Water Heater Rocket

I had an inspection the other day on a bank-owned property. When it came time to check the water heater, this is what caught my attention.

This line is the one that releases pressure from the T and P valve (temperature and pressure valve). From time to time, pressure will build up in the the tank of the water heater unit. In order to allow this pressure to escape, a valve exists with a pipe that ends close to the floor drain. As you can see, this pipe is clamped shut. Luckily, the water heater was not turned on at the time of the inspection, due to the house being winterized. A couple months ago, I saw what could happen to a water heater that had the T and P valve closed off while under pressure. In the clip, they had built a one room structure to the building code. They put a standard water heater inside and closed off the relief pipe from the T and P valve. The pressure was raised in the unit and there was an explosion. It made tooth picks out of the structure as the heater unit shot off like a rocket. Needless to say, in a house there would be major structural damage. If someone was near the unit, death could occur instantly.