9-AXIS Contour Scanner
This state of the art 9-axis scanner can inspect complex shaped aircraft structures using through-transmission and pulse-echo techniques. During scanning, the squirter nozzles have to remain axially aligned with each other while maintaining the water stream in a perpendicular orientation to the surface being scanned. This requires the utmost precision in mechanical system performance as well as ruggedness to survive the demands of the aerospace production environment.
The mechanical portion was engineered and managed by our Mechanical Engineer ('77, Va. Tech) while he was employed at McDonnell Douglas Corporation in St. Louis (now Boeing Corporation).
DSAW Full Body and Weld Line Pipe Scanner
The Full Body System shown above was designed and built at NDT Research by personnel who went on to start Innovative Test Systems after NDT Research was shut down by the owners shortly after this installation. The system was designed to inspect DSAW (Deep Submerged Arc Welded) pipe ranging from approx 16" to 42 " in diameter with walls up to 1" thick. Two separate heads were used, one to inspect the full body of the pipe in one pass. A second head was then used in a second pass to inspect the weld.
The prominent DSAW weld provided an additional challenge to the mechanical design as it needed to pass the transducers on each successive rotation. The challenge was met with a special "compliant " shoe. The weld was also used to index the data to zero degrees.
The pipe to be inspected was held on a cart equipped with rotators that spun the pipe. The cart was then translated through the machine at a fixed rate under the stationary full body head which came down and engaged the pipe. The cart speed was controlled along with the spin rate to produce the desired helical scan path to insure complete coverage of the pipe volume with all transducers.
The pipe rotation was then stopped, the weld positioned by the operator using a joy stick and laser beam, and then the pipe was translated back through the system using the weldline head with it's transducers spanning the weld on each side.
The Full Body head used two rows of 16 transducers each. 16 of the transducers were used for thickness measurements and 16 were used for flaw detection, each set 22.5 degrees apart to cover a full 360 degree scan.
The weldline head incorporated two rows of 4 spring loaded cantilever arms that were fully gimballed on the ends and that could be adjusted for perpendicular distance from the weld. The transducers were set to inspect the ID, mid wall, and OD areas of the weld from each side as well as one transducer placed on top of the weld facing rearward and one facing forward to inspect for transverse defects.
Since then, Innovative Test has gone on to using ALL spring loaded cantilever arms for both weld line and full body systems. This provides for individual tracking for each transducer providing better couplant and constant location relative to the pipe. Local deviations in pipe diameter, roundness, etc, can be tracked by the individual transducers without affecting the position of the other transducers. Also, each arm can be adjusted laterally providing more flexibility in helix selection to insure 100% coverage during full body scanning. These cantilever arms can be seen in our current pipe and plate scanning systems such as the Plate Scanner, DSAW Weld Scanners, ERW Weld Scanners, and Drill Pipe Scanners.
The above photograph shows close-up detail of the weld-line head. The two vertical rods were adjustable up and down along radial lines pointing to the center of the pipe. These were changed for each pipe diameter. A coarse adjustment was provided by sliding the rods inside split collets. A fine adjustment was provided by screwing the collets in and out of their holders. The rubber isolation bag provided additional compliance to the head. This method was used on both the weld line and full body heads. Our current method of using cantilever arms eliminates these additional adjustments. Also, with individual arms, each transducer can be carried to the edge of the pipe where this design requires lifting the head before it is halfway off the end, leaving the trailing transducers many inches from the end.
The above photo shows some of the attention to detail. All wires are enclosed in their own wireways, isolated from other electrical control signals as well as stray signals which might exist within customer's facility. These methods have been and always will be practices of our designs.
This system used Krautkramer KB-6000's and WDMU's tied together with custom NDT Research data acquisition and display software. Today, Innovative Test Systems uses one of several off-the-shelf data acquisition systems that are available.
Full Body System
The system shown in the above photos also is a full body system that was designed to inspect casing ranging from approx 4" to 15" in diameter. This system was also designed partially by personnel who went on to form Innovative Test Systems. This system was designed , manufactured , and installed just prior to the DSAW System shown above.
There were no provisions for weld inspection as in the above DSAW Full Body System. In this system, the pipe to be inspected was held on a stationary set of rotators that spun the pipe up to speed. An end stop with an encoder insured the pipe remained at the same lengthwise station while feeding accurate rotational position and speed information. The head then translated down the length of the pipe, carried by a cart in the overhead gantry, thus creating the desired helical path.