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MS Bolt Options

MS Bolt Options

MS Bolt Options


I'm currently using two MS9556-32 bolts in an assembly and might need a stronger bolt. Details being worked with my customer. I have found the same size in Waspaloy MS9696-33. I'm wondering if I can find a stronger standard or MS bolt the same size as MS9556-32 in a more conventional material. I don't think I need the Waspaloy. Is there an index for MS and the AS replacement standard bolts?

RE: MS Bolt Options

The MS9556 (now AS9556) bolt is AMS 5731 (A286 130ksi min) and the MS9696 (now AS9696) bolt is AMS 5708 (Waspaloy 165ksi min). So not a huge difference in tensile strength.

A286 and Waspaloy are corrosion resistant materials with good elevated temperature capability. The nice thing about MS955X series bolts is that they are widely used on turbine engines, so they tend to be more available. You did not mention why you require an MS standard bolt, but if a commercial aerospace quality equivalent is acceptable you might consider using one of them. The most common high-strength, corrosion resistant, high temp fastener material currently used is AMS 5662 (718 Inconel 220ksi min). The SPS website has a very nice tool for searching their aircraft fastener catalog.

Since the MS standards are now maintained by the SAE, most of them have replaced the "MS" prefix with an "AS" prefix. If you want to see what similar standard bolt types are covered by the SAE, you might try searching the SAE standards database using keywords like "Bolt, Machine - Double hexagon".

Hope that helps.

RE: MS Bolt Options

Thanks Terry,

The application is commercial aerospace. I do understand MS standards are now maintained by SAE. We typically use and buy a large number of MS955X fasteners. I have an installation physically designed for the MS955X and need a higher strength material based upon installed operating conditions (Temperature). I prefer not to redesign the assembly for a different fastener.

You have provided the input I need to identify a fix. Thanks again.

RE: MS Bolt Options


Based on the configuration/material of Your bolts [as-is/proposed] I assume they perform a mechanical function in high-heat, and a corrosive/erosive environment [engine?]. I am personally not very familiar with non-precision shank tension-fatigue rated bolts, like these. Also, these 3/16 bolts are smaller than I would have ever-guessed for a mechanical tension application...

Tbuelna... FYI... CAUTION regarding part numbers...

MS9556-XX are now represented in specification SAE AS9556, and MS9696-XX are now represented in specification SAE AS9696... but the PART NUMBERS REMAIN MS9556-XX and MS9696-XX.

This happened to hundreds of AN, MS, MIL, etc specs, which were transitioned to SAE or AIA 'ownership'. The base digits [xxxx] remained the same but the specification prefix changed to [mostly] ASxxxx or NASMxxxxx... but part numbers remained unchanged [original]... to avoid mass confusion within the parts supply channels and established engineering drawings, IPBs, AMMs, SRMs, etc.

... Except for raw materials... which are a whole different story...

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: MS Bolt Options


I have a follow up question. AS9556-xx and AS9696-xx define the same physical bolt size/geometry constructed of different materials. AS9556 -->(AMS 5731/130 ksi/A286). AS9696 --> (AMS 5708/165 ksi/ Waspaloy). Is there a similar MS/AS spec, same physical bolt size/geometry constructed using Inconel 718?

RE: MS Bolt Options


You might take a look at the NASM14181 bolt standard, which s/s the MS14181 bolt standard, but as WKTaylor reminds us the p/n remains unchanged. This bolt is made from AMS5662/AMS5663/AMS5962 (718 Inconel 220ksi Ftu). It is the same basic configuration as MS955X, except it uses a spline drive instead of a 12pt drive. Some of the dimensions/tolerances may also differ slightly.

The link provided for the spec is the Coast Fabrication website. They are a race component supplier just down the road from me in Huntington Beach, CA. I would assume that since these bolts are being used in the racing industry, they should have good availability.

Good luck with your project.

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