Strength of ungraded Steel machines screws

[sloccc]

Anyone know what can I use for allowable strength or stress for ungraded, zinc plated steel machine screws? Like for example this one

http://www.fastenal.com/web/products/detail.ex?sku=28141

Thanks

 

[drawoh]

sloccc,

You can assume annealed 1010 steel, you can ask the vendor what they recommend, or you can select a screw from a vendor who specifies the material.

JHG

 

[QAFitz]

Look at the applicable ANSI B18 spec, the minimum is a tensile strength of 60,000 psi

 

[drawoh]

QAFitz,

Would that not make it a "graded" screw?

Is that proof, yield, or ultimate stress?

JHG

 

[MiketheEngineer]

I would not use an "ungraded" screw.

NASA had to replace thousands of fasteners on the Space Shuttles once they realized they had "ungraded" screws.

 

[MintJulep]

The main reason for getting "graded" screws is that you know what you get.

If you get "ungraded" screws, you get what you get, and and you never know what you might get.

Get it?

 

[MotorVib]

I would also use a gr screw but in the past when I used ungraded screws I used GR 2 Torques for screws like that. Is this something that is it Critial joint?

I have worked with Fastenal in the past and they are always will to help.

Chris

"In this house, we obey the laws of thermodynamics." Homer Simpson

 

[hydtools]

Fastenal tells you what the screw strength is. See their product specifications on the link you provided.

http://www.fastenal.com/content/product_specifications/MS.FSL.Z.pdf

Ted

 

[metengr]

The main reason for getting "graded" screws is that you know what you get.

If you get "ungraded" screws, you get what you get, and and you never know what you might get.

Get it?

Got it!

 

[evelrod]

Ungraded is unknown! Even using graded hardware you stand the chance of getting unknown...If it can happen to Boeing, it can happen to you!

Try the FAQ's of the forum.

Rod

 

[dbooker630]

Even if the fasteners are identified as the correct grade, there is no substitute for a good inspection and assessment program to ensure that the fastener manufacturer, heat treater, and finisher are capable.