Abstract: A method to control the performance of desiccant dryers is disclosed that senses multiple variables and optimizes the regeneration cycle to deliver the gas at the desired dew point. The length of the stripping step is reduced or eliminated depending on the desired set point and the operating conditions of the compression system. The control system has the capability to switch to high efficiency mode of operation should the dew point set point be changed. The savings come from not purging as much or any gas during stripping should the system requirements be only to meet the ISA standards for instrument air, despite the system capability of delivering far dryer air.

Abstract: An exhaust system for a two-cycle internal combustion engine combusting a normally gaseous hydrocarbon as fuel, the engine having a cylinder having an exhaust port in communication with an exhaust manifold. The exhaust system has an exhaust gas inlet connectable to the exhaust manifold of the internal combustion engine and an exhaust gas outlet spaced from the exhaust gas inlet in the direction of flow of exhaust gas through the system. A first tubular portion is disposed between the exhaust gas inlet and outlet, the first tubular portion diverging in the direction of flow. A second tubular portion is disposed between the exhaust gas inlet and outlet and spaced from the first tubular portion in the direction of flow, the second tubular portion converging in the direction of flow.

Abstract: An air-cooled multi-stage compression system using centrifugal compressors is disclosed. It is packaged in a comparable volume to a water-cooled unit having the same driver horsepower. The performance is comparable and opportunities for use of the waste heat are available. Existing water-cooled units can be retrofit to run in an air-cooled mode. Special applications such as combined air compression and nitrogen compression useful in air separation applications are presented. The circulating cooling air can make the unit into an air filter of its surrounding space. Cooling air is drawn through the enclosure before being forced through the coolers above. This air movement can cool compressor housings, the control panel and the drive motors mounted in the enclosure.

Abstract: A centrifugal compressor assembly, especially one having two or more stages, comprises a first compressor casing having. A fluid inlet and a fluid outlet and a first impeller rotatable within the first compressor casing. The assembly further comprises a second compressor casing having a fluid inlet and a fluid outlet and a second impeller rotatable within the second compressor casing. Drive for the compressors is provided by an electric motor, preferably a permanent magnet motor, disposed between the first and second compressor casings and comprising a stator and a rotor rotatable within the stator. A drive shaft is provided, wherein the first impeller, second impeller and the rotor are mounted on the drive shaft and rotatable therewith.

Abstract: A fail-safe gate valve for sub-sea use features a floating, pressure biased compensating piston whose movement prevents internal pressure buildup from opening movement of the gate. A pre-charged fluid chamber provides the bias on the balancing piston. Using unequal piston diameters reduces the charge pressure. The balancing piston is not connected to the gate so that internal pressures can be employed to act on a net area, which biases the gate toward its fail-safe position.

Abstract: A method and apparatus for connecting riser between a floating vessel and a subsea structure that reduces the size of the air tanks used and thereby allow closer positioning of the well slots and overall reduction in size of the floating vessel is disclosed. The apparatus includes an inverted hydraulically actuated connector positioned on the subsea structure and oriented to receive and sealingly attach to a complementary end connection member on the lower end of the riser string.

Abstract: An electrically operated valve actuator with an eddy current clutch is disclosed. The use of the eddy current clutch provides an actuator that can control the rate of closing of the valve in a predetermined linear manner to avoid slamming the valve shut in an emergency shutdown.

Abstract: An actuator for use with a subsea choke or similar apparatus is disclosed. The actuator uses a planetary roller screw mechanism to allow greater control of the torque output while allowing a fast closing of the choke when well conditions require so. A handle is positioned on one end of the actuator housing for manipulation of the actuator housing by a remotely operated vehicle, when required. A pressure responsive axially reciprocable piston is positioned around the driven shaft and controls movement thereof. Other embodiments show the actuator controlling the position of the cage in a cage type choke. A final embodiment shows the actuator configured for use on a subsea tree.

Abstract: A visual signal of pressure between valve stem seals is given by a rising ring, which moves upwardly with the upper stem seal when there is pressure between the stem seals. The rising ring is held to the stem or valve body around the stem by a retaining ring. The rising ring, in its up position, precludes removal of the retaining ring.

Abstract: A valve and valve actuator utilizing a disconnected piston design that separates under conditions of excessive actuator internal pressure to prevent overloading and damaging the threaded connection between the valve stem and actuator piston is disclosed. The hydraulically actuated valve actuator comprises a spring housing including a bonnet for coupling the spring housing to a valve. The spring housing includes an upper head and a packing gland that are sealingly attached to the spring housing to form an interior pressure chamber. The interior pressure chamber has a pressure responsive actuator piston disposed therein with a coil spring designed to move the actuator piston from a normally open to a fail closed position. The pressure responsive actuator piston includes a piston and a spring retainer nut that are separable after closing of the valve to prevent ambient pressure acting within the pressure chamber on the pressure responsive actuator piston from overloading the valve stem.

Abstract: A riser connector is provided for connecting a riser to a wellhead assembly having a bore therethrough. The connector includes a housing having a first and a second end. The first end of the housing has an opening and is adapted for mounting to the wellhead assembly with the opening in communication with the bore of the wellhead assembly. The second end has a first opening connectable to the riser having a diameter at least the same as the inner diameter of the riser, and a second opening, having a diameter at least substantially the same as the diameter of the bore of the wellhead assembly. The housing further includes a first conduit connecting the opening in the first end of the housing to the first opening in the second end of the housing, and a second conduit connecting the opening in the first end of the housing to the second opening in the second end of the housing. In use, first well operations are conducted through the riser in the conventional manner.

