FAQs

What are the maximum working pressures for copper tubing?

These are calculated in accordance with the following formula:

P = 20Ft/ (D-t)

Where P = pressure (1bar)
(1 bar = 0.1 N/mm²)

F = design stress (N/mm²)

t = wall thickness (mm)

D = maximum outside diameter (mm)

(At 65°C)

For hard condition R290 F = 72.5 N/mm²

For ½ hard condition R250 F = 60 N/mm²

For annealed condition R220 F = 46 N/mm²

If tubes in the hard or ½ hard condition are annealed, eg for bending or during brazing or hard soldering, the stress value quoted above for condition "O" should be used for calculating working pressures.

Copper tubes are suitable in some circumstances for use up to a maximum temperature of 200°C, but for pressure calculations a stress value appropriate to the particular temperature should be used as follows:

Temperature (°C )	110°C	150°C	175°C	200°C
Maximum admissible stress for annealed R220 condition (N/mm²)	40	34	26	18