WO2000055594A2 - Retards ultrasonores utilises dans des environnements sujets a des explosions - Google Patents

Retards ultrasonores utilises dans des environnements sujets a des explosions Download PDF

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Publication number
WO2000055594A2
WO2000055594A2 PCT/US2000/007247 US0007247W WO0055594A2 WO 2000055594 A2 WO2000055594 A2 WO 2000055594A2 US 0007247 W US0007247 W US 0007247W WO 0055594 A2 WO0055594 A2 WO 0055594A2
Authority
WO
WIPO (PCT)
Prior art keywords
ultrasonic
probe
delay
delays
retainer
Prior art date
Application number
PCT/US2000/007247
Other languages
English (en)
Other versions
WO2000055594A3 (fr
Inventor
Kerry Trahan
W. Thor Zollinger
Kerry Klingler
Charles B. Isom
Scott Bauer
Original Assignee
Bechtel Bwxt Idaho, Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bechtel Bwxt Idaho, Llc filed Critical Bechtel Bwxt Idaho, Llc
Priority to AU55863/00A priority Critical patent/AU5586300A/en
Publication of WO2000055594A2 publication Critical patent/WO2000055594A2/fr
Publication of WO2000055594A3 publication Critical patent/WO2000055594A3/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/28—Details, e.g. general constructional or apparatus details providing acoustic coupling, e.g. water
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B17/00—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
    • G01B17/02—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations for measuring thickness
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02854—Length, thickness
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/044—Internal reflections (echoes), e.g. on walls or defects

