Patent Publication Number: US-2023160644-A1

Title: Gasket arrangement, method of manufacturing a gasket arrangement and assembly

Description:
TECHNICAL FIELD 
     The invention relates to a gasket arrangement for a plate heat exchanger, a method of manufacturing such and an assembly comprising such. 
     BACKGROUND ART 
     Plate heat exchangers typically consist of two end plates in between which a number of heat transfer plates are arranged in an aligned manner, i.e. in a stack or pack. The heat transfer plates of a PHE may be of the same or different types and they may be stacked in different ways. In some PHEs, the heat transfer plates are stacked with the front side and the back side of one heat transfer plate facing the back side and the front side, respectively, of other heat transfer plates, and every other heat transfer plate turned upside down in relation to the rest of the heat transfer plates. Typically, this is referred to as the heat transfer plates being “rotated” in relation to each other. In other PHEs, the heat transfer plates are stacked with the front side and the back side of one heat transfer plate facing the front side and back side, respectively, of other heat transfer plates, and every other heat transfer plate turned upside down in relation to the rest of the heat transfer plates. Typically, this is referred to as the heat transfer plates being “flipped” in relation to each other. 
     The heat transfer plates are typically corrugated so as to comprise ridges extending in an upper plane, and valleys extending in a lower plane. In one type of well-known PHEs, the so called gasketed plate heat exchangers, gaskets are arranged between the heat transfer plates, more particularly in gasket grooves extending along outer edges and around port holes of the heat transfer plates. The gasket grooves may extend in the lower plane and/or in an intermediate plane arranged between the upper and lower planes. The intermediate plane could extend halfway between the upper and lower planes, i.e. be a so-called as half-plane. The end plates, and therefore the heat transfer plates, are pressed towards each other whereby the gaskets seal between the heat transfer plates. The gaskets define parallel flow channels between the heat  transfer plates, one channel between each pair of heat transfer plates. Two fluids of initially different temperatures can flow through every second channel for transferring heat from one fluid to the other. 
     The fluids enter and exit the channels through inlet and outlet ports, respectively, which extend through the PHE and are formed by respective aligned port holes of the heat transfer plates and the gaskets sealing, completely or partly, around the port holes. The inlet and outlet ports communicate with inlets and outlets, respectively, of the PHE for feeding the fluids to and from the PHE. 
     The gaskets are often marked with information about the gaskets, more particularly information which is common for gaskets of a certain type, such as article number and material of the gaskets. However, the gaskets are not provided with any “dynamic” information, such as batch number, manufacturing date, etc. Instead, the gasket manufacturer typically provides this “dynamic” information on an easily removable label fastened to the gaskets or the gasket packaging. In connection with assembly of the gaskets in a plate heat exchanger, the label is typically separated from the gaskets and lost. This makes it impossible to later trace the gaskets, which is desirable in many situations, for example in connection with claims to be able to find the source of the problem. 
     SUMMARY 
     An object of the present invention is to provide a gasket arrangement for a plate heat exchanger, a method of manufacturing such a gasket arrangement and an assembly comprising such a gasket arrangement, that at least partly solve the issue above. The basic concept of the invention is to provide a gasket with an RFID tag for storing information at a location where it does not impair the sealing function of the gasket and where it can be read by means of an external reader. The gasket arrangement, the method and the assembly for achieving the object above are defined in the appended claims and discussed below.  
     A gasket arrangement according to the invention is adapted for use in a plate heat exchanger. It comprises a gasket, which is arranged to be positioned between first and second aligned heat transfer plates of the plate heat exchanger with a lower side of the gasket abutting the first heat transfer plate, and an opposing upper side of the gasket abutting the second heat transfer plate. It further comprises a projection projecting from an outside of the gasket. The projection comprises an outer part having a length or longitudinal extension and being arranged to extend outside or beyond the first and second heat transfer plates, and a first connection part, which connects the gasket and the outer part of the projection. The gasket arrangement is characterized in that it further comprises an RFID tag which at least partly is embedded in at least said outer part of the projection. 
     The outside and an inside of the gasket are opposing and extend between the upper and lower sides of the gasket. 
     The RFID tag may or may not extend beyond the outer part of the projection, for example also partly in the first connection part. 
     The RFID tag may or may not be completely embedded in the projection of the gasket arrangement. 
