GB2188148A - Structural inspection device - Google Patents

Abstract

The device comprises an inspection (eg ultrasonic) transducer (14) mounted on a body (10) provided with three pointed members (16) for engagement with a test surface to ensure correct alignment of the transducer (14) with the surface. Electric circuit means may be included for checking correct engagement of the pointed members (16). <IMAGE>

Description

SPECIFICATION Structural inspection device This invention relates to a device for the inspection ofstructural members. It is particularly, but not exclusively, directed to the ultrasonic inspection of submerged structures such as those used in the offshore oil industry.

British Patent 2094977 shows a device for inspecting submerged members by ultrasonics. The device is based on the fact that, if there is a crack in the members, its interiorwill be flooded. An ultrasonic transducer is positioned spaced from the exterior of the member. If the member is free of defects, a singie echo is received from the adjacent wall, but if a crack is present and the member is flooded, a double echo from the adjacent and farwall is received.

This known device relies on a relatively intricate mechanism to align the ultrasonictransducer accurately with the surface of the member. This mechanism not only increases the cost and complexity and reduces the reliability of the device, but also it makes the operation ofthe device difficult for a diver and virtually impossible with a remotely-operated vehicle (ROV). It may also be necessary when using this prior art device to scrape the test site free of marine growth.

An object of the present invention is to overcome or mitigate these disadvantages.

Accordingly the present invention provides an inspection device for application to a surface of a structural member, comprising a main body and an inspection transducer mounted at the front ofthe main body, and in which the transducer is aligned with said surface by means of three or more elongate pointed members extending from the main body forwardly of the transducer.

Three such elongate members are preferred; this enables the transducer to be aligned automatically in the correct orientation to a flat or curved surface.

However, where a surface with a sharp convex curvature isto be inspected, it may be necessary to providefourelongate members.

Preferably also, the device includes electrical means for indicating correct positioning, comprising means for applying a current two one of said elongate members and means for detecting current flow in the other elongate members.

An embodimentofthe invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of a device in accordance with the invention; and Figure2 is an underneath plan view of the device of Figure 1.

The device comprises a main body 10 in theform of a small pressure housing, with a handle 1 2.An ultrasonic transducer 14 of known type is mounted on the body 10. Arranged in a triangle around the transducer 14 are three sharp-pointed contact members 16; these may suitably be provided with interchangeable hardened tips.

The body 10 contains the necessary electronics for the transducer 14 and electronics to be described for checking correct orientation of the device. These are connected to a surface power supply and display via a cable (not shown) exiting via a watertight cable connector 18.

In use, the device is applied by being firmly pushed against the surface of a structureto be inspected, either manually or by the robotic arm of an ROV. The sharp points of the contact members 1 6 enable them to penetratea certain amountof marinegrowth and/or paint and make electrical contact with the metal underneath. The electronics within the housing 10 includes a sourcefor passing a small electrical current into the structure via one of the contact members 10, and a detectorfor sensing this currentvia both of the other contact members 1 stro transmit a signal indicating to the operatorthat correct contact has been made. In this condition, the transducer is correctly aligned for optimum operation.If one ofthe members 16 is not properly in contact, no signal passes to the operator, who then knows that the display from the transducer is not reliable.

In the above embodiment,the transducer 14 is prefereably an ultrasonic transducer for determining whether or not an underwater structure is flooded.

However, the invention could equally be used with othertransducers whose orientation to the test piece is important eg eddy current or electromagnetic probes.

Athree-point device is suitable for most applications, but where the test structure has a diameter which is small in relation to the device it may be necessary to use four points.

In certain applications, the contact members may be positioned and dimensioned to bring the transducer into contact with a test surface of a specified curvature, ratherthan being spaced from it as described above.

Although, as described above, the device ofthe present invention can deal with a certain amount of marine growth, scraping of the test site may still be required if the growth is heavy.

1. An inspection device for application to a surface of a structural member, comprising a main body and an inspection transducer mounted at the front ofthe main body, and in which thetransducer is aligned with said surface by means ofthree or more elongate pointed members extending from the main bodyforwardly ofthetransducer.

2. The device claim 1, includingthreesaid elongate members.

3. The device ofclaim 1,includingfoursaid elongate members.

4. The device of any preceding claim including electrical means for indicating correct positioning, comprising meansforapplying acurrentto one of said elongate members and means for detecting current flow in the other elongate members.

