For few valves(Different sizes, operating conditions, etc.) in my current plant, i am landing up with calculated sound at normal operating conditions of 90 to 95 dbA. As per ISA norms, i understand that the allowable limits is 85dbA.
The line is insulated with either hot insulation, cold insulation or personal protection insulation by the piping contractor for the pipe and the valve body.
The insulation thickness may vary from 25mm to 100mm depending on case to case basis.
Is there a general philosophy that an insulation (irrespective of type like, cold insulation, hot insulation or personal protection etc.) on the pipe and valve body will be able to reduce the percieved sound level in dbA for a person standing 1m away from the valve.
If yes , then is there any relation between the reduction in sound level and the thickness of the insulation? (To explain with clarity, is there a relation that “x” mm thickness of any insulation will be able to attenuate the calculated sound level by “y” dbA.)?