A piston for use in a rotary steerable system includes a body formed from a first material. A sealing surface extends around the circumferential wall of the body. The sealing surface is formed from a plurality of layers of a second material. The second material is harder than the first material. The piston can be within a downhole piston assembly that also includes a housing, and the piston being longitudinally movable in a bore in the housing. A method for producing a piston includes preparing a piston formed from a first material, with the piston including a first end. A sealing surface is applied to the piston using laser cladding, with the sealing surface including a second material harder than the first material. The sealing surface is finished to a sealing surface diameter.

A seal member is disposed in a seal groove at a sliding gap between a shaft and a case. The seal member includes an outer periphery, a curved inner periphery, a mounting face, and an upper face. The mounting face is recessed toward the upper face. The upper face is recessed toward the mounting face. The relation of 0.755≤h/H≤0.769 is satisfied, where H [mm] denotes the longest length between the mounting face and the upper face and h [mm] denotes the shortest length between the mounting face and the upper face in the direction in which the center line of the seal member extends, in a cross section of the seal member taken along an imaginary plane in parallel with a direction orthogonal to a radial direction of the seal member and passing through the center line of the seal member,

The present invention relates to a combined crushing super-variable-diameter drill bit for natural gas hydrate exploitation, including a joint, an outer cylinder connected to the joint by thread, a nozzle I mounted in the outer cylinder, a mechanical locking mechanism, a blade telescoping mechanism, an end cap connected to the outer cylinder by thread, a seal ring IV mounted to the end cap, and a nozzle II mounted in the end cap by threaded connection. The present invention achieves integrated operation of conventional drilling and draw-back expanding, which can effectively solve the problems that the existing hydrate drill bit cannot drill a large borehole, cannot mechanically lock an extending position of the blade to stabilize the size of the borehole, and a single crushing method is inefficient.

The present invention relates to a combined crushing super-variable-diameter drill bit for natural gas hydrate exploitation, including a joint, an outer cylinder connected to the joint by thread, a nozzle I mounted in the outer cylinder, a mechanical locking mechanism, a blade telescoping mechanism, an end cap connected to the outer cylinder by thread, a seal ring IV mounted to the end cap, and a nozzle II mounted in the end cap by threaded connection. The present invention achieves integrated operation of conventional drilling and draw-back expanding, which can effectively solve the problems that the existing hydrate drill bit cannot drill a large borehole, cannot mechanically lock an extending position of the blade to stabilize the size of the borehole, and a single crushing method is inefficient.

At least one mechanical face seal is disposed within a cutter cartridge of a roller reamer. The cutter cartridge includes a roller cutter and a retention assembly. A bearing shaft of the retention assembly extends through an inner channel of the roller cutter. A first mechanical face seal is disposed or shared between the roller cutter and a first pillow block of the retention assembly. An optional second mechanical face seal is disposed or shared between the roller cutter and a second pillow block of the retention assembly. Each pillow block is rotatably coupled at an opposing end of the bearing shaft. The retention assembly includes two separately matched sets of one pillow block and a wedge. The wedges in combination detachably secure the pillow blocks to a tool body of the roller reamer.

At least one mechanical face seal is disposed within a cutter cartridge of a roller reamer. The cutter cartridge includes a roller cutter and a retention assembly. A bearing shaft of the retention assembly extends through an inner channel of the roller cutter. A first mechanical face seal is disposed or shared between the roller cutter and a first pillow block of the retention assembly. An optional second mechanical face seal is disposed or shared between the roller cutter and a second pillow block of the retention assembly. Each pillow block is rotatably coupled at an opposing end of the bearing shaft. The retention assembly includes two separately matched sets of one pillow block and a wedge. The wedges in combination detachably secure the pillow blocks to a tool body of the roller reamer.

An earth-boring rotary tool includes a body comprising a pin, a roller cone mounted on the pin, and a seal assembly disposed between the pin and the roller cone. The seal assembly includes a seal ring to form a seal between the seal ring and the roller cone. The seal assembly includes a first polymer ring, while compressed, applies a first force on the seal ring that biases the seal ring towards the roller cone. The seal assembly includes a second polymer ring proximate the first polymer ring. The second polymer ring, while compressed, applies a second force on the seal ring to further bias the seal ring towards the roller cone. The second force is greater than the first force.

An earth-boring rotary tool includes a body comprising a pin, a roller cone mounted on the pin, and a seal assembly disposed between the pin and the roller cone. The seal assembly includes a seal ring to form a seal between the seal ring and the roller cone. The seal assembly includes a first polymer ring, while compressed, applies a first force on the seal ring that biases the seal ring towards the roller cone. The seal assembly includes a second polymer ring proximate the first polymer ring. The second polymer ring, while compressed, applies a second force on the seal ring to further bias the seal ring towards the roller cone. The second force is greater than the first force.

A rotatable element for an earth-boring tool in a subterranean borehole includes a rotatable element and a stationary element. The rotatable element and stationary element include a seal arrangement between the rotatable element and the stationary element. The seal arrangement encloses a volume that remains substantially constant as the rotatable element moves relative to the stationary element.

A rotatable element for an earth-boring tool in a subterranean borehole includes a rotatable element and a stationary element. The rotatable element and stationary element include a seal arrangement between the rotatable element and the stationary element. The seal arrangement encloses a volume that remains substantially constant as the rotatable element moves relative to the stationary element.