US 9,316,319 B2 · Pressure-balanced floating seal housing assembly and method · patentgrep

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Abstract

A dynamic sealing mechanism for a machine assembly that includes a seal housing of generally cylindrical form having opposed ends, the seal housing axially positioned between a pressure housing and a retaining member and laterally translatable relative to the pressure housing. The dynamic sealing mechanism includes a shaft located at least partially within the seal housing, the shaft having a sealing surface of generally cylindrical form, relatively movable with respect to the seal housing, and having at least one radial bearing positioned radially by the shaft and locating the radial position of the seal housing. At least three fluid pressure-generated forces act axially on the seal housing to produce a net fluid pressure-generated axial force that is negligible.

Drawings

Claims195

Dependent claims

A dynamic sealing mechanism for a machine assembly, comprising:

a pressure housing;
a retaining member;
an annular seal housing having opposed first and second ends and a generally axially oriented throughbore extending from the first end to the second end, the retaining member capturing the seal housing axially relative to the pressure housing while allowing the seal housing to move laterally relative to the pressure housing;
a shaft having an external sealing surface of generally cylindrical form having a shaft sealing surface diameter, the sealing surface of the shaft being movable relative to the seal housing, and the sealing surface of the shaft extending completely through the seal housing and locating the seal housing laterally;
a dynamic seal contacting and establishing a sealed relationship with the seal housing and contacting and establishing a sealed relationship with the sealing surface of the shaft and being a barrier to a first fluid having a first fluid pressure, the sealing surface of the shaft being relatively movable with respect to the dynamic seal;
a first portion of the throughbore extending from the first end of the seal housing to the dynamic seal and exposed to the first fluid, and a second portion of the throughbore extending from the dynamic seal to the second end of the seal housing and exposed to a second fluid, wherein all of the first and second portions of the throughbore being larger than the sealing surface of the shaft and being located radially outward of and encircling the sealing surface of the shaft;
an axially compressed inner sliding seal and an axially compressed outer sliding seal in face sealing contact with the seal housing, the inner and outer sliding seals and the dynamic seal cooperating to define first, second and third sealed portions of the seal housing in sealingly isolated relationship from one another:
the first sealed portion of the seal housing being exposed to the first fluid, the first fluid pressure producing a first fluid pressure-generated force acting axially on the seal housing with a first force magnitude;
the second sealed portion of the seal housing being exposed to the second fluid having a second fluid pressure producing a second fluid pressure-generated force acting axially on the seal housing with a second force magnitude, the second fluid-pressure generated force acting in axial opposition to the first fluid pressure-generated force, the first force magnitude being different than the second force magnitude;
the third sealed portion of the seal housing being exposed to a balancing fluid having a balancing fluid pressure producing a fluid pressure-generated balancing force acting axially on the seal housing, the balancing fluid pressure having a pressure magnitude;
the first, second and third sealed portions being separate and distinct from one another and lacking fluid communication with one another;
the inner and outer sliding seals defining the third sealed portion of the seal housing exposed to the balancing fluid, wherein one of the inner and outer sliding seals is located between the balancing fluid and the second fluid and is a barrier separating the balancing fluid from the second fluid;
and
a pressure supply mechanism automatically controlling the pressure magnitude of the balancing fluid such that the fluid pressure-generated forces acting axially on the seal housing produce a negligible net fluid pressure-generated axial force on the seal housing.

11 more elements

A dynamic sealing mechanism for a machine assembly, comprising:

a retaining member;
a seal housing having opposed first and second ends, the retaining member capturing the seal housing axially relative to a pressure housing, allowing the seal housing to move laterally relative to the pressure housing;
a shaft having an external sealing surface of generally cylindrical form passing completely through the seal housing and being relatively movable with respect to the seal housing;
a dynamic seal contacting and establishing a sealed relationship with the seal housing and encircling and contacting the sealing surface of the shaft and establishing a sealed relationship therewith;
an inner sliding seal and an outer sliding seal in face sealing contact with the seal housing and located radially outward of and encircling the sealing surface of the shaft,
the dynamic seal and the inner sliding seal defining a seal housing first sealed portion exposed to a first fluid having a first fluid pressure producing a first fluid pressure-generated force acting axially on the seal housing with a first force magnitude;
the dynamic seal and outer sliding seal defining a seal housing second sealed portion exposed to a second fluid having a second fluid pressure producing a second fluid pressure-generated force acting axially on the seal housing with a second force magnitude, the second fluid-pressure generated force acting in axial opposition to the first fluid pressure-generated force, the first force magnitude being different than the second force magnitude;
the inner and outer sliding seals defining a seal housing third sealed portion exposed to a balancing fluid having a balancing fluid pressure producing a fluid pressure-generated balancing force acting axially on the seal housing, the balancing fluid pressure having a pressure magnitude;
wherein the first, second and third sealed portions are separate and distinct from one another and lack fluid communication with one another;
and
a pressure supply mechanism automatically controlling the pressure magnitude of the balancing fluid such that the fluid pressure-generated forces acting axially on the seal housing produce a negligible net fluid pressure-generated axial force on the seal housing.

