What must be done after replacing a gauge glass before placing it in service?

After replacing a gauge glass, it is crucial to crack open the steam valve to warm the gauge glass before placing it into service. This step is important because the gauge glass, which is typically made of glass, can become thermally shocked if it is subjected to sudden changes in temperature. By slowly warming the glass, you minimize the risk of breakage caused by thermal stress. This practice ensures that the gauge glass can accurately reflect the water level within the boiler without the risk of damage.

The other considerations, while important for overall boiler safety and operation, do not specifically address the immediate need after a gauge glass replacement. Calibrating gauges and inspecting other boiler components are also part of regular maintenance, but they do not directly relate to the proper handling and preparation of a newly installed gauge glass for service. Closing the steam valve immediately after replacement would prevent the gauge from functioning properly, which is why it is necessary to carefully introduce steam to the system to ensure the glass reaches a safe operational temperature gradually.