Screw holes and through holes on the reinforcement rings and shims
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I’ve seen that the regular screw holes are present on the reinforcement rings, and the gusset plates of standard lifting lugs also have many screw holes. However, I’ve noticed in a few cases that the gusset plate bases have only plain holes. Is there anything special regarding screw holes with no threads? After the screw holes in the reinforcement rings and lifting lugs are drilled, are these holes actually plugged with plugs in the final products? If not, aren’t they the same as bare holes?
The threaded holes are to be subjected to a pneumatic test in order to check the strength of the welds, based on my personal understanding
The screw holes on the reinforcement ring are used to inspect the quality of the welded joint. The perforations in the ear pad are designed to allow gases inside the pad to escape during welding.
It is only for the opening reinforcement that threaded holes need to be machined, to facilitate airtightness testing. The lug shims and other accessory shims do not require threaded holes to be machined; plain holes can be used, or a portion of the weld area can be left unwelded.
The standard provisions displayed on the 4th floor serve as a basis; the reinforcement rings at the openings need to have threaded holes drilled in them for airtightness testing. The open holes at the other shims serve for ventilation; of course, leaving a section for patch welding will also work.
Thank you, but from what I remember, the standard gusset plates in GB specifications seem to use M10 or some other size of screw holes