You should inspect your red line gauge glass regularly for signs of degradation, including scratches, chips, cracks, or visible clouding/etching on the internal glass surface. Because gauge glass is subject to extreme pressures and temperatures, any structural imperfections can create a failure point and an increased risk of a blowout. Additionally, if the red line has become difficult to distinguish due to interior staining or etching, it is time for a replacement to ensure that your water level readings remain clear and reliable, preventing potentially dangerous errors in boiler operation.