MFL Tank Floor Scanning 2009

Download MFL Tank Floor Scanning 2009

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<p>MFLTRAINING TANK BOTTOM FLOOR SCANNER</p> <p>INTRODUCTION-Floor Map VS A New generation Magnetic Flux Leakage system for the inspection of Storage Tank bottom floors scanning. Self propelled by a motor run by a sealed lead acid battery. On board computer allows full data acquisition of signals detected by MFL. Mapping of defect indications in the graphical reporting software in a laptop or desktop computer. Grouping of defects according to severity by colour coded bands.</p> <p>After this training you should know...</p> <p>The basic background of MFL The safety related issues The basic functions of the unit How to handle the Equipment How to perform the scanning Data aquisition saving. Importing data to the reporting software Preparation and printing of final report How to perform basic maintenance</p> <p>MEASURING PRINCIPLEMAGNETIC SHOE FIELD LINES</p> <p>HALL SENSOR</p> <p>STEEL PIPE OR PLATE</p> <p>MATERIAL LOSS, VOLUME AND SHAPE INFLUENCE SIGNAL</p> <p>GENERAL DESCRIPTIOIN</p> <p> The Magnet Carriage, magnet and Hall effect sensor module.</p> <p> The motor unit and battery compartment.</p> <p> The electronics module housed within the main chasis/handle unit.</p> <p> The detachable Site master 400 computer.</p> <p>METHOD OF OPERATIONBefore commencing a tank floor inspection with Floormap VS, the operator should ensure the following information is available: a) Floor plate and annular plate thickness. The Floormap VS is limited to 12.5mm floor thickness in mapping mode. b) Any floor coating thickness in excess of 2mm thickness will have to be simulated during calibration. Any non-magnetic material of the correct thickness can be placed over the calibration plate to simulate the coating. c) General condition of the top surface. Floormap VS will produce a colour coded map of the total floor condition not just the under floor condition. d) Presence of heater coils or other obstructions. These may necessitate the use of manual mode rather than mapping or may require the use of Hand scan to cover areas missed by the larger motorised scanner. e) Floor plate numbering system to be used. A set floor plate numbering system must be used while using the data acquisition software, but this</p> <p>MECHANICAL SET-UPSensor Height adjustment in Mapping (Auto) Mode (Floormap VS)Plate Thick Sensor Gap (coating thinner than 2mm) Sensor Gap Scan width (coating thicker than 2mm) Thick RangeSwi tch</p> <p>8 mm 10 mm</p> <p>3.5 mm (7shims) 2mm (4 shims) 2 mm (4 shims) 1mm (2 shims)</p> <p>250mm 250mm</p> <p>FM FM</p> <p>12.5mm</p> <p>1 mm (2 shims) 1mm (2 shims)</p> <p>250mm</p> <p>FM</p> <p>MECHANICAL SET-UPDETECTION MODE (Manual)Plate Sensor Gap Thicknes (coating s thinner than 2mm) 8 mm or less 3.5 mm (7shims) Sensor Gap (coating thicker than 2mm) 2mm (4 shims) Scan width Thickness Range Switch -8 +8 if coating is thicker than 2mm +8 +8</p> <p>300mm</p> <p>10 mm 12.5mm</p> <p>2 mm (4 shims) 1 mm (2 shims)</p> <p>1mm (2 shims) 1mm (2 shims)</p> <p>250mm 250mm</p> <p>Limitations with coating/plate thickness The maximum thickness of coating on plate thicknesses up to 10mm is 6mm. The maximum thickness of coating on plate thicknesses between 10mm and 12.5 mm is 2-3mm. The maximum plate thickness for Mapping mode. The maximum Plate thickness for Detection mode is 20mm (sensitivity will be reduced)</p> <p>MANUAL INSPECTION MODEa) Switch on the unit and allow to warm up for a period of 10 minutes. b) Ensure the plate thickness selector switch is set to the correct position. c) Ensure the sensor head height is correct. d) Set the threshold to approximately 15 and scan over the 40% artificial defect, checking that the appropriate LEDs turn red and the unit stops automatically.</p> <p>MANUAL INSPECTION MODEe) Re-set the system and adjust the threshold either up or down until, whilst scanning over artificial defects, until the desired percentage material loss threshold is obtained. At the end of each scan the unit must be turned through 180 degrees and the subsequent scan made in the opposite direction. f) This is to avoid building up a residual magnetic field in the plate will prevent accurate calibration of the system.