age limit for material testing certificate

[bahathur]

good morning,
i just want to know about age limit for mill testing certificates(MTC). otherwise, how long i keep the same MTC for the same materials.

 

[racookpe1978]

I'm not sure what is the purpose of you keeping the MTC: Are you the owner of the final assembly? The machining company that provides the parts to somebody else who needs to certify their assemblies? A "retail" company who must be able to provide future companies with certification for future parts? A mid-supply-chain-point company who doesn't know who in the future will need what kind of parts?

See, unlike banana's or cornflakes, metal will pretty much stay "forever" on the shelf. The same original piece of metal will be used by various future clients in different ways. SO, a few weeks ago, I only needed 4 inches long of a 2 inch diameter rod of a specific alloy and heat treatment to fabrication a bushing. Found a supplier who could get it to my site before the weekend, and we received it and its certification sheet by UPS on Friday morning. (Only a couple dozen dollars total.) But we has the certification, I could still assure my engineering, my boss, and ultimately my customer that the metal was the right stuff for machining, welding, and final delivery - since it did NOT come through our regular supply chain and their certifications. The short rod came off a longer bar that may have been on the shelf for 12 years - I didn't care.

The Nuke industry, some military and gov parts, some food manufacturing, some health and now car companies, many shipping and transportation fabricators need different cert's for their final assemblies.

If you don't know where your metal ultimately ends up, you need to keep EACH HEAT's certifications until all of the material from that heat or production run is used up from your "on the shelf" inventory - or you will potentially lose future sales because you cannot provide documents with the metal.

Now, some other companies (customers) and countries don't care. Plowshares and counter-tops and restroom partition assemblies in Indonesia will likely never need certification paper.

Most of the time in the EU and US, a company that needs to machine 50000 valve bodies also needs the same certification as I did for my 2 lbs of rod.

 

[metengr]

There is no age limit for MTR's. One can keep an MTR for traceability of material for the life of the component.

 

[bahathur]

I getting material from supplier (ex..2010 they send MTC)whether, it is acceptable.. in othercase finished product they manufactured in the year of 2012 they will send the MTC and mechanical strength test (load test) report in the same year...it is valid one or not.....

 

[racookpe1978]

Why would it have changed? Why do you think it is no longer any good?

 

[EdStainless]

If they melted the raw material in 2010 (or bought a large quantity) then the material is the same. When they finished it doesn't really matter.
Unless your PO has requirements for product testing of your actual shipment.
Is there some other reason that you are questioning this?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[bahathur]

what are the factors which may included to perform material test again. example, if the material stored in different temperature levels for a long time sure it have some changes in their mechanical behaviour.

 

[IRstuff]

I don't any natural storage temperature will have any effect on the metal properties. If that were the case, the metal wouldn't even survive normal operation; it would be impossible to design for infinite life.

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[metengr]

what are the factors which may included to perform material test again. example, if the material stored in different temperature levels for a long time sure it have some changes in their mechanical behaviour.

Some materials can strengthen by aging at room temperature, like certain aluminum alloys after heat treatment. However, the concern for re-testing may not be necessary given the predictability of the material. Normally, if aging is performed, the material will be tested after aging is completed, based on conditions stated in the MTR.

 

[redpicker]

A lot depends on what the material is.

For steels, for example, I have seen a concern by users with products being produced with "old steel". There is an impression that products made with "old steel" are considerably inferior compared to those made with "new steel". In fact, I have seen product specifications that require the parts be manufactured by steel that has been received by the manufacturing facility within the past 3 months.

On one hand, this is ridiculous. As racookpe1978 has stated, the steel isn't going to change by sitting on the shelf.

From a practical standpoint, however, I can see know why this perception exists. If a shop has a piece of steel stock that has been sitting around for 10 years, you can bet there is a reason it hasn't been used. In that time, the people who knew the reason not to use it (and, therefor, would know what types of products it could be used for) have moved on (retired, found a better job, were promoted, fired, or laid-off). But, the stock is still on the shelf with the heat number steel stamped. Ten years later, someone finds the steel, runs the MTR from records and finds that it seems to be fine. They use it and the product fails, because the steel had serious quality issues not reflected on the MTR (heavy stingers, internal bursts, spotty hardness, there could be a host of issues why the quality was bad).

Another issue with old steel is that in the time it has been on the shelf, the identification could be lost. Someone saws the stamped end off to use for a part and mis-stamps the traceability number. Next inventory, it is found to not have a valid traceability number, so they make the assumption that it should be the same as the piece next to it. Traceability is lost, but it appears that the traceability is good.

While both of these could happen with new stock, it is much more likely to occur the longer the material stays around. Most places I've worked had a policy that any material over 3 years old had to be signed off by the plant metallurgist and I've scrapped material just for being old and I wasn't sure I could trust it.

 

[IRstuff]

"Another issue with old steel is that in the time it has been on the shelf, the identification could be lost."

Worse yet is if it gets labeled as something else.

TTFN
I can do absolutely anything. I'm an expert!
faq731-376 forum1529

 

[BUGGAR]

If you are McMaster Carr, you can charge significantly more for your product if you have certs.

 

[mrfailure]

Specifications do get revised. On occasion material that met spec limits under an older version will not meet the current version; this is why certs always reference the version of the spec. Usually revisions do not impact usability of the material but there are occasions where the material will need to be retested to current specs, especially if additional requirements are added for the specification since the material was certified.