Sealing and Electrical Insulation of the Field Device Interface

Abstract

The industrial process field device (102) includes a pressure sensor (126) and a housing (144) that houses the pressure sensor. The housing (144) includes a base (146) having a base interface (150) and a first base process opening. A flange (155) is attached to the base (146) and includes a flange interface (152) having a first flange process opening. Pressure (126) at the first flange process opening is communicated to the pressure sensor (126) through the first base process opening. A first gasket process opening (170) of the gasket (115) is aligned with the first base process opening and the first flange process opening. A first surface of the gasket (115) engages the base interface (150) and a second surface of the gasket (115) engages the flange interface (152). The dielectric insulation system (120) includes at least one dielectric layer (184) that insulates the housing (114) from electrical current conducted through the flange (155). Each dielectric layer (184) includes a layer of ceramic material, an anodized layer, or a plastic overmold.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to an industrial process control system for an industrial plant. More specifically, embodiments of the present disclosure relate to applying dielectric insulation to industrial process field devices to protect the electronics of the field devices from the current of a cathodic protection method conducted through a process interface.

Background Art

[0002] In an industrial environment, control systems are used to monitor and control industrial processes and inventories of chemical processes, and the like. Typically, the control system performs these functions using industrial process field devices that are distributed at key locations in the industrial process and coupled to control circuit sections within the control system by process control loops. The term "field device" refers to any device that performs a function within a distributed control or process monitoring system used for measuring, controlling, and / or monitoring an industrial process, including all devices now known or hereafter to become known.

Summary of the Invention

Problems to be Solved by the Invention

[0003] A typical field device includes a device circuit that can cause the field device to perform tasks of conventional field devices, such as monitoring and measuring process parameters using one or more sensors and / or performing process control operations using one or more control devices. Exemplary sensors include pressure sensors, level sensors, temperature sensors, and other sensors used in industrial processes. Exemplary control devices include actuators, solenoids, valves, and other control devices.

[0004] The equipment circuit section of the field device controls sensors and / or control devices and may also include a controller used to communicate with a process control system or other circuit sections via a process control loop such as a 4-20 mA process control loop. In a certain facility, the process control loop is used to send regulated current and / or voltage to the field device to power the field device. The process control loop can also carry data such as process parameter values corresponding to the detected process parameters. This data may be communicated as an analog signal or as a digital signal via the process control loop.

[0005] The cathodic protection method is a technique used to protect metal structures such as pipes and tanks from corrosion by making the structure the cathode side of an electrochemical cell in many industrial applications. For example, a large pipeline structure may use an external power source cathodic protection system that connects the structure to a DC power source. When such a cathodic protection method is implemented on a structure, it is necessary to electrically insulate the field device coupled to the structure from this method to protect the electronics of the field device.

Means for Solving the Problem

[0006] Embodiments of the present disclosure include a field device assembly including a dielectric insulation system and a dielectric insulation system for use in an industrial process field device assembly. One embodiment of the field device assembly includes an industrial process field device, which includes a pressure sensor and a housing that houses the pressure sensor. The housing includes a base having a base interface surface and a first base process opening. A flange is attached to the base and includes a flange interface surface having a first flange process opening. The pressure of the first flange process opening is transmitted to the pressure sensor through the first base process opening. The first gasket process opening of the gasket is aligned with the first base process opening and the first flange process opening. The gasket includes a first surface that engages the base interface surface and a second surface that engages the flange interface surface on the opposite side of the first surface. A dielectric insulation system including at least one dielectric layer insulates the housing from current conducted through the flange. Each of the at least one dielectric layer includes a layer of ceramic material, an anodized layer, or a plastic overmold.

[0007] One embodiment of the dielectric insulation system includes a gasket having a metal body and a dielectric layer. The dielectric layer includes a ceramic coating on the outer surface of the metal body or an anodized outer surface of the metal body.

[0008] Another embodiment of the dielectric insulation system includes a sleeve portion, a shoulder attached to an end of the sleeve portion, and a bolt spacer having a dielectric layer. The shoulder has a diameter larger than the outer diameter of the sleeve portion. The dielectric layer is a ceramic body forming the sleeve portion and the shoulder, a ceramic material overmolded with a plastic material to form the shoulder, a metal body having an anodized outer surface, the metal body forming the sleeve portion and the shoulder, or a metal body having a ceramic coating on the outer surface of the metal body, the metal body forming the sleeve portion and the shoulder.