     In that the gasket arrangement comprises an RFID tag, it can easily be programmed with information of all kinds, also “dynamic”, information, such as batch number, which later may be read by means of a suitable external reader, fixedly mounted or hand-held. As an example, the RFID tag may be provided with a unique code, such as a number, which code may be connected to different kinds of information stored in a database. The RFID tag may facilitate full traceability, genuine parts identification, inventory control, etc. 
     In that the RFID tag is at least partly embedded in the projection of the gasket arrangement, it is not disconnected from the gasket in connection with gasket assembly, but rather follows the gasket, and enables traceability of the same, throughout its life. 
     The RFID tag may be of any suitable kind, such as of NFC-standard, or UHF-standard having a reading distance of 0,5-1 meter. Thereby, easy reading of the RFID tag with the reader through a packaging containing the gasket  arrangement is enabled. Further, when the gasket assembly is mounted in the plate heat exchanger, since the RFID tag is at least partly arranged in the outer part of the gasket arrangement, it will extend outside the first and second heat transfer plate, and thus the complete plate pack of the plate heat exchanger, and not be “shielded” by the plate pack. Thereby, easy reading of the RFID tag with the reader is enabled even when the gasket arrangement is assembled in the plate heat exchanger. 
     The gasket arrangement may be so designed that a length extension of the outer part of the projection is essentially parallel to a length extension of the RFID tag. This may facilitate embedding of the RFID tag in the outer part of the projection and enable a relatively compact and sleek design of the gasket arrangement. Further, this may extend the reading distance of the RFID tag. 
     The length extension of the outer part of the projection may be essentially parallel to a length extension of the gasket at the first connection part, i.e. where the first connection part joins the gasket. This may enable a relatively compact and sleek design of the gasket arrangement. 
     Further, a length extension of the first connection part of the projection may be essentially perpendicular to the length extension of the outer part of the projection. This may enable a relatively material effective design of the gasket arrangement. Further, it may enable a relatively straightforward and conventional design of the first and second heat transfer plates arranged to engage with the gasket arrangement in the plate heat exchanger. 
     The gasket arrangement may be so designed that the first connection part extends between the gasket and an intermediate portion of the outer part of the projection. This may enable a relatively mechanically robust gasket arrangement which is little prone to tangling. 
     The projection of the gasket arrangement may have any suitable design and/or function. As an example, it may be designed as a dedicated marking tab which also may be provided with printed or embossed information about the gasket. Alternatively, it may be designed as a means for attaching the gasket to the first heat transfer plate. In accordance therewith, the gasket arrangement may be so designed that the projection further comprises a first finger extending  from the outer part of the projection towards the gasket, a free end of the finger facing the gasket. Further, the first connection part and the first finger of the projection may be arranged to engage with opposite sides of the first heat transfer plate to fasten the gasket to the first heat transfer plate. Such a design makes it possible to give the projection of the gasket arrangement one or more functions in addition to the function of accommodating the RFID tag. 
     The gasket may comprise a first porthole gasket portion arranged to extend around a first porthole of the first heat transfer plate, a second porthole gasket portion arranged to extend around a second porthole of the first heat transfer plate, and an annular gasket portion having an inside which is arranged to define a fluid flow channel between the first and second heat transfer plates. The gasket may further comprise at least one first link gasket portion connecting the first porthole gasket portion and the annular gasket portion, and at least one second link gasket portion connecting the second porthole gasket portion and the annular gasket portion. The projection may project from an outer one of said at least one first link gasket portion. This may enable a positioning of the projection on the gasket having the least possible impact on the sealing function of the gasket. 
     As an alternative to the above, the gasket may comprise a first porthole gasket portion arranged to extend around a first porthole of the first heat transfer plate, wherein the projection projects from the outside of the first porthole gasket portion. This configuration may be suitable when the gasket consist of the first porthole gasket portion. It may also be suitable when the gasket lacks link gasket portions connecting the porthole gasket portions and the annular gasket portion such that these are separate, which may be the case for gasket adapted for use in semi-welded plate heat exchangers. 
     As yet an alternative, the gasket may comprise an annular gasket portion an inside of which is arranged to define a fluid flow channel between the first and second heat transfer plates, wherein the projection projects from the outside of the annular gasket portion. This configuration may be suitable when the gasket consist of the annular gasket portion. It may also be suitable when  the gasket lacks link gasket portions connecting the porthole gasket portions and the annular gasket portion such that these are separate. 
     The first and second porthole gasket portions and the annular gasket portion may be made of the same or different materials, irrespective of if they are separate or connected. 
