Wrote off soapy water bubble tests until a 2 psi drop on a Tuesday hydro told me otherwise
Spent an hour chasing a leak on a 30 inch vessel flange with nothing but a spray bottle and kept missing it, so I finally broke down and borrowed the shop's ultrasonic detector, which found a pinhole at the gasket in about 90 seconds, and now I'm wondering what else I've been waving bubbles at and calling good.