[0009] This summary is provided to introduce in concise form a selection of concepts that are further described in detail in the following detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to embodiments that solve any or all of the disadvantages noted in the background. **Brief Description of the Drawings**

[0010]

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DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Elements identified using the same or similar reference numerals indicate the same or similar elements. The various embodiments of the present disclosure can be implemented in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided to make the present disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art.

[0012] FIG. 1 is a schematic diagram of an exemplary industrial process measurement or control system 100 according to the prior art. System 100 is used in the processing of materials to convert them from a low-value state to more valuable useful products such as oil, chemicals, paper, food, etc. For example, an oil refinery performs an industrial process that can process crude oil into gasoline, fuel oil, and other petrochemical products.

[0013] System 100 includes a field device assembly 101, which includes industrial process field devices 102, transmitter flanges or adapters 103, manifolds 104, and / or a process interface 106 that connects the manifold 104 and the field devices 102 to the industrial process 108. In some embodiments, the process 108 requires process materials such as fluids (i.e., liquids or gases) that are contained or conveyed by a process vessel 110 such as a pipe, tank, or another process vessel.

[0014] The cathodic protection system 112 can be used to apply corrosion protection to the pipe 110 or to other structures to which the field device 102, such as a tank, is attached. The cathodic protection system 112 can take any suitable form, such as, for example, an impressed current cathodic protection system or a galvanic cathodic protection system.

[0015] Figure 2 is an isometric view of an example of a field device assembly 101A disassembled from the process interface 106 according to an embodiment of the present disclosure, and Figure 3 is an isometric view of the assembly 101A of Figure 2 attached to the process interface 106. Here, the field device 102 of the assembly 101A may be attached to an adapter 103, which is attached to a manifold 104 attached to the process interface 106. The adapter 103 substantially conforms the flow path of the field device 102 to the flow path of the manifold 104. The assembly 101A can be sealed and electrically insulated from the cathodic protection system 112 using conventional techniques and / or the techniques described herein at the junction or interface 113A between the field device 102 and the adapter 103, the junction 113B between the adapter 103 and the manifold 104, and the junction 113C between the manifold 104 and the process interface 106. The assembly 101A requires sealing of four potential leak paths. Three of the leak paths are located at the interfaces or junctions 113A - 113C, and one of the leak paths is located at the junction between the process interface 106 and the process 108.

[0016] Alternatively, the field device assembly 101B may include a field device 102 directly attached to the manifold 104, as shown in the side view of Figure 4 and the exploded isometric view of Figure 5. Figure 4 also schematically shows the attachment of the field device assembly 101B to the process interface 106 and the process 108, indicated by phantom lines. This embodiment of the field device assembly 101 reduces the number of potential leak paths to three. For example, the assembly 101B includes a leak path between the process interface 106 and the process 108 and a leak path 113C between the manifold 104 and the process interface 106, but replaces the two leak paths 113A and 113B associated with the adapter 103 with one leak path 113D between the manifold 104 and the field device 102. Thus, the field device assembly 101B may be more preferable than the assembly 101A.

[0017] Embodiments of the present disclosure can be applied to other field device assembly configurations, along with field device assemblies 101A and 101B, which may also be referred to as field device assembly 101 in its entirety.

[0018] The field device assembly 101 can include gaskets 115 on one or more of the illustrated boundary surfaces 113 that are potential leak paths, as shown in FIGS. 2 and 5. Each of the gaskets 115 serves to seal the flow paths through the boundary surfaces 113 between the components of the assembly 101. Additionally, the seals formed on the boundary surfaces 113 of the assembly 101 may include O-rings and other components to provide the desired seal, if necessary. For example, an O-ring 118 can form a seal between the field device 102 and the gasket 113 at the boundary surface 113D of the assembly 101B, as shown in FIG. 6, which is a partial cross-sectional view of the field device assembly 101B at the boundary surface 113D according to an embodiment of the present disclosure.

[0019] In some embodiments, the field devices 101A and 101B each include a dielectric insulation system 120 (phantom lines) as shown in FIGS. 2 and 4, formed according to one or more embodiments of the present disclosure. The system 120 serves to protect the electronics 121 (FIG. 4) of the field device 102 from charges and currents that can be conducted through the process boundary 106 and other components of the assembly 101, such as those generated by the cathodic protection method implemented by the system 112 (FIG. 1).