     A method according to the invention is for manufacturing of a gasket arrangement for a plate heat exchanger, which gasket arrangement includes a gasket and a projection projecting from an outside of the gasket. The method comprises the step of providing the gasket of an elastomeric first material, the step of providing the projection of a second material, and the step of permanently joining the gasket and the projection. The method is characterized in that it further comprises the step of providing an RFID tag at least partly molded into the projection. 
     The elastomeric first material may be any suitable material, such as rubber, for example EPDM, FKM or NBR. 
     The second material can be any suitable material, such as a plastic, for example a thermo plastic or a thermosetting plastic, or rubber, for example EPDM, FKM or NBR. If the second material is rubber, this may be vulcanized or plasticized for embedding of the RFID tag. If the second material is a thermo plastic, this may be injection molded around the RFID tag for embedding of the same, or it may be preformed into a “clip” which is snapped around the RFID tag. If the second material is a thermosetting plastic, it may be of one-component type hardened by heat or UV-light, or of two-component type hardened by a chemical reaction, around the RFID tag for embedding of the same. 
     The gasket and the projection may be manufactured separately before being permanently joined. However, according to one embodiment of the method according to the invention, the step of providing the gasket comprises the sub-step of providing a mold comprising a gasket portion for molding the gasket of the gasket arrangement, the sub-step of arranging at least one blank of the elastomeric first material in the gasket portion of the mold, and the sub-step of applying heat to the mold to achieve the gasket and said permanent  joining of the gasket and the projection. According to this embodiment the projection may be separately manufactured before being permanently joined with the gasket in connection with the molding of the gasket. 
     According to another embodiment of the method according to the invention, the steps of providing the gasket and the projection comprise the sub-step of providing a mold, which comprises a gasket portion for molding the gasket of the gasket arrangement, and a projection portion projecting from an outside of the gasket portion for molding the projection of the gasket arrangement, the sub-step of arranging the RFID tag in the projection part of the mold, the sub-step of arranging at least one blank of the elastomeric first material in the gasket portion of the mold, and at least one blank of the second material in the projection portion of the mold, and the sub-step of applying heat to the mold to achieve the gasket, the projection, the RFID tag at least partly molded into the projection, and said permanent joining of the gasket and the projection. According to this embodiment the gasket and the projection are manufactured simultaneously and integrally formed. 
     The elastomeric first material and the second material may be different materials. However, according to one embodiment of the inventive method the first material and the second material is the same material, which is an elastomeric material. This may facilitate the permanent joining of the projection and the gasket. 
     The steps and sub-steps of the methods above need not be performed in the specific order given above, but could be performed in other orders. 
     An assembly according to the invention comprises a first heat transfer plate and a gasket arrangement as described above. The first heat transfer plate comprises a groove accommodating the gasket and the outer part of the projection extends outside the first heat transfer plate. 
     The above discussed advantages of the different embodiments of the gasket arrangement according to the invention are naturally transferable to the different embodiments of the method and the assembly according to the invention.  
     Still other objectives, features, aspects and advantages of the invention will appear from the following detailed description as well as from the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described in more detail with reference to the appended schematic drawings, in which 
         FIG.  1    schematically illustrates an assembly, i.e. a heat transfer plate and a gasket arrangement placed on top of the heat transfer plate, 
         FIG.  2    schematically illustrates abutting outer edges of adjacent heat transfer plates in a plate pack, as seen from the outside of a long side of the plate pack, 
         FIG.  3    schematically illustrates a cross section of a sealing portion of the gasket in  FIG.  1   , 
         FIG.  4    contains an enlargement of a first part of the gasket arrangement in  FIG.  1    and illustrates a first embodiment of the invention, 
         FIG.  5    contains an enlargement of a second part of the gasket arrangement in  FIG.  1    and illustrates a second embodiment of the invention, 
         FIG.  6    schematically illustrates proper engagement between the heat transfer plate and the gasket arrangement in  FIG.  1   , and 
         FIG.  7    schematically illustrates an RFID tag. 
