Patent Description:
The invention further relates to methods for installation of a thermocouple assembly.

Sheathed thermocouple (TC) sensor cables are known in the prior art for their accuracy and fast response time in temperature measurement applications. They are therefore often used for temperature measurement in industrial processes. Such sensor cables typically comprise at least two conductors of different material, which extend along the length of the cable. The conductors are embedded in an electrical insulation material, typically a mineral powder insulation. The conductors and insulation are enclosed by a metal sheath. Because of the mineral insulation material, such sheathed thermocouple sensor cables are sometimes also referred to as mineral insulated (MI) cables. The distal ends of these conductors are joined at a location close to or directly at a closed distal end of the sensor cable sheath, thereby forming a thermocouple junction.

When thermocouple sensors are used to measure the temperature at the surface of tubes, pipes or conduits or flat surfaces of objects inside of a furnace, reactor or the like, the thermocouple is exposed to extreme heat and/or other harsh environmental influences. To protect the sensor, it is known in the prior art to protect such tube skin thermocouples (TSTC) with a thermal insulation material and a shielding. The thermocouple assembly including the sheath gets exposed to high temperature in installations inside or outside the heater; in those cases the purpose of the shield and the insulation is to secure the measuring junction at a specified location on the tube and also to act as a composite medium to distribute the heat between a hot and a cold side to read the actual tube skin temperature at the thermocouple junction in a repeatable manner. There may be certain applications where the measuring junction is hotter than the environment, for example cases where the assembly is attached to a hot tube in a cold atmosphere and where the functionality of the shield and insulation may be to prevent heat loss along with other functionality discussed above.

The installation process for such designs, as widely accepted in the industry, requires two steps: In a first step, the thermocouple sensor cable is connected to the desired measurement point with a so called weld pad. The weld pad is attached to the surface of the tube or object to be measured by welding. The thermocouple sensor cable may be integrally formed with the weld pad or may be detachably mountable to the weld pad. In a second step, the insulation material is placed upon the thermocouple sensor cable; sensor and insulation are covered by a metal shielding which is fixed to the surface by a second welding process.

This two-step process has some disadvantages, because mistakes during the installation are likely to result in reduced measurement accuracy, and temperature reading offset. Also, in certain cases, while measurement accuracy is initially achieved, poor installation methods can also result in degraded readings over time.

<CIT> describes a temperature sensing assembly for measuring temperature of a surface of a structure. The temperature sensing assembly comprises a thermocouple device having a pair of conductors of dissimilar materials disposed within an elongate sheath. The pair of conductors joined at a junction point to measure the temperature of a surface of a structure at a desired location. The temperature sensing assembly further comprises a docking device having a bottom surface to attach to the surface of the structure adjacent the desired location and a top surface having a recessed portion to receive the thermocouple device and to position the junction point adjacent the surface of the structure at the desired location. The thermocouple device further comprises a mounting pad attached to the elongate sheath, the mounting pad removably couplable with the docking device to maintain the thermocouple device in the recessed portion. Further the thermocouple device comprises a heat shield removably attachable to the docking device to shield the junction point from heat from thermal sources other than the surface of the structure. The temperature sensing assembly is closely coupled thermally to the surface of a tube and is shielded from heat from thermal sources other than the surface of the tube. The mounting pad is attached to the top surface docking device by welding the pad. The docking device is positioned on the tube by attaching a bottom surface of the device to the surface of the tube by welding. The heat shield is placed over a portion of the sheath and is attached to the surface of the tube at attachment points by welding.

<CIT> describes a mounting structure of a sheathed thermocouple. A pad is formed with an insertion groove part and a locking groove part, and a sheathed thermocouple is formed with a recessed groove extending in a circumferential direction. The locking grove part is constituted of an inwardly expanding groove formed with a relatively wide groove part externally opened in a radial direction and a relatively narrow groove part. A comingoff prevention member is mounted via an externally opened site of the locking groove part on the internal sheathed thermocouple is abutted to an inner wall surface such that the sheathed thermocouple is prevented from moving to an axial direction base side.

<CIT> describes a structure for mounting a thermocouple on a heat transfer tube. The structure includes a pad welded to the outer peripheral surface of the tube and having a notch into which the temperature measuring portion of the thermocouple can be inserted and abutted along the bus line of the tube. The pad has a pressure means for holding the temperature measuring portion in place on the outer peripheral surface of the tube. Block retaining walls that are undercut coupled to a retaining block like a sliding pair are formed on both sides of the notch of the pad, so that with the temperature measuring portion of the thermocouple inserted into the notch, the pressure means knocks the retaining block in between the block retaining walls.

The objects of the invention are therefore directed towards improving a structure, comprising a thermocouple sensor with an improved design by reducing susceptibility to errors of the installation process and improve measuring characteristics of a thermocouple sensor assembly.

The objects of the invention are achieved by a structure, comprising a thermocouple assembly for temperature measurement on or at the surface of the structure, the thermocouple assembly comprises.

wherein the positioning pad is mechanically connected to the shielding, i.e. at least the shielding and the positioning pad are rigidly connected or connectable to each other, or are made in a one-piece design. The shielding is connected by one welding to the surface of the structure and a recessed portion of the shielding, corresponding to the shape and size of a protruding portion of the positioning pad and receiving the protruding portion therein, is covered and sealed by the welding.

The mechanical connection of shielding and positioning pad provides numerous advantages:
Installation of the thermocouple sensor assembly is significantly simplified, in comparison with state-of-the-art assemblies with a shielding and separate weld pad. The shielding and mechanically connected positioning pad may be fixed to the structure in one step by one single welding process. Therefore, installation time and costs are significantly reduced, especially, because after the one and only welding process, also only one inspection of the welding area is required.

