No such certification for engineers (the designer) exists in the USA, and I doubt that it exists oversees. This applies to Section VIII, Div 1, B31.1 and B31.3. B31.3 recently added provisions for qualifications for the designer (para. 301.1) but this calls for a combination of education and experience (including an option for a PE), and is not based on any certification program.
In the USA, PE is professional engineer which is a licensing program not specifically associated with the codes.
A licensed PE is required by code to be involved in Section VIII, Div 2 vessel design (User's Design Spec and Manufacturer's Design Report).
Leanne, I asked 2 things different : certification for welding engineer (AWS Forum) and certification for pressure vessel and piping designer (ASME Forum).
I conclude that there is a AWSCWEng not equivalent to EWE (EWF). And for pressure vessel there is a kind of "chatered engineer" but not overseas.
No special certification program, however as mentioned by cb4 above, a Professional Engineer is required for Section VIII div 2. In addition in some juridictions a P.E. is required for repair and alterations.
You are correct in that the AWS CWEng is not equivalent to the EWE program. AWS is the USA acceditation body for the IWE dipolma which is equivalent, though at the present time having an IWE diploma is generally not required in the USA. It haowever hmay become important in the future due to the European Pessure Equipment Directive.
Australia
Though the Insitute of Engineers,Australia and the National Engineering Registration Board there is a Pressure Equipment Design Verifier