     
    
    
     DETAILED DESCRIPTION 
     In  FIG.  1    a gasket arrangement  2  and a first heat transfer plate  4  for a plate heat exchanger (not illustrated) are shown. The gasket arrangement  2  and the first heat transfer plate  4  constitute an assembly  5 . The gasket arrangement  2  comprises a rubber gasket  6 . The first heat transfer plate is essentially rectangular and made of stainless steel. In the plate heat exchanger, the first heat transfer plate  4  is arranged between a second heat transfer plate  8  (illustrated in  FIG.  2   ) and a third heat transfer plate  10  (illustrated in  FIG.  2   ), and the gasket  6  seals between the first heat transfer plate  4  and the second heat transfer plate  8 . In the plate heat exchanger, the first, second and third heat transfer plates form part of a plate pack. The plates in the plate pack are all of  the same type, but in alternative embodiments they could be of different types. Further, with reference to the section of the text describing the background of the invention, the heat transfer plates in the plate pack are “rotated” in relation to each other, but in alternative embodiments they could instead be “flipped” in relation to each other. 
     The first heat transfer plate  4  comprises ( FIGS.  1  and  2   ) a first side  12 , an opposing second side  14  and first, second, third and fourth portholes  16   a - d  arranged in a respective corner of the first heat transfer plate  4 . The first heat transfer plate  4  further comprises a groove  18  on the first side  12  for receiving the gasket  6 . First and second porthole groove portions  18   a  and  18   b , respectively, of the groove  18  extend completely around a respective one of the first and second portholes  16   a  and  16   b . An annular groove portion  18   e  of the groove  18  extends along an outer edge  20  of the first heat transfer plate  4  and on the inside of the first and second porthole groove portions  18   a  and  18   b , respectively, of the groove  18 . A plurality of first link groove portions  18   f , here  7 , of the groove  18  extend between the first porthole groove portion  18   a  and the annular groove portion  18   e , while a plurality of second link groove portions  18   g , here  7 , of the groove  18  extend between the second porthole groove portion  18   b  and the annular groove portion  18   e.    
     Different areas of the first heat transfer plate  4  are provided with different corrugation patterns (not illustrated in  FIG.  1   ), and the corrugation pattern within a specific plate area is adapted to the main function of this plate area. For example, with reference to  FIGS.  1 ,  2  and  6   , an outer edge portion  22  of the first heat transfer plate  4  is provided with a strengthening corrugation extending along most of the outer edge  20  of the first heat transfer plate  4  so as to give it a wave-shape. This corrugation, which comprises alternately arranged ridges  24  and valleys  26  as seen from the first side  12  of the heat transfer plate  4 , and also corrugations within other areas of the heat transfer plate  4 , extend between and in an imaginary first plane p 1  and an imaginary second plane p 2 . A bottom of the gasket groove  18  extends in the first plane p 1 . An imaginary intermediate plane pi arranged halfway between, and parallel to, the imaginary  first and second planes p 1  and p 2  defines the border between the ridges  24  and the valleys  26  within the outer edge portion  22  of the first heat transfer plate  4 . 
     Since the first, second and third heat transfer plates are all of the same kind, the above description of the first heat transfer plate  4  is valid also for the second and third heat transfer plates  8  and  10 . 
     In the plate heat exchanger, the first side  12  of the first heat transfer plate  4  faces the second heat transfer plate  8 , while the second opposing side  14  of the first heat transfer plate  4  faces the third heat transfer plate  10 . Arranged like that, corrugations of the first heat transfer plate  4  abut corrugations of the second and third heat transfer plates  8  and  10 . 
     Simultaneously, the gasket  6  is accommodated in the gasket grooves of, and compressed between, the first and second heat transfer plates  4  and  8 , with a lower side  28  of the gasket  6  ( FIG.  3   ) facing the first heat transfer plate  4  and an upper side  30  ( FIG.  3   ) of the gasket  6  facing the second heat transfer plate  8 . A similar gasket is correspondingly arranged, and compressed between, the first and third heat transfer plates.  4  and  10   
     To fit in the groove  18 , the gasket  6  comprises, with reference to  FIG.  1   , first and second porthole gasket portions  6   a  and  6   b , respectively, arranged to be received in the first and second porthole groove portions  18   a  and  18   b , respectively, an annular gasket portion  6   e  arranged to be received in the annular groove portion  18   e , a plurality of first link gasket portions  6   f , here 7, arranged to be received in a respective one of the first link groove portions  18   f , and a plurality of second link gasket portions  6   g , here 7, arranged to be received in a respective one of the second link groove portions  18   g . Thus, in the plate heat exchanger, the first and second porthole gasket portions  6   a  and  6   b  of the gasket  6  are arranged to surround a respective one of the first and second portholes  16   a  and  16   b  of the first heat transfer plate  4  and a respective one of the portholes of the second heat transfer plate  8 , while an inside  32  of the annular gasket portion  6   e  of the gasket  6  is arranged to define a fluid flow channel between the first and second heat transfer plates  4  and  8 . The first and second link gasket portions  6   f  and  6   g  are non-sealing portions of a reduced height connecting the first and second porthole gasket portions  6   a  and  6   b  and  the annular gasket portion  6   e . It alternative embodiments these non-sealing gasket portions may be of the same height as the rest of the gasket. 
