Difference Between R, RX, and BX Gaskets

(1) #R-Type Gasket:
Application: Fits API 6B flanges.
Pressure Rating: Up to 5,000 psi.
Shape: Oval or Octagonal.

  • Material: Soft metal, no filler.
    Temperature Rating: Low to medium.
  • Drawback: Not self-sealing, sealing may weaken if vibration occurs or pressure drops.
  • Installation Notes: Sensitive to torque; proper tightening required to avoid leakage.
    Typical Applications: Medium-pressure oil & gas pipelines.
  • Interchangeability: Cannot replace RX in high-pressure applications where Self-sealing is needed.

(2) #RX-Type Gasket:
Application: Fits API 6B flanges.
Pressure Rating: Up to 5,000 psi.
Shape: Almost octagonal, deeper and slightly wider than R.
Material: Same metal as R, with soft filler for Self-sealing.

  • Temperature Rating: Low to medium.
  • Advantage: Self-sealing, internal pressure increases, the gasket presses itself into the groove for better sealing.
    Installation Notes: Less sensitive to torque than R.
    Typical Applications: Lines with vibration, variable pressure, or need for reduced leakage.
  • Interchangeability: Can replace R in the same flange.

(3) #BX-Type Gasket:
Application: Fits API 6BX flanges only (different flange design).

  • Pressure Rating: 10,000 – 20,000 psi.
    Shape: Nearly square with a small Pressure Balance Hole.
    Material: Special solid metal designed for high pressure.
  • Temperature Rating: High-temperature capability.
    Advantages:
    Handles very high pressures.
    Pressure Balance Hole distributes pressure evenly, preventing gasket buckling or deformation.
    Installation Notes: Requires dedicated
    6BX flange and high torque.
  • Typical Applications: High-pressure oil & gas wells.
    Interchangeability: Not interchangeable with R or RX, requires 6BX flange
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