Plate-type lugs without shims for horizontal boilers
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For horizontal boilers, plate-type lugs of type TPA are used – these types do not have gaskets. They belong to the top-mounted plate type; however, the diameter of 2260 does not correspond to any available values, so it is not possible to find information from tables. Although the HP type is a horizontal container, it has gaskets; even though the container diameter (2260 mm) is indicated, it is still impossible to consult the table without the gaskets. The boiler’s cylinder thickness is 14 mm, and its weight is 13.5 tons; I would like to choose a plate-type lifting lug without shims.
Firstly, it should be noted that the original lifting lugs, which were 20 mm thick and 350 mm wide, have been calculated in accordance with HG/T21574-2018. However, only the calculations related to the lifting lugs themselves have been done; no calculation has been made regarding the impact of these lugs on the boiler drum. Since the boiler drum is 14 mm thick, there is still no complete basis for the design of the boiler lifting lugs.
An attempt was also made to calculate the local stress in the cylinder using SW6, but without shims, it is not possible to perform such calculations when the length-to-width ratio exceeds 4. Many boiler lugs are 20 mm thick; it’s not clear what standard governs this
Many horizontal boilers use plate-type lugs without shims; it’s absurd to expect thousands of different boilers to require individual verification of the stresses in the lugs and the boiler drum. I just want to know how to choose plate-type lugs for horizontal containers that don’t have gussets.
It should provide a basis for plate-type lugs that are 20 thick without gussets
The focus in boiler textbooks is on whether the boiler will explode; for the accessories attached to the boiler itself, such as support and lifting components, only weld requirements are specified. In the absence of any standard basis, reliance is placed on experience. The boiler lugs designed by so-and-so have torn, and the boiler legs designed by so-and-so have become weak and sunken – these are all lessons learned from experience! Anyway, the lifting lugs don’t cost thousands of dollars; as long as there are no issues with the manufacturing process, it’s sufficient to follow the standards of other industries and adopt a more conservative approach.
There are strict requirements regarding welds on boilers, and the inspections are also limited. The selection of the lifting lug location is very important, as it is necessary to ensure that there are no issues during post-welding inspections. Secondly, the use of lifting lugs must not exert pressure or pulling forces on the surrounding flanges. Regarding whether shims should be used under the lifting lugs, the weld issues also need to be taken into consideration (the boiler standards seem to mention the term stress concentration; I can’t recall exactly which page it is). But in reality, it’s difficult to find a suitable location for the lifting lugs with shims, as there isn’t much space left after holes are drilled in the top of the horizontal boiler shell. Regarding the stress check of the lugs... as long as the boiler doesn’t explode, it can be calculated in one’s free time.