Boiler lugs
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Are shims needed for the lugs on the boiler drum of a horizontal boiler? What is the basis for this?
I hadn’t noticed. The lifting lugs take into account the weight of the boiler to be lifted; shims are added to facilitate welding and maintain connection strength.
It would be better to place the lifting lugs on the base.
It mainly depends on the weight of the boiler and the connection area between the lifting lugs and the boiler shell. . It is recommended that boilers with an evaporation capacity of over 10 tons use double lugs or additional shims
Shims are not necessary; it mainly depends on whether the contact area is appropriate.
On the boiler drawings I’ve seen, double lugs are used on the boiler drum; most of the areas between the lugs and the drum are fitted with gussets, which are connected to the drum by fillet welds, while the lugs and gussets are joined through full-penetration welding using double-bevel grooves； There are also small-tonnage boilers that do not use gussets; in such cases, the lifting lugs and the boiler drum wall are welded together using a full-penetration welding method with double bevels on both sides.
Whether shims are needed for the lifting lugs depends on factors such as the lifting weight and the welding method; for details, refer to \"Equipment Lifting Lugs\" HG/T21574-2008
Shoes require shims to be installed! Due to the limited contact area between the lifting lugs and the boiler drum, weak welding may occur during welding; for safety reasons, shims need to be added!
Adding lugs increases the contact area, allowing for even stress distribution there.
Generally, shims are used, and the thickness of these shims should not exceed that of the boiler drum; this is to ensure that in the event of any problems during lifting, it is the shims that deform first, rather than the boiler drum.