Abstract: A retaining apparatus, in particular an internal tree cap, for use in a wellhead having a central bore and first and second retaining means, such as a shoulder and a groove, within the bore of the wellhead. The retaining apparatus has a housing for location within the bore of the wellhead. A first engagement assembly is provided for engaging with the first retaining means in the bore of the wellhead to thereby retain the housing within the bore of the wellhead. A second engagement assembly for engaging with the second retaining means in the bore of the wellhead is also provided. The apparatus further comprises a preload assembly operable when the housing is located within the bore of the wellhead to apply a preload to the housing between the first and second retaining means. A method for retaining an assembly within a wellhead bore, in which a preload is applied between the first and second retaining means, is also disclosed.

Abstract: An apparatus for securing a tubular member under tension is provided, the member secured to and extending between a first and second fixed assembly. The apparatus comprises a first tubular assembly connectable at a first region to the tubular member to be tensioned and a second tubular assembly having a first and a second engageable portion, the second tubular assembly being arranged concentrically with respect to the first tubular assembly and movable longitudinally with respect to the first tubular assembly. A first engagement assembly is provided for engaging the first engageable portion of the second tubular assembly with the first fixed assembly, such that movement of the second tubular assembly toward the tubular member to be tensioned is prevented.

Abstract: A pre-combustion chamber assembly for an internal combustion engine is disclosed having an inner housing having a receiver for receiving a spark plug and an inlet for fuel. A connector is provided for securing the pre-combustion chamber in a spark plug well of the internal combustion engine. An outer housing has a first end and a second end and extends around the inner housing, with a chamber being defined between the inner and outer housings. The outer housing is releasably retained around the inner housing so as to allow relative movement between portions of the inner and outer housings while maintaining the integrity of the chamber. A method of modifying an internal combustion engine and an internal combustion engine incorporating the pre-combustion chamber are also provided.

Abstract: A wellhead assembly comprises a central bore through the wellhead assembly having a pressure boundary region. A port is provided in the wellhead assembly having an opening in the central bore in the pressure boundary region of the wellhead assembly. The port preferably extends through the high pressure housing into the bore of the wellhead assembly. A first casing string is secured at a first end within the wellhead assembly below the opening of the port in the central bore of the wellhead assembly. A second casing string is secured at a first end within the wellhead assembly above the opening of the port in the central bore of the wellhead assembly. A fluid flowpath is thereby formed comprising the port in the wellhead assembly and an annulus between the first and second casing strings. In this way, access is provided to an annulus within the well.

Abstract: A casting technique is disclosed which improves efficiency and reduces fabrication and assembly cost for a centrifugal compressor. The volute is cast integrally with the impeller housing to allow closer radial tolerances to be used to improve efficiency. In the preferred embodiment, compressors for multi-stage compression are assembled with intercoolers and the integral volute is cast together with the impeller housing and the lower gearbox housing and the associated intercooler. Efficiency increases of 2% or more are achievable. In multistage applications, efficiency gains in the early stages are compounded in each subsequent stage.

Abstract: A wellhead assembly comprises an outer housing having a central bore therethrough and an inner housing having a central bore therethrough secured in the central bore of the outer housing. The inner housing has a first end within the outer housing. A first inner casing having a central bore therethrough is secured at a first end in the outer housing and spaced from the first end of the inner housing. A port is provided through the outer housing in communication with the central bore therethrough, the port opening into the central bore of the outer housing between the first end of the inner housing and the first end of the first inner casing. A second inner casing is secured in the wellhead assembly at a first end, whereby the port opens into the central bore of the outer housing between the first end of the first inner housing and the first end of the second inner housing. An annulus is formed between the first and second inner casings.

Abstract: A tubular connection, an example of which is a subsea wellhead having a primary and secondary seal areas allows the use of a backup or contingency gasket for engagement with the secondary seal area in the wellhead should a failure occur in the primary seal area. In the preferred embodiment, the primary and secondary seal areas are sufficiently separated such that the erosion damage which occurs from leakage with the original gasket adjacent the primary seal area, which can spread below the primary seal area, leaves the secondary seal area unaffected. A backup or contingency gasket can be inserted for sealable contact with the secondary sealing area for further well operations.

Abstract: A composite pipe assembly comprises a pipe having a pipe wall, a housing comprising a tubular portion having an inner surface, said tubular portion being disposed around the outside of the pipe, and a tubular forge member having an outer surface. The forge member is disposed within the housing whereby a portion of the pipe wall is disposed between the inner surface of the tubular portion of the housing and the outer surface of said forge member. The forge member is deformed radially outwards against the pipe and the housing, preferably to beyond its yield point, and the tubular portion of the housing is thereby deformed radially outwards to a partial yield point. As a result, the tubular portion of the housing applies a compressive force radially inwards against the pipe wall and the forge member applies a force radially outwards against the pipe wall which serves to secure the housing to the pipe and provide a seal between the pipe and the inner surface of the tubular portion of the housing.

Abstract: An automatic locking mechanism for a telescoping joint for a riser functions in several modes. In an operating mode, the joint is free to have its inner and outer barrels move with respect to each other without engaging each other in a locking relationship. In a second position, the telescoping joint locks when it is fully retracted. In a third position, the system locks the inner and outer barrels together to hold them in a fixed position. The inner and outer barrels are locked when a movable sleeve is properly positioned to allow spring-loaded dogs to be biased through windows in the sleeve so as to act as a landing shoulder to catch a groove on the outer barrel. By putting the actuating sleeve in a variety of positions, the various modes of the locking assembly can be deployed.