FIELD OF INVENTION

[001] The invention relates to a reference block that can be used to perform Time of Flight Diffraction (TOFD) inspection for curved structure including pipes and shells. In particular, the invention relates to reference block that can be used to determine the dead zone of a TOFD probe while inspecting longitudinal welds present in pipes. The reference block can also be employed to determine the depth of coverage of TOFD probe set up.
BACKGROUND/PRIOR ART OF THE INVENTION
[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[003] Non Destructive testing is an important stage for any industry where quality of the product is ensured at final stage of the product. Ultrasonic testing is a significant testing process which is implemented extensively in medical and in industrial scenario. The field of ultrasonic testing is significantly growing. Time of flight diffraction technique is one of the advancement of ultrasonic testing technique in which diffraction of ultrasound is used to detect and size the defect. TOFD probes differ from conventional UT probes by its highly damped characteristics and small diameter crystal. High damping is made in these probes to have good resolution and to have better accuracy in sizing the defect. The dead zone present in TOFD while inspecting flat surface is due to the ringing time of the receiver probe only. Whereas in case of curved surface the dead zone is increased, because of straight travel path of the beam which is not close to the surface. The dead zone varies by the probe center separation (PCS). The beam from the transmitter follows a straight path to reach the receiver thereby missing some region close to the surface.
[004] Reference may be made to the following prior arts: -
[005] US8746069: It claims a device that can be used to set the equipment sensitivity for Time of Flight Diffraction inspection. This block consists of EDM notches that represent reheat cracks and they are used to set and confirm the detectability of defect using ToFD technique.
[006] CN 203595688U: It provides a T shaped welded block used to check the instrument settings during T shaped welded component. This block can be used to set the sensitivity level of inspection for T joints
[007] However, none of the above can fulfill the requirements of the present invention, for which it is designed.
OBJECTS OF THE INVENTION
[008] The object of the invention is to provide reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers which is simple in construction.
[009] Another object of the invention is to propose reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers which can be used to assess the dead zone of a TOFD setup while inspecting the curved surface.
[010] Still another object of the invention is to propose reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers that supports the operator in selecting a proper PCS distance with less dead zone.
[011] Yet another object of the invention is to propose reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers that can be used to determine the coverage of TOFD setup for a given PCS.
[012] Still further object of the invention is to propose reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers which can be used to measure far surface resolution capability of the probe.
[013] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY OF THE INVENTION
[014] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.
[015] According to this invention, there is provided reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers comprising a block having two notches and three side drilled holes, wherein depth of the notch varies along the longitudinal direction from edge of the pipe towards middle of pipe section and the side drilled holes are provided to determine coverage of the TOFD probe.
[016] The depth at the edge of the pipe is more, which decreases along the length towards the middle section of the pipe.
[017] One notch is provided at the outer diameter surface and another notch is placed in the inner diameter surface of the block.
[018] The depth of the side drilled holes are selected according to the number of zones divided for inspection.
[019] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
[020] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[021] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[022] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein: -
FIG. 1 shows: The front view of the reference block of present invention.
FIG. 2 shows: The side view of the reference block according to present invention.
FIG. 3 shows: The rear view of the reference block in accordance with present invention.
FIG. 4 shows: Cross isometric view of the reference block of invention.
FIG. 5 shows: TOFD set up with increased dead zone.
FIG. 6 shows: TOFD set up with comparatively less dead zone.
[023] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS OF PREFERRED EMBODIMENTS
[024] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[025] Time of Flight Diffraction (TOFD) technique is an advanced ultrasonic testing technique where defects present in components are detected by the principle of diffraction. It differs from conventional ultrasonic testing which uses the principle of reflection.
[026] In TOFD technique two probes are used in pitch catch configuration i.e. Transmitter on one side and receiver on other side of the weld. The time taken by sound to travel and reach the receiver is different when the path changes. Lateral wave is the first wave that travels beneath the top surface and reaches the receiver in short travel path and in less time. Any surface defects present in the surface blocks the wave and gets detected. Ultrasonic wave gets diffracted as it reaches the defect and the diffracted wave reaches the receiver with increased transit time compared with the lateral wave. The time of flight gives the information about the depth of the defect.
[027] In flat surface, the lateral wave travels just beneath the surface but in curved components like pipes and boiler headers, they travel in a straight line along the chord that connects the probe index. This causes a dead zone in the pipe and the portion of pipe above this lateral wave path remains undetected. This dead zone increases as the PCS increases. There is no standard block or procedure available in the market to determine this dead zone. Hence, the invention introduces a reference block which can be used to determine the depth of dead zone practically for a given probe PCS. The volume for coverage of a given TOFD set up can also be determined by using the block of present invention.
[028] Now, reference may be made to figure 1-4 indicating reference block of instant invention.
[029] The block comprises of two notches (N1, N2) of varying depth and three side drilled holes (D1, D2, D3) present at different depth of the block. The depth of the notch varies along the longitudinal direction from edge of the pipe towards the middle of pipe section. The depth at the edge of the pipe is more and it decreases along the length towards the middle section of the pipe. One notch (N1) is present at the outer diameter surface and another notch (N2) is present in the inner diameter surface. The block is having three side drilled holes which can be used to determine the coverage of the TOFD probe. The depth of the side drilled holes are selected depending on the number of zones divided for inspection.
[030] The notch is scanned with TOFD set up, lateral wave travels straight along the chord connecting the probe. The region above the lateral wave path remains uninspected. When the OD notch is scanned with TOFD probe pair, the lateral wave is straight till the region where the wave gets disturbed by notch. After this point the lateral wave bends according to the depth of the notch at that point. The point at which the lateral wave bends is determined to practically measure the depth of the dead zone.
Application of present invention
- To evaluate the dead zone of the TOFD probe.
- To determine and select proper PCS with acceptable dead zone.
- To evaluate the volume of coverage for a given PCS.
- For the number of zones required to cover a given weld volume in case of a thicker component.
[031] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[032] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
[033] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.
[034] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[036] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[037] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims:

Reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers comprising a block having two notches (N1, N2) and three side drilled holes (D1, D2, D3), wherein depth of the notch varies along the longitudinal direction from edge of the pipe towards middle of pipe section and the side drilled holes (D1-D3) are provided to determine coverage of the TOFD probe.
2. Reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers as claimed in claim 1, wherein the depth at the edge of the pipe is more, which decreases along the length towards the middle section of the pipe.
3. Reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers as claimed in claim 1 or 2, wherein one notch (N1) is provided at the outer diameter surface and another notch (N2) is placed in the inner diameter surface of the block.
4. Reference block to determine the dead zone and volume of coverage for TOFD inspection in pipes and headers as claimed in claim 1-3, wherein the depth of the side drilled holes (D1-D3) are selected according to the number of zones divided for inspection. ,