Metal finishing Q&As since 1989

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NADCAP Requirements for Certifying Hood Furnaces

September 3, 2009

We are performing initial/validation Temp Uniformity Surveys (TUS) on HOOD Annealing Furnaces to be in compliance with AMS2750D in preparation for NADCAP Certification for Heat Treating per AC7103 Rev E - planning for NADCAP later in 2010.

We have (4) fixed bases for the HOOD Furnaces. They are identical with each other and compatible for all (3) HOOD Furnaces

We have (3) HOOD Furnaces that are basically all the same type & size and all operate at the same temp ranges. There is no dedicated HOOD for any Heat Treat Process - they all can be used for Annealing Orders. They are natural gas fired furnaces - no special atmosphere is used.

The (3) HOOD Furnaces can be used and are used with any of the (4) furnace fixed bases. They are used for annealing of SS steel flat sheets, bars & billets (not TI or AL).

So our question is:

1. In order to be in compliance with AMS2750 D & NADCAP HEAT TREAT (AC 7102 Rev E) can we perform our initial/validation Temp Uniformity Surveys (TUS) on HOOD Annealing Furnaces to be in compliance with AMS2750 D by doing a total of (3) TUS Surveys - one done on each of the (3) HOOD Furnaces located on their existing bases at the time of TUS Survey and document as such.

OR

2. Do we really have to perform a total of (12) TUS Surveys which would include the combination of each of the (3) HOOD Furnaces located on each of the (4) Bases - to eliminate any potential variation ?

3. As you would imagine our preference would be to do Number #1 and if we choose this route what documentation would we need to provide to NADCAP Auditors to justify this method ?

We are looking for comments from heat treat experts that others could also apply to their operations for efficiency and cost savings.

Thank you !

Dale Gabauer
Electrical Engineer to Heat Treaters - Pittsburgh, Pennsylvania

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September 7, 2009

Really the best people to tell you about the requirements are PRI themselves.

Have you tried auditing against the relevant NADCAP checklist? This should give you a clue as to what you need to do. If it is still not clear, go to the horse's mouth.

Finally, you may want to consider the eQualPrep service that PRI offers. It is a sort of pre-audit and will give you a clue about where your gaps are.

Brian Terry
Aerospace - Yeovil, Somerset, UK

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February 10, 2010

It's probably too late but consider yourself lucky you didn't have to work to the Revision C issue of AMS2750.

In answer to your questions...

1. In order to be in compliance with AMS2750 D & NADCAP HEAT TREAT (AC 7102 Rev E) can we perform our initial/validation Temp Uniformity Surveys (TUS) on HOOD Annealing Furnaces to be in compliance with AMS2750 D by doing a total of (3) TUS Surveys - one done on each of the (3) HOOD Furnaces located on their existing bases at the time of TUS Survey and document as such.

OR

2. Do we really have to perform a total of (12) TUS Surveys which would include the combination of each of the (3) HOOD Furnaces located on each of the (4) Bases - to eliminate any potential variation ?

>>>It's likely that an Auditor would question any variation due to setup and I personally would do the TUS' for each possible combination/configuration. This is only because of my interpretation of the spec. (as already stated, the staff engineer is the person you're best getting confirmation from)... Any change/repair to a furnace that might alter it's uniformity characteristics is reason alone to revert to an Initial TUS frequency. Depends on the auditor you get but I'm guessing sooner or later you'll be asked to explain how you know the different bases don't affect uniformity - The objective evidence would require data - i.e. a TUS report to close it (the NCR) out.

Also the frequency of TUS is dependent on your furnace control setup.. does it just have a single thermocouple for control/recording and another independent TC for the over-temp? If so that's TYPE D and what is your operating tolerance? ±5°C ? If so that's a TYPE D2 furnace, you'd need to Survey it monthly.. after 8 monthly surveys you'd be able to go to a bi-monthly plan.

Lee Stanley
- Manchester, UK