Definitions

  • This invention generally relates to ultrasonic probes or detection devices intended for measuring the wall thickness of storage tanks and for detecting abnormalities therein. More particularly, this invention relates to ultrasonic probes having unique protective delays in which the ultrasonic transducer of the probe is enclosed. The use of these delays allows the probes to be employed in explosive environments.
  • the current method of inspecting tanks such as those which enclose petroleum or other caustic chemicals, especially large tanks, can range from $100,000 to $250,000 depending upon the size of the tank. Further, the tank is rendered unserviceable for a month or more as the tank is drained, ventilated, and thereafter inspected.
  • the robotic vehicle disclosed in U.S. Patent No. 5,819,863 may carry one or more sensors which can measure various characteristics of the fluid within the tank or which can inspect the integrity of the storage tank itself.
  • One contemplated sensor is an ultrasonic probe that can be used to determine the thickness of the underlying supporting surface of the tank.
  • ultrasonic transducers Unfortunately, heretofore, no ultrasonic transducers have been available that are capable of safe operation in an explosive fluid environment.
  • ultrasonic probes construct probes with delays. These delays act as wear shoes to protect the ultrasonic transducers.
  • commercial transducers are manufactured with the high- voltage elements protected by a very thin layer (0.005 inch) of epoxy that can be damaged very easily. By damaging the epoxy, the high voltage leads to the piezoelectric crystal, carrying up to 300 volts, are exposed. These exposed damaged wires could easily spark and ignite the atmosphere if an explosive mixture is present. This condition is unacceptable for operations within an explosive environment, such as with a tank filled with hydrocarbon based products.
  • the present invention is directed to ultrasonic probes having unique protective delays in which the ultrasonic transducer of the probe is enclosed.
  • the probes may be used for measuring the wall thickness of storage tanks and for detecting abnormalities therein, even when the storage tanks are filled or partially filled with explosive fluids.
  • FIG. 1 shows a final assembly of a submergible vehicle with drawing (A) displaying a top view of a bottom assembly, drawing (B) displaying a top view of a top assembly, and drawing (C) displaying a front view of the top and bottom assembly in relation with each other;
  • FIG. 2 shows the bottom assembly in greater detail with drawing (A) displaying a top view, and drawing (B) displaying an exploded side view;
  • FIG. 3 shows a top view of a probe retainer
  • FIG. 4 shows a front view of an ultrasonic delay of the present invention.
  • FIG. 1 shows, in part, the final assembly of a submergible vehicle similar to that described in U.S. Patent No. 5,819,863.
  • a vehicle provides a convenient means whereby storage tanks of various designs may be conveniently inspected from a remote location without requiring the tank to be emptied or otherwise purged of its contents.
  • Drawing (A) displays a top view of a bottom assembly 1 of the vehicle, with an electronics mounting plate subassembly 3.
  • -An o-ring 14 of about V* inch diameter provides a continuous seal when the bottom assembly 1 mates with the top assembly 2 of drawing (B).
  • Such an enclosure thus formed by the top and bottom assembly may be purged and pressurized enclosure.
  • the top assembly includes a rollbar weldment 6.
  • Drawing (C) displays a front view of the top and bottom assembly in relation with each other such that a plurality of screws 7 and 8 can be secured with respective washers and nuts 9.
  • Drawing (C) also shows two side covers 10.
  • FIG. 2 there is shown the bottom assembly in greater detail with drawing (A) displaying a top view, and drawing (B) displaying an exploded side view.
  • the bottom assembly 1 or bottom shell includes at least one stepper motor 2 secured to respective motor mounts 3 and motor isolation mounts 7 with sealed screws.
  • Drawings (A) and (B) show a probe retainer 23 with a plurality of central hollow vertical channels or bores for holding a linear array of ultrasonic delays 19 and ultrasonic probes 21. As seen more clearly in drawing (B) of FIG. 2, there are shown the delays 19, o-rings 20, probes 21, probe washers 22, and the probe retainer 23.
  • the bottom assembly 1 also has a truck subassembly 15.
  • an ultrasonic probe is a device which is mainly constituted by a piezoelectric element (also called a piezoelectric transducer or an ultrasonic transducer) and adapted to be used for imaging the inner structure of an object.
  • the imaging of the inner structure of the object can be performed by emitting ultrasonic waves to the object and then receiving reflected waves from various interfaces of the object, the interfaces of which being different in acoustic impedance from each other.
  • the term "ultrasonic” as used herein generally refers to acoustic vibration frequencies greater than about 18,000 Hertz.
  • a conventional ultrasonic probe is fabricated by bonding a piezoelectric transducer composed of a piezoelectric ceramic plate, whose two principal surfaces are provided with a pair of electrodes, to an acoustic backing layer and further bonding an acoustic matching layer and an acoustic lens thereto.
  • a pulser applies pulsed energizing voltage in the hundreds of volts to the piezoelectric transducer, so that a rapid morphology change is caused to occur by the converse piezoelectric effect (the so-called inverse effect) of the piezoelectric transducer.
  • the resultant vibration is transmitted through the acoustic matching layer and the acoustic lens to thereby effectively transmit pulses toward an object to be observed.
  • the transmitted pulses are reflected at each interface of the object to be examined in nondestructive inspections and retransmitted through the acoustic lens and the acoustic matching layer to thereby apply mechanical vibration to the piezoelectric transducer.
