Interpret API RP 13C in the Form of Question & Answer

  1. What is API RP 13C?
    • A new physical testing and labeling procedure for shale shaker screens. To be API RP 13C compliant, a screen must be tested and labeled in accordance with the new recommended practice.
    • Two tests were devised
      • D100 cut point
      • Conductance.
      The tests describe a screen without predicting its performance and can be performed anywhere in the world.
    • Once we identify the cut point and conductance complying with API RP 13C, a permanent tag or label should be attached on the visible and legible position of the screen. Both cut point expressed as an API number and conductance shown in kD/mm are required on the screen label.
    • Internationally, API RP 13C is ISO 13501.
    • The new procedure is a revision of the previous API RP 13E.
  2. What is D100 cut point meaning?
    • Particle size, expressed in micrometers, determined by plotting the percentage of aluminum oxide sample separated.
    • D100 is a single number determined from a prescribed laboratory procedure – the results of the procedure should yield the same value for any given screen.
    • The D100 should not be compared in any way to the D50 value used in RP13E.
  3. What is conductance number meaning?
    • Conductance, permeability per unit thickness of a static (not in motion) shale shaker screen.
    • Measured in kilodarcies per millimeter (kD/mm).
    • Defines a Newtonian fluid's ability to flow through a unit area of screen in a laminar flow regime under prescribed test conditions.
    • All other factors being equal the screen with the higher conductance number should process more flow.
  4. What is API screen number?
    • Number in an API system used to designate the D100 separation range of a mesh screen cloth.
    • Both mesh and mesh count are obsolete terms and have been replaced by the API screen number.
    • The term "mesh" was formerly used to refer to the number of openings (and fraction thereof) per linear inch in a screen, counted in both directions from the center of a wire.
    • The term "mesh count" was formerly used to describe the fineness of a square or rectangular mesh screen cloth, e.g. a mesh count such as 30 × 30 (or, often, 30 mesh) indicates a square mesh, while a designation such as 70 × 30 mesh indicates a rectangular mesh.
  5. What does the API screen number tell us?
    • The API Screen Number corresponds to the API defined range of sizes into which the D100 value falls.
  6. What does the API Screen Number Not tell us?
    • The API Screen Number is a single number which defines solids separation potential under specific test conditions.
    • It does NOT define how a screen will operate on a shaker in the field as this will depend upon several other parameters such as fluid type & properties, shaker design, operating parameters, ROP, bit type, etc.
  7. What is Non-blanked Area?
    • The non-blanked area of a screen describes the net unblocked area in square feet (ft²) or square meters (m²) available to permit the passage of fluid.
  8. What is the practical value of RP 13C to the end user?
    • RP 13C provides an unequivocal procedure and benchmark for comparing different screens.
    • The primary intent of RP 13C is to provide a standard measuring system for screens.
  9. Should I use the old screen number or the new API Screen Number when ordering replacement screens?
    • Although some companies are changing their part numbers to reflect their conformance to RP 13C, others are not. It is therefore best to specify the RP13C value you want.

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