How to select of seamless tubing

Proper selection, handling, and installation of Seamless Tubing and pipes, when combine with proper selection of FITOK tube fittings, are essential for reliable tubing systems. The following variables should be consider when ordering tubing for use with tube fittings :
Surface finish
Material
Wall thickness
Surface Finish
Surface finish is very important for proper sealing. Tubing with any kind of depression, scratch, raised portion, or other surface defect will be difficult to seal, particularly in gas service.
Material
Metal tubing material should be softer than fitting material.
For example, stainless steel tubing should not be used with brass fittings. When tubing and fittings are made of the same material, tubing must be fully anneal.

Wall Thickness
The accompanying tables show working pressure ratings of Seamless Tubing and pipes in a wide range of wall thicknesses. Except as note, allowable pressure ratings are calculate from S values as specified by ASME B31.3, Process Piping. FITOK tube fittings have been repeatedly test in both the minimum and maximum wall thicknesses shown. FITOK tube fittings are not recommend for tube wall thicknesses outside the ranges shown in the accompanying tables for each size.

Tubing Handling Seamless Tubing

It is important to properly handle the seamless tubing and pipes in order to reduce the scratches and protect the surface finish.
Tubing should never be drag 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.

Gas Service

Gases air, hydrogen, helium, nitrogen, etc.) have very small molecules that can escape through even the most minute leak path. Some surface defects on the tubing can provide such a leak path. As tube outside diameter (O.D.) increases, so does the likelihood of a scratch or other surface defect interfering with proper sealing. The most successful connection for gas service will occur if all installation instructions are carefully follow
and the heavier wall thicknesses of tubing on the accompanying tables are select.

Suggested Allowable Pressure Tables

Figures and tables are for reference only for seamless tubing and pipes. No implication is made that these values can be used for design work. Applicable codes and practices in industry should be consider.
* All pressures are calculate from formulas in ASME B31.3, Process Piping. See factors for calculating working pressures in accordance with ASME B31.1, Power Piping.
* Calculations are based on maximum O.D. and minimum wall thickness, except as noted in individual tables.
Example: 1/2 in. O.D.×0.049 in. wall thickness stainless steel tubing purchased to ASTM A269 :
O.D. Tolerance ±0.005 in. / Wall Thickness Tolerance ±10%
Calculations are based on 0.505 in.O.D.×0.0441 in. wall thickness tubing.
* No allowance is made for corrosion or erosion.

Suggested Allowable Working Pressure for Stainless Steel Tubing

Table 1 — Fractional Stainless Steel Seamless Tubing
Allowable working pressures are calculated from an S value of 20 000 psi (137.8 MPa) for ASTM A269 tubing at -20°F to 100°F (-28°C to 37°C), as listed in ASME B31.3, except as noted. Multiply stainless steel rating by 0.94 for working pressure in accordance with ASME B31.1.
For Welded Tubing
For welded and drawn tubing, a derating factor must be applied for weld integrity.
Tubing, multiply working pressure by 0.85.
For single-welded tubing, multiply working pressure by 0.80.

Suggested Ordering Information
High-quality, fully annealed (Type 304, 304/304L, 316,316/316L,317, 317/317L) (seamless or welded and drawn) stainless steel hydraulic tube, ASTM A269 or A213, or
equivalent. Hardness not to exceed 90 HRB or 200 HV.
Tubing to be free of scratches, suitable for bending and flaring. O.D. tolerances not to exceed ±0.003 in. for 1/16 in. O.D. tubing.
Note : Certain austenitic stainless tubing has an allowable ovality tolerance double the O.D. tolerance and may not fit into FITOK precision tube fittings.
Dual-certified grades such as 304/304L, 316/316L, and 317/317L meet the minimum chemistry and the mechanical properties of both alloy grades.

Table 2 — Metric Stainless Steel Seamless Tubing

For Welded Tubing
Allowable working pressures are based on equations from ASME B31.3 for EN ISO 1127 tubing (D4, T4 tolerance for 3 to 12 mm ; D4, T3 tolerance 14 to 50 mm), using a stress value of 137.8 MPa (20 000 psi) and tensile strength of 516.4 MPa (74 900 psi), except as noted. Multiply stainless steel rating by 0.94 for working pressure in accordance with ASME B31.1.
Suggested Ordering Information
High-quality, fully annealed (Type 304, 304L, 316, 316L) stainless steel tubing, EN ISO 1127 or equivalent. Hardness not to exceed 90 HRB or 200 HV. Tubing to be free of scratches, suitable for bending and flaring. O.D. tolerances not to exceed ± 0.076 mm
for 3 mm O.D. tubing.
Note : Dual-certified grades such as 304/304L, 316/316L is need to meet the minimum chemistry and the mechanical properties of both alloy grades.

Suggested Allowable Working Pressure for Copper Tubing

Table 5 — Fractional Copper Tubing
Allowable working pressures are calculate from an S value of 6000 psi (41.3 MPa) for ASTM B75 (B75M) and ASTM B88 (B88M) tubing at 20 to 100 ( 28 to 37 ), as listed in ASME B31.3 and ASME B31.1.
Suggested Ordering Information
High-quality and soft annealed seamless copper tubing, ASTM B75 (B75M) or equivalent. and also soft annealed (Temperature) copper water tube which type K or type L to ASTM B88 (type A or type B to ASTM B88M).

Table 6 — Metric Copper Tubing
Allowable working pressures calculated from an S value of 6000 psi (41.3 MPa) for ASTM B75 (B75M) and ASTM B88 (B88M) tubing at -20°F to 100°F ( -28°C to 37°C ), as listed in ASME B31.3 and ASME B31.1.
Suggested Ordering Information
High-quality, soft annealed seamless copper tubing, ASTM B75 (B75M) or equivalent. Also soft annealed (Temperature) copper water tube, type K or type L to ASTM B88 (type A or type B to ASTM B88M).