[0020] System 120 generally includes one or more dielectric layers that insulate the field device 102 or the electronics of the field device 102 from charge or current conducted through the process interface 106, such as at the interface 113A between, for example, the field device 102 and the adapter 103 of the field device 101A (FIG. 3), or at the interface 113D between the field device 102 and the manifold 104 of the assembly 101B (FIG. 4). Those skilled in the art will understand that one or more dielectric layers of the system 120 may be located at other interfaces of the field assembly 101A or 101B while providing the desired electrical insulation, such as at the interfaces 113B and / or 113C (FIG. 2). Thus, although examples of embodiments of the system 120 may be described with reference to the interface 113D between the manifold 104 of the assembly 101B and the field device 102, it is understood that the disclosed embodiments relate to the other interfaces 113 of the assembly 101B as well as the interfaces 113 of the assembly 101A. Accordingly, the embodiments described in relation to the interface 113D can be applied to these other interfaces as well.

[0021] Before describing embodiments of the system 120 in detail, the features of the field device 102 will be described with reference to FIG. 1 and FIG. 7, which is a simplified block diagram of an exemplary field device 102 in the form of a pressure transmitter according to an embodiment of the present disclosure.

[0022] The field device 102 can communicate with a computerized control unit 122 that can be configured to control the field device 102. The control unit 122 can be located remotely from the field device 102, such as in the control room of the system 100 as shown in FIG. 1. The control unit 122 can be communicatively coupled to the field device 102 via a suitable physical communication link, such as a two-wire control loop 123, or a wireless communication link.

[0023] The communication between the control unit 122 and the field device 102 may be performed via the control loop 123 in accordance with conventional analog and / or digital communication protocols. In some embodiments, the process control loop 123 includes a 4 - 20 milliamp process control loop, where the process variable may be represented by the level of the loop current I (FIG. 7) flowing through the process control loop 123. Exemplary digital communication protocols include modulation of a digital signal onto the analog current level of the two - wire process control loop 123, such as that according to the HART (registered trademark) communication standard. Other pure digital technologies may be employed, including fieldbus and Profibus communication protocols. Wireless protocols such as IEC 62591 may also be employed.

[0024] In some embodiments, the field device 102 is in the form of a pressure transmitter configured to sense a single pressure or differential pressure of the process 108. The field device includes a controller 124, one or more pressure sensors 126, a measurement circuit section 128, a digital - to - analog converter (DAC) 130, a communication circuit 132, and / or a terminal block 134, as illustrated in FIG. 7.

[0025] The controller 124 may be one or more processors (i.e., microprocessors, central processing units, etc.) that control the components of the field device 102 in response to the execution of instructions, where the instructions can be stored locally in a non-transitory computer-readable medium or memory 136 of the device 102. In some embodiments, the processor of the controller 124 is a component of one or more computer-based systems. The controller 124 can include one or more control circuits, a microprocessor-based engine control system, one or more programmable hardware components such as a field programmable gate array (FPGA), and use these to control the components of the device 102 to perform one or more functions described herein. The controller 124 may also be other conventional field device circuitry.

[0026] The valves 125 of the manifold 104 can be adjusted to expose the field device 102 to the process 108, such as through the process interface 106, in accordance with a conventional manifold 104. Thereby, the field device 102 can detect or measure the pressure or differential pressure of the process 108 using one or more pressure sensors represented by block 126 in FIG. 7.

[0027] The measurement circuitry 128 represents circuitry that interacts with the sensor 126. For example, the circuitry 128 can include circuitry that converts the output from the sensor 126 for use by the controller 124 of the field device 102.

[0028] The DAC 130 can be used by the controller 124 to convert a digital signal into an analog signal that is communicated to the control unit 122, for example, by adjusting the loop current I to indicate the value of a process parameter detected by the sensor 126, such as via the two-wire process control loop 123, using the communication circuit 132. The controller 124 can also receive communications from the control unit 122 through the communication circuit 132 using conventional techniques.

[0029] As shown in FIG. 4, the field device 102 includes a housing 144 that surrounds the electronics 121 of the field device 102 and protects it from environmental conditions. The housing 144 includes a base 146 that can be attached to the adapter 103 or the manifold 104 using bolts 148, as shown in FIGS. 3 and 4 respectively.

[0030] FIG. 8 is a simplified cross-sectional view of a portion of the assembly 101B taken generally along line 8-8 of FIG. 5 when the assembly 101B is assembled (FIG. 4). In some embodiments, the interface surface 113D between the field device 102 and the manifold 104 is formed between the base surface of the base 146 or the interface surface 150 and the flange surface of the flange 155 of the manifold 104 or the interface surface 152 (e.g., an interface surface on the same plane). The interface surface 152 includes one or more manifold process openings 154 that are aligned with the plane of the flange 155 of the manifold 104, such as the manifold process openings 154A and 154B.

