Flange safety shields are required on flammable or combustible liquid piping that can exceed what level of pressure?

Flange safety shields are an essential safety feature in piping systems that handle flammable or combustible liquids. They are specifically required when the pressure in the system can exceed 20 PSI. The purpose of these shields is to contain any potential leaks or spray from flanges, which could pose a significant fire risk if combustible materials come into contact with ignition sources.

The reason a threshold of 20 PSI is critical is rooted in safety standards and engineering practices that recognize the potential for pressurized liquid to create hazardous conditions. At this pressure, mechanical failures can lead to significant spray or leaks that a safety shield is designed to control, thus reducing the risk of ignition and protecting personnel and property.

Lower pressures, such as those below 20 PSI, may not present the same level of risk for leaks that could lead to a fire, which is why the regulations set this specific threshold.