Whether you can use a "prequalified" procedure, an "AWS Standard Welding Procedure Specification" or have to perform procedure qualification tests will be governed by the code or standard that applies to the work you are performing. A good start is to find out what code applies, then get a copy and see what it says about procedure qualification. From the way you asked the question, there is a serious need for a CWI or someone else knowledgable in the applicable welding code to help sort this out. You can check with AWS by phone to find a CWI in your area.