4M nitric acid

Please let me know what is 4M Nitric acid. Will this help in cleaning and passivation of Stainless steel tube inner surface.

4M sounds slightly less concentrated than the 20% solution usually mentioned in the specs; but run the numbers on paper, I was just doing them in my head.

Please describe your own situation, Somashekar, rather than posing the question in such an abstract way. Your question as it stands is rather like asking if adding cauliflower helps soup. Thanks!

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

4M stands for 4 Molar or 4 moles of acid per liter. It is a measure of the concentration of the acid. If you used reagent quality full strength nitric, you would dilute 256 ml to a liter of final solution or 744 ml of water.
since you are buying a technical grade of acid, (which comes in various strengths) it will take closer to 300 ml of acid to 700 ml of water. Find out the strength of your acid and ask your local high school chemistry teacher for an appropriate dilution. NOW, you need to titrate and make corrections as required. Talk to the chemistry teacher about this also. He probably will refer you to a contract lab.