I have had good experience with commercial nitric acid formulations. The reps will be able to recommend something. (I used "Pascal" from JohnsonDiversey)
The tanks etc. have to be cleaned and rinsed in advance of course. Mostly concentrations (of the formulation) of 1-3% are recommended. Contact time should be around an hour and the temp shouldn't go over 60 C (140F).
Under these conditions I never noticed any problems with seals and gaskets.
Some people recommend letting the tank dry off before rinsing it after the acid cycle. Others claim this isn't necessary. What seems to be important is ensuring that enough air resp. oxygen, gets to the surfaces - vent out all CO2 adequately.