Furthermore, as the positioning pad receives and/or secures the closed thermocouple sensor cable end, i.e. the sensitive measuring tip (also referred to as the distal end or closed end of the sheathed thermocouple sensor cable), in a defined location, the thermocouple sensor cable end is also positioned in a defined location relative to the shielding. Especially, the thermocouple sensor cable end might be positioned along a central longitudinal axis of the shielding. Non-central positioning of the sensor end, as it can easily occur with lack of caution during the two-step installation process of state-of-the-art thermocouple sensor assemblies, is effectively prevented. This may increase repeatability, long-term stability and accuracy of the measurement.

To receive the sensor cable end at a desired measuring point, in an exemplary embodiment of the thermocouple assembly, the positioning pad comprises a receiving means, which may be formed by a slot or a recess corresponding to the shape and size of the sensor cable end, to receive the thermocouple sensor cable end therein. The sensor cable end may be withdrawable from said receiving means. In such an embodiment, the sheathed thermocouple sensor cable may be fixed to the structure, after the insertion of the sensor cable into the shielding and the receiving means of the positioning pad, by other means, e.g. by a positioning tube clip that is welded to the structure. Such an arrangement allows an easy replacement of the sheathed thermocouple sensor cable without the need to remove the shielding from the structure.

To secure the sensor cable end at a desired measuring point, in an exemplary embodiment of the thermocouple assembly, the positioning pad comprises a receiving means, which may be formed by a slot or a recess that corresponds to the shape of the sensor cable end, but has a smaller size to provide a stronger mechanical fit, e.g. an interference fit, when the thermocouple sensor cable end is pushed into the receiving means. Alternatively, the thermocouple sensor cable end may be secured to the positioning pad by welding, a clamping means, screws or other ways. In such an arrangement the thermocouple sensor cable might not be easily replaced. However, the installation will be very robust and the installation is further simplified as tube clips may not be necessary to hold the thermocouple sensor cable into the shielding.

While the weld pads of the prior art are only in thermal contact with the surface of the structure, the mechanical connection of the shielding and the positioning pad of the present invention can provide a controlled means of additional thermal contact / heat transfer between the walls of the shielding (which are in thermal contact with the environment, e.g. with a process atmosphere, process fluid or flames inside a furnace, etc.) and the sensitive thermocouple sensor cable end, which is received and/or secured by the positioning pad at and in thermal contact with the surface of the structure. Thereby, absolute measurement accuracy of the thermocouple sensor can be improved significantly: The heat transfer through the mechanical connection between the shielding and the positioning pad can compensate for a temperature deviation at the part of the surface of the structure that is covered by the shielding, compared to the actual temperature of the surface, that would be measurable at the same location if that part of the surface was not covered by the shielding. In other words, the mechanical contact between the shielding and the positioning pad becomes a tailor-made thermal bridge.

In exemplary embodiments of the thermocouple assembly, the ratio between a height (i.e. material thickness) of the positioning pad and diameter of the thermocouple sensor cable is chosen between <NUM>:<NUM> and <NUM>:<NUM>, preferably between <NUM>:<NUM> and <NUM>:<NUM>, particularly preferably between <NUM>:<NUM> and <NUM>:<NUM>. As an example, for a sensor cable with a diameter of ¼ inch (<NUM>), the material thickness of the positioning pad should particularly preferably be chosen between <NUM>/<NUM> inch (<NUM>) and <NUM>/<NUM> inch (<NUM>). The given ratios enable a controlled, effective transfer of heat between positioning pad and the closed thermocouple sensor cable end, while at the same time reduce weight of the assembly and amount of material required, resulting in reduced manufacturing cost and easier installation.

In other exemplary embodiments of the thermocouple assembly, the ratio between a length of the section of the thermocouple sensor cable, which is in mechanical (and therefore also thermal) contact with the positioning pad, and the diameter of the thermocouple sensor cable is at least <NUM>:<NUM>, preferably at least <NUM>:<NUM>, particularly preferably between <NUM>:<NUM> and <NUM>:<NUM>. This length may also be described as a penetration depth of the sensor cable into the positioning pad. As an example, for a sensor cable with a diameter of ¼ inch (<NUM>), the penetration depth should particularly preferably be chosen between <NUM>/<NUM> inch (<NUM>) and ½ inch (<NUM>). The given ratios enable a controlled, effective transfer of heat between positioning pad and the closed thermocouple sensor cable end and the positioning pad may receive and/or secure the sensor cable end very reliably and durably. At the same time, weight of the assembly and amount of material required are reduced, resulting in reduced manufacturing cost and easier installation.

In an exemplary embodiment of the thermocouple assembly the positioning pad is mechanically connected to the shielding by welding or brazing of at least two pieces. The first piece would be the positioning pad, which may be a flat piece of steel or other suitable material. However, the pad could also have a curved or rounded shape to fit to a curved surface of a structure. The second piece would be the shielding in form of a box with an open bottom face and an opening in one of its walls, for example a side wall or a side face of the shielding, where the sheathed thermocouple sensor cable may enter the shielding. In case of a welded connection, the assembly of shielding and positioning pad might be achieved in a very durable manner. As the two parts are inseparably connected to each other, one may refer to this exemplary embodiment as an integral form of positioning pad and shielding. Alternative embodiments of such an integral form of shielding and positioning pad may be achieved by the use of adhesives or by press-fit stemming or by shaping from one piece or by additive shaping.

