I would suggest taking all of the precautions..

But seriously, you must tell us just a little bit more about your project if you want an answer.

I was going to post more sarcasm, but, like Lawrence said, we need more info. 

What grade AL are the plates?
What AL electrode were you planning to use?
What is your applicable code?
What process are you planning to use?
Have you, your welders, the company, welded AL previously?
What cleaning procedures were you intending to employ?
ETC, ETC,

He Is In Control, Have a Great Day,  Brent

Hi Sanny,  Welcome to the Forum

i want to certify on ALUMINUM, I get confused on what to fill out on the APPLICATION FORM



I don't know what "application form" you are talking about...  You need to say more about that.

SUPPLEMENT:
CODE:  You need to tell us which code you are working to
PROCESS:  Aluminum can be welded with many processes... You must tell us which you are able to use
FILLER METAL:  This depends on the base metal and the service conditons of the thing you are welding.
BASE METAL:   You must tell us which base metal you are going to weld.
POSITION:   Aluminum can be welded in all positions with many processes... Some more easily than others.
THICKNESS:   We don't know what thickness you need to weld... You must tell us.

THANKS