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What's Manhole?

Views: 2     Author: Site Editor     Publish Time: 2021-09-23      Origin: Site


Manhole is a door which should be install on a sealing vessel. And engineers could go inside the vessel through the manhole, so that they can clean, maintenance and installation inside the vessel. A manhole has a short tube, flange, cover with handle, and other parts. We have SS304 and SS316L two types. According to its max pressure, it has pressure and non pressure two types. According to the shape, it has round, square, and elliptical three types. Manholes could be install horizontally or vertically on the vessel. For more details, please be free to contact us. And our manhole catalog is also available on our website.



Manhole can be a ventilation device install on the top of the storage tank. It is usually use with fire extinguishers and mechanical breathing valves. When the pressure or minus pressure inside the vessel exceeds its limit, the vessel can be broken. So we could exhaust the pressure through the manhole to prevent the vessel. It is a safety device to protect the storage tank. It is especially suitable for the vaulted atmospheric tank with nitrogen topped by the storage material. It has constant pressure discharge, constant pressure suction, flexible opening and closing, safe fire resistance, compact structure, good sealing performance, safety and reliability.

The manhole of the non-metal oil tank is install on the top of the tank, and the manhole of the metal oil tank is installed on the bottom of the tank wall. The center of the manhole is 750mm away from the bottom plate. They are use for oil tank cleaning or maintenance. People enter and exit the oil tank through this manhole. During maintenance and cleaning of oil tanks, manholes should be open for lighting and ventilation at all times. Vertical oil tanks have 1 or 2 manholes when the capacity is smaller than 5000m3, and 2 manholes for those bigger than 5000m3.


Because the manhole is install at the lower part of the oil tank, the manhole stands a lot of liquid pressure. In order to prevent leakage, the manhole must be strictly installed. First, the joint surface of the two flanges must be flat. Second, there are sealing rings on the flange and cover plate, so special attention should be paid to keep clean and perfect. And no cracks are allow on the seal. When installing the manhole cover and tightening the bolts, be careful and prevent the manhole cover from deforming. At last, remember to make a mark every time the manhole is remove, so as to avoid dislocation when reinstalling, which affects the tightness.

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