ACR Tubing

Pressure Ratings and Allowable Stresses

The allowable internal pressure for any copper tube in service is based on the Barlow formula for thin-walled, hollow cylinders used in the ASME B31 Code, for Pressure Piping.

The value of ‘S’ is the allowable design strength for continuous long-term service of the tube, as determined by the ASME Boiler and Pressure Vessel Code, Section 1 - Materials.

Allowable stresses for annealed and drawn temper copper tube are shown in the table below. They are only a small fraction of copper’s ultimate tensile or burst strength. In system design, joint ratings must also be considered, as the lower of the two ratings (tube or joint) will govern the installation. The rated joint strength in soldered tube systems often governs design. However, annealed ratings must be used in brazed systems since the brazing operation may anneal the tube near the joints.

Allowable stresses for Copper Tube as a Function of Temp.

ACR Tubing

Barlow formula for thin walled, hollow cylinders

ACR Tubing

P = Allowable Pressure
S = Allowable Stress
t = Wall Thickness
D = Outside Diameter

Conversion Factors

Psi x 0.006895 = MPa
MPa x 145.04 = Psi

F = [(F - 32) / 1.8]C
C = [(C - 1.8) / 32]F

National Standards Authority of Ireland - Irish Standard - I.S. EN 1057:1996

Copper and copper alloys - seamless, round copper tubes for water and gas in sanitary and heating applications.

ACR Tubing

This Irish Standards adopts CEN European Standard EN 1057 as an Irish Standard.

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