Should not the record of pressure testing be documented rather than scrawled on the boiler itself? Just a passing thought.
Looking at the pictures I agree with your implied doubts – anything but neat, particularly underneath. But who am I to criticise having never built a boiler?!
However, I regard ‘professional’ as meaning anyone who gains reward in return for services rendered: even a cowboy builder can claim to be professional!
Sorry to be a misery – now to get shot down in flames
Eric Lougheed