  • This mechanical vibration is converted to an electrical signal by the piezoelectric effect of the piezoelectric transducer (the so-called direct effect), which is observed by means of a diagnostic equipment.
  • piezoelectric transducers While primarily piezoelectric transducers have been discussed, other transducers such as electromagnet, electrostatic, magnetostrictive, laser, or optical transducers may be used. Today, ultrasonic transducers work almost exclusively according to the piezoelectric effect. Depending on the application, the transducers may differ, however, with respect to the size of the active piezoelectric elements, their frequency, bandwidth, and the basic design. Likewise, straight beam, angle beam, delay line, or twin crystal transducers may be used in the present invention.
  • FIG. 3 shows a close-up top view, with dimensional spacing of the bore centers (and other dimensional information), of a probe retainer 23 capable of holding at least ten delays and probes. While a linear array of ten delays and probes are shown, the present invention contemplates the use of only one delay and one probe, or any multiple thereof, and in any geometric shape or arrangement thereof. Likewise, the probes may scan alone, in pairs, in triplets, or in any combination thereof, or may scan independently, sequentially, or simultaneously together.
  • FIG. 4 a front view of an ultrasonic delay of the present invention.
  • FIG. 4 also provides detailed dimensional information.
  • the ultrasonic delays mount into the purged and pressurized enclosure formed by the top and bottom assembly, and pass through the wall of the enclosure.
  • the delay is a plastic part, non- sparking, and chemically resistant, which channels ultrasonic sound through the enclosure wall and into the fluid outside. It seals to the enclosure wall, allowing the interior to be purged and pressurized with an inert gas.
  • the plastic is specially selected for its ability to conduct sound.
  • an ultrasonic probe or transducer is mounted on the end of the delay such that its sound is directed through the delay to the outside of the enclosure and into the liquid outside. This keeps the high- voltage electronics of the ultrasonic transducer safely inside the enclosure, fully protected and isolated from the explosive environmental outside.
  • the ultrasonic delays are made from Techtron (a chemically resistant plastic) which has similar acoustic characteristics to the liquids in which it is submerged. Other materials could be used in place of Techtron, the plastic selected for this specific application and environment.
  • This feature allows sound signals to be effectively coupled from the delay into the fluid outside. Sound is transmitted from the transducer, through the delay, through the liquid, and into the material to be inspected.
  • the delay is designed to allow a transducer to be screwed into the top end tightly onto a precision surface, and an oil couplant is used to fill any voids between the transducer face and the delay. A tiny vent hole allows excess couplant to be squeezed out the side.
  • Other couplant medium such as a liquid, grease, paste, or pliable solid maybe interposed between the transducer and the surface of the delay to permit transmission of ultrasonic energy between them.
  • the delay with the attached transducer, is pressed down into a stepped sleeve for installation through the enclosure wall.
  • Two o-rings are used on the outside of the delay; one is used in a groove for a pressure seal, the other is pinched between the sleeve step and the delay to act as a spring to allow some movement for focusing the direction of the ultrasound.
  • a bar is mounted above the array of delays inside the enclosure, and secured to the inside of the enclosure locking the delays into place. This bar holds the delays firmly in place and also allows each individual delay to move slightly to control the direction of the acoustic signal. This is accomplished using the four screws in the bar around the top of the delay, one for each quadrant of a delay.
  • the length of the delay is also a critical factor in the acoustics of the inspection system.
  • the delay length is selected such that echoes within the delay do not interfere with the measurements.
  • the length of the delay is adjusted so that internal echoes occur at a different location in time than the returning measurement signals. This calculation is a familiar exercise to all delay manufacturers and to others skilled in the art.
  • the present invention is based on echo ranging, by which the elapsed time between the transmission of ultrasonic energy from an ultrasonic transducer and the detection of ultrasonic echoes can be used to determine the distance of the reflecting surface to the ultrasonic transducer.
  • Such reflections occur at boundaries that define impedance mismatches between the liquid and another surface or object.
  • the ultrasonic signals allow the user to measure the wall thickness of storage tanks and to detect metal cracks, lack of weld fusion, or other abnormalities in the storage tank walls.
  • the tip of the delays can also be shaped to allow additional focusing of the acoustic signals.
  • transducers This is commonly done on transducers for different situations, and can be performed on the ends of the delays as well.
  • Highly corroded surfaces require tightly focused sound to compensate for the scattering of the sound, and a concave optical-like lens is commonly formed into the end of transducers to focus the sound into an intense point.
  • the delay tip can also be formed into a parabolic channel to focus the sound onto a line rather than a point, and many other combinations are possible.
  • various methods know in the art are available for enhancing the resolution in the imaging. These include modifying the acoustic lens and the pattern of the electrode of the piezoelectric transducer and curving the surface of the piezoelectric transducer itself to slenderize the transmitted ultrasonic beam. Further, an annular array sound field forming may be used in which the electrode is split into several parts to thereby cause applied energizing pulse voltages to have differences.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Acoustics & Sound (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