In an exemplary embodiment of the thermocouple assembly the mechanical connection between the positioning pad and the shielding may comprise at least one protrusion or protruding portion of the positioning pad, engaging with at least one corresponding recess or recessed portion at or through a wall of the shielding. The wall could be a side wall, a lid or any other wall of a housing, which is part of the shielding or forms the shielding. Protrusion and protruding portion are considered as synonyms throughout this document. Likewise, recess and recessed portion are also considered as synonyms. Here, the shielding having a recess 'through' a wall means that the recess actually is forming an opening between the inner free volume of the shielding and the outside of the shielding, for example at the bottom of a side wall of the shielding. For this design, the protruding portion of the positioning pad may be formed to fit in and through this opening, being flush with the external surface of the wall of the shielding. At the other hand, the shielding having a recess `at' a wall, means that the recess is arranged at an inner side of the wall and does not break through the wall. The first one of these possible designs has the advantage of a very easy, low-cost manufacturing of the recesses / openings; however, this also means that there will be small slits between the recesses and the protruding portions of the positioning pad at the outer surface of the walls of the shielding, which need to be sealed during the installation process. A possible method for this is described in the following paragraph. The second possible design does not need such sealing process, since there are no gaps, openings or slits in or through the walls of the shielding, except for the necessary opening, where the thermocouple sensor cable enters the shielding. This design might require a more complex manufacturing process of the shielding, however.

In both of these described embodiments (i.e. with at least one recess through a wall or at least one recess at a wall, respectively), the shielding and the positioning pad are initially two separate parts, as with a weld pad and shielding of state-of-the-art thermocouple assemblies. However, through the engagement of a protruding portion or portions of the positioning pad with a recessed portion or recessed portions of the shielding, both parts are rigidly connected or connectable and aligned in a defined position relative to each other. For example, after the parts are brought into engagement with each other and when the thermocouple assembly is placed on and secured to the surface of the structure, the engagement is formed such that the positioning pad, the shielding and the surface of the structure form a positive-fit connection, that will firmly hold the positioning pad in place, relative to the shielding. Alternatively, after the parts are brought into engagement with each other, the positioning pad and shielding are joined together, e.g. by welding, before the thermocouple assembly is placed on and secured to the surface of the structure.

In a possible advancement of this embodiment, the positioning pad comprises two protrusions at opposing sides of the pad, wherein the shielding comprises corresponding recesses on each of two opposing walls, e.g. on each of two opposing side walls. When both parts are brought into engagement and the thermocouple assembly is placed on the surface of the structure, for example welding is used to fix it to the surface. For example, the recesses form openings at the bottom of and through the side walls of the shielding and the protruding portions of the positioning pad fit in these openings, being flush with the external surface of the walls of the shielding, for example side walls. The size of the welding may be chosen big enough to not only fix the shielding to the surface, but also completely seal the recessed portions of the shielding, welding the protrusions of the positioning pad directly to the shielding. This method and construction enables a very simple design of all parts, while at the same time keeping the installation process uncomplicated with only one welding process and the resulting thermocouple assembly is very robust. While the method, to use the welding to secure the shielding to the surface and to sealingly cover possible slits or gaps at the recessed portion of the shielding at the same time, is described in the context of the embodiment with two recessed portions at opposing walls of the shielding, it might as well be applied to any design or embodiment with at least one recess through any wall of the shielding and at least one protruding portion of a positioning pad, engaging with that recess. In some exemplary embodiments, where the recess is not positioned directly at or close to the bottom side of the shielding, it might not be possible to seal slits or gaps of the recess with the same weld seam that connects the shielding to the structure. However, additional weld seams that would only cover the area of the recessed portion located anywhere on the shielding could still be applied during the same welding process and do not require additional inspections steps, as they do not affect the surface of the structure. Therefore, the positive effect of low installation cost and time-saving installation process are achievable with all aforementioned embodiments.

In another possible advancement of this embodiment, the shielding comprises two corresponding recesses on each of two opposing walls, e.g. on each of two opposing side walls, that are not located at the bottom of that sidewalls. The positioning pad comprises two protruding portions, e.g. noses, each protruding from vertically extending members of the positioning pad and correspond to the recesses of the shielding. When the shielding is placed on top of the positioning pad and pressed down towards it, the protruding portions, e.g. noses, will clip into the recesses, thereby mechanically connecting the shielding and the positioning pad. This assembly would position the pad such that it would establish a robust contact with the tube surface. Furthermore, the inner sidewalls of the shielding may comprise guiding grooves that correspond to the vertically extending members to provide additional mechanical connection between shielding and positioning pad and prevent misalignment. In case the recesses are arranged 'through' the shielding, as described above, the protruding portions, e.g. noses, might be formed to fit in and through these recesses, and may be recessed or flush with the external surface of the sidewalls of the shielding. A welding can be used to sealingly close any openings or slits and/or rigidly connect both parts. In case the recesses are arranged 'at' the shielding, as described above, no welding is needed.

All the aforementioned different ways of construction and assembly may allow customizing the design to various applications and budgets.

In an exemplary embodiment of the thermocouple assembly, the mechanical connection and - if applicable, as defined above - the integral form of shielding and positioning pad may be achieved.