5. The device of any preceding claim, in which the inspection transducer is an ultrasonic transducer.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Structural inspection device This invention relates to a device for the inspection ofstructural members. It is particularly, but not exclusively, directed to the ultrasonic inspection of submerged structures such as those used in the offshore oil industry. British Patent 2094977 shows a device for inspecting submerged members by ultrasonics. The device is based on the fact that, if there is a crack in the members, its interiorwill be flooded. An ultrasonic transducer is positioned spaced from the exterior of the member. If the member is free of defects, a singie echo is received from the adjacent wall, but if a crack is present and the member is flooded, a double echo from the adjacent and farwall is received. This known device relies on a relatively intricate mechanism to align the ultrasonictransducer accurately with the surface of the member. This mechanism not only increases the cost and complexity and reduces the reliability of the device, but also it makes the operation ofthe device difficult for a diver and virtually impossible with a remotely-operated vehicle (ROV). It may also be necessary when using this prior art device to scrape the test site free of marine growth. An object of the present invention is to overcome or mitigate these disadvantages. Accordingly the present invention provides an inspection device for application to a surface of a structural member, comprising a main body and an inspection transducer mounted at the front ofthe main body, and in which the transducer is aligned with said surface by means of three or more elongate pointed members extending from the main body forwardly of the transducer. Three such elongate members are preferred; this enables the transducer to be aligned automatically in the correct orientation to a flat or curved surface. However, where a surface with a sharp convex curvature isto be inspected, it may be necessary to providefourelongate members. Preferably also, the device includes electrical means for indicating correct positioning, comprising means for applying a current two one of said elongate members and means for detecting current flow in the other elongate members. An embodimentofthe invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of a device in accordance with the invention; and Figure2 is an underneath plan view of the device of Figure 1. The device comprises a main body 10 in theform of a small pressure housing, with a handle 1 2.An ultrasonic transducer 14 of known type is mounted on the body 10. Arranged in a triangle around the transducer 14 are three sharp-pointed contact members 16; these may suitably be provided with interchangeable hardened tips. The body 10 contains the necessary electronics for the transducer 14 and electronics to be described for checking correct orientation of the device. These are connected to a surface power supply and display via a cable (not shown) exiting via a watertight cable connector 18. In use, the device is applied by being firmly pushed against the surface of a structureto be inspected, either manually or by the robotic arm of an ROV. The sharp points of the contact members 1 6 enable them to penetratea certain amountof marinegrowth and/or paint and make electrical contact with the metal underneath. The electronics within the housing 10 includes a sourcefor passing a small electrical current into the structure via one of the contact members 10, and a detectorfor sensing this currentvia both of the other contact members 1 stro transmit a signal indicating to the operatorthat correct contact has been made. In this condition, the transducer is correctly aligned for optimum operation.If one ofthe members 16 is not properly in contact, no signal passes to the operator, who then knows that the display from the transducer is not reliable. In the above embodiment,the transducer 14 is prefereably an ultrasonic transducer for determining whether or not an underwater structure is flooded. However, the invention could equally be used with othertransducers whose orientation to the test piece is important eg eddy current or electromagnetic probes. Athree-point device is suitable for most applications, but where the test structure has a diameter which is small in relation to the device it may be necessary to use four points. In certain applications, the contact members may be positioned and dimensioned to bring the transducer into contact with a test surface of a specified curvature, ratherthan being spaced from it as described above. Although, as described above, the device ofthe present invention can deal with a certain amount of marine growth, scraping of the test site may still be required if the growth is heavy. CLAIMS

1. An inspection device for application to a surface of a structural member, comprising a main body and an inspection transducer mounted at the front ofthe main body, and in which thetransducer is aligned with said surface by means ofthree or more elongate pointed members extending from the main bodyforwardly ofthetransducer.

2. The device claim 1, includingthreesaid elongate members.

3. The device ofclaim 1,includingfoursaid elongate members.

4. The device of any preceding claim including electrical means for indicating correct positioning, comprising meansforapplying acurrentto one of said elongate members and means for detecting current flow in the other elongate members.

5. The device of any preceding claim, in which the inspection transducer is an ultrasonic transducer.

6. An inspection device substantially as herein described with reference to and as illustrated in the drawings.