After tightening the flange connection bolts and nuts, by how much should the bolt end face extend beyond the nut end face? What are the hazards of being too long?
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It was previously found that after tightening the flange connection bolts and nuts, the end face of the bolt should extend 2 to 3 threads beyond the end face of the nut. Yesterday, in some of the flange bolts at the workplace, the protruding part exceeded the end face of the nut by too much; the manager ordered that all such excess portions be cut off. What are the potential hazards if the bolt protrudes too much beyond the end face of the nut in the future? Why must it be cut off? Can’t it just be done for aesthetic reasons? Seeking advice from experts :)
I used to hear that after tightening the bolts and nuts in a flange connection, the end face of the bolt should extend 2–3 threads beyond the end face of the nut, but now some people say it’s fine if they are level with each other. It doesn’t seem like there will be any harm if it’s longer; it definitely won’t work if it’s shorter. Since it’s already installed, there’s no need to disconnect it.
The part of the bolt that extends beyond the end face of the nut will rust, and the nut won’t be able to be removed next time
Get another nut and tighten it on; will that prevent the threads from being damaged during cutting?
It’s all for aesthetic reasons; if it grows and isn’t removed, there’s no point in considering that it won’t be easy to take off later.
I agree with you; in the past, the ends of the bolts that were exposed had to be covered to prevent rust
The last edit to this post was made by leo_0088 on 2015-8-7 at 09:02. Cutting it off is pointless; it only damages the threads； The excess can be coated with lubricant to prevent rusting.
After tightening the bolts and nuts for flange connections, the end face of the bolt should extend 2–3 threads beyond the end face of the nut; however, it should not be too long for aesthetic reasons. For pipes containing non-hazardous media or at low pressure, it is sufficient to tighten them until they are level.
Three to four filaments – that’s the rule we have in place
An overly long exposure makes it prone to corrosion, affecting disassembly
The nut should extend 2 to 3 threads beyond its end face. Being too long can sometimes be a hindrance, and it’s not aesthetically pleasing either.