Alternatively, the positioning pad and the shielding are connected over multiple connection sections distributed over at least one, two or three sides of the shielding's inner perimeter, e.g. on any side of the positioning pad there may be a series of connection sections or connections points. A connection section in the sense of this embodiment should be understood as a point or section of direct physical contact between a surface section or a part of the shielding and a surface section or a part of the positioning pad and/or an integral connection between these parts, e.g. a welded connection. In this embodiment the mechanical connection or integral form of shielding and positioning pad may be adapted to the requirement of a particular application. For example, a connection with only one connection section or with only a few connection points formed on one side of the positioning pad may be manufactured at low cost and will also provide the feature of a higher thermal insulation between the shielding's outer surface and the thermocouple sensor end at the measuring point inside the shielding. However, a higher number of connection sections, e.g. three connection sections arranged on three adjacent sides of positioning pad, may provide the benefits of a very durable and rigid construction and also provide a lower thermal insulation between the shielding's outer surface and the thermocouple sensor end at the measuring point inside the shielding, i.e. the higher number of connection sections work as thermal bridges, conducting more heat between the shielding and the thermocouple sensor end, positioned with the positioning pad. Measurement accuracy may be increased depending on the application under consideration, as the actual amount of heat transferred between shielding and thermocouple sensor end may be adapted to requirements of the application.

In an exemplary embodiment of the thermocouple assembly the positioning pad and/or the shielding is integrally formed or at least mechanically connected with a guiding conduit and the thermocouple sensor cable is inserted or insertable into the guiding conduit. The guiding conduit may be connected with one end to the shielding, at the position of an opening in a wall of the shielding, for example a side wall or a side face of the shielding, where the thermocouple sensor cable enters the shielding and may be connected with its other end to the positioning pad at the means of the positioning pad for receiving and/or securing the thermocouple sensor end at the measuring point, e.g. at a slot of the positioning pad. In this particular embodiment the shielding, the positioning pad and the guiding conduit may be integrally formed as a one-piece design. The guiding conduit might be formed by a downward-open channel structure, like a half round tube, or might be formed by a conduit or tube, that is not open downwards and completely surrounds the thermocouple sensor cable.

The guiding conduit may comprise a receiving end portion to press the thermocouple sensor cable against the surface of the tube. Such receiving portion may be in the form of a dent or a tapered section. By pressing the thermocouple sensor cable end against the surface of the structure a better defined thermal contact is achieved and measuring accuracy, response time and repeatability are improved.

In an exemplary embodiment of the thermocouple assembly, the thermocouple sensor cable is integrally formed with the positioning pad and/or the shielding. For example, the sensor cable end might be welded or brazed to the positioning pad and/or to the shielding at an opening in a wall of the shielding, for example a side wall or a side face of the shielding, where the thermocouple sensor cable enters the shielding. This embodiment further simplifies the installation process. Because the sheathed thermocouple sensor cable is fixedly connected to the other parts of the thermocouple assembly, the sensor cable end is effectively prevented from dislocation during the installation process. Therefore, measurement repeatability and accuracy are improved. Also, this embodiment provides high durability and high stability.

In an exemplary embodiment of the thermocouple assembly, the thermocouple sensor cable is detachably connected with the positioning pad. In this embodiment the securing of the shielding to the structure is further simplified, as the lengthy sensor cable can be separated from the shielding. After successful installation of the shielding on the structure, the sensor cable may simply be pushed or slid into the shielding through an opening in a wall of the shielding, for example a side wall or a side face of the shielding, until it mates or engages with the positioning pad, i.e. a slot in the positioning pad, where the thermocouple sensor cable end is received and/or secured. Furthermore, the sensor cable may easily be extracted from the shielding without the need to remove the whole assembly. Thus, the thermocouple sensor cable may be exchanged to a new one, in case of a damage or necessary recalibration.

In an exemplary embodiment of the thermocouple assembly, the thermocouple sensor cable comprises a locking means that engages with a corresponding holding means of the shielding when the thermocouple sensor cable is inserted into the shielding and the thermocouple sensor end meets with a receiving means of the positioning pad, wherein the thermocouple sensor cable is mechanically blocked from being extracted from the shielding. The locking means may be in the form of a ring, a ring segment or any other protrusion on the surface of the sheath of the thermocouple cable, or a taper of the sheath.

In an exemplary embodiment, the locking means does not protrude from a bottom side of the thermocouple sensor cable, so that the sensor cable may be placed flat directly on the surface of a structure to be measured. In the simplest form the holding means may just be the edge of the opening in a wall of the shielding, for example a side wall or a side face of the shielding, where the thermocouple sensor cable enters the shielding. With this design manufacturing costs can be significantly reduced: a shielding with a holding means may be used for both applications / designs where the thermocouple sensor cable is either required to be extractable or is required to be non-extractable from the shielding, once the shielding is fixed to the surface of a structure. The decision on extractability does only impact the thermocouple sensor cable, which either comprises a locking means or not. Hence, only one shielding design is needed for both versions, manufacturing and storage costs can be reduced. Also, when the whole thermocouple assembly is removed from the structure, the sensor cable may be easily removed from the shielding. Thus, costs for dismantling and disposal, compared to embodiments where a sheathed thermocouple sensor cable may be integrally formed with the shielding and/or positioning pad, can be reduced.

In an exemplary embodiment of any of the aforementioned embodiments the shielding and/or the positioning pad and/or at least a portion of the thermocouple sensor cable, which is covered by the shielding, are formed to match the surface of the structure, to which the thermocouple assembly is installed, e.g. formed either curved to match the surface of a pipe or formed straight to match the surface of a flat structure. By matching the form of the bottom of the thermocouple assembly to the form of the surface, to which the thermocouple assembly is to be installed, several benefits can be achieved: The thermocouple assembly can be installed with minimum space requirements and the connection to the surface, e.g. by welding, can be achieved easily and without any gaps or slits, therefore being very robust and reliable. In exemplary embodiments, where also the positioning pad's bottom surface matches the form of the surface of the structure, i.e. the positioning is in areal contact with the surface, the thermal contact to the structure is improved. Thereby the contribution of heat transfer from or to the surface of the structure or pipe is increased, which may reduce response time and improve absolute measurement accuracy of the thermocouple sensor in some applications. At the other hand, a shielding with a curved bottom side may be combined with a flat positioning pad to reduce the thermal contact between positioning pad and the surface of the structure or pipe, thereby providing a defined point or line of contact right at the desired measurement point, decreasing the contribution of heat transfer from and to the surface of the structure or pipe through the positioning pad, which may increase absolute measurement accuracy in other applications.

