NL2023144B1

NL2023144B1 - Measurement device

Info

Publication number: NL2023144B1
Application number: NL2023144A
Authority: NL
Inventors: André Ferreira Gonçalves João; Antonius Johannes Jacobs Gerardus; Hendricus Franciscus Van Schaik Johannes
Original assignee: Intero Integrity Services
Priority date: 2019-05-15
Filing date: 2019-05-15
Publication date: 2020-12-01

Abstract

Measurement device comprising an enclosure (15), wherein the enclosure (15) supports at least one transducer (2), and the at least one transducer (2) is housed within the enclosure (15) so as to shield the at least one transducer (2) from the environment which is external of the measurement de— vice. The enclosure (15) comprises a window (3) which is sub— stantially transparent for ultrasound waves, and is preferably made of polymethylpentene (PMP).

Description

Measurement device The invention relates to a measurement device com- prising an enclosure, wherein the enclosure supports at least one transducer. WoO00/55594 discloses an apparatus for measuring the wall thickness of storage tanks and for detecting abnormali- ties therein, comprising an uitrascnic probe, said ultrasonic probe having an ultrasonic transducer; and a protective delay in which the ultrasonic transducer of the probe is enclosed. The delay is a plastic part, non-sparking, and chemically re- io sistant, which channels ultrasonic sound through the enclosure wall and into the fluid outside. With regard to the measurement device according to the preamble, reference is further made to US 5,819,863; WOO0/ 73739 and to EP 0 635 719, In the measurement device according to the preamble, the at least one transducer is usually an ultrascnic transduc- er for wall thickness measurement, but it can also be a sonar transducer or a pinger which can be used for localization of the measurement device. To avoid unnecessary and lengthy repe- tition, the following disclosure concentrates on the transduc- er being an ultrasonic (immersion) transducer. The invention is however also applicable to other types of acoustic trans- ducers.

Such an instrument is generally known in the field of Non-destructive Testing. The ultrasonic non-destructive test- ing method is a widely used fechnigue in thickness gaging ap- plications that permit reliable measurement of thickness. With this kind of inspection the reflections of the ultrasonic sig- nal are used to derive the wall thickness of a test specimen, To this end, the transmitted sound waves are produced perpen- dicular to the test specimen, For the thickness measurement ultrasonic immersion search units are applied, also known as transducers, which operate with central frequencies in the range of 0.5 to 10 MHz.

With reference to figure 1 a measurement device em- bodied as a robot is shown, which is intended to be used in an industrial installation e.g. an Aboveground Storage Tank as shown in the figure. During the measurements the aboveground storage tank remains in service. These tanks typically contain chemicals or hydrocarbon fluids that may degrade materials (due to chemical reaction), specifically non-metallic materi- als that are used in the equipment for Non-destructive Test- ing. Furthermore these chemicals and hydro-carbons can create a potentially explosive atmosphere, The invention is aimed to provide a measurement de- vice capable to withstand these challenging operational condi- tions and to avoid ignition of potentially explosive atmos- pheres.

For this purpose and according to the invention a measurement device is proposed having the features of one or more of the appended claims.

According to the invention wherein the enclosure of the measurement device supports at least one transducer that is housed within the enclosure so as to shield the at least one transducer from the environment which is external of the measurement device, and wherein the enclosure comprises a win- dow which is substantially transparent for ultrasound waves.

Between the at least one transducer and the window, enabling the transmission and reception of acoustic signals, an oil chamber is provided that connects with an cil filled piston cylinder for pressurizing and balancing the pressure. The oil chamber is preferably filled with a mineral insulating oil which shields the transducer{s) from: external impacts; chemi- cal reactions with the inspection medium; and, prevents the transducer {s) from acting as an ignition source. The measure- ment device of the invention is thus suitable for use in po- tentially explosive atmospheres, fulfilling the ATEX114 equip- ment directive 2014/34/EC reguirements. It goes without saving that there can be multiple (types of) transducers comprised in the enclosure, such as an array of transducers.

Suitably the at least one transducer is housed within a transducer housing that forms part of the enclosure.

Preferably the window is made of polymethylipentene (PMP). This material has suitable properties for ultrasound propagation.