</p> <p>NORMAL SCANNING PROCEDURE</p> <p>i.</p> <p>Motor driven. Twisting the right hand handle towards the operator causes the motor to turn. To stop the motor, simply twist the handle away from the operator. Hand propelled. By putting a downwards pressure on the handle the drive motor is lifted clear of the floor. The unit can then run on the magnet carriage rollers alone.</p> <p>ii.</p> <p>DETECTION (Manual Mode) When a discontinuity is encountered, the Floormap VS automatically stops. The LED or LEDs, on the control panel, corresponding to the sensors that detected the discontinuity light up RED and will remain illuminated until the re-set button is pushed. A corresponding numbered strip is fitted to the Magnet Bridge. This allows the operator to determine where across the width of the unit the corrosion is located. A delay in the auto-stop circuitry ensures that the discontinuity is in line with the rear of the rear rollers, allowing the position to be marked on the floor. The motor can be restarted by pushing the re-set button. Due to the delay in the auto stop circuit the unit has stopped approximately 100mm forward from the discontinuity. For complete coverage the unit should be pulled backwards 100mm before restarting the scanning.</p> <p>Fundamentals and DefinitionsTank DatumThe tank datum is the nominal position to which all measurements are co-ordinated. The plate numbering system, the plate reference point and the plate orientation (horizontal or vertical) are all referenced to the Tank Datum. When viewing the floor from above the plates are aligned so that they lay in either the vertical or horizontal plane as illustrated below. The Tank datum point is then set in the bottom left hand corner of the tank.</p> <p>Tank Datum</p> <p>Vertical</p> <p>Tank Datum</p> <p>Horizontal</p> <p>Numbering Scheme At present the Floormap VS system supports the use of row / plate co-ordinates only. These are normally numbered from the top left hand corner of the tank.</p> <p>1/1 2/1</p> <p>1/2</p> <p>1/3</p> <p>1/4</p> <p>1/5 2/2</p> <p>3/1 3/3</p> <p>3/2</p> <p>4/1 5/1 5/3 Plate Numbering System 5/4 5/2 5/5</p> <p>4/2</p> <p>Plate ReferenceFloormap allows the operator to start scanning a plate from any 4 corners of a rectangular or square plate. In order to position the defect location correctly it is necessary to identify which corner of the plate scanning started. This corner called the Plate Reference or PR. As with the numbering system the plate reference is identified relative to the Tank Datum which is always positioned in the bottom left hand corner of the tank. Care must be taken identifying the PR, when the operator is looking towards the Tank Datum rather than away as is normal convention, not to become disorientated and put the PR 180 out of phase.</p> <p>Plate viewed</p> <p>with tank datum behind the operators left hand shoulder</p> <p>Plate viewed</p> <p>with tank datum in front of the operator</p> <p>Vertical and Horizontal PlatesPlates are described as1/1 2/1 1/2 1/3 1/4 1/5 2/2</p> <p>either vertical or horizontal in relation to the tank datum. Therefore</p> <p>3/1 3/3</p> <p>3/2</p> <p>plate 1/2 will be classed as vertical and plate 2/2 classed as horizontal.</p> <p>4/1 5/1 5/3 5/4 5/2 5/5</p> <p>4/2</p> <p>Tank Datum</p> <p>Scanning ModesThe Floormap VS system uses two types of scanning mode: i) Parallel or Uni-directional scanning This involves starting each scan of the plate from the same side of the plate, and is normally used to scan nonrectangular plates. ii) Raster or Bi-directional Scanning This involves starting alternate scans from opposite ends of the plate. This is the most efficient method of scanning but should only be used to scan rectangular plates.</p> <p>Plate CoverageThe active scanning width of the Floomap VS system is 250 mm (10 inches). To calculate the number of scans required per plate, simple divide the plate width by 250. The reporting software will automatically allow for an overlap last scan if the number of scans required is not a whole number. Plate width / 250 = number of scans 2000 mm / 250 mm = 8 scans 1850 mm / 250 mm = 8 scans</p>