Difference between MIL-C-5541E, AMSC5541, and MIL-DTL-541F?

A. It's been a confusing few years as it seems that the feds were trying to move specs from the Mil system to AMS standards, Billie. So new standards were written but old ones are not cancelled, etc.

Because of that, I think you are not asking quite the right question. I think the right "update" for MIL-C-5541 would actually be MIL-DTL-5541 [on DLA] F. In that case, Class 3, is for "protection against corrosion where low electrical resistance is required" and you would spec Type I for "Compositions containing hexavalent chromium" or Type 2 for "Compositions containing no hexavalent chromium" (which would be the new TCP formulations). I don't know what "Grade C" means -- sorry. Good luck and get back to us if I have misunderstood the situation.

A. The actual change, I believe, is that TCP (trivalent chromate product) is now permitted under MIL-DTL-5541 [on DLA]F.

Why the "style" of the spec went from "C" to "DTL", I don't know and I'm not in the loop. I hope that someone can help us out. But my interim understanding is that DTL is an abbreviation for 'detail' and it is used when a spec requires that certain "process details" be adhered to, as opposed to just being a "performance" spec.

A. Hey, at least they upped the revision letter!

I agree, Ted -- the biggest difference between MIL-C-5541E and MIL-DTL-5541F is that the buyer can ask for a "Type II" coating which will contain no hexavalent chromium. Currently, only the trivalent chromate formulation developed by NAVAIR is listed in the MIL-DTL-81706 [on DLA] spec, which governs the materials one can use for a proper MIL-DTL-5541 coating.

We consider a cert with "MIL-DTL-5541F" to be acceptable for parts requiring chemical conversion coating per MIL-C-5541.

The "DTL" is indeed short for "detail", and was done to reflect the move away from 'how-to' type specifications, to one that merely lists the important details of the requirements. I have to say I'm not certain of the difference between a 'detail' specification and a 'performance' specification such as MIL-PRF-46010 [from DLA] , which lists the performance criteria the coating is supposed to withstand.

By the way, the letter in the Mil and Fed specs is merely the first letter in the title of the specification. So here "C" is for "Chemical", and in QQ-P-35C [link is to free spec at Defense Logistics Agency, dla.mil], the "P" was for "Passivation".

It doesn't have to make sense.

A. Mr. Sidorovsky, I hope you've got the answer to your question by now but my two cents after poring over the specs for a couple hours:

If the drawing doesn't specify Type II (non-hexavalent chromium), then it shouldn't be RoHS compliant. 5541 says to default to hex chrome material (Type I) if a material type isn't specified in the contract. For a copy of 5541 (it's now MIL-DTL-5541) and other mil specs, go to  assist.daps.dla.mil/quicksearch/  or www.landandmaritime.dla.mil/Programs/MilSpec/DocSearch.aspx

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Ed. note, April 2014: the URL for the 'assist' site is presently quicksearch.dla.mil/

A. Through conversations with others, I was able to grasp the difference between MIL-DTL-81706 and MIL-DTL-5541 and wanted to post for anyone else who may have questions about it:

81706 is the spec to which the conversion coatings themselves are qualified. Suppliers develop materials and processes that are approved for use after much testing. This is the "theoretical standard" to be met under ideal conditions.

5541 is the spec against which the manufacturer measures their coating _process_ to ensure that the process is being performed properly. Allowance is made for manufacturing tolerances and consumption of the chemical after processing several lots, hence an allowance for slight corrosion. This is the "practical standard" to be met under real life conditions of manufacturing.

A. Hi R. We appended your question to a thread which hopefully answers it for you. Supplier companies like Henkel, Macdermid, Chemetall, etc., get their products qualified to be listed in MIL-DTL-81706 (used to be QPL-81706 for 'Qualified Products List'), then you as the applicator follow the instructions in MIL-DTL-5541, but you must use one of the products listed in MIL-DTL-81706 when doing so.

Regards,

Thanks for your help and linking my question to a previous thread. Nothing like a conversation that spans a few years!

A. Hi Lydia. As you can now see from the earlier postings on this thread, MIL-DTL-5541 is the current standard, and Mil-C-5541 is the older standard. You should probably ask your Mil-C-5541 customer to update their requirements to the current specification. Good luck.

Regards,

A. On the DLA Assist Quicksearch page, MIL-C-5541 revision E is found on the same page as MIL-DTL-5541 revision F. At some point a great many standards got changed over to the DTL designation (according to Wikipedia it means "Detail Specification", no idea what the "C" used to refer to*) but it seems to be a distinction without a difference.

Though obviously everybody should be looking at revision F rather than the older copies.

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Ed. note: * Lee Gearhart advised an earlier writer that "C" stood for "Chemical".

Joseph,
Probably the answer you are looking for is from Lee Gearhart up near the top of the page from 2002.

A. Hi B. Although it might be unlikely that there would be any reaction between the two materials, who would want to be on the hook to have to prove it if anywhere down the line the component had trouble of any sort, related or unrelated? I wouldn't do it; I'd get some material made for touching up Type II.

Regards,