[0031] The interface surface 152 on the same plane is depicted as being formed on the flange 155 of the manifold 104. However, embodiments of the field device assembly 101 can utilize any suitable flange having an interface surface 152, such as the flange of the adapter 103, a traditional flange, a coplanar flange, a flange of the German Institute for Standardization (DIN), or other flanges, instead of the illustrated manifold 104. Thus, in some embodiments, the flange 155 represents these flanges and is not limited to the flange of the manifold 104. In this way, embodiments of the field device assembly 101 to which embodiments of the present disclosure pertain include, for example, a combination of a field device 102, a flange 155 having an interface surface 152 (e.g., a flange interface surface), and one or more openings 154.

[0032] In some embodiments, the openings 154A and 154B are open to corresponding fluid passages 156 of the manifold 104 (i.e., the flange 155), such as the fluid passages 156A and 156B, as illustrated in FIG. 8. The fluid passages 156A and 156B can be coupled to the process 108 through a suitable process interface 106, as illustrated in FIG. 4. The manifold interface surface 152 can be made substantially flat.

[0033] The base interface surface 150 includes one or more base process openings 158 configured to align with corresponding manifold process openings 154A and 154B, such as the base process openings 158A and 158B. The base process openings 158 expose one or more sensors 126 of the field device 102 to the process provided by the manifold 104 through the passage 156. The base interface surface 150 can be made substantially flat.

[0034] One or more manifold process openings 154 and base process openings 158 can be used to expose sensor 126 to process parameters of process 108 communicated through process interface 106. For example, the field device 102 illustrated in FIG. 8 is in the form of a differential pressure transmitter including diaphragms 160A and 160B, which are exposed to pressures P1 and P2 of process 108 within passages 156A and 156B of manifold 104 through manifold process openings 154A and 154B and base process openings 158A and 158B, respectively. Diaphragms 160A and 160B curve in response to pressures P1 and P2. The curved diaphragms 160A and 160B transmit the sensed pressures to pressure sensor 126 through lines 162A and 162B, which may be filled with a hydraulic fluid. Measurement circuitry 128 can receive one or more signals from sensor 126 and generate a differential pressure signal indicated by arrow 164. Controller 124 can communicate the differential pressure measurement indicated by signal 164 to control unit 122 using any suitable technique, such as adjusting current I through two-wire process control loop 123 as described above with reference to FIG. 7.

[0035] In some embodiments, gasket 115, and optionally, O-ring 118, act to form sealed passages 165A and 165B at interface 113D between manifold process openings 154A and 154B and base process openings 158A and 158B, preventing leakage of process fluid at interface 113D and ensuring that appropriate process measurements (e.g., pressure measurements) are made.

[0036] The exemplary field device 102 of FIGS. 3, 4, and 8 can be in the form of a differential pressure transmitter, but it is understood that embodiments of the present disclosure are not limited to differential pressure transmitters. That is, embodiments of the system 120 described herein can be used with other types of field devices 102 and assemblies 101 where the system 120 may be useful for applying dielectric insulation, such as, for example, field devices that measure pressure, measure temperature, measure flow rate, measure another process parameter, and / or control a process.

[0037] The gasket 115 can take any suitable form for sealing one or more passages at the interface 113D, such as passages 165A and 165B. FIG. 9 is a bottom view of an example of a gasket 115 configured to seal passages 165A and 165B. The gasket 115 includes one or more gasket process openings 170 corresponding to the base process opening 158 and the manifold process opening 154. For example, the gasket 115 may include gasket process openings 170A and 170B that are aligned with corresponding base process openings 158A and 158B and manifold process openings 154A and 154B, respectively, as illustrated in FIG. 10, which is an isometric view of an exemplary manifold 104 illustrating the alignment of gasket opening 170 with manifold opening 154. The gasket 115 may also include bolt openings 171 through which bolts 148 can pass to attach the manifold 104 to the base 146. The gasket 115 is clamped between the surfaces 150 and 152 to seal the passages 165A and 165B and the interface 113D. The gasket 115 of FIG. 9 may include an annular protrusion 174 around the openings 170A and 170B to assist in sealing the passages 165A and 165B.

