fine magnetic particles are applied to the part and accumulate around any magnetic flux leakage (MFL). Colored indication form around cracks and other surface discontinuities. There are three main magnetic particle non-destructive testing methods;
• Visible dry magnetic particle non-destructive testing method
• Visible wet magnetic particle non-destructive testing method
• Wet fluorescent magnetic particle non-destructive testing method
- How is the liquid penetrant testing (PT) non-destructive testing method applied to the industry? Liquid penetrant testing or dye penetrant testing is performed in accordance with ASTM E165, Standard Practice for Liquid Penetrant Examination for General Industry. Dye or liquid penetrant inspection is a widely applied to locate surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). Penetrant may be applied to both non-ferrous and ferrous (magnetic) materials, but for inspection of ferrous components magnetic particle inspection is preferred for its sub-surface detection capability. PT is used to detect casting and forging defects, cracks, and leaks in new products, and fatigue cracks on in-service components. Penetrant testing consists of a series of well-defined steps which at least will include;
• Pre-cleaning: Components must be clean to assure a pathway for penetrant into the surface cracks.
• Application of liquid penetrant: Liquid penetrant is applied in a controlled fashion at the specified pressure and flow rate.
• Liquid penetrant dwell time: Penetrant is allowed to dwell on the surface and penetrate into cracks via the capillary effect. Penetrant dwell time depends on the manufacturer recommendation, size of defect sought, and experience on comparable components.
• Liquid penetrant removal: Liquid penetrant removal is controlled step that is designed to remove excess penetrant from the tested surface while penetrant remains in subsurface in cracks. Over washing can remove penetrant from the internal crack crevice and reduce probability of detection and inspection sensitivity. In some instances an emulsification step is required.
• Liquid penetrant developer application: Application of developer is required to draw out the penetrant from crack cavities. Like the penetrant dwell time there is also a liquid penetrant developer dwell time.
• Liquid penetrant post-cleaning: Liquid penetrant testing can be a dirty process, especially when using a red dye. It is important to clean the surface post-inspection with the specified cleaning products before returning the part to service.
- How is the ultrasonic testing (UT) non-destructive testing method applied to the industry? Ultrasound is used to find deep metal flaws (ex. cracking and inclusions) and to check thicknesses of parts. Ultrasonic testing is performed in accordance with ASTM A788 / A788M - 18b. Many amusement park structures and components are inspected in accordance with American Welding Society AWS D1.1 Structural Welding – Steel. Ultrasonic testing of pins is the most common inspection application. Ultrasonic thickness testing and ultrasonic weld inspection are also common.
- How is the eddy-current (ET) non-destructive testing method applied to the industry? Eddy current testing is applied more and more these days as an alternative to magnetic particle testing, particularly for cracks underneath paint. Eddy current testing is performed in accordance with ASTM A450/A450M General requirements for carbon, ferritic alloys and austenitic alloy steel tubes. Welds and other suspected areas are inspected with eddy current testing.
- How is the magnetic flux leakage (MFL) non-destructive testing method applied to the industry? Magnetic flux leakage is used on roller coaster launch cables, return cables, chair lift cables and for other wire rope inspections. Wire rope inspection is performed in accordance with;
• ISO 4309:2010 Wire Rope: Care and maintenance, inspection and discard
• ASTM E1571: Standard Practice for Electromagnetic Examination of Ferromagnetic Steel Wire Rope
• DIN EN 12927-6: Safety requirements for cable way inspections designed to carry persons Part 6: Discard Criteria
Advanced Nondestructive Testing (NDT) Methods
• Advanced ultrasonic rail track inspection inspects train track for rail flaws in the head region.
• Guided wave tubing inspections inspects tubular track and pipe columns and pile for cracking and corrosion.
• Phased array ultrasonic inspection is an advanced ultrasound technique that has the ability to sweep inspection angles to maximize the visible inspection area in parts with complicated geometry.
• Robotic unmanned drone non-destructive testing is for visually gaining access to areas that are inaccessible for other NDT examinations.
• Bolt torqueing is performed to ASTM standards. Bolt inspection reveals the condition of in-use hardware and will also determine if the bolts and nuts are properly torqued.
TKS provides owners with technical inspection reports that can be filed with state inspectors or other regulators. TECHKNOWSERV’s American Society for Nondestructive Testing (ASNT) certified inspectors have complementary training in fall protection and confined space safety. Additionally TKS inspectors are rope access (SPRAT) certified. This gives inspectors the ability to use climb ropes in order to gain access to inspection locations rather than using costly man-lifts or cranes. TKS has a proven record of high quality inspection services and safety.