Welcome to the Forum thinhnguyen111
Your question about Welding Procedure Specification (WPS) Qualification
If your production T-joint is going to be joined with a fillet weld, I think you may use the configurations found in Figures-4.9-4.11
If your production T-Joint will be joined with a groove weld than see 4.9.1.1 for direction on your test specimens.
Also see table 4.2
For welder performance qualifications see Table 4.10