[0038] FIG. 11 is an isometric view of an example of a gasket 115 having one gasket process opening 170 for sealing one of the passages 165. Thus, when the field device 102 is configured to couple to two process parameters (e.g., process pressure) through individual passages 165, one of the gaskets 115 may be used for each of the passages 165 at the interface surface 113C as shown in FIG. 2. The gasket 115 may include bolt openings or cutout holes 172 through which bolts connecting the manifold 104 to the base 146 can pass. In some embodiments, the gasket 115 includes an annular protrusion 174 around the opening 170 to assist in the sealing function.

[0039] FIG. 12 is a simplified cross-sectional view showing the features of an electrical insulation system 120 according to an embodiment of the present disclosure at the interface 113 between the metal components 180 and 182 of the field device assembly 101. The system 120 includes one or more dielectric layers 184 that electrically insulate the field device 102 from the interface surface 106 or the process vessel 110 and act to protect the electronics 121 of the field device 102 from cathodic protection methods implemented in the process vessel 110, such as by the system 112 (FIG. 1). As a result, the system 120 eliminates conductive paths between the housing 144 of the field device, the manifold 104, the adapter 103 (if present), the process interface 106 (FIGS. 3 and 4), and the process vessel 110 to protect the electronics 121 (FIG. 4) of the field device 102.

[0040] In some embodiments, the dielectric layer 184 may form a portion of the gasket 115 that seals the interface 113 between the components 180 and 182, a portion of the surface 186 of the component 180, and / or a portion of the surface 188 of the component 182. For example, the component 180 may be the base 146, and the component 182 may be a flange, such as the flange 155 (interface 113D) of the manifold 104, the flange of the adapter 103 (interface 113A), or another flange attached to the base 146. Here, embodiments of the dielectric layer 184 may include, for example, a seal between the components 180 and 182 (e.g., sealing the interface 113A or 113B), a coating or layer on the surface 150 of the base 146 corresponding to the surface 186, and / or a coating or layer on the surface 152 of the flange of the manifold 104 or the adapter 103 corresponding to the surface 188, which acts to form such.

[0041] In some embodiments, the interface 113 illustrated in FIG. 12 may be the interface or junction between one of the bolts 148 and the base 146 or the manifold 104, and the insulation system 120 may form a portion of the bolt spacer 190 through which one of the bolts 148 passes, as illustrated in FIGS. 2 and 5. Here, the dielectric layer 184 of the bolt spacer 190 prevents current from passing between the base 146 and the manifold 104 through the bolt 148.

[0042] Each dielectric layer 184 of system 120 can take various forms. In one embodiment, the dielectric layer 184 includes a layer of ceramic material. In one embodiment, the layer 184 of ceramic material includes alumina, which can be applied to the metal bodies 180 and / or 182 by chemical vapor deposition or another suitable technique. Other examples of suitable ceramic materials that can form one of the dielectric layers 184 include nanopolymer adhesion coatings such as silicon dioxide (SiO2) or titanium dioxide (TiO2), or spray coatings such as ceramcoats (epoxy-ceramic formulations). In some examples, the layer 184 of ceramic material has a thickness of about 300 micrometers, and when the layer 184 is made of alumina, the layer 184 should withstand electricity of about DC 2500V. The thickness of the layer 184 can be increased or decreased to provide the desired electrical insulation.

[0043] In some embodiments, the layer 184 of ceramic material may be formed on the surface 186 and / or the surface 188, for example, the metal surface 150 of the base 146, and / or the metal surface 152 of the flange 155 of the manifold 104 or the flange of the adapter 103 as shown in FIG. 12. The layer 184 of ceramic material may be applied to the metal bodies forming the gasket 115 or the bolt spacer 190 as described below.

[0044] In some embodiments, one or more dielectric layers 184 forming the system 120 include a number of layers 192 such as layers 192A - 192C shown by the phantom lines in FIG. 12. For example, in some embodiments, the layer 184 includes a layer 192A of ceramic material overmolded with layers 192B and / or 192C of plastic material such as, for example, PEEK, Delrin® (acetal homopolymer), nylon, Santoprene TM , and other thermoplastic elastomers.

[0045] In yet another embodiment, the dielectric layer 184 includes an anodized layer or anodic layer, such as one formed on an anodized metal body or an anodic coating on a metal body. When the metal body is aluminum, the anodized layer or anodic layer 184 should provide a breakdown voltage of about 900 - 1000 volts / mil. In some embodiments, the anodized layer or anodic layer 184 can be about 0.0025 inches thick, which should provide insulation from about 2250 - 2500 volts.

