155516 ⎘
Water-tube boilers of vertical or steeply-inclined type, i.e. the water-tube sets being arranged vertically or substantially vertically built-up from substantially straight water tubes involving a single upper drum and a single lower drum, e.g. the drums being arranged transversely the water tubes being arranged sectionally in groups or in banks, e.g. bent over at their ends Frames built-up from water tubes