So, you are qualifying the welders with backing and purge?
I typically have the client make a fixture so they have it available for practice and anytime they need to qualify their welders. Also, maintenance is their problem, because it will be abused over, and over, and over.
I have a similar design, but there is a deep slot for open root. The purge, a pipe with numerous holes drilled through it, can be inserted if it is needed.
The fixture for procedure qualified includes a 22 inch slot so I can weld 20 inch long coupons when necessary.
Best regards - Al
Very nice and clean, that is exactly what we used for welder qualifiation here in aerospace
Hardest part would be finding customers.
PM me what part of socal you're in, I operate out of Los Angeles nice to network with people in the industry here.