     Besides the rubber gasket  6  the gasket arrangement  2  comprises rubber projections in the form of a marking tab  34 , outer gasket attachment means  36  and inner gasket attachment means  38 . The marking tab  34  and the outer gasket attachment means  36  project from an outside  40  of the gasket  6 , while the inner gasket attachment means  38  project from an inside  42  of the first and second porthole gasket portions  6   a  and  6   b , and the inside  32  of the annular gasket portion  6   e , of the gasket  6 . The marking tab  34  and a first one  36   a  of the outer gasket attachment means  36  project from an outer one  6   f ′ of the first link gasket portions  6   f  and are illustrated in more detail in  FIGS.  4  and  5   , respectively. Each of the marking tab  34  and the first outer gasket attachment means  36   a  comprises an outer part or bridge  44  and  46 , respectively, and a first connection part  48  and  50 , respectively. The first connection parts  48  and  50  are arranged to connect the outer parts  44  and  46  to the gasket  6 . The first connection parts  48  and  50  extend from the gasket  6  essentially perpendicular to a length extension of the gasket  6  where the first connection parts  48  and  50  join the gasket  6 . Further, a respective length extension of the outer parts  44  and  46  is essentially parallel to the length extension of the gasket  6  where the first connection parts  48  and  50  join the gasket  6 . As is clear from  FIGS.  1  and  4 - 6   , the first connection parts  48  and  50  have such a length that the outer parts  44  and  46  are arranged to extend just outside the first heat transfer plate  4  and, thus, the plate pack of the plate heat exchanger. 
     The first connection part  48  of the marking tab  34  connects to an intermediate or center portion C of the outer part  44  of the marking tab  34 , while the first connection part  50  of the outer gasket attachment means  36   a  connects to a first end portion El of the outer part  46  of the outer gasket attachment means  36   a . The outer gasket attachment means  36   a  further comprises a second connection part  52  arranged to connect the outer part  46  to the gasket  6 . The second connection part  52  extend essentially parallel to, and have a similar length as, the first connection part  50 . The second connection part  52  of  the outer gasket attachment means  36   a  connects to a second end portion E 2  of the outer part  46  of the outer gasket attachment means  36   a . Finally, the outer gasket attachment means  36   a  comprises first, second and third fingers  54 ,  56  and  58 , respectively, extending, essentially parallel to the first and second connection parts  50  and  52 , from the outer part  46  of the outer gasket attachment means  36   a  towards the gasket  6 . 
     All the outer gasket attachment means  36  are configured according to the above description of the outer gasket attachment means  36   a . They are arranged to engage with the first heat transfer plate  4  to attach the gasket  6  thereto. In  FIG.  6    the engagement between the first heat transfer plate  4  and one of the outer gasket attachment means  36  is illustrated, but all of the outer gasket attachment means  36  engage in a similar way with the first heat transfer plate  4 . When the outer gasket attachment means  36  properly engage with the first heat transfer plate  4 , the first and second connection parts  50  and  52  and the second finger  56  are arranged in a respective one of the valleys  26  of the outer edge portion  22 , the first and third fingers  54  and  58  are arranged under a respective one of the ridges  24  of the outer edge portion  22 , and the outer part  46  extends outside the first heat transfer plate  4 , essentially parallel to the outer edge  20  thereof. Accordingly, the first and second connection parts  50  and  52  and the second finger  56  of the outer gasket attachment means  36  will engage with the first side  12  of the first heat transfer plate  4 , while the first and third fingers  54  and  58  of the outer gasket attachment means  36  will engage with the opposing second side  14  ( FIG.  2   ) of the first heat transfer plate  4 , to fasten the gasket  6  to the first heat transfer plate  4 . 
