Mica-Gasket-Glass Assembly for YARWAY Color-Port Water Level Gauge (Repair Kit Part No. 924329)

Glasses are accurately molded and tempered to Yarway specifications. The assembly of glass, mica and gasket is registered precisely in the gasket groove in the body. At boiler pressures above 300 psig, high temperature water will corrode unprotected gage glass. A thin sheet of high quality ruby mica on the inner surface of each port protects the gage glass from corrosive attack of steam, water and alkalis; however, this protection is not permanent. Continual exposure to high temperature, high pressure water will also corrode the mica shield. The rate at which this corrosion occurs is significantly less than that of glass, and is dependent upon a number of factors. Generally, the higher the operating temperature, the higher the rate of attack. WARNING: Replace immediately when glass appears white or opaque. Failure to promptly replace the mica-gasket-glass assembly that appears white or opaque can result in catastrophic failure of the glass with violent discharge of hazardous high velocity steam. The discharge of high velocity steam can result in personal injury and property damage may occur. Yarway recommends each customer establish a preventative maintenance schedule which insures the mica-gasket-glass assembly is replaced previous to the dissolution of the mica shield. In-service gages that have glass which appears white or is opaque, should be isolated immediately and the mica-gasket-glass assembly should be replaced before returning to service. Should any question develop on the condition of the gage glass, the procedure given under the section on preparation for washdown, auxiliary service or gage inspection of the installation, operation and maintenance manual of colour-port water level gages should be used to evaluate port glass condition.