WELDCOME to the World's Greatest Welding Forum!
A few questions if I may... Have you ever welded stainless steel before? Do You know what grade of Stainless steel the 1/2 tank vessel is made of and, is it a new 1/2 tank or a used one? is this vessel to welded to a specific code or standard? What is 1/2 tank and where's the other half (Sorry but I couldn't resist
)? What processes do you have available to eventually perform the welding you're attempting to describe?
The first thing you need to find out is the grade of stainless you're dealing with that the 1/2 tank vessel is made of, and if the 1/2 tank vessel has been exposed to any potentially flammable liquids that usually leave a thin film residue in the 1/2 tank vessel unless it has already been pressure washed and tested to be safe for hot work etc...
And if it's an ASME stamped vessel presuming it's a used one then you'll need to either be qualified to do the welding on the tank, or you'll have to farm out that part of the job to someone else who is qualified to whatever stamp that's required in order to do any sort of repairs including welding... And then if you can answer the other questions, we may be able to guide towards the right direction in order for you to safely start completing this job...
In other words, you need to supply us with much more details than what you posted so far to even begin to offer you some suggestions that make sense and are relevant to your job and the more details the better.
Respectfully,
Henry