Preferably the window has a minimum thickness of 3 mm and a maximum thickness of 7,27 mm over a length of 15 mm an- 40 gled at 15,87". The distance of the transducer tc the window is preferably 10 mm, It is further preferred that the at least one (ultra- sonic} transducer is oriented so that the transmitted sound waves have an incident angle of 10° to the (preferably Folymethylpentene -PMP) window, while the normal to the re- ferred interface of the window is angled 15,87" with respect to the longitudinal direction of sound waves produced towards the external test object. This supports that it is possible to produce perpendicular refracted, i.e. zero degrees, longitudi- nal waves in a test medium outside of the device and inde- pendently of the scund velccity of this medium, It further avoids internal unwanted reverberation signals that occur when an uitrasound beam encounters an interface and part of the signal is reflected. The angled design of the window reduces internal reverberations and Therefore the thickness of the window material does not have to be related to the thickness nf the object of measuring. The angled interface design offer advantages over the parallel interfaces used on most pricr art delay line designs. This enables that the inspection can be made on a wide thickness range of test specimens without need to replace the enclosure window.

Ancther desirable aspect of the invention is that the oil chamber is in gas communication with a gas chamber com- prised in the enclosure. This gas chamber is instrumental in 2E promoting the explosion resistant properties of the measure- ment device of the invention, particularly by arranging that the gas chamber connects with pressurization valves which are usable for purging the gas chamber (to drive out oxygen) and filling it with an inert gas such as nitrogen.

Suitably a printed circuit board for controlling the operation of the device is housed in the gas chamber.

Other notable features are mentioned hereafter.

One such a notable feature is that at the outer sur- face of the enclosure a protective grid is provided adjacent to the window. This protective grid protects the measurement device of the invention against the impact of external ob- jects, and prevents that a static energy imbalance will be generated in the window.

A further desirable feature is that a support plate 40 with apertures maintains the at least one transducer or the array of transducers in the transducer housing forming part of the enclosure, Suitably further the transducer housing is separable from the remainder of the enclosure, providing easy access to the transducer {s} and window for maintenance purposes.

The invention will hereinafter be further elucidated with reference to a drawing cf a non-limiting exemplary embod- iment of the ultrasound measurement device and its use in ac- cordance with the invention.

In the drawing: ~figure 1 shows a measurement device of the invention as applied in an above ground storage tank; figure 2 shows an embodiment of an ultrasound meas- urement device according toe the invention in an exploded view; "figure 3 shows the ultrasound measurement device of figure 2 in a cross-sectional view; figure 4 shows the ultrasound measurement device of figure 2 in a further cross-sectional view which is perpendic- ular to the view of figure 3; and figure 5 shows a detail of the refraction angles that apply to the window of the device.

Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

As mentioned above, figure 1 shows a measurement de- vice of the invention in operation. As better shown in figures 2 — 4, the device comprises an enclosure 15, which supports at least one transducer 2, wherein the at least one transducer 2 is housed within the enclosure 15 so as to shield the at least one transducer 2 from the environment which is external of the measurement device, Part of the enclosure 15 is a transducer housing 3 which actually contains the transducer 2 or array of transduc- ers. In this example the transducers) is/are for transmitting and receiving ultra-sound waves. The transducer housing S fur- ther contains an oil chamber 7 for a coupling medium between the transducer (s) 2 and an interface window 3. A preferably stainless steel protective grid 6 at the exterior of the transducer housing 9 protects against possible impacts and prevents static energy imbalance from being generated in the window 3. Furthermore, the oil chamber 7 prevents the trans- ducer (s} 2 from becoming an ignition source, which could re- sult in hazardous and explosive situations.

Through the window 3 in the enclosure 15 the ultra- sound waves from the transducer{s} 2 are directed to an object of measuring outside of the enclosure 15. This object of meas- uring may be a plate whose thickness and possible irregulari- ties have to be detected and evaluated, The window 3 is ar- ranged such that a desired refraction is produced. Both the ultra-sound waves leaving the transducer housing 9 via the window 3, and the waves reflected by the object of measuring {not shown) will be free from internal window reverberations, i.e. reflections due to the construction and placement of the window 3. The geometry of this window 3 is angled in such a i5 way that internal reflected waves are directed away from the transducer {s) 2 thus minimizing internal reverberations which could otherwise have an unfavourable influence on the measure- ments. Preferably therefore the at least one (ultrascnic) transducer is oriented so that the transmitted sound waves have an incident angle of 10° to the window, while the normal to the referred interface of the window is angled 15,87" with respect to the longitudinal direction of sound waves produced towards the external test object.

