Select the principle of bimetallic thermometer casing is what?

Bimetallic thermometer casing, is generally used and bimetallic thermometer, then you know to choose what is the principle of the bimetallic thermometer casing? Is generally considered from two aspects, on the one hand is to install remove. We all know the bimetallic thermometer is mainly used in petroleum, chemical industry, heating system, pipelines, power plants, Marine equipment, this equipment is usually more expensive, use cycle is long, but there will be updated equipment or technology upgrading, bimetallic thermometer needs to be replaced, if the bimetallic thermometer is directly welded on the device, the replacement cost is high, in such a consideration, many large equipment need to install the bimetallic temperature time, through the bimetallic thermometer casing connect bimetallic thermometer and equipment. Is to consider the use of environmental pressure on the other hand, when using the environment pressure more than 40 gk, will need to match on casing, otherwise the bimetallic thermometer heat pipe fracture may occur.