When preparing a boiler for long-term layup, what material is commonly placed inside the boiler?

When preparing a boiler for long-term layup, using silica gel or quick lime/hydrated lime is a common practice because these materials are effective moisture absorbents. The primary goal of laying up a boiler is to prevent corrosion and other damage that can occur due to moisture accumulation inside the boiler during periods of inactivity.

Silica gel is known for its ability to absorb moisture from the air, helping to maintain a dry environment within the boiler. Quick lime or hydrated lime also serves a similar purpose, as it reacts with moisture to form calcium hydroxide, effectively reducing humidity levels inside the boiler. By keeping the internal atmosphere dry, these materials help protect the metal components of the boiler from oxidation and scaling that can lead to significant damage.

Additionally, other materials like activated carbon, wood shavings, and sand are less effective for this particular purpose. While they may serve other functions, they do not provide the same level of moisture control that silica gel and lime provide during long-term storage. Hence, using silica gel or quick lime/hydrated lime is the best approach for preparing a boiler for prolonged layup.