The pressure rating of instrumentation tubing depends on several factors, including the material, size, wall thickness, and temperature of the tubing. The pressure rating indicates the maximum allowable working pressure (MAWP) that the tubing can withstand under specific operating conditions.
To calculate the pressure rating of instrumentation tubing, the following formula can be used:
Pressure Rating = 2 x S x t / D
where: S = allowable stress of the tubing material at the operating temperature t = wall thickness of the tubing D = outside diameter of the tubing
The allowable stress of the tubing material can be found in industry standards such as ASME B31.3 or ASTM A269. It is typically provided in units of pounds per square inch (psi) or megapascals (MPa).
The wall thickness and outside diameter of the tubing can be measured or obtained from manufacturer specifications.
It is important to note that the calculated pressure rating is only valid under the specific operating conditions for which it was calculated, including the temperature and the medium being transported through the tubing. Any changes in operating conditions may require a recalculation of the pressure rating. Additionally, it is recommended to always follow industry standards and guidelines for the selection and installation of instrumentation tubing.