Seal assembly for nested dual drill pipe

A seal assembly for a drill pipe, comprising:

• a drill pipe segment having a female seal assembly at one longitudinal end thereof and male seal assembly at the other longitudinal end thereof, the segment of drill pipe having a tapered thread assembly guide at each longitudinal end;
• wherein the female seal assembly includes a larger internal diameter portion at an open end thereof, a taper adjacent to the larger internal diameter portion and a smaller internal diameter portion adjacent to the taper;
• wherein the male seal assembly includes a smaller external diameter portion at an open end thereof, a seal area adjacent to the smaller external diameter portion and a larger external diameter portion adjacent to the seal area;
• and
• wherein the larger internal diameter portion and the smaller external diameter portion have diameters selected to prevent contact with each other during assembly of two adjacent drill pipe segments at a maximum axial misalignment allowed upon initial engagement of the tapered threads on the assembly guides on adjacent segments of drill pipe prior to the threads becoming fully engage, and wherein the larger and smaller internal diameter portions and the larger and smaller external diameter portions have diameters selected to enable free longitudinal movement of the male seal assembly into the female seal assembly while maintaining a seal ring in the seal area fully energized.

A seal assembly for a nested dual drill pipe, comprising:

• a tube having a female seal assembly at one longitudinal end thereof and male seal assembly at the other longitudinal end thereof, the tube nestable in a segment of drill pipe having a tapered assembly guide at each longitudinal end;
• wherein the female seal assembly includes a larger internal diameter portion at an open end thereof, a taper adjacent to the larger internal diameter portion and a smaller internal diameter portion adjacent to the taper;
• wherein the male seal assembly includes a smaller external diameter portion at an open end thereof, a seal area adjacent to the smaller external diameter portion and a larger external diameter portion adjacent to the seal area;
• wherein the larger internal diameter portion and the smaller external diameter portion have diameters selected to prevent contact with each other during assembly of two adjacent drill pipe segments at maximum axial displacement thereof, and wherein the larger and smaller internal diameter portions and the larger and smaller external diameter portions have diameters selected to enable free longitudinal movement of the male seal assembly into the female seal assembly while maintaining a seal ring in the seal area fully energized;
• and
• wherein the seal area further comprises an anti-extrusion ring on at least one side of the seal ring, the anti extrusion ring having a diameter selected to fit within at least one of the smaller internal diameter portion and the larger internal diameter portion.