Hydril 521™

Available in Sizes from 4" to 18-5/8"

Key Achievement

Completed industry-first, large-OD clearance application in 1987 (15", in 7,500 ft of water).  Today, larger diameters of Hydril 521 are used conventionally by many operators as surface casing in deep water.


  • Large-diameter surface casing
  • Intermediate casing
  • Drilling liners
  • Horizontal liners
  • Extended-reach strings
  • Drilling with casing
  • Rotating while cementing
  • Slotted liners for geothermal wells

Key Features/Benefits

  • Wedge Thread™ connection provides exceptional torque strength
  • Tension and bending strengths of 65-75% of pipe body, even on thin-wall pipe
  • Compression exceeds tension, typically 80-89%
  • 100% pipe body collapse strength
  • Non-API sizes for clearance