This embodiment is applicable to installations, where the thermocouple sensor cable inside the shielding is oriented perpendicular to the cylinder axis of a pipe or tube structure, i.e. the thermocouple assembly partly winds around the tube or pipe. Thus, the shielding and positioning pad are curved about an axis perpendicular to the direction of extension of the thermocouple sensor cable. This installation is particularly suitable to structures with bigger tube diameters and/or more space in between pipes. However, this embodiment is also applicable to installations, where the thermocouple sensor cable inside the shielding is oriented in parallel to the cylinder axis of a pipe or tube structure, what may be referred to as an in-line installation of the thermocouple assembly. In such cases the shielding or at least the bottom side of the shielding and the positioning pad are curved about an axis parallel to the direction of extension of the thermocouple sensor cable. This installation is particularly suitable to structures with small tube diameters and/or less space in between pipes. With a suitable curvature of the parts of the thermocouple sensor assembly the aforementioned benefits of this embodiment can be achieved in different kinds of installation orientations.

Another aspect of the invention relates to a method for installation of a thermocouple assembly. The thermocouple assembly comprises a.

The surface of the structure around the desired position may be cleaned and/or prepared beforehand.

Subsequently, in case that the thermocouple sensor cable is not integrally formed with the other parts of the assembly and therefore not already in place with the shielding, the thermocouple sensor cable may be inserted into the shielding until it reaches the positioning pad and the thermocouple sensor cable end meets the desired measuring point, defined by a receiving means of the positioning pad.

In exemplary embodiments of this method, mechanically connecting the positioning pad to the shielding means that these parts are integrally formed or rigidly connected to each other, before they are placed on the surface of the structure, to which the shielding will be secured in the following step.

However, in another exemplary embodiment of this method, wherein the positioning pad comprises at least one protruding portion and the shielding comprises at least one recessed portion that corresponds to the protruding portion of the positioning pad, the step of mechanically connecting the positioning pad to the shielding comprises the further steps of.

Another aspect of the invention relates to another method for installation of a thermocouple assembly, comprising.

wherein the positioning pad is mechanically connected to and/or integrally formed with the shielding, wherein the thermocouple sensor cable comprises a locking means that engages with a corresponding holding means of the shielding. The method comprises the steps of.

In exemplary embodiments of the above mentioned methods, the shielding is secured to the surface by welding, and the shielding and the positioning pad are permanently joined together by this same welding process and/or the recessed portion of the shielding is covered and sealed by the welding. This embodiment has the advantage of a very robust and reliable installation, while at the same time the design of the parts is simple and the installation process is easy and cost-efficient.

All aforementioned methods for the installation of a thermocouple assembly share the advantage, that at least the shielding and the positioning pad may be installed and secured to the surface of the structure in one single step, because by securing the shielding to the structure, the positioning pad may also be secured, as it is mechanically connected to and/or integrally formed with the shielding. Especially in the case, where the thermocouple assembly is secured to the surface of the structure by welding, this means a significant saving in time and cost, since only one welding process is required with only one following inspection of the welded area, as well as only one cycle of pre-heating for the welding process, and following cooling after the welding process, if such pre-heating and cooling is required.

Exemplary embodiments of the invention are explained in more detail with reference to the following drawings.

In all figures corresponding parts are provided with the same reference numbers.

<FIG> shows an exemplary embodiment of a thermocouple assembly <NUM> in a perspective view as well as in three side views / sectional views.

The thermocouple assembly <NUM> comprises a sheathed thermocouple sensor cable <NUM>, a positioning pad <NUM> for receiving and/or securing a thermocouple sensor end <NUM> at a desired measuring point on or close to a surface of a structure, and a shielding <NUM>.

The shielding covers the positioning pad <NUM> and at least a part of the sheathed thermocouple sensor cable <NUM> and an insulation body <NUM>, filling the inner free volume of the shielding <NUM>, wherein the positioning pad <NUM> is integrally formed with the shielding <NUM>.

In this exemplary embodiment the positioning pad <NUM> is in the form of a bridge, extending between two opposing inner side walls of the shielding <NUM>; the connection between shielding <NUM> and positioning pad <NUM> is formed by two connection sections <NUM>, opposing each other. The thermocouple sensor cable <NUM> enters the shielding through an opening <NUM> of a side face <NUM> of the shielding <NUM>.

<FIG> shows another exemplary embodiment of a thermocouple assembly <NUM> in a perspective view as well as in three side views / sectional views.

In contrast to <FIG>, the positioning pad <NUM> of <FIG> is connected to the shielding <NUM> through three connection sections <NUM>, arranged on three adjacent sides of the positioning pad <NUM>. Hence, the positioning pad <NUM> covers part of the otherwise open bottom face of the box-like shielding <NUM>.

While the connection between positioning pad <NUM> and shielding <NUM> is similar to that shown in <FIG> ("bridge-type"), the thermocouple assembly <NUM> in <FIG> additionally comprises a guiding conduit <NUM>, which is connected with one end to the shielding <NUM> at the position of an opening <NUM>, where the thermocouple sensor cable <NUM> enters the shielding <NUM>. Further, the guiding conduit <NUM> is connected with its other end to the positioning pad <NUM> at the means of the positioning pad <NUM> for receiving and/or securing the thermocouple sensor end <NUM>. While the guiding conduit <NUM> is shown as a downward-open channel in this embodiment, a closed conduit, like a tube, may also be used without leaving the scope of the invention.

