cleaning fuel tank

I bought some evapo rust to clean light rust in tank,,,,will i need to remove petcock and fuel gauge so as not to damage with chemical or is it safe on seals?

Since their site says you can use it to treat a tank without removing the tank from the bike, I'd guess it's okay. However, I would contact them. They provided a quick response when I asked them about treating an exhaust system.

No. I used Evapo-rust on my 82 KZ1000 LTD. The gas gauge still works great. I did plug the petcock hole while I did this so I could rebuild the petcock. I used 2 gallons of Evapo-rust, and lots of fish tank glass beads to “displace” the Evapo-rust and get the entire tank. I plugged the fill hole with a plastic bag, set it on a rubber drip pan, and switched sides once a day for about a week. Rinsed it out with gas and filled it up. No rust, no leaks.