Designating Double Stage Gas Nitriding

The best way is to write up a step by step internal standards document with the methods and final properties that are required and referencing the correct test methods to test them in a controlled document and reference that document on your drawing and supply them both to the vendor. Alternately if there is an ANSI/ASME/Mil-Spec that you can reference that accomplishes the same end, then you can forgo the separate document and just reference your external standard. Look to a similar ASTM or MIL-Spec as a guide to the level of detail required for such a document.

The alternative is to put ALL of this information on the face of the drawing, which for a one-off bit is not that big of a deal, but if you make more than one part number using this process you are in for a major ordeal to maintain these documents.

The advantage of the separate CONTROLLED, internal standards document is that it is reusable and you don't have to re-write it for every drawing and then have to make sure that you didn't make a typo in the process. And if the process is changed (due to a typo that the heat treater caught hopefully!) at a later date, then you don't have to go and make sure you have changed EVERY SINGLE document that might have used that process.

I would suggest that every company strongly consider this methodology (most larger companies do in one form or fashion.).

I would further suggest that if you specify materials that must be supplied in a condition that may differ in ANY respect from a documented industry standard (such as requiring low temp charpy tests on structural tubing otherwise meeting ASTM-500 grade B as an example, or requiring specific heats of a material to have a restricted range of hardnesses, or chemistry to meet NACE MR0175 as another example) that you develop material standards documents as well.

Same with painting/coating/plating specs for all of the same reasons.

Remember, he who does not fully document what he wants, deserves what he gets!