Are shims and nuts necessary when tightening anchor bolts?
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On site, it was observed that at the anchor bolts of the pipe racks and some stationary equipment, some were fastened using shims and a single nut, while others were fastened with two nuts without any shims. Are both methods in compliance with the specifications?
Tightening the anchor bolts requires the use of washers and nuts. Gaskets can help distribute loads, increase friction, and ensure even tightening force. The practice of tightening with two nuts without gaskets does not comply with the specifications, as this method can lead to issues such as uneven tightening force and thread damage. Therefore, it is preferable to use washers and nuts for installing the anchor bolts, in order to ensure the stability and safety of the equipment. .
These are all standard features; how else can the equipment base be fixed without nuts?
The equipment footings must use double nuts + washers
I would like to ask: what is the basis for your claim that anchor bolts must be equipped with double nuts? Please let me know, thank you
Whether to use a single nut or two nuts depends on the specific equipment; it is not a mandatory requirement. However, towers generally use two nuts – you can refer to HG/T 21545-2006 for details
Thank you for the replies from floors 6 and 7, thanks
The diameter of the holes for equipment foundation bolts is larger than that of ordinary coarse assembly bolts; therefore, a washer should be placed under the foundation bolt nut to increase the contact area between the nut and the perimeter of the bolt holes in the equipment base plate, thereby improving the stress distribution on the edges of those bolt holes. For the diameter specifications of equipment foundation bolt holes, refer to the fasteners section of the Mechanical Design Manual