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TUBING INSTRUMENTATION SELECTION OF OUR PARTNER FITOK

TUBING INSTRUMENTATION SELECTION OF OUR PARTNER FITOK

Tubing Selection

Proper selection, handling, and installation of tubing, when combined with proper selection of FITOK tube fittings, are

essential for reliable tubing systems.

The following variables should be considered when ordering tubing for use with tube fittings:

  • Surface finish
  • Material
  • Hardness
  • Wall thickness

Tubing Surface Finish

Many ASTM specifications cover the above requirements, but they often are not very detailed on surface finish. For example,

ASTM A450, a general tubing specification, reads:

12. Straightness and Finish

12.1 Finished tubes shall be reasonably straight and have smooth ends free of burrs. They shall have a workmanlike finish.

Surface imperfections (Note) may be removed by grinding, provided that a smooth curved surface is maintained, and the

wall thickness is not decreased to less than that permitted by this or the product specification. The outside diameter at the

point of grinding may be reduced by the amount so removed.

Note: An imperfection is any discontinuity or irregularity found in the tube.

Material

Our suggested ordering instructions for each type of tubing are shown under the respective tables.

Hardness

The key to selecting proper tubing for use with metal FITOK tube fittings is that the tubing must be softer than the

fitting material. tube fittings are designed to work properly with the tubing that is suggested in the ordering

instructions.

Wall Thickness

The accompanying tables show working pressure ratings of tubing in a wide range of wall thicknesses. Allowable pressure

ratings are calculated from S values as specified by ASME B31.3, Process Piping. FITOK tube fittings have been repeatedly

tested in both the minimum and maximum wall thicknesses shown. FITOK tube fittings are not recommended for tube wall

thicknesses outside the ranges shown in the accompanying tables for each size.

Tubing Handling

It is important to properly handle the tubing in order to reduce the scratches and protect the surface finish.

Tubing should never be dragged out of a tubing rack or across a rough surface.

Tube cutters or hacksaws should be sharp. Do not take deep cuts with each turn of the cutter or stroke of the saw.

The tubing will go all the way through the ferrules without damaging the ferrule sealing edge.