The UNS of Alloy 825 is N08825.

You can make a quick search with the key word "N08825" if you have an electronic ASME B&PVC Section II Part C.
You will find the suitable AWS Classifications as below:

ENiCrMo-18 for SMAW
ERNiFeCr-1 for GTAW and GMAW

Not sure about SAW but with the above information, the welding consumbles manufacturer may provide further recommendation.

Hope it helps.