Manhole
In shipbuilding , plant construction and apparatus engineering, as well as in mining, a manhole is an entry point or a processing opening into a container or a room. Round, oval or, more rarely, rectangular cross-sections with a clear width of 400 to 600 mm are common, so that a person of normal build can climb through without great difficulty. Only if large tools or parts have to be brought through the manhole on a regular basis is it made larger.
The manhole is closed with a so-called manhole cover or a manhole door using screws or a quick-release fastener in a pressure-tight and liquid-tight manner. Pivoting devices are sometimes used to open and move heavy manhole covers. Covers of vertical shafts are also called manhole covers . You will e.g. B. opened with manhole hooks.
The term inspection opening means a closable opening on a pressure vessel . Such openings are often built as a blind flange with any diameter . Inspection openings made in this way can easily be climbed through by a person when repair work is to be carried out inside the pressure vessel. For nominal sizes from DN 500, it may be necessary to remove the cover , which weighs several hundred kilograms, from the pressure vessel using a separate lifting device.
Furthermore, elliptical lids with dimensions of up to 350 mm × 450 mm are common, which are inserted through the opening and held by the pressure prevailing inside . In the event that the container is depressurized, one or two screws with steel brackets prevent the lid from falling inwards.
Smaller inspection openings are used on small pressure vessels (or when entering the interior space is not necessary or not possible due to built-in components), which are then called head or hand holes in decreasing size . This allows a visual inspection and cleaning of the interior to be carried out with suitable tools.