While the connection between positioning pad <NUM> and shielding <NUM> is similar to that shown in <FIG>, the assembly in <FIG> additionally comprises a guiding conduit <NUM>, which is connected with one end to the shielding <NUM> at the position of an opening <NUM>, where the thermocouple sensor cable <NUM> enters the shielding <NUM>. Further, the guiding conduit <NUM> is connected with its other end to the positioning pad <NUM> at the means of the positioning pad <NUM> for receiving and/or securing the thermocouple sensor end <NUM>.

<FIG> show exemplary embodiments of a thermocouple assembly <NUM> in a side view of the bottom side. The embodiments each comprise a sheathed thermocouple sensor cable <NUM> and a positioning pad <NUM> for receiving and/or securing the thermocouple sensor end <NUM> at a desired measuring point on or close to a surface of a structure. Further, the embodiments comprise a shielding <NUM>, covering the positioning pad <NUM> and at least a part of the sheathed thermocouple sensor cable <NUM>, and an insulation body (not shown), filling the inner free volume of the shielding <NUM>, wherein the positioning pad <NUM> is mechanically connected to and/or integrally formed with the shielding <NUM>.

In <FIG> the positioning pad <NUM> is connected to the shielding <NUM> through one connection section <NUM>. While the connection section <NUM> in this embodiment is arranged on an upper side on the positioning pad <NUM>, it may as well be arranged on a left, right or lower side of the positioning pad <NUM>, without leaving the scope of this invention. While the connection section <NUM> is shown in this embodiment as one continuous connection, e.g. a continuous weld along the full width of the side of the positioning pad <NUM>, a shorter connection section <NUM> that does not cover the full width of the side of the positioning pad <NUM>, a series of shorter connection sections <NUM> or a series of connections points may as well be used, without leaving the scope of the invention.

In <FIG> the positioning pad <NUM> is connected to the shielding <NUM> through two connection sections <NUM>, arranged on opposing sides of the positioning pad <NUM>. This arrangement may be referred to as a "bridge-type" positioning pad <NUM>. While the connection sections <NUM> are shown in this embodiment as continuous connections, e.g. continuous welds along the full width of each side of the positioning pad <NUM>, shorter connection sections <NUM> that do not cover the full width of each side of the positioning pad <NUM>, a series of shorter connection sections <NUM> or a series of connections points may as well be used, without leaving the scope of the invention.

Furthermore, this embodiment additionally comprises a locking means <NUM> in form of a ring, a ring segment or other protrusion, that is attached to the sheath of the thermocouple sensor cable <NUM>. The shielding comprises a holding means <NUM>, which is formed by the inner wall of the shielding <NUM> surrounding the opening <NUM> of the shielding, where the thermocouple sensor cable <NUM> enters. The locking means <NUM> abuts the holding means <NUM>, therefore the sensor cable <NUM> cannot be extracted from the shielding <NUM>, once the shielding <NUM> is fixed to the surface of a structure. The assembly of this embodiment may comprise the steps of inserting the thermocouple sensor cable end <NUM> into a slot <NUM> of the positioning pad <NUM> under an angle and pivoting the sensor cable <NUM> about the sensor cable end <NUM>, which is secured in or with the positioning pad <NUM>, until the thermocouple sensor cable <NUM> fits into the opening <NUM> and locking means <NUM> engages the holding means <NUM>.

In <FIG> the positioning pad <NUM> is connected to the shielding <NUM> through two connection sections <NUM>, arranged on adjacent sides of the positioning pad <NUM>. This arrangement may be referred to as a "corner-type" positioning pad <NUM>. While the connection sections <NUM> are shown in this embodiment as continuous connections, e.g. continuous welds along the full width of each side of the positioning pad <NUM>, shorter connection sections <NUM> that do not cover the full width of each side of the positioning pad <NUM>, a series of shorter connection sections <NUM> or a series of connections points may as well be used, without leaving the scope of the invention.

In <FIG> the positioning pad <NUM> is connected to the shielding <NUM> through three connection sections <NUM>, arranged on adjacent sides of the positioning pad <NUM>. While the connection sections <NUM> are shown in this embodiment as continuous connections, e.g. continuous welds along the full width of each side of the positioning pad <NUM>, shorter connection sections <NUM> that do not cover the full width of each side of the positioning pad <NUM>, a series of shorter connection sections <NUM> or a series of connections points may as well be used, without leaving the scope of the invention.

<FIG> show exemplary embodiments of a thermocouple assembly <NUM> in a side view of the bottom side. The embodiments each comprise a sheathed thermocouple sensor cable <NUM> and a positioning pad <NUM> for receiving and/or securing the thermocouple sensor end <NUM> at a desired measuring point on or close to a surface of a structure. Further, the embodiments each comprise a shielding <NUM>, covering the positioning pad <NUM> and at least a part of the sheathed thermocouple sensor cable <NUM>, and an insulation body (not shown), filling the inner free volume of the shielding <NUM>. The positioning pad <NUM> is mechanically connected and/or integrally formed with the shielding <NUM>.

In <FIG> the positioning pad <NUM> is connected to the shielding <NUM> in another "bridge-type" arrangement. In contrast to <FIG>, however, the connection comprises two separate connection sections <NUM> on both opposing sides of the positioning pad <NUM>. Between the two connection sections <NUM> on each side of the positioning pad <NUM> there is a non-connected void section. While these connection section <NUM> are shown in this embodiment as continuous connections, e.g. continuous welds, a series of shorter connection sections <NUM> or a series of connections points may as well be used, without leaving the scope of the invention.