     When the gasket arrangement  2  is properly fastened to the first heat transfer plate  4 , the gasket  6  is arranged in the groove  18 , the outer gasket attachment means  36  all engage with the first heat transfer plate  4  as described above, the inner gasket attachment means  38  all engage with porthole edges of the first heat transfer plate  4  in not further described way, the first connection part  48  of the marking tab  34  is arranged in one of the valleys  26  of the outer edge portion  22  of the first heat transfer plate  4 , and the outer part  44  of the  marking tab  34  extends outside the first heat transfer plate  4 , essentially parallel to the outer edge  20  thereof. 
     The gasket arrangement  2  further comprises an RFID tag  60  of UHF-standard which is illustrated in  FIG.  7   .  FIGS.  4  and  5    illustrate two possible positions for the RFID tag  60 , and, thus, two different embodiments of the gasket arrangement  2  according to the invention. In  FIG.  4    the RFID tag  60  is arranged in the outer part  44  of the marking tab  34 , and in  FIG.  5    the RFID tag  60  is arranged in the outer part  46  of the first outer gasket attachment means  36   a . In both embodiments, the RFID tag  60  is embedded in the rubber and not visible from the outside, and, therefore, illustrated with ghost lines in  FIGS.  4  and  5   . Further, in both embodiments, a length extension of the RFID tag  60 , and especially a longitudinal center axis of two antennas  62  extending from a chip  61  thereof ( FIG.  7   ), is essentially parallel to the length extension of the outer part  44  and  46 , respectively. The antennas  62  have been illustrated with solid lines in the figures even if they in reality are formed as spirals extending around the longitudinal center axis of the antennas. 
     A mold (not illustrated), which comprises a gasket portion for molding the gasket  6  and projection portions for molding the marking tab  34 , the outer gasket attachment means  36  and the inner gasket attachment means  38 , is used to manufacture the gasket arrangement  2 . The mold is a conventional mold comprising two opposite parts pressed against each other to define the mold cavity, and it is not described in further detail herein. The projection portions for molding the marking tab  34  and the outer gasket attachment means  36  project from an outside of the gasket portion, while the projection portions for molding the inner gasket attachment means  38  project from an inside of the gasket portion. In a first step, the RFID tag  60  is arranged in an outer portion of the projection portion for molding the marking tab  34 , or in an outer portion of the projection portion for molding the first outer gasket attachment means  36   a , depending on whether a gasket arrangement according to  FIG.  4    or  FIG.  5    is to be manufactured. In a second step, the gasket and projection portions of the mold are filled with blanks of rubber. In a third step, the mold is heated to plasticize or vulcanize the blanks of rubber and achieve the gasket  arrangement. In connection therewith, plasticized or vulcanized rubber encapsulates the RFID tag  60  which thereby becomes embedded in the marking tab  34  or the first outer gasket arrangement  36   a . After forming, the gasket arrangement is removed from the mold in one piece. 
     Either the RFID tag is pre-programmed with a random number when received by the gasket manufacturer, or the gasket manufacturer programs the RFID tag with a random number. The random number should have a minimal chance of repetition or interference with other systems. For example, the random number could be generated by means of the UUID4 technology. The random number is paired with the corresponding manufacturing batch number in a data base, which batch number, in turn, provides information on article number, material quality, manufacturing date, manufacturing parameters, etc. At a later stage, the RFID tag  60  of the gasket arrangement  2  can be read by means of a suitable reader to access all this information for full traceability of the gasket arrangement throughout its product life cycle. For example, this could facilitate claims handling. The random number may also be paired with additional information, like information on the customer who has bought the gasket arrangement, identity of the plate heat exchanger containing the gasket arrangement, installation date, plate heat exchanger operation parameters, etc., which information may be updated if required. Such additional information could be used to make digital twins of plate heat exchangers and facilitate and predict service and maintenance of them. 
     The above described embodiments of the present invention should only be seen as examples. A person skilled in the art realizes that the embodiments discussed can be varied in a number of ways without deviating from the inventive conception. 
