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RTD-INCOTEST®Verification of sphere leg stability without removal of fire proofing
Herman J. Quakkelsteijn, February 2006
Contents
IntroductionStability verificationPrinciple RTD-INCOTESTInspection examplesSummary
Why?
Stability verification
Section strenght verification
Leftside
Right side
Reference-
Recommandations
DIN 18800/4
Proven Strategy
Inspection plan
Inspection of the legs
Verification of stability
Inspection and testing
Most used inspection techniques:Visual inspectionUltrasonic Testing
RTD-INCOTEST is a cost saving alternativeHigh productionNo need of special surface cleaning and preparationMonitoringOptimisation of maintenance activities
Inspection and testing
Traditional approach:Take tank out of storage capacityErect ScafoldingRemoval of fire proofing (concrete)Sand blastingPerform Ultrasonic measurementsApply concrete
Alternative: RTD-INCOTESTMeasurements are on streamThrough fire proofingOther meanings of access possible
RTD-INCOTEST vs Ultrasonics
Measurement deviation up to 1mm (in contact)RTD-INCOTEST and UT accuracy ± 1mm
Sample 1, Test line A
0,0
2,0
4,0
6,0
8,0
10,0
12,0
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18Grid position
Mea
sure
d W
all T
hick
ness
RTD-INCOTEST Ultrasonic Testing
RTD-INCOTEST®
INsulated COmponent TESTOn streamThrough fire proofingScreening toolDetection of reduced WT areasMeasurement of the averageremaining wall thickness, within the interrogated area(footprint).
Principle of operation
Pipe wall
Insulation
Sheeting
Magnetic Field
Eddy Currents
Coil
Measurement principle
Time
Am
plitu
de
Data display
AWT%
Inspection Grid
Signal QualityControl
Eddy CurrentDecay
System specifications
Carbon steel (ferromagnetic)Leg thickness 6-65 mmFire proofing thickness <200 mmOne measurement takes up to 10 secondsChicken wire has no influenceSteel bars or beton ijzer can influencesignaling
Performance
Detection of internalor external corrosion
Performance
INCOTEST detected a 1 mm loss
Accessibility
Accessibility
Reporting
Cost savings
Conventional:ScaffoldingConcrete removalSand blastingUTApply concreteDown time
Costs: 100k€ to 300k€per tank
RTD-INCOTESTRope access or extension toolOn stream, no down timeDirectly on concrete2-4 days inspection
Costs: approx 20k€ per tank
Cost savings
On average an RTD-INCOTEST inspection costs about 20% or less of a traditional inspection
Additional; Planning is less complicatedLess risks in terms of human and financial Less waste
Experience
In Europe and North America over 1500 spherical tanks have been inspected, manyunder country codes.Several major oil companies now have a world wide recommendation to use RTD-INCOTEST.
Summary
Corrosion detectionScreening toolNo direct surface contact neededNo surface preparation neededOn-streamSaves time, reduces risks and > 80% on the inspection and associated costs
More information ?
RTD GroupRotterdam, the Netherlands
e-mail : h.j.quakkelsteijn@rtd-group.comphone : +31 10 208 8 291fax : +31 10 415 8 022web : www.rtd-group.com
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