[0046] The dielectric layer 184 can be formed by an anodized layer on a metal surface 186 that can also be the surface 150 of the base 146, and / or on a metal surface 188 that can also be the surface 152 of the flange 155 of the manifold 104, the flange of the adapter 103, or another flange connected to the base 146. The metal body forming the gasket 115 or the bolt spacer 190 can also include an anodized layer form of the dielectric layer 184, as described below.

[0047] FIG. 13 is an isometric view of an example of a bolt spacer 190 forming components of a dielectric insulation system 120 according to an embodiment of the present disclosure, and FIGS. 14 and 15 are cross-sectional views of the bolt spacer 190 of FIG. 13. As shown in FIG. 13, the bolt spacer 190 may include a sleeve portion 200 and a shoulder 202 attached to an end 204 of the sleeve portion 200. The sleeve portion 200 is generally configured to be inserted into a hole in the base 146 or the manifold 104 and includes a hole 206 through which one of the bolts 148 can pass, as schematically illustrated in FIG. 5. The shoulder 202 has an outer diameter larger than that of the sleeve portion 200 and the hole into which the sleeve portion 200 is inserted, separating the head of the bolt 148 or the nut attached to the bolt 148 from the base 146 or the manifold 104 into which the bolt spacer 190 is inserted, and limiting the distance that the bolt spacer 190 can be inserted into the hole in the base 146 or the manifold 104, as illustrated in FIG. 4.

[0048] Conventional plastic gaskets and bolt spacers, such as those made from polyoxymethylene (POM) sold under the trademark Derlin® (registered trademark), are subject to creep and environmental degradation. Additionally, plastic gaskets and bolt spacers have limited pressure ratings. As a result, conventional plastic gaskets and bolt spacers are generally not suitable for high-pressure applications (e.g., 6k - 10k psi) and have short lifetimes and require frequent replacement (e.g., every 3 - 12 months). Using polyetheretherketone (PEEK) instead of POM may not significantly improve the problems of POM.

[0049] In one embodiment, each sleeve portion 200 and shoulder portion 202 of the bolt spacer 190 of the field device assembly 101 includes or is made from a ceramic material. Thus, the bolt spacer 190 can include a ceramic body forming the sleeve portion 200 and the shoulder portion 202. Accordingly, each bolt spacer 190 forms one of the dielectric layers 184 of the system 120. This embodiment of the bolt spacer 190 is determined to be able to withstand high tightening forces of 5,000 lbf or more, which are generally required to achieve the operating pressure of the devices disclosed for interfacing surfaces on the same plane in a field device assembly. The ceramic form of the bolt spacer 190 provides advantages such as reduced deformation at high tightening forces compared to bolt spacers made from other materials such as PEEK.

[0050] In the embodiment illustrated in FIG. 14, the bolt spacer 190 includes a ring of ceramic material 210 in the shoulder portion 202, forming a layer of ceramic material of the dielectric layer 184. In one embodiment, the ring of ceramic material 210 is overmolded with a plastic material 212. Thus, the ring of ceramic material 210 generally corresponds to layer 194A of the dielectric layer 184 illustrated in FIG. 12, and the overmolded plastic material 212 generally corresponds to layers 192B and 192C.

[0051] As shown in FIG. 14, the overmolded plastic 212 may also form a sleeve portion 200. The ring of ceramic material 210 adds rigidity to the bolt spacer 190, preventing creep while providing the electrical insulation properties necessary for dielectric insulation. The combination of ceramic material and plastic material gives the bolt spacer 190 improved strength and electrical insulation properties over conventional single-material bolt spacers such as those made from POM or PEEK.

[0052] Due to the dielectric insulation provided by the ring of ceramic material 210, the overmolded plastic material 212 is not limited to low-performance plastics such as PEEK or POM. Instead, the plastic overmold material 212 can include plastics that are softer compared to PEEK or POM, which provide compressive energy, such as Santoprene TM or other thermoplastic elastomers.

[0053] In the embodiment illustrated in FIG. 15, the bolt spacer 190 includes a metal body 214 (e.g., stainless steel) that forms the structure of the sleeve portion 200 and the shoulder portion 202, and a coating or layer 216 that covers the outer surface 218 of the metal body 214. In one embodiment, the layer 216 includes the layer 192 of the ceramic material described above and forms one of the dielectric layers 184 of the system 120.

[0054] In another embodiment, the coating or layer 216 includes the anodized layer described above and forms one of the dielectric layers 184 of the system 120 on the bolt spacer 190.

