Valve tightening principle
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It’s understandable to turn the bolt back half a turn after tightening it. But why, as mentioned above, does turning it directly to that half-turn position not yield the same result? I spent a long time studying it but still didn’t figure it out
This post was last edited by CHANGBAISHI on 2018-6-30 08:20. The article you shared titled “Coal Chemical Industry Alliance” seems to have some issues. The preload of bolts should be applied using special digital torque wrenches for those bolts that require extremely high precision. Phrases like “loosen by half a turn and tighten by two turns” simply don’t seem precise enough. The distance covered by one \"half turn\" of a metric bolt is different from that of an imperial bolt; moreover, the pitch per \"half turn\" varies depending on the diameter of the bolt. I’m not sure what kind of organization this \"Coal Chemical Industry Alliance\" is – the articles written by it seem unreliable, which makes me uncomfortable, hence I’m speaking up :) I’ve never worked in the coal chemical industry, but I imagine that if such information were presented as educational content, it would be absolutely terrible – really frightening. Additionally, any special requirements for the fastening bolts should be noted in the design, and they should be implemented in accordance with those requirements.
Indeed, what each person understands by a half circle is not necessarily the same~~~ It can be maintained according to the manufacturer’s instructions, or the manufacturer can come and carry out the maintenance directly~~~
There are relevant standards specifying to what extent bolts should be tightened; you can refer to HB 6586-1992 on the tightening torque for bolt threads – the tightening force required varies depending on the size of the bolt.
Based on the information provided by the original poster, I would like to ask which entity is responsible for the \"elastic deformation\"? Does it refer to the bolt, or the gasket, or………
Generally, we know that if bolts are tightened too much after tightening, the high stress can lead to loosening; therefore, they don’t need to be tightened excessively. I think this elasticity comes from the bolts themselves, as they should be able to undergo some elastic deformation. But as mentioned in the article, there is a difference between tightening them 3 turns and then turning them back half a turn versus tightening them directly to 2.5 turns, and even though there’s an explanation below, I still don’t understand it
What is the difference between loosening the bolt by half a turn after tightening it and tightening it all the way to the proper position? There’s an explanation provided below, but I still don’t understand it; I hope fellow users can offer some guidance
The torque for bolt tightening is expressed in newton-meters, and referring to it in terms of \"turns\" is an irresponsible way of expressing it. Can’t understand it; it’s probably an internal language used by experienced drivers
What is the difference between loosening it by half a turn after three turns with the lemon tool, and turning it directly to two and a half turns? Just by looking at it, one can’t understand it; marine enthusiasts actively discuss it