SDI-8150 Scan-Trax LD Radioscopic Pipe Inspection System
SDI-8150 System Overview
The Scan-Trax LD Radioscopic Pipe Inspection System is designed to provide real-time x-ray inspection of longitudinally and circumferentially welded steel pipe with diameters ranging from 6 ft to over 20 ft. It is ideally suited for use where the standard Scan-Trax moving pipe system is impractical due to the size of the pipe.
For this LD version, the pipe remains stationary and the source and detector move down the pipe, scanning the length of the weld, during the inspection sequence.
The detector is housed in a steerable motorized cart which travels inside the pipe synchronized to the external X-ray tube position. The X-ray tube and generator move by means of a motorized carriage running on linear tracks. During circumferential weld inspection the pipe rotates with the detector cart wheels set in the transverse direction.
The speed of the cart is synchronized to the pipe rotation, maintaining position directly over the X-ray tube. The sequence of operations is controlled by the SDI-1830 X-ray controller as used on a variety of multi-axis real time X-ray systems.
The synchronized motion of the source and detector allows the system to keep the weld in the x-ray beam during the scan of the entire weld. Scan speeds can be varied depending on specification requirements.
X-Ray Generation Components
These include the X-ray high voltage generator, HT cables, the closed loop chiller, and the X-ray tube. The system can use any X-ray tube and generator as dictated by customer preference. Remotely controllable rack mount X ray controllers are preferred to allow full integration with the SDI 1830 controller.
A Philips 225kV unit has produced excellent results with pipe wall thicknesses up to 1.5 inches. The actual thickness penetrated depends on a number of factors including the alloy of the material. For typical steel a 320kV system will inspect up 2 inches and a 450kV up to 3 inches.
Above this thickness it would be necessary to use an isotope. The ScanTrax system can be upgraded to a more powerful source by changing the X-ray generation components and increasing the shielding.
X-ray Image Chain Components
These include the image intensifier and the CCD camera. The system will operate with any industrial quality 9 inch image intensifier/camera detector. A 6 high resolution 13” monochrome monitor is provided as standard. Image enhancement is provided with a remotely controllable image processor if required.
The motorized cart is moved into the pipe under joystick control and the inspection sequence is initiated from the control console. The pipe is rotated until the weld is centered in the x-ray beam. The x-rays are activated and the inspection sequence is begun.
For longitudinal inspection the cart travels along the pipe with the operator adjusting the pipe rotation if necessary to maintain the weld on the video monitor. During circumferential inspection the operator is able to make adjustments to the detector/tube longitudinal position to allow for movement of the weld in the field of view.
If the operator views an indication believed may be rejectable, the scan can be interrupted and viewed in the stationary mode. A digital image processing system is supplied to allow the operator to apply processing functions that will make the indication clearer. This system also allows the operator to do on-screen sizing of indications.
External Tracked Carriage
This carriage houses the x-ray generation components and transports them down the track during the inspection sequence. The high voltage generator and cable are mounted behind the x-ray tube which is housed in a double shielded enclosure mounted on the external carriage.
The x-ray beam is collimated radially, with respect to the vessel, by a diaphragm attached directly to the tube window. The entire tube assembly is then housed in a lead enclosure which fits closely to the outside of the pipe wall.
X-Ray Generation Components
Located alongside the x-ray generator is the refrigerated, closed-loop water chiller. This cools the x-ray tube even under high load, continuous operation in adverse ambient conditions. The carriage travels along a track positioned alongside, or under the vessel during the inspection sequence.
Drive is provided by a rack and pinion DC servo mechanism. Power and control lines are distributed in an armored cable carrier. An industrial ink marking system can also be mounted on the cart.
Internal Motorized Cart
The motorized cart houses the image chain components and a CCD surveillance TV used while maneuvering the cart. The carriage is fitted with steerable wheels which can be aligned either longitudinally or transversely with respect to the pipe. The image intensifier can be mounted on an extended arm to position it for inspection from outside the roller base.
The video signals, control signals and power are supplied through an armored umbilical cable. Synchronization of the cart with the tube and encoded pipe rotation is provided through the servo controllers housed in the control console.
The control station consists of a three bay console which houses the SDI-1830 system controller, the X-ray controller and monitors for the X-ray image, control computer and surveillance camera. Accessories such as video recorders and type writers can also be built into the console.
The control station can be housed in any convenient room with standard air conditioning. Alternatively, a ruggedized two bay mobile console can be supplied for simple transportation between inspection sites.
The surveillance monitors are used both to help the operator during joystick control of the cart and as area safety monitors.
The controller also displays onto the video screen the linear distance the cart has traveled along the vessel together with the rotational position. By tracking the linear distance and recording this measurement in inches on the video tape, any defects can be accurately located on the surface of the pipe.
An enclosed housing is provided for the cart at the start and end of the scan. This shielded parking station is positioned at he end of the pipe or vessel to allow the cart to run on and off.
It also allows the inspection of the pipe longitudinal weld to the end of the pipe, provides a location for X-ray system set-up, test and calibration and simplifies entry and exit of the cart.