Field device interface seal and electrical insulation

A field device assembly for an industrial process comprising:

• an industrial process field device comprising:
• a pressure sensor;
• and
• a housing containing the pressure sensor and comprising a base including a base interface having a first base process opening and a second base process opening;
• a flange attached to the base of the housing and including a coplanar interface having a first flange process opening and a second flange process opening;
• and
• a sealing and electrically insulating system comprising:
• a gasket comprising a dielectric material, a first gasket process opening aligned with the first base process opening and the first flange process opening, a second gasket process opening aligned with the second base process opening and the second flange process opening, a first surface engaging the base interface, a second surface opposite the first surface and engaging the coplanar interface, wherein the gasket electrically insulates the housing of the field device from the flange;
• a first O-ring engaging the first surface of the gasket surrounding the first gasket process opening and the base interface surrounding the first base process opening;
• a second O-ring engaging the first surface of the gasket surrounding the second gasket process opening and the base interface surrounding the second base process opening;
• and
• wherein a pressure at the first flange process opening is communicated to the pressure sensor through the first base process opening and a first pressure sensing line, and a pressure at the second flange process opening is communicated to the pressure sensor through the second base process opening and a second pressure sensing line.

A method of sealing a fluid passageway between a coplanar interface of a flange and a base interface of a field device for an industrial process having a pressure sensor, and electrically insulating the field device from the flange using a sealing and electrically insulating system, the method comprising:

• a gasket comprising a dielectric material, the gasket having a first gasket process opening, a first surface, a second surface opposite the first surface, and a first annular protuberance extending from the second surface and surrounding the first gasket process opening;
• and
• a first O-ring engaging the first surface of the gasket surrounding the first gasket process opening;
• the method comprising:
• engaging the coplanar interface surrounding a first flange process opening with the first annular protuberance;
• engaging the base interface surrounding a first base process opening with the O-ring;
• electrically insulating the field device from the flange using the gasket;
• and
• forming a first sealed passageway between the coplanar interface and the base interface and through the first flange process opening, the first gasket process opening, the O-ring and the first base process opening comprising compressing the O-ring and the gasket between the base interface and the coplanar interface,
• wherein a pressure at the first flange process opening is communicated to the pressure sensor through the first base process opening and via a first pressure sensing line.