Abstract: A component made of an alloy including carbon at less than approximately 0.04 weight percent, manganese at about 0.0 to about 0.2 weight percent, silicon at about 0.0 to about 0.25 weight percent, phosphorus at about 0.0 to about 0.015 weight percent, sulfur at about 0.0 to about 0.015 weight percent, chromium from about 20.0 to about 23.0 weight percent, molybdenum from about 8.5 to about 9.5 weight percent, niobium from about 3.25 to about 4 weight percent, tantalum at about 0.0 to about 0.05 weight percent, titanium from about 0.2 to about 0.4 weight percent, aluminum from about 0.15 to about 0.3 weight percent, iron from about 3.0 to about 4.5 weight percent, and the remainder being nickel. The alloy may then be subjected to heat treatment procedures such as annealing at a temperature of less than approximately 982° C. and a duration of less than approximately one hour and aging at a temperature between approximately 538° C. and 760° C. and a duration of up to approximately 100 hours.

Abstract: A method for assembling a turbine assembly is provided. The method includes providing at least two buckets that each include an axial entry dovetail, a tip and an airfoil extending therebetween. The method also includes coupling the at least two buckets to a rotor wheel by inserting the axial entry dovetail into at least one complementary-configured mating dovetail slot defined in the rotor wheel, and coupling a bucket cover to the tip of the at least two buckets such that the bucket cover substantially circumscribes the rotor wheel in a continuous band.

Abstract: Rhombic shrouded tangential entry buckets are circumferentially applied to the rotor wheel rim of a turbine. A fixture is releasably secured to a lug on each bucket and includes a chamfered surface for engaging a complementary surface on the lug. Upon applying a tangential assembly force, the shroud and airfoil of adjacent buckets are pre-twisted in a rotational direction about a generally radial axis enabling dovetail faces to contact one another notwithstanding interference fit shroud contacting surfaces. The removal of the fixture from the lug enables the bias of the airfoil to rotate the shroud in an opposite direction into final assembly with the shroud edges of adjacent buckets in contact with one another and the dovetail faces thereof in contact with one another.

Abstract: Steam turbine bucket covers have forward and aft clearance surfaces on a pressure side edge of the cover, a contact surface between the clearance surfaces and an undercut fillet between the forward clearance surface and the contact surface. The adjoining bucket cover has forward and aft clearance surfaces, a contact surface between the clearance surfaces and an outside radius between the forward clearance surface and the contact surfaces along the suction side edge of the cover. The undercut fillet includes two different radii to minimize or eliminate fretting damage caused by high stresses in the interference fit between the contact surfaces of adjacent covers.

Abstract: The control stage buckets for a steam turbine have airfoils which are hollowed out to form an interior cavity within the airfoil. The cavity opens through the radial inner platform of the bucket and terminates short of the tip of the bucket. The buckets are therefore of reduced weight. This reduced weight causes reduced creep damage in the axially extending dovetails along the rotor rim.

Abstract: A seal assembly and method for a turbomachine having a rotary member and a stationary member circumscribing the rotary member. The seal assembly comprises an annular-shaped platform on the rotary member so as to be disposed at an outer circumferential region thereof. The platform is supported radially outward from the rotary member so as to project beyond axially-adjacent regions of the rotary member. The platform has a contact region radially separated from the rotary member by a cavity. A sealing member is disposed at a radially inward region of the stationary member, with a portion of the sealing member in rubbing contact with the contact region.

Abstract: A seal assembly and method for a turbomachine having a rotary member and a stationary member circumscribing the rotary member. The seal assembly comprises an annular-shaped platform on the rotary member so as to be disposed at an outer circumferential region thereof. The platform is supported radially outward from the rotary member so as to project beyond axially-adjacent regions of the rotary member. The platform has a contact region radially separated from the rotary member by a cavity. A sealing member is disposed at a radially inward region of the stationary member, with a portion of the sealing member in rubbing contact with the contact region.

Abstract: A unique finger dovetail pin configuration is provided to attach the buckets of a control stage of a turbine to the rotor wheel. More particularly, as an embodiment of the invention, a bore is provided through the center of the pin to form a hollow pin. The primary benefit of providing a hollow pin configuration is that a passage is defined for the axial flow of steam through the dovetail attachment. For a control stage bucket, this axial flow is desirable to minimize the leakage of steam from the space between the first stage nozzle and bucket, and to provide a source of cooling flow to the forward side of the turbine wheel. Another benefit of the hollow pin is to facilitate removal of the pins when servicing of the high pressure rotor is required.

Abstract: Coverplates are disposed to axially overlie end faces of the shanks of buckets and the dovetail connections of the buckets within turbine wheel slots. The coverplates have axially projecting angel wing seals. The coverplates also have balance weights on axial faces thereof opposite the angel wing seals to balance out any bending moments applied to the coverplate resulting from centrifugal forces when the turbine rotor is at speed. Thus, the centers of gravity of the coverplates are located close to or in the plane of the coverplates. A centering slot is provided along an inner face of each dovetail connection for the coverplates. Coverplate retention pins reside in wide sub-slots at the bases of the wheel slots. When the coverplates are secured against axial movement, the retention pins engage in the centering slots of the coverplate dovetails to prevent circumferential movement of the retention pins in the wide sub-slots.