Regarding breathing voids
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What are people’s opinions on the breathing space between the smoke tubes on the tube sheet and the furnace chamber in fuel/gas shell-type boilers, especially for boilers operating at different pressures?
What was expressed above isn’t quite clear enough; let me add more details: For example, in boilers of the fire-tube type, there are various connection points on the tube sheet, such as those between the flue tubes and the furnace chamber, and the temperatures at these locations are certainly different, which leads to temperature stresses. The question now is: Under different pressures, what are the strength calculation standards for shell-type boilers? These standards apply to situations where the outlet pressure is 0.1 MPa or higher. But for boilers operating at atmospheric pressure or in a vacuum environment, does it still be necessary to take into account this ‘breathing space’ on the tube sheet?
For atmospheric and vacuum boilers, check whether there is temperature stress and determine the extent of its impact
Temperature stress is definitely present, just as it is in pressure-bearing boilers. If we consider the temperature differences on both the gas and water sides, these differences are even greater in such cases. Temperature stress is inevitable; it’s just that there is no significant pressure, so the compressive stress is low. Some organizations do not take this allowance for thermal expansion into account, which means that the welding distance between different temperature zones may be less than what is required by this allowance...
There is no thermal stress, so the impact should be minimal
Upstairs: Why is there no thermal stress? Please explain
What needs to be considered is that as long as the temperatures of the components differ, thermal stress will exist.