[0055] In another example, the ring of material 210 of the exemplary bolt spacer 190 illustrated in FIG. 14 is made of a metal body and overmolded with plastic 212. Similarly, the embodiment of the bolt spacer 190 illustrated in FIG. 15 may utilize a plastic overmold as the coating 216 on the metal body 214.

[0056] FIG. 16 is a simplified cross-sectional view of a portion of an example gasket 115 of a field device assembly 101 that forms components of a dielectric insulation system 120, according to an embodiment of the present disclosure. The gasket 115 can be configured to seal an interface 113 of the field device assembly, such as an interface between the base 146 and a flange 155 to which the base 146 is attached, such as a flange of the manifold 104 (FIGS. 4 and 5), a flange of the adapter 103 (FIGS. 2 and 3), or another flange attached to the base 146. The gasket 115 includes at least one process opening 170 configured to align with a process opening 158 of the base 146 and process openings of a flange 155 attached to the base 146, such as a process opening 154 of the manifold 104. The gasket 115 may include two process openings 170 as illustrated by the gasket 115 of FIG. 9, one process opening 170 as illustrated by the gasket 115 of FIG. 11, or the gasket 115 may have another process opening configuration determined by the base 146 of the field device 102 and the flange 155 to which the base 146 is connected.

[0057] In some embodiments, the gasket 115 includes a metal body 220 and at least one coating or layer 222, such as a layer 222A on the top surface 224 and / or a layer 222B on the bottom surface 226, as illustrated in FIG. 16. The layers can each form one of the dielectric layers 184 of the system 120. Thus, of the dielectric layers 184 illustrated in FIG. 12, the metal body 220 can correspond to layer 192A, the coating or layer 222A can correspond to layer 192B, and the coating or layer 222B can correspond to layer 192C. The metal body 220 of the gasket 115 provides improvements over its plastic counterpart, such as reduced deformation, extended life, and increased maximum operating pressure (e.g., 6092 - 10 k psi).

[0058] In one embodiment, each of the one or more layers 222 includes a layer of ceramic material that forms the dielectric layer 184 of the system 120. Alternatively, each of the one or more layers 222 may include an anodized material or layer that forms one of the dielectric layers 184.

[0059] Embodiments of the dielectric layer 184 that include an anodized layer or anode layer on a metallic body can be formed using any suitable technique. FIGS. 17-20 are simplified cross-sectional views of examples of techniques for forming an anodized layer or anode layer on a surface 230 of a metallic body 232, such as the upper surface 224 or bottom surface 226 of the metallic body 220 of the gasket 115 (FIG. 16), the outer surface 218 of the metallic body 214 of the bolt spacer 190 (FIG. 15), the surface 150 of the base 146 of the field device 102, the surface 152 of the flange 155 (e.g., the manifold 104 or adapter 103), and / or another metallic surface that forms one of the dielectric layers 184 of the dielectric insulation system 120.

[0060] In some embodiments, the metallic body 232 can include aluminum (e.g., 6061 aluminum) or another suitable metal. Initially, the metallic body 220 may have an outer surface 230 that is dirty, contaminated with oil or other material 234, and may include one or more defects 236 as shown in FIG. 17. In one embodiment, the surface 230 is cleaned and / or polished using any suitable technique to obtain the clean surface 230 shown in FIG. 18. For example, the contaminated surface 230 of FIG. 17 may be cleaned using an alkaline or by another suitable technique.

[0061] The metallic body 232 can be anodized using conventional anodizing techniques such that the surface 230 is converted to an anode layer 238 (e.g., a porous oxide layer) as illustrated in FIG. 19. The anode layer 238 may form one of the dielectric layers 184 of the system 120.

[0062] In some embodiments, the anode layer 238 can also be acid-etched to provide an etched outer surface 240, as shown in FIG. 20. This can provide a more uniform appearance to the surface 230 and can also be used to adjust the electrical insulation of the anode layer 238.

[0063] Although the embodiments of the present disclosure have been described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the present disclosure.

