test fasteners

[Daniel Martins]

Hi,

I need to test some fasteners to shear, torsion and traction.
The fasteners are M20, Cl 10.9 l=100mm

Some one knows some lab in UK?

Regards
Daniel Machado

 

[DaveB]

Not meant as a silly question but why is the manufacturers data or the nominal design spec for the fasteners not adequate?

What are the fasteners holding, how do you know they are the weak link.

A normal 8.8 grade M20 coarse pitch bolt has an Ultimate strength of 20 tonnes.

Can't help with the test lab, it's the torsion test that is the unusual one.

Dave

 

[Welderpaul]

A lot of fasteners will have batch test certificates available if you ask for them. The majority of big fixing suppliers have in-house testing facilities and can issue ISO certification.
When we buy 10.9's they come with certification whether we ask for it or not.

There are many companies that will come out to site to test in situ. As Dave says, manufacturers test certificates should do in 99.9% of cases?..

 

[Daniel Martins]

We need to test the fastener because we have a tower with 80 meter and 5 of 7 fasteners broken in one conection.
we replaced it and they are lose again.
The company that project the tower tell us that the problem are the fastners, so we went test them. But I put my money in the errors of project.

 

[snowcat]

That would make sense, TWI would be my first port of call here in the UK, Not welding related but certainly be the type of work they would be involved in.

 

[DaveB]

That makes sense, I've seen an odd fastener in a box that when loaded was clearly not to spec - all credit to the supplier they were suitably worried when contacted but we never got any feedback from further up the supply chain. Fortunately the job was a temporary fixture for a test, wasted the test but no one was put in danger.

Try TWI or SCI
TWI - The Welding Institute
SCI - Steel Construction Institute

The boss will kill me for suggestion competitors but I can't offer a torsion test.

Dave

 

[hotrodder]

No idea how useful, just throwing another name out there... http://www.boltscience.com/pages/services.htm

 

[Hitch]

Theres a hell of a lot of info if you download the Unbrako engineering guide.

Possibly a supplier of traceable and certifiable fasteners.

 

[DaveB]

Been think about this on and off during the day....

Are the fasteners high tensile steel with a surface treatment to deter corrosion or are they stainless? I'm wondering if they've been embrittled.

Is the application putting a large cyclic shear load on them?

How are you controlling the torque of the bolts on installation?

Is any lubricant or other coating being put on the threads during installation?

And I'm supposed to be on holiday this week forgetting about work !!

Dave