L'invention concerne un tableau de retards ultrasonores et un appareil permettant l'utilisation de transducteurs ultrasonores existants dans des environnements sujets à des explosions. Les transducteurs ont une surface frontale très fragile, qui est vulnérable aux détériorations de l'élément de haute tension et à son exposition. Les retards permettent aux transducteurs d'être montés au niveau supérieur du retard à l'intérieur d'une enceinte purifiée et pressurisée. Le retard fonctionne comme une barrière de sécurité pour l'environnement sujet à des explosions. Le tableau comprend un montage unique qui permet aux retards d'être focalisés de manière optimale.
PCT/US2000/007247 1999-03-18 2000-03-17 Retards ultrasonores utilises dans des environnements sujets a des explosions WO2000055594A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU55863/00A AU5586300A (en) 1999-03-18 2000-03-17 Ultrasonic delays for use in explosive environments

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US12521899A 1999-03-18 1999-03-18
US06/125,218 1999-03-18

Publications (2)

Publication Number Publication Date
WO2000055594A2 true WO2000055594A2 (fr) 2000-09-21
WO2000055594A3 WO2000055594A3 (fr) 2001-01-18

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PCT/US2000/007247 WO2000055594A2 (fr) 1999-03-18 2000-03-17 Retards ultrasonores utilises dans des environnements sujets a des explosions

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WO (1) WO2000055594A2 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011084143A1 (fr) * 2009-12-21 2011-07-14 Intrepid Robotics, Inc. Procédés d'inspection de réservoirs atmosphériques de stockage situés au sol ou dans des vaisseaux flottants
WO2015024646A1 (fr) * 2013-08-22 2015-02-26 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Dispositif et procédé permettant de surveiller par ultrasons un objet dans une zone protégée contre les explosions
NL2023144B1 (en) * 2019-05-15 2020-12-01 Intero Integrity Services Measurement device
US11181438B2 (en) 2017-12-15 2021-11-23 Tankbots, Inc. Methods for performing tasks in a tank containing hazardous substances
US11828731B2 (en) 2019-02-20 2023-11-28 Tankbots, Inc. Methods for performing tasks inherently safely in a tank containing hazardous substances

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4616152A (en) * 1983-11-09 1986-10-07 Matsushita Electric Industrial Co., Ltd. Piezoelectric ultrasonic probe using an epoxy resin and iron carbonyl acoustic matching layer
US4984449A (en) * 1989-07-03 1991-01-15 Caldwell System Corp. Ultrasonic liquid level monitoring system
US5819863A (en) * 1996-08-28 1998-10-13 Lockheed Martin Idaho Technologies Company Vehicle for carrying an object of interest

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4616152A (en) * 1983-11-09 1986-10-07 Matsushita Electric Industrial Co., Ltd. Piezoelectric ultrasonic probe using an epoxy resin and iron carbonyl acoustic matching layer
US4984449A (en) * 1989-07-03 1991-01-15 Caldwell System Corp. Ultrasonic liquid level monitoring system
US5819863A (en) * 1996-08-28 1998-10-13 Lockheed Martin Idaho Technologies Company Vehicle for carrying an object of interest

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011084143A1 (fr) * 2009-12-21 2011-07-14 Intrepid Robotics, Inc. Procédés d'inspection de réservoirs atmosphériques de stockage situés au sol ou dans des vaisseaux flottants
WO2015024646A1 (fr) * 2013-08-22 2015-02-26 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Dispositif et procédé permettant de surveiller par ultrasons un objet dans une zone protégée contre les explosions
US11181438B2 (en) 2017-12-15 2021-11-23 Tankbots, Inc. Methods for performing tasks in a tank containing hazardous substances
US11415566B2 (en) 2017-12-15 2022-08-16 Tankbots, Inc. Methods utilizing a tethered buoyant body to retrieve a mobile platform from a tank containing a hazardous substance
US11536705B2 (en) 2017-12-15 2022-12-27 Tankbots, Inc. Methods for controlling charge accumulation while operating a mobile platform immersed in a hazardous, non-conductive substance
US11604180B2 (en) 2017-12-15 2023-03-14 Tankbots, Inc. Voltage differential reduction methods used while retrieving a mobile platform from a tank containing a hazardous, non-conductive substance
US11828731B2 (en) 2019-02-20 2023-11-28 Tankbots, Inc. Methods for performing tasks inherently safely in a tank containing hazardous substances
NL2023144B1 (en) * 2019-05-15 2020-12-01 Intero Integrity Services Measurement device

Also Published As

Publication number Publication date
WO2000055594A3 (fr) 2001-01-18
AU5586300A (en) 2000-10-04

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