99988018 mfl tank floor scanning 2009

MFLTRAINING

TANK BOTTOM FLOOR

SCANNER

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.

• 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

After this training you should know...

MEASURING PRINCIPLE

MAGNETIC SHOE FIELD LINES

STEEL PIPEOR PLATE

HALL SENSOR

MATERIAL LOSS, VOLUME AND SHAPE INFLUENCE

SIGNAL

GENERAL DESCRIPTIOIN

The Magnet Carriage, magnet and Hall effect sensor module.

The motor unit and battery compartment.

The electronics module housed within the main chasis/handle unit.

The detachable Site master 400 computer.

Before 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 can be changed when generating the final report.

METHOD OF OPERATION

MECHANICAL SET-UPSensor Height adjustment in Mapping (Auto) Mode (Floormap VS)

Plate Thick Sensor Gap(coating thinner than

2mm)

Sensor Gap (coating thicker

than 2mm)

Scan width Thick RangeSwi

tch

8 mm 3.5 mm (7shims) 2mm (4 shims) 250mm FM

10 mm 2 mm (4 shims) 1mm (2 shims) 250mm FM

12.5mm 1 mm (2 shims) 1mm (2 shims) 250mm FM

MECHANICAL SET-UP

Plate Thicknes

s

Sensor Gap (coating thinner

than 2mm)

Sensor Gap (coating

thicker than 2mm)

Scan width

Thickness Range Switch

8 mm or less 3.5 mm(7shims)

2mm(4 shims)

300mm -8+8 if coating is

thicker than 2mm

10 mm 2 mm(4 shims)

1mm(2 shims)

250mm +8

12.5mm 1 mm(2 shims)

1mm(2 shims)

250mm +8

DETECTION MODE (Manual)

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)

MANUAL INSPECTION MODE

a) 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

LED’s turn red and the unit stops automatically.

MANUAL INSPECTION MODE

e) 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.

NORMAL SCANNING PROCEDURE

i. 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.

ii. 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.

DETECTION (Manual Mode)• When a discontinuity is encountered, the Floormap VS

automatically stops. The LED or LED’s, 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.

Fundamentals and Definitions

Tank 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.

Tank Datum

Vertical

Horizontal

Tank Datum

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.

1/1 1/2 1/3 1/4 1/5

2/1 2/2

3/1 3/2 3/3

4/1 4/2

5/1 5/2 5/3 5/4 5/5Plate Numbering System

Plate Reference

Floormap 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.

Plate viewed with tank datum behind the operator’s left hand shoulder

Plate viewed with tank datum in front of the operator

1/1 1/2 1/3 1/4 1/5

2/1 2/2

3/1 3/2 3/3

4/1 4/2

5/1 5/2 5/3 5/4 5/5Tank Datum

Vertical and Horizontal PlatesPlates are

described as

either

vertical or

horizontal in

relation to

the tank

datum.

Therefore

plate 1/2 will

be classed

as vertical

and plate 2/2

classed as

horizontal.

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 non-rectangular 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.

Plate Coverage

The 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