In <FIG> the positioning pad <NUM> is connected to the shielding <NUM> in another "bridge-type" arrangement. In contrast to <FIG>, however, the connection sections <NUM> do not extend over the full side length of the positioning pad, but are recessed on both sides.

In <FIG> the positioning pad <NUM> is connected to the shielding <NUM> in another "bridge-type" arrangement. In contrast to <FIG>, however, the connection comprises a series of connection points <NUM> on both sides of the positioning pad <NUM> instead of continuous connection sections <NUM>.

<FIG> show exemplary embodiments of a thermocouple assembly <NUM> which have a rounded/curved shape to fit the surface of a tube or pipe structure.

<FIG> however, displays an embodiment of a thermocouple assembly <NUM> that has a straight form, to match a flat surface <NUM> of a structure. The thermocouple assembly <NUM> of this embodiment comprises a guiding conduit <NUM> in the form of a channel that is open downwards. A receiving end portion <NUM> of the guiding conduit <NUM> presses the thermocouple sensor cable end <NUM> against the surface <NUM> of the structure at the measuring point.

The sheathed thermocouple sensor cable <NUM> comprises a protrusion on an upper side as a locking means <NUM>, which is positioned along the length of the sensor cable <NUM> to abut against a holding means <NUM> of the shielding <NUM>, when the sensor cable end <NUM> meets with a receiving means of the positioning pad <NUM> at the measuring point.

The holding means <NUM> is formed by the inner wall of the shielding <NUM>, that surrounds the opening <NUM>, where the sheathed thermocouple sensor cable <NUM> enters the shielding <NUM>.

The guiding conduit <NUM> is flared in proximity of this opening <NUM> to leave room for the locking means <NUM>. The features shown in this figure are also applicable to the embodiments shown in other figures, where the thermocouple assembly parts are formed curved to match a non-straight surface of a structure, like a pipe.

<FIG> show an exemplary embodiment of a shielding <NUM> with two recessed portions <NUM>, one on each of its two side faces <NUM>, and an opening <NUM>, where a thermocouple sensor cable <NUM> can be inserted into the shielding <NUM>. The recessed portions <NUM> are formed 'through' the walls of the shielding, thereby forming openings between the inner free volume of the shielding and the outside.

<FIG> shows a bottom view of such shielding, whereas <FIG> shows a side view.

<FIG> show an exemplary embodiment of a positioning pad <NUM> with two protruding portions <NUM> on opposing sides with a thermocouple sensor cable <NUM> attached to the positioning pad <NUM>.

Two dotted lines cross the <FIG> to indicate, that the recessed portions <NUM> of the shielding and the protrusions <NUM> of the positioning pad <NUM> match in size, such that they might be referred to as corresponding to each other. Not only the width of the protrusions <NUM> fits the width of the recessed portions <NUM>. The height is also matched and the length of the protruding portions <NUM> is matched to the thickness of the wall of the shielding <NUM>, such that the protruding portions <NUM> end flush with the outer surface of the shielding <NUM>, when the shielding <NUM> of <FIG> is placed on the positioning pad <NUM> of <FIG>. The parts in these figures are formed curved to match the curved surface of pipe structure. However, the shown design might as well be applied to straight parts that match a flat surface.

<FIG> show exemplary steps of a method to install a thermocouple assembly <NUM> on a structure <NUM> for surface temperature measurements. The shown structure <NUM> is a pipe.

In a first step, shown in <FIG>, a thermocouple sensor cable <NUM> with a connected positioning pad <NUM> is placed on a desired measuring point on the surface of the structure <NUM>. Beforehand, a surface area <NUM> might be cleaned or grinded to provide good conditions for a later welding. The positioning pad <NUM> comprises two protruding portions <NUM>.

In a second step, shown in <FIG>, a shielding <NUM>, comprising recessed portions <NUM> that correspond to the protruding portions <NUM> of the positioning pad <NUM>, is placed on the positioning pad <NUM> and the surface of the structure <NUM>, such that the recessed portions <NUM> and protruding portions <NUM> mate and/or engage with each other.

In a third and final step, as shown in <FIG>, the shielding <NUM> is secured to the surface of the structure <NUM> by a welding <NUM>. Dimensions and parameters of the welding <NUM> might be chosen such that the recessed portions <NUM> are completely covered and sealed by the welding <NUM>. Also, in an exemplary embodiment, the protruding portions <NUM> of the positioning pad <NUM> might be permanently connected to the shielding <NUM> by the welding <NUM> at the same time.

<FIG> shows another exemplary embodiment of a thermocouple assembly <NUM>, that is installed in-line with a pipe structure <NUM> on the surface <NUM> of the pipe.

The thermocouple sensor cable <NUM> therefore is oriented in a straight manner. A shielding <NUM> is secured to the structure by welding <NUM> to provide protection for the thermocouple sensor cable end <NUM>. A positioning pad <NUM> is mechanically connected to the shielding <NUM> and receives and holds the thermocouple sensor cable end <NUM> at a desired measuring point. In contrast to the exemplary embodiments of <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG>, where, respectively, shielding <NUM>, positioning pad <NUM> and a part of thermocouple sensor cable <NUM> are shown curved around an axis perpendicular to the direction of extension of the thermocouple sensor cable, to be fitted around a pipe or tube structure, the assembly of <FIG> comprises a shielding <NUM> and thermocouple sensor cable <NUM> with a straight form, parallel to the structure. However, the bottom side of the shielding <NUM> as well as the positioning pad <NUM> are curved about an axis parallel to the direction of extension of the thermocouple sensor cable <NUM> to still fit perfectly to the curved surface <NUM> of the structure <NUM>. This is further illustrated in <FIG> and <FIG>.