The window 3 of the measurement device of the inven- tion is preferably made from a material that exhibits low ap- parent attenuation in the transducer frequency range. A pre- ferred material is Polymethylpentene (PMP).

The voltages, currents and/or power applied to an electronics printed circuit board 14 that is placed inside the gas chamber 8, and that is applied to the transducer 2 or ar- ray of transducers may exnceed the specified limits for intrin- sic safety and could therefore present a potential source of ignition when exposed to a potentially explosive atmosphere, The design of the ultrasonic measurement device of the inven- tion separates the printed circuit board 1d and the transducer 2 or transducer array from the exterior environment by means of a hermetically sealed enclosure 15 which is partially filled with an inert gas, preferably Nitrogen, in gas chamber 8 and partially filled with an inert oil in oil chamber 7.

G The integrity of the enclosure 15 is continuously monitored by redundant, intrinsically safe, pressure monitor- ing devices, i.e. pressure sensor 11 and pressure switch 10, which in themselves do nct present a potential source of igni- tion in case the integrity of the enclosure 15 is compromised. The oil chamber 7 for the coupling medium between the transducer (s) 2 and the interface window 3 is filled with oil. During the filling process all air is removed from oil chamber 7, and piston 13 is secured in its bottom position in cylinder

12. Once the oil chamber 7 is completely filled, piston 13 is released. An additional volume of oil is then added to oil chamber 7 to ensure that piston 13 is located at a predefined distance from the bottom of cylinder 12. Once the oil chamber 7 is completely filled with oil and piston 13 is in the de- i5 sired position, gas chamber § is purged and pressurized with an inert gas, e.g. Nitrogen. The static positive pressure in gas chamber 8 is transferred to oil chamber 7 via piston 13 and monitored by pressure sensor 11 and pressure switch 10. Exposure of the ultrasonic measurement device 1 to an environ- ment with a lower ambient temperature results in : Gas chamber 8 . temperature decrease of the inert gas 25 . pressure decrease of the inert gas Oil chamber 7 s temperature decrease of the oil : thermal contraction of the oil . piston 13 descends to the bottom of the cylinder 12 ® pressure decrease of the oil - is related to the pressure of the Gas - Same pressure Exposure of the uitrasonic measurement device 1 to an environ- ment with a higher ambient temperature results in : Gas chamber 8 s temperature increase of the inert gas . pressure increase of the inert gas

Cil chamber 7 ® Temperature increase of the oil . thermal expansion of the cil 5 . piston 13 ascends towards the top of the cylinder 12 e pressure increase of the oil - is related to the pressure cf the Gas — Same pressure The pressure that is monitored by pressure sensor 11 and pressure switch 10 represents the pressure in oil chamber 7 as well as in gas chamber 3, under the condition that move- ment of piston 13 is not restricted. The design cf the device of the invention ensures that neither the minimum piston posi- tion (i.e. at the bottom of cylinder 12} nor the maximum pis- ton position (i.e. at the top of cylinder 12) is achieved over the specified operating temperature range of the ultrasonic measurement device.

In case, due to some unforeseen failure, the static overpressure inside either oil chamber 7 or gas chamber 8 can- not be maintained and pressure sensor 11 and/or pressure switch 10 indicate loss of pressure, circuitry (not shown) that connects to pressure sensor 11 and/or pressure switch 10 provides for an automatic shutdown of the electric power Lo the ultrasonic measurement device once the static pressure as monitored with the pressure sensor 11 and/or pressure switch 10 drops below a predefined threshold value.

Aithough the invention has been discussed in the foregoing with reference to an exemplary embodiment of the ul- trasonic measurement device of the invention, the invention is not restricted to this particular embodiment which can be var- ied in many ways without departing from the invention. The discussed exemplary embodiment shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary the embodiment is merely intended to explain the wording of the appended claims without intent to limit the claims to this exemplary embodiment. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using this exem-

q plary embodiment. Aspects of the inventicn are itemized in the following sec- tion,

1. Measurement device comprising an enclosure (15), wherein the enclosure {15} supports at least one transducer {2}, that is housed within the enclosure (15} so as to shield the at least one transducer {2} from the environment which is external of the measurement device, wherein the enclosure {15) comprises a window (3) which is substantially transparent for ultrasound waves, characterized in that between the at least cne transducer (2) and the window (3) an oil chamber (7) is provided, which oil chamber {7) connects with an oil filled piston-cylinder (12, 13) combination for pressurizing the oil chamber (7).

