Weld on Top Rim of Tank

Question:

Why didn’t you weld the tank all around the top rim? My tank looks unfinished!

Answer:

The tanks cannot be sealed in anyway. The heat and expansion of the water in the jacket must not be contained or it will expand and explode. The tanks are 18 gauge SS but they are not made to be steam kettles. Steam kettles are made to withstand explosive pressure similar to pressure cookers. Even these have safety valves when the pressure gets too high.

This is why we “stitch weld” around the rim cap so heat and steam can slowly escape. If we did not, the water would spew up out of the fill hole and that would definitely scald someone.