<FIG> shows a sectional view of the thermocouple assembly <NUM> of <FIG> through sectional plane A as indicated in <FIG> for an embodiment where the mechanical connection between shielding <NUM> and positioning pad <NUM> comprises two protruding portions <NUM> of the positioning pad <NUM>, mating with two corresponding recessed portions <NUM> of the shielding. The welding <NUM>, which secures the shielding to the surface <NUM> of the structure <NUM>, completely covers the recessed portions <NUM>, thereby sealingly and rigidly connecting the shielding <NUM>, the positioning pad <NUM> and the surface <NUM>.

<FIG> also shows a sectional view of the thermocouple assembly <NUM> of <FIG> through sectional plane A as indicated in <FIG>, but for an embodiment where the mechanical connection between shielding <NUM> and positioning pad <NUM> comprises an integral form of both parts, i.e. the positioning pad <NUM> is integrally formed with / connected to the shielding <NUM> by welding <NUM>', before the shielding itself is secured to the structure by welding <NUM>.

<FIG> also shows a sectional view of a thermocouple assembly <NUM> installed in-line on a tube structure <NUM>, similar to the assembly of <FIG>. The bottom side of the shielding <NUM> is curved to match the surface of the tube. However, in this embodiment, the positioning pad <NUM> is not curved to fit the surface of the structure, but is flat instead. Thereby, a defined thermal and mechanical contact point or line between the positioning pad <NUM> and the surface is formed at or through a desired measuring point <NUM>. The thermocouple sensor cable end <NUM> is positioned and held at exact this point.

<FIG> shows another example for a thermocouple assembly <NUM>, comprising a shielding <NUM> and a thermocouple sensor cable <NUM>, which are formed curved to be arranged around a tube <NUM> and match the surface of the tube structure <NUM>, combined with a positioning pad <NUM> that is not curved. The flat positioning pad <NUM> receives and holds the thermocouple sensor cable end <NUM> at a desired measuring point <NUM>. Because of the flat form of the positioning pad <NUM>, the mechanical and thermal contact between it and the surface of the structure <NUM> is reduced to only a narrow line going through the measuring point <NUM>, perpendicular to the orientation of extension of the thermocouple sensor cable <NUM>. Thereby the influence of the heat transfer through the positioning pad <NUM> between the walls of the shielding <NUM> and the sensitive tip of the thermocouple sensor cable end <NUM>, compared to the heat transfer through the positioning pad <NUM> between the area of the surface of the structure <NUM> surrounding the measuring point <NUM> and the sensitive tip of thermocouple sensor cable end <NUM>, is increased. Consequently, this heat transfer may even compensate for large deviations in surface temperature under the shielding <NUM>.

<FIG> shows another example for a thermocouple assembly <NUM> in a sectional view, similar to the sectional views of <FIG>; however, in this example, the thermocouple assembly <NUM> is arranged on the surface of a flat structure. The shielding <NUM> comprises two recessed portions <NUM> arranged at the inner surface of opposing side walls. These recesses <NUM> are formed to engage with protruding portions <NUM> of a positioning pad <NUM>. However, in contrast to the configurations of recesses and protrusions of other exemplary embodiments, e.g., as shown in the <FIG>, <FIG> and <FIG>, the recesses <NUM> of the shielding <NUM> are not positioned at the bottom of the respective side walls. For the protruding portions <NUM> of the positioning pad <NUM> to engage with these recesses <NUM> while at least a portion of the positioning pad <NUM> stays in firm contact with the surface <NUM> of the structure <NUM>, the positioning pad <NUM> comprises vertically extending members <NUM>, which provide the protrusions <NUM>, e.g. in the shape of noses, at the required position, i.e. at the required height. The part of the positioning pad <NUM>, which is in contact with the surface <NUM>, receives and/or secures the closed thermocouple sensor cable end <NUM> at a desired measuring point.

<FIG> shows the shielding <NUM> and positioning pad <NUM> of <FIG> in a sectional view, before engagement of the parts. To achieve the mechanical connection between positioning pad <NUM> and shielding <NUM>, i.e. to achieve engagement of the protruding portions <NUM> with the recessed portions <NUM>, the shielding <NUM> may be placed on top of the positioning pad <NUM> and pushed downwards. The vertically extending members <NUM> are designed flexible, such that they can bend inwards to allow the protrusions <NUM> so slide up to meet and engage with, i.e. snap or clip into the recessed portions <NUM>. To provide additional guidance during engagement of both parts, to provide additional stability and to prevent any misalignment or slipping of the positioning pad <NUM>, the inner side walls of the shielding <NUM> comprise guiding grooves <NUM>, that receive and guide the vertically extending members <NUM>.

Claim 1:
Structure (<NUM>), comprising a thermocouple assembly (<NUM>) for surface temperature measurement on a surface (<NUM>) of the structure (<NUM>), the thermocouple assembly (<NUM>) comprising
- a sheathed thermocouple sensor cable (<NUM>),
- a positioning pad (<NUM>), receiving and/or securing a thermocouple sensor end (<NUM>) at a desired measuring point,
- an insulation body (<NUM>), and
- a shielding (<NUM>),
characterized in that
the positioning pad (<NUM>) is mechanically connected to the shielding (<NUM>) and the shielding (<NUM>) is connected by one welding (<NUM>, <NUM>') to the surface (<NUM>) of the structure (<NUM>) and a recessed portion (<NUM>) of the shielding (<NUM>), corresponding to the shape and size of a protruding portion (<NUM>) of the positioning pad (<NUM>) and receiving the protruding portion (<NUM>) therein, is covered and sealed by the welding (<NUM>, <NUM>').