8 more elements

A dynamic sealing mechanism for a machine assembly, comprising:

a pressure housing;
a shaft located at least partially within the pressure housing and relatively movable with respect to the pressure housing, the shaft having a sealing surface of generally cylindrical form;
an annular seal housing having a generally axially oriented bore extending completely therethrough and first and second ends in axially opposed relation to one another, the first and second ends being located directly radially outward of and encircling the sealing surface, the seal housing having equal opposite axially-facing areas, the sealing surface extending completely through the seal housing and the seal housing positioned axially relative to the pressure housing and laterally movable relative to the pressure housing, the seal housing being positioned laterally by the sealing surface of the shaft;
a dynamic seal contacting and establishing a sealed relationship with the seal housing and contacting and encircling the sealing surface of the shaft and establishing a sealed relationship therewith;
a first portion of the bore being located between the first end of the seal housing and the dynamic seal, and a second portion of the bore being located between the dynamic seal and the second end of the seal housing, the first and second portions of the bore being larger than the sealing surface of the shaft, and being located radially outward of and encircling the sealing surface of the shaft, the entire bore being larger than the sealing surface;
an annular inner sliding seal and an annular outer sliding seal in face sealing contact with the first end of the seal housing defining a sealed axially-facing balancing area of the seal housing, the balancing area comprising the axially-facing area sealed by and between the inner and outer sliding seals;
the inner sliding seal and the dynamic seal defining an axially-facing first effective area of the first end of the seal housing;
the outer sliding seal and the dynamic seal defining an axially-facing net second effective area of the second end of the seal housing,
wherein the axially-facing first effective area is exposed to a first fluid having a first fluid pressure producing a first fluid pressure-generated force acting axially on the seal housing with a first force magnitude,
the axially-facing net second effective area is exposed to a second fluid having a second fluid pressure producing a second fluid pressure-generated force acting axially on the seal housing with a second force magnitude, the second fluid-pressure generated force acting in opposition to the first fluid pressure-generated force, the first force magnitude being different than the second force magnitude, and
the axially-facing balancing area is exposed to a balancing fluid having a balancing fluid pressure producing a fluid pressure-generated balancing force acting axially on the seal housing, the balancing fluid pressure having a pressure magnitude;
and
a pressure supply mechanism automatically controlling the pressure magnitude of the balancing fluid causing the fluid pressure-generated forces acting axially on the seal housing to produce a negligible net fluid pressure-generated axial force on the seal housing.

10 more elements

A dynamic sealing mechanism for a machine assembly, comprising:

