High Strength Structural Bolts

leevis · 30 Jun 2008

Hi
Not sure if anyone can help me on this. I am in the process of helping out with a loft extension and have have the steels delivered, got one in place all bolted up but the bolts are those high strength black ones. I managed to get them tightened up with a pair of adjustable spanners which was a bit of a chore.
Does anyone know if there is a socket set for these, i dont know the size but they are probably bigger than M24. I think that the bolts are M24 but they have a bigger head. Just wondered if anyone has come across these before and how they managed to do them up.
Cheers
Lee

^neo^ · 30 Jun 2008

m24 is a 36mm spanner (or two). Can get a socket for them from pretty much any decent tool shop

^woody^ · 30 Jun 2008

An inch thick bolt in a domestic loft

Does the engineer have shares in Corus?

Jasonb · 30 Jun 2008

A Podger wrench is what steel fixers use, you can get them in open ended or ring types but a 36mm socket will also do with a spaner to stop the bolt turning.

Jason

IJWS15 · 1 Jul 2008

Are you sure they are high strength or just a different head - i.e. not hexagon.

Strength of the bolt is indicated by the number on the head - standard is 8.8, you do get 10.9, 12.9, 14.9 and have even seen 16.9 but they are normally special orders.

Should also be a makers mark on the head - nothing on the head - don't use them.

Edit - 8s changed for 9s - my memory is failing - numbers relate to metric bolts, imperial are marked differently.

Eng33 · 1 Jul 2008

IJWS15 said:
Are you sure they are high strength or just a different head - i.e. not hexagon.

Strength of the bolt is indicated by the number on the head - standard is 8.8, you do get 10.9, 12.9, 14.9 and have even seen 16.9 but they are normally special orders.

Should also be a makers mark on the head - nothing on the head - don't use them.

Edit - 8s changed for 9s - my memory is failing - numbers relate to metric bolts, imperial are marked differently.

4.6 and 6.8 would be regarded as 'standard' grade, whereas 8.8 and above as 'high tensile'. All bolts regardless of grade can be obtained just black or zinc plated. I would suggest 8.8 grade as a minimum for structural steelwork.

Bowness72 · 1 Jul 2008

Could be high strength friction grip bolts ? Possibly in a splice connection ?

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High Strength Structural Bolts

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