Large diameter Stainless Steel Fasteners?

[Dinosaur]

This could be asked in several different fora, but I'm going to give it a shot here first.

We own a number of bridges, including several trusses. Most of these trusses are made of built-up riveted steel members. The sections of the trusses are assembled with very large diameter pins, often located at both ends of a single member in each plane of the truss. This permits some relief of forces due to changes in temperature, but has other consequences.

Our consultant engineer was asked to specify stainless steel (ASTM A276, type 316) for these pins. The engineer called to ask me if such a thing was available. My involvement with stailness steel to this point has been limited to threaded fasteners up to about 1 inch diameter. Does anyone know where type 316 stainless steel is produced in pins five inches in diameter?

Our standard specifications for pins in this size range call for ASTM A668, Class D or Class F. Therefore, I believe we will be searching for somethig with comparable strength to these grades. Thanks for your help.

 

[TVP]

I am not aware of any manufacturer that makes "standard" 5 inch diameter stainless steel parts, but this type of product is a little out of my realm of expertise. I think you will have to work with a machine shop to fabricate large parts like this. There are not many sources for large diameter stainless steel bar, which may be another issue. Cartech and Universal Stainless are the only ones that immediately spring to mind. This forum does not get as much traffic as some of the others-- I would recommend posting in Metal and Metallurgy or Welding, Bonding & Fastener engineering.

 

[Dinosaur]

Thanks for the response. I am considering having an undersized structural steel pin somehow coated with a layer of 316 stainless. I don't know if it would be appropriate to wrap a sheet of 316 around the ASTM A668 material and then have the seam welded with stainless, or if I should just have a A668 pin "surfaced" using stainless welding and then milled to the final diameter. We will likely want to use a fully threaded stainless steel rod and nuts to hold the retainer caps on. Which ASTM spec might have these products?

 

[CoryPad]

Stainless steel fasteners of type 316 composition are included in multiple standards. I believe the most appropriate ones for your application are ASTM F 593 Standard Specification for Stainless Steel Bolts, Hex Cap Screws, and Studs and ASTM F 594 Standard Specification for Stainless Steel Nuts.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[IFRs]

5 inch stainless steel bar should be available. Any decent shop should be able to machint it and make them into pins

 

[hokie66]

You should be able to procure 316 stainless billets to that size or larger, and machine as required. I'm not sure where, but have seen big pins like that used here in Australia.

 

[EdStainless]

What strength level are you needing? In 316 you will only find very low strength material.
Try contacting Outokumpu stainless. They have a sales office in the Chicago area. They have a bar facility here in the US. They might be able to get you either cold finished 316 or duplex LDX2101 bar. The duplex is much stronger and has similar corrosion resistance.

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