What does CWP stand for?

CWP stands for Cold Working Pressure 

The WOG rating has not been a good description and there is movement within the industry to the more descriptive CWP (Cold Working Pressure) rating. 

Regardless of what it is called, it remains a limitation of the pressure valve only. The valve type, material, and trim are different for each application. The pressure and temperature limitations of the pressure containing vessel are a few of the several variables that must be considered.