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Snupa
18-04-2011, 11:17 PM
Can someone direct me where to find some information on the above.

I would like to know if there is a 'standard' which dictates the minimum number of exposed threads on a bolt of a flanged pipe joint.

I would also like to know if bolt torques in this application are specified anywhere. Are these generally applied, or is a general degree of 'handtighness' acceptable.

Thanks.
Brian_UK
18-04-2011, 11:35 PM
Does this help at all?
http://www.buystainless.co.uk/products/metric/nut-bolt.htm

I think that the correct torque setting is two loud grunts, one on each spanner.
Snupa
19-04-2011, 08:14 PM
Thanks, Brian.

That's a useful table, but doesn't give me what I'm looking for.

As for the torque, I think you are spot on !

Anyone else ?

Thanks
Brian_UK
19-04-2011, 09:30 PM
It's fun playing with Google and Wikipedia...

You are looking at/for EN ISO 4753 but I haven't found a free copy yet.

There is an engineering forum which has discussed this and one thread (pun) which may answer your question is here..
http://www.eng-tips.com/viewthread.cfm?qid=57019

Basically it seems that you should have one thread diameter length through the nut.
Tayters
19-04-2011, 11:36 PM
A mate of mine who did an apprenticship at a dockyards remarked to me once that he was taught that there should be 2 threads poking out the end. Funny but I never thought I'd ever have the need to pass that nugget of infomation on.
As for the tightness I believe there are generic torque settings for certain pitches and materials. Not looked but I suppose the mighty Interweb will have it somewhere. If there is oil/grease on the threads then the final tightness will be tighter than a dry thread. Friction and all that jazz.

As Brian says though, a Jackson Overtorque should do it.

Cheers,

Andy.
Snupa
20-04-2011, 09:51 PM
Thanks Guys. I'll try and find those standards quoted. In the meantime, I've found that the HVCA (Heating and Ventilation Contractors Association) have a publication on this topic which calls for two threads protruding from through the nut. This is consistent with other answers here.
Thanks again.