Broken water tank connections
Each of my water tanks have one 1/2" drain connection and two 3/8" connections (high and low) for water level indication. When I turned one of the 3/8" ball valves it came away in my hand!
The connections appear to be a pipe stub welded to the tank with a pipe coupling welded to the pipe stub. The adapter between the ball valve and the coupling apparently deteriorated and became very weak. I couldn't tell what material it was made from, it was black and crumbly.
The threaded portion of the adapter remained in the coupling and was impossible to remove. I checked the others and one broke easily; two others took a little more force. Only two were intact enough to unscrew.
I decided to simply hose clamp larger diameter tubing to the OD of the welded coupling. For the level indication connections, I simply ran the hose from one connection to the other with no valves.
For the drains, I adapted down to 1/2" tubing and installed two new ball valves. I reused the bronze check valves (one of them had been stuck so that side tank wouldn't drain).
Not a whole lot of fun but I'm glad it's done now.