     As an example, the first outer gasket attachment means  36   a  and the marking tab  34  need not be positioned as illustrated in  FIG.  1    but can have other positions. For example, the first outer gasket attachment means  36   a  and the marking tab  34  could instead project from the other outer one of the first link gasket portions  6   f , or from a bridge portion of the gasket  6  adapted to be positioned below a center recess of the first heat transfer plate  4 , which bridge  portion is illustrated in  FIG.  1   . As another example, the first outer gasket attachment means  36   a  and the marking tab  34  could instead project from a sealing portion of the gasket, such as from the first porthole gasket portion  6   a , for example at ‘A’ in  FIG.  1   , or from the annular gasket portion  6   e , for example at ‘B’ in  FIG.  1   . Naturally, the gasket arrangement could also comprise two marking tabs housing a respective RFID tag; for example one marking tab projecting from the first porthole gasket portion  6   a  and one marking tab projecting from the annular gasket portion  6   e . Such an embodiment could allow separate traceability of the first porthole gasket portion and the annular gasket portion. Instead of being embedded solely in the outer portion of a projection as described above, the RFID tag could be embedded also in the first connection part of the projection, with the length extension of the RFID tag being essentially parallel to the length extension of the first connection part or not. 
     The RFID tag need not be designed as described above and illustrated in the drawings but could have any suitable design. As an example, the antennas need not be formed as three dimensional spirals but could extend, in any suitable way, in a plane. As an example, the antennas could extend from opposite sides of the chip with a wave-shape. As another example, the antennas could extend one or more turns around the chip, and the turns could have any shape, such as a round or a polygonal shape. Further, the RFID tag could comprise more or less than two antennas, and the chip may have any suitable design. Finally, the RFID tag may be comprised in a label and thus provided on a support which may be embedded in the projection. 
     The length extension of the outer part of the projection need not extend essentially perpendicular to the length extension of the first connection part of the projection, but could instead extend essentially parallel thereto to form a “prolongation” of the first connection part. 
     The first outer gasket attachment means  36   a  need not be designed as illustrated in the figures but could have other designs. For example, the first outer gasket attachment means could be designed according to U.S. Pat. No. 4,635,715 or U.S. Pat. No. 10,451,361.  
     All the outer gasket attachment means may, or may not, have a similar design. 
     The gasket assembly illustrated in  FIG.  1    is adapted for use in a plate heat exchanger of parallel flow type which means that the first and second porthole gasket portions  6   a  and  6   b  are arranged on the same side of a longitudinal center axis of the gasket arrangement. Naturally, the present invention is equally applicable in connection with a plate heat exchanger of diagonal flow type and the first and second porthole gasket portions  6   a  and  6   b  arranged on opposite sides of a longitudinal center axis of the gasket arrangement. Further, the present invention is also applicable in connection with other types of plate heat exchangers, such as fresh water generators having portholes arranged along a longitudinal center axis of the plate heat exchanger. 
     The complete gasket arrangement need not be molded in one single step. For example, the marking tab including the RFID tag could be molded in a first step, and the rest of the gasket arrangement could be molded in a second step. Then, the pre-molded marking tab, including the RFID tag, could be arranged in the mold for making the gasket arrangement and be “automatically” bonded to the gasket in connection with molding of the rest of the gasket arrangement. Alternatively, the marking tab, including the RFID tag could be molded in a separate mold, and the rest of the gasket could be molded in a separate mold, and then the marking tab and the rest of the gasket arrangement could be connected in a separate step. Naturally, corresponding alternative manufacturing methods are possible with the RFID tag instead arranged embedded in the first outer gasket attachment means. 
     The RFID tag need not be molded into the marking tab or the first outer gasket attachment means by letting plasticized or vulcanized rubber or other material encapsulate the RFID tag. According to an alternative manufacturing method, an incision is made in the marking tab or the first outer gasket attachment means after molding, and the RFID tag is inserted through this incision.  
     The complete or a part of the gasket arrangement could be made of another material than rubber. Similarly, the heat transfer plates could be made of another material than stainless steel, such as titanium or aluminum. 
     The above described heat transfer plates are so designed that the gasket groove and the valleys within the outer edge portion are in the same plane. Naturally, the present invention is equally applicable in connection with heat transfer plates of other designs, for example heat transfer plates comprising gasket grooves arranged in half-plane. 
     Finally, the present invention could be used in connection with other types of plate heat exchangers than purely gasketed ones, e.g. plate heat exchangers comprising partly/only permanently joined heat transfer plates, such as welded and semi-welded heat exchangers. 
     It should be stressed that a description of details not relevant to the present invention has been omitted and that the figures are just schematic and not drawn according to scale. It should also be said that some of the figures have been more simplified than others. Therefore, some components may be illustrated in one figure but left out in another figure. Finally, as used herein, the prefixes “first”, “second”, “top”, “bottom”, “upper”, “lower”, “horizontal”, “vertical” etc. are used only to distinguish between different components and pose no requirements as regards relative positioning or orientation.