a pressure housing;
a retaining member;
an annular seal housing having opposed first and second ends, a generally axially oriented throughbore, and an outer periphery, the retaining member capturing the annular seal housing axially relative to the pressure housing while allowing the annular seal housing to move laterally relative to the pressure housing, the annular seal housing being located at least partially within the pressure housing;
a shaft having an external sealing surface of generally cylindrical form, the throughbore being larger than the sealing surface of the shaft, and the sealing surface of the shaft extending completely through the annular seal housing from the first end to the second end of the annular seal housing, and locating the annular seal housing laterally;
a dynamic seal contacting and being axially located by the annular seal housing and contacting and establishing a sealed relationship with the shaft sealing surface of the shaft and being a barrier to a first fluid having a first pressure, the shaft sealing surface of the shaft being relatively movable with respect to the dynamic seal and with respect to the annular seal housing;
the throughbore having first and second throughbore portions, the first throughbore portion being located between the dynamic seal and the first end of the annular seal housing and the second throughbore portion being located between the dynamic seal and the second end of the annular seal housing;
axially compressed inner and outer sliding seals in face sealing contact with the first end of the annular seal housing, the inner and outer sliding seals located directly radially outward from and encircling the sealing surface of the shaft, the inner and outer sliding seals cooperating to define a balancing area on the first end of the annular seal housing, a pressure communication path penetrating and communicating through at least a portion of the pressure housing to the balancing area, the pressure communication path comprising at least one hole in the pressure housing,
the dynamic seal and the inner sliding seal being exposed to the first fluid, the dynamic seal and the outer sliding seal being exposed to and retaining a second fluid having a second pressure, the second pressure being greater than the first pressure,
at least a portion of the first end of the annular seal housing being exposed to the first fluid and at least a portion of the first end of the annular seal housing being exposed to the second fluid, the first pressure producing an axially acting hydraulic force on at least a portion of the first end of the annular seal housing in a first axial direction, the second pressure creating an axially acting hydraulic force on at least a portion of the first end of the annular seal housing in the first axial direction and creating an axially acting hydraulic force on at least a portion of the second end of the annular seal housing in a second axial direction, the first axial direction being opposite to the second axial direction, the first throughbore portion of the annular seal housing being exposed to the first fluid, at least part of the first throughbore portion being located directly radially outward of and encircling the sealing surface of the shaft, and the first and second ends of the seal housing being located directly radially outward of and encircling the sealing surface of the shaft.

6 more elements

A dynamic sealing mechanism for a machine assembly, comprising:

a retaining member;
an annular seal housing having opposed first and second ends and inner and outer peripheries, the retaining member capturing the annular seal housing axially relative to a pressure housing, allowing the annular seal housing to move laterally relative to the pressure housing;
a shaft having an external sealing surface of generally cylindrical form located at least partially within the annular seal housing;
a dynamic seal contacting and axially located by the annular seal housing and encircling and contacting the sealing surface of the shaft and establishing a sealed relationship therewith, the sealing surface of the shaft being relatively movable with respect to the dynamic seal and the annular seal housing;
an inner sliding seal and an outer sliding seal in face sealing contact with the first end of the annular seal housing and encircling and radially spaced from the shaft, the radial space between the outer sliding seal and the shaft being greater than the radial space between the inner sliding seal and the shaft;
the dynamic seal and the inner sliding seal defining an annular seal housing first sealed portion exposed to a first fluid having a first pressure, the dynamic seal, the inner sliding seal, and at least a part of the inner periphery of the annular seal housing being exposed to the first fluid;
at least part of the first end of the annular seal housing and at least a part of the second end of the annular seal housing being exposed to a second fluid having a second pressure, the second pressure being greater than the first pressure, the dynamic seal and the outer sliding seal being exposed to and retaining the second fluid;
the inner and outer sliding seals defining an annular housing balancing area, the first sealed portion and the annular housing balancing area being separate and distinct from one another and lacking fluid communication with one another;
and
a pressure communication path penetrating and communicating through the pressure housing to the balancing area, the pressure communication path comprising at least one hole in the pressure housing having an open end opening into the balancing area and facing toward the annular seal housing, the radial distance between the open end and the shaft being greater than the radial distance between the inner sliding seal and the shaft and being less than the radial distance between the outer siding seal and the shaft.

7 more elements

A dynamic sealing mechanism for a machine assembly, comprising:

a pressure housing;
a shaft located at least partially within the pressure housing and relatively movable with respect to the pressure housing, the shaft having a sealing surface of generally cylindrical form;
an annular seal housing having a generally axially oriented bore extending completely through the annular seal housing, an outer periphery, and first and second ends in axially opposed relation to one another, all of the first and second ends being located radially outward of and encircling the shaft sealing surface, and the entire bore being larger than the shaft sealing surface of the shaft, the sealing surface extending completely through the annular seal housing from the first end to the second end, and the annular seal housing positioned axially relative to the pressure housing and laterally movable relative to the pressure housing, the annular seal housing being positioned laterally by the sealing surface of the shaft;
a dynamic seal contacting and located at least partially within the annular seal housing and contacting the sealing surface of the shaft and establishing a sealed relationship therewith, the sealing surface of the shaft being relatively movable with respect to the dynamic seal and with respect to the annular seal housing;
an annular inner sliding seal and an annular outer sliding seal in face sealing contact with the first end of the annular seal housing and defining a sealed axially-facing balancing area on the first end of the annular seal housing, the balancing area comprising the area sealed by and between the inner and outer sliding seals;
the inner sliding seal and the dynamic seal being located radially outward of and encircling the sealing surface of the shaft and defining an axially-facing first effective area of the first end of the annular seal housing;
the second end of the annular seal housing having an axially-facing net second effective area having inner and outer boundaries, the dynamic seal defining at least one of the inner and outer boundaries,
wherein the axially-facing first effective area is exposed to a first fluid having a first pressure producing a first pressure-generated force acting axially on the annular seal housing with a first force magnitude, the dynamic seal and the inner sliding seal being exposed to the first fluid, and the dynamic seal and the outer sliding seal being exposed to a second fluid having a second pressure, the second pressure being greater than the first pressure;
the second fluid producing a second pressure-generated force acting axially on the axially-facing net second effective area of the annular seal housing with a second force magnitude, the second fluid-pressure generated force acting in opposition to the first pressure-generated force, the first force magnitude being less than the second force magnitude, and
a pressure communication path communicating with the balancing area and having an open end opening into the balancing area and facing the annular seal housing, the radial distance between the open end and the shaft being greater than the radial distance between the inner sliding seal and the shaft and being less than the radial distance between the outer siding seal and the shaft.