Description of Reference Numerals

[0064] 102…Industrial process field device 115…Gasket 120…Dielectric insulation system 126…Pressure sensor 144…Housing 146…Base 150…Base interface 152…Flange interface 155…Flange 170…First gasket process opening 184…Dielectric layer

Claims

1. A field device assembly comprising: a pressure sensor, and a housing comprising a base that houses the pressure sensor and includes a base interface surface having a first base process opening, an industrial process field device; a flange mounted to the base of the housing and including a flange interface surface having a first flange process opening, wherein pressure in the first flange process opening is transmitted to the pressure sensor through the first base process opening; a gasket including a first gasket process opening aligned with the first base process opening and the first flange process opening, a first surface engaging the base interface surface, and a second surface engaging the flange interface surface on an opposite side of the first surface; a dielectric insulation system including at least one dielectric layer that insulates the housing from an electric current conducted through the flange, each of the at least one dielectric layer including a layer of ceramic material and / or an anodized layer; wherein a surface of the base interface surface and / or a surface of the flange interface surface includes a metallic body having an outer surface that includes the anodized layer, the metallic body forming one of the at least one dielectric layer. A field device assembly

2. The field device assembly of claim 1, wherein one of the at least one dielectric layer includes a layer of the ceramic material on a metallic surface.

3. The field device assembly of claim 1, wherein one of the at least one dielectric layer includes a layer of the ceramic material overmolded with a plastic material.

4. The field device assembly of claim 1, wherein one of the at least one dielectric layer includes the anodized layer.

5. The field device assembly of claim 2, wherein the gasket includes a metallic body having a ceramic coating that forms a layer of the ceramic material on a metallic surface.

6. The field device assembly of claim 1, wherein the gasket includes a metallic body having an outer surface that includes the anodized layer.

7. The base interface surface includes a second base process opening, the flange interface surface includes a second flange process opening, and pressure in the second flange process opening is transmitted to the pressure sensor through the second base process opening via a second pressure sensing line. ​ ​ The gasket includes a second gasket process opening that is aligned with the second base process opening and the second flange process opening, the gasket includes one of the at least one dielectric layer, The field device assembly according to claim 1.

8. The assembly includes a plurality of bolts and a plurality of bolt spacers, each bolt passes through the base and the flange, and further extends through one of the bolt spacers that separates the bolt from the base or the flange, each of the bolt spacers includes one of the at least one dielectric layer, The field device assembly according to claim 1.

9. The field device assembly according to claim 8, wherein each of the plurality of bolt spacers includes a portion made of a ceramic material that forms a layer of the ceramic material.

10. The field device assembly according to claim 9, wherein each of the bolt spacers includes a sleeve portion configured to be received in a corresponding hole in the base or the flange, and a shoulder mounted to an end of the sleeve portion, the shoulder having a diameter larger than an outer diameter of the sleeve portion and including the portion made of a ceramic material.

11. The field device assembly according to claim 10, wherein the portion of each of the bolt spacers made of a ceramic material is overmolded with a plastic material.

12. The field device assembly according to claim 8, wherein each of the plurality of bolt spacers includes a metal body coated with a layer of the ceramic material, which forms one of the at least one dielectric layer.

13. The field device assembly according to claim 8, wherein each of the plurality of bolt spacers includes a metal body having an outer surface including the anodized layer, which forms one of the at least one dielectric layer.

14. The field device assembly according to claim 1, wherein a surface of the base interface and / or a surface of the flange interface includes a layer of the ceramic material, which forms one of the at least one dielectric layer.

15. A dielectric insulation system including a bolt spacer, a sleeve portion, a shoulder mounted to an end of the sleeve portion and having a diameter larger than an outer diameter of the sleeve portion, The dielectric layer includes one of the following: a ceramic body in which the sleeve portion and the shoulder portion include a ceramic body; a ceramic material overmolded with a plastic material, in which the shoulder portion includes a ceramic material overmolded with a plastic material; a metal body with an anodized outer surface, in which the sleeve portion and the shoulder portion include a metal body; a metal body with a ceramic coating on the outer surface of the metal body, in which the sleeve portion and the shoulder portion include a metal body; a metal body overmolded with a plastic material, in which the shoulder portion includes a metal body overmolded with a plastic material, and a metal body overmolded with a plastic material, in which the sleeve portion and the shoulder portion include a metal body overmolded with a plastic material, and a dielectric layer comprising one of the above. A dielectric insulation system. **Claim 16** The system according to claim 15, wherein the dielectric layer includes the ceramic body. **Claim 17** The system according to claim 15, wherein the dielectric layer includes the ceramic material overmolded with a plastic material. **Claim 18** The system according to claim 15, wherein the dielectric layer includes the metal body with the anodized outer surface. **Claim 19** The system according to claim 15, wherein the dielectric layer includes the metal body with the ceramic coating on the outer surface. **Claim 20** The system according to claim 15, wherein the dielectric layer includes the metal body overmolded with the plastic material.

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