Under what circumstances should the strength of a boiler drum or header be calculated?

1. For the pressure-bearing components of boilers, such as the boiler drum, header, and tube sheet, during modifications and overhauls, it is necessary to weld or expand-bond additional furnace tubes to the boiler drum or header. When the structure of these pressure-bearing components changes – for example, when holes need to be added to the boiler drum, header, or tube sheet, or when the existing hole diameters need to be increased – it is essential to conduct strength calculations for the hole bridge factors of the holes in those components. Making arbitrary openings in the boiler drum or header without conducting strength calculations often weakens the strength of these components, which is extremely dangerous. 2. When the wall thickness of the pressure-bearing components of a boiler is reduced due to severe corrosion or wear, a strength assessment should be conducted; if the strength is insufficient, patching or operation at reduced pressure should be carried out. 3. When the boiler has not been in use for many years. When there are doubts regarding the operating pressure of the boiler, or when the data necessary for calculating its strength are lost and it is not possible to determine the operating pressure, measurements should be taken based on the actual structure of the boiler; strength calculations should then be performed using these measured dimensions, in order to determine the operating pressure. The maximum operating pressure that a boiler can withstand is determined during its design by performing strength calculations on its pressure-bearing components in accordance with the specified strength calculation standards; it must not be determined arbitrarily through hydrostatic testing. Since the hydrostatic test is used to check the tightness of the boiler and to determine whether there are any leaks in the pressure-bearing components, it is not appropriate to set an excessively high hydrostatic test pressure. Instead, it will create hidden risks and lead to damage to the pressure-bearing components of the boiler. Therefore, the strength of the pressure-bearing components of a boiler is primarily determined through calculation.

Of course, strength calculations must be carried out under all circumstances.

Factors to consider for nozzle reaction force and bending moment

All pressure-bearing components that have just left the factory must undergo strength calculations. Additionally, when special equipment stops operating for a certain period of time – I can’t remember exactly how long; the special work permit is valid for half a year, but I forget how long the equipment itself needs to be out of service before it can be put back into use – calculations are also required in such cases.