2. Measurement device according to claim 1, charac- terized in that the at least one transducer {2} is housed within a transducer housing {9} that forms part of the enclo- sure (15).

3. Measurement device according to claim 1 or Z, characterized in that the window (3} is made of polymethyipen- tene (PMP), 4, Measurement device according to any one of claims 1 — 3, characterized in that the at least cone transducer (2) is oriented so that sound waves transmitted by the at least one transducer (2) have an incident angle of about 10° to the window (3), and a normal toc a referred interface of the window (3) is angled 15,87" with respect to a longitudinal direction of the sald sound waves.

5. Measurement device according to any cone of claims 1 —- 4, characterized in that the oil chamber (7) is in gas communication with a gas chamber (8) comprised in the enclo- sure (15).

6. Measurement device according te claim 5, charac- terized in that the gas chamber {8} connects with pressuriza- tion valves {5) which are usable for purging the gas chamber {7) and filling it with an inert gas, preferably nitrogen.

7. Measurement device according to claim 5 cr claim 6, characterized in that the gas chamber {8} is provided with at least one pressure monitoring device (10, 11).

8. Measurement device according to claim 7, charac- terized in that the at least one pressure monitoring device (10, 11} connects to circuitry that is equipped to provide an automatic shutdown of electric power to the device once a static pressure monitored by the at least one pressure moni- toring device (10, 11} drops below a predefined threshold val- us,

9. Measurement device according to any one of claims 5 — 8, characterized in that a printed circuit board (14) for controlling the operation of the device is housed in the gas chamber (8).

10. Measurement device according to any one of claims 2 — 3, characterized in that at the outer surface cf the en- closure {15} a protective grid (&) is provided adjacent to the window {3}.

11. Measurement device according to any one of claims 2 — 10, characterized in that a support plate (4) with aper- tures maintains the at least one transducer (2) in the trans- ducer housing {9} forming part of the enclosure (13).

12. Measurement device according to claim 11, charac- terized in that the transducer housing (8) is separable from the remainder of the enclosure (15).

Claims

CONCLUSIONS

Measuring device comprising a housing {15}, the housing (15) supporting at least one transducer {2}, which is housed within the housing (15) in order to shield the at least one transducer (2) from the environment. screens located outside the measuring device, the housing (15) having a window (3) which is substantially transparent to ultrasound waves, characterized in that between the at least one transducer (2} and the window (3) an oil chamber {7) is provided, which oil chamber {7} connects to an oil-filled piston-cylinder (12, 13) combination for pressurizing the oil chamber (7).

Measuring device according to claim 1, characterized in that the at least one transducer (£} is housed in a transducer housing (9) which forms part of the housing {15}.

Measuring device according to claim 1 or 2, characterized in that the window (3) is made of polymethylpene (PMP).

Measuring device according to any one of claims 1 - 3, characterized in that the at least one transducer {2} is oriented such that sound waves emitted by the at least one transducer {2} have an angle of incidence of approximately 10 ° to the window {3}, and a normal to a reference interface of the window (3) has an angle of 15.87 ° with respect to a longitudinal direction of the sound waves.

Measuring device according to any one of claims 1 to 4, characterized in that the oil chamber {7} is in gas communication with a gas chamber (3) located in the housing (12).

Measuring device according to claim 5, characterized in that the gas chamber (8) is connected to pressure control valves {5) which can be used for flushing the gas chamber (7) and filling it with an inert gas, preferably nitrogen.

Measuring device according to claim 5 or 6, characterized in that the gas chamber (8) is provided with at least one pressure measuring device (10, 11).

8. Measuring device according to claim 7, characterized in that the at least one pressure measuring device {10, 11} is connected to a circuit which is arranged to provide an automatic switch-off of electrical power to the device when a static pressure rises. monitored by the at least one pressure measuring device (10, 11) drops below a predefined threshold value,

Measuring device according to any one of claims 5 - B, characterized in that a printed circuit board {14} for controlling the operation of the device is housed in the gas chamber (8).

Measuring device according to any one of claims 2 to 9, characterized in that a protective grid (6) adjacent to the window (3) ib is provided on the outer surface of the housing {15}.

Measuring device according to any one of claims 2 to 10, characterized in that a support plate (4) with openings holds the at least one transducer (2) in the transducer housing (9) forming part of the housing (15).

Measuring device according to claim 11, characterized in that the transducer housing (8) is separable from the rest of the housing (15).