7 more elements

A dynamic sealing mechanism for a machine assembly, comprising:

a pressure housing assembly comprising an upper housing and a lower housing;
a shaft located at least partially within the pressure housing assembly and relatively movable with respect to the pressure housing assembly, the shaft having a sealing surface of generally cylindrical form and uniform diameter;
an annular seal housing having first and second ends in axially opposed relation to one another and a generally axially oriented bore extending completely therethrough, the sealing surface of the shaft extending completely through the annular seal housing from the first end to the second end, and extending completely through the seal housing bore;
the pressure housing assembly capturing the seal housing axially relative to the pressure housing assembly while allowing the seal housing to move laterally relative to the pressure housing assembly;
a first seal disposed between the seal housing and the sealing surface of the shaft, the first seal maintaining sealing contact to limit fluid flow between the seal housing and the sealing surface of the shaft;
a second seal disposed between the seal housing and the pressure housing assembly, the second seal maintaining sealing contact to limit fluid flow between the seal housing and the pressure housing assembly;
a third seal disposed between the seal housing and the pressure housing assembly, the third seal maintaining sealing contact to limit fluid flow between the seal housing and the pressure housing assembly;
the first and second seals defining a seal housing first sealed portion exposed to a first fluid having a first fluid pressure producing a first fluid pressure-generated force acting axially on the seal housing with a first force magnitude;
the first and third seals defining a seal housing second sealed portion exposed to a second fluid having a second fluid pressure producing a second fluid pressure-generated force acting axially on the seal housing with a second force magnitude, the second fluid-pressure generated force acting in axial opposition to the first fluid pressure-generated force, the first force magnitude being different than the second force magnitude;
the second and third seals defining a seal housing third sealed portion exposed to a balancing fluid having a balancing fluid pressure producing a fluid pressure-generated balancing force acting axially on the seal housing, the balancing fluid pressure having a pressure magnitude;
wherein the first, second and third sealed portions are separate and distinct from one another and lack fluid communication with one another;
and
a pressure supply mechanism automatically pressurizing the balancing fluid to a pressure magnitude such that the fluid pressure-generated balancing force and the first and second fluid pressure-generated forces acting axially on the seal housing produce a negligible net fluid pressure-generated axial force on the seal housing.

10 more elements

A dynamic sealing mechanism for a machine assembly, comprising:

a pressure housing;
a retaining member;
a seal housing having oppositely facing first and second ends and an outer peripheral surface, a generally axially oriented throughbore extending from said first end to said second end, the retaining member capturing the seal housing axially relative to the pressure housing while allowing the seal housing to move laterally relative to the pressure housing, the seal housing located at least partially within the pressure housing;
a shaft having an externally oriented sealing surface of cylindrical form, the entire throughbore and the first and second ends of the seal housing being larger than the sealing surface, the sealing surface locating the seal housing laterally;
a dynamic seal contacting and being axially located by the seal housing and contacting and establishing a sealed relationship with the sealing surface of the shaft and being a barrier to a first fluid having a first pressure, the sealing surface of the shaft being relatively movable with respect to the dynamic seal and with respect to the seal housing;
axially compressed inner and outer sliding seals in face sealing contact with the first end of the seal housing, the inner and outer sliding seals cooperating to define a sealed balancing area on the first end of the seal housing, at least a portion of the balancing area being located between the inner and outer sliding seals;
a first pressure communication path in the form of a hole having first and second open ends, the first pressure communication path penetrating and communicating through at least a portion of the seal housing, at least part of the first pressure communication path located radially outward of the dynamic seal between the dynamic seal and the outer peripheral surface of the seal housing, the first open end of the first pressure communication path opening into the portion of the balancing area located between the inner and outer sliding seals;
a second pressure communication path in the form of a generally radially oriented hole having an open end exposed to the first fluid and opening into the throughbore, the second pressure communication path located between the dynamic seal and the inner sliding seal and located between the dynamic seal and the first end of the seal housing;
the dynamic seal and the inner sliding seal being exposed to the first fluid, the dynamic seal and the outer sliding seal being exposed to and retaining a second fluid having a second pressure, the second pressure being greater than the first pressure;
at least a portion of the first end of the seal housing being exposed to the first fluid and at least a portion of the first end of the seal housing being exposed to the second fluid;
the first pressure producing an axially acting hydraulic force on at least a portion of the first end of the seal housing in a first axial direction, the second pressure creating an axially acting hydraulic force on at least a portion of the first end of the seal housing in the first axial direction and creating an axially acting hydraulic force on at least a portion of the second end of the seal housing in a second axial direction, the first axial direction being opposite to the second axial direction, at least a portion of the throughbore of the seal housing being exposed to the first fluid and at least a portion of the throughbore of the seal housing being exposed to the second fluid;
a stepped piston and first and second reciprocating seals located in a mating stepped bore of the seal housing, the first and second reciprocating seals establishing sealed contact with the stepped piston and with the seal housing, establishing a sealed region located between the first and second reciprocating seals, the first and second reciprocating seals establishing first and second sealed areas and a sealed balancing area, a first portion of the stepped piston being exposed to the first fluid, a second portion of the stepped piston exposed to the second fluid, and a third portion of the stepped piston being exposed to a balancing fluid, at least some of the balancing fluid being located within the sealed region of the stepped bore between the first and second reciprocating seals;
the first pressure communication path communicating balancing fluid from the sealed region of the stepped bore to the portion of the balancing area located between the inner and outer sliding seals, the second open end of the first pressure communication path opening into the sealed region of the stepped bore;
the second pressure communication path intersecting the stepped bore of the seal housing, and communicating the first fluid and the pressure of the first fluid to the first portion of the stepped piston;
and
at least part of the stepped bore located radially between the external sealing surface of the shaft and the outer peripheral surface of the seal housing.

13 more elements

A dynamic sealing mechanism for a machine assembly, comprising:

a pressure housing;
a retaining member;
a seal housing having oppositely facing first and second ends and an outer peripheral surface, a generally axially oriented bore extending completely through the seal housing from the first end to the second end, the retaining member capturing the seal housing axially relative to the pressure housing while allowing the seal housing to move laterally relative to the pressure housing;
a shaft having an externally oriented sealing surface of cylindrical form having a surface diameter, the sealing surface locating the seal housing laterally;
a dynamic seal contacting and axially located by the seal housing and contacting and establishing a sealed relationship with the sealing surface of the shaft, the sealing surface of the shaft being relatively movable with respect to the dynamic seal and with respect to the seal housing;
a first portion of the bore located between the first end of the seal housing and the dynamic seal and exposed to a first fluid having a pressure, and a second portion of the bore located between the dynamic seal and the second end of the seal housing and exposed to a second fluid having a pressure, the pressure of the second fluid being greater than the pressure of the first fluid, the first and second portions of the bore and the first and second ends of the seal housing being larger in diameter than the surface diameter of the sealing surface;
the seal housing having a generally radially oriented hole located between the first end of the seal housing and the dynamic seal, with an open end facing generally radially inward, and having a generally axially oriented hole located radially outward of the dynamic seal and radially between the dynamic seal and the outer peripheral surface of the seal housing, the generally radially oriented hole intersecting the generally axially oriented hole, together the radially oriented hole and the generally axially oriented hole forming a cross-drilled hole, the generally radially oriented hole and at least a portion of the generally axially oriented hole being exposed to the first fluid and the pressure of the first fluid;
axially compressed annular inner and outer sliding seals in face sealing contact with the seal housing and encircling the shaft, the inner and outer sliding seals cooperating to define an annular sliding area, the outer sliding seal being radially spaced from the inner sliding seal and both the inner and outer sliding seals being radially spaced from the shaft, the inner sliding seal being held by and located at least partially within an inner face seal groove of annular form, the outer sliding seal being held by and located at least partially within an outer face seal groove of annular form;
the dynamic seal and the inner sliding seal exposed to and being barriers to the first fluid, the dynamic seal and the outer sliding seal being exposed to and being barriers to the second fluid;
at least a portion of the first end of the seal housing being exposed to the first fluid and the pressure of the first fluid,
the outer peripheral surface of the seal housing, at least a portion of the first end of the seal housing, and at least a portion of the second end of the seal housing being exposed to the second fluid and the pressure of the second fluid, and
the first pressure producing an axially acting hydraulic force on at least a portion of the first end of the seal housing in a first axial direction, the second pressure creating an axially acting hydraulic force on at least a portion of the first end of the seal housing in the first axial direction and creating an axially acting hydraulic force on at least a portion of the second end of the seal housing in a second axial direction, the first axial direction being opposite to the second axial direction.

9 more elements

Dependencies are inferred from the claim text.

Description14,492 words

Summary1,489 words

#The present invention pertains to rotary equipment that seals differential pressure. While applicable to many types of rotary equipment, it is believed to be particularly well suited for underbalanced oilfield drilling equipment of the type that is used for pressure control of wells while drilling. Such drilling equipment is called by various names such as rotary blowout preventer, rotary head, rotary diverter, and rotating control device.

#The invention solves the type of problem that is described in conjunction with the laterally translatable seal housings of U.S. Pat. No. 5,195,754, entitled “Laterally Translating Seal Housing for a Drilling Mud Motor Sealed Bearing Assembly,” and U.S. Pat. No. 6,227,547, entitled “High Pressure Rotary Shaft Sealing Mechanism.” Unlike the prior art, the present invention does not require a stepped diameter shaft. It is therefore compatible with the reciprocating shafts found in rotating annular blowout preventers of the type shown in U.S. Pat. Nos. 5,588,491 and 5,662,171, which are titled “Rotating Blowout Preventer and Method.” It also eliminates the need for two different seal diameters when pressure staging.

#A high pressure rotary seal requires a small seal-to-housing extrusion gap clearance to avoid extrusion damage, yet the clearance must be large enough to avoid shaft-to-housing contact. If shaft-to-housing contact occurs at the extrusion gap, the housing assumes the load intended for the bearings. The resulting friction and heat can destroy the seal, and may damage the seal housing and the shaft sealing surface in ways that are highly detrimental to the effective life of the rotary seal.

Brief description of the drawings11 figures

#So that the manner in which the above recited features of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof that are illustrated in the appended drawings. It is to be noted, however, that the appended drawings only illustrate preferred embodiments of this invention, and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments that vary only in specific detail.

#In the drawings:

#FIG. 1 is a schematic view, partially in cross-section, of a rotating blowout preventer incorporating pressure-balanced floating seal housings according to a preferred embodiment of the present invention;

Detailed description12,535 words

#Features throughout this specification that are represented by like numbers have the same basic function. FIG. 1 shows a fragmentary view of a rotating blowout preventer that incorporates embodiments of the pressure-balanced floating seal housing of the present invention. The drawing illustrates a rotating annular blowout preventer of the general type shown in U.S. Pat. Nos. 5,588,491 and 5,662,171. It is to be understood, however, the invention is applicable to other types of machine assemblies, including but not limited to other types of rotating control devices used for control of well pressure while drilling.

#The machine assembly 2 may contain or be exposed to a first fluid 6 at pressure Pw. For purposes of this specification, the term fluid has its broadest possible meaning and encompasses both liquids and gases. In a rotating blowout preventer, the first fluid 6 may typically be drilling fluid. A pressure housing 4 may contain a second fluid 10, such as a hydraulic fluid, for the lubrication and actuation of relatively movable components of the machine assembly 2.

#The pressure housing 4 may be comprised of upper and lower housings, as shown, that each have mating flanges for threaded fasteners, as shown. A static seal 5 may provide sealing between the upper and lower housings 4. Oppositely facing pressure housing ends may provide surfaces for engaging and sealing with respect to other connecting oilfield equipment. Each of those ends may preferably incorporate a groove for a ring gasket. Each end surface may preferably also include a circle of tapped holes (not shown) for connecting with the other oilfield equipment. It is understood that additional non-illustrated pressure passages can be used, if desired, to move the reciprocatable piston 37 in a downward direction to open the packer element 31.