Manhole (boiler, sewer for people in and out of maintenance), maintenance hole, sewer access hole: a hole often with a cover, people can enter and exit the drainage channel, boiler, sewer, and including telecommunications, cable TV use of the weak well, large bridges with internal access for maintenance, etc..
Manhole is a safety emergency ventilation device installed on the top of the tank, usually used in conjunction with the fire arrester, mechanical breathing valve, not only to avoid accidents caused by accidental causes of acute overpressure or vacuum in the tank, damage to the tank, but also to play a role in the safety of fire, is a safety device to protect the tank, especially for storage materials to nitrogen capped vaulted atmospheric tanks. It has the advantages of constant pressure discharge, constant pressure inhalation, flexible opening and closing, safe fire stopping, compact structure, good sealing performance, safety and reliability, etc.
Manhole is divided into emergency pressure relief manhole, explosion-proof fireproof breathing manhole, tank top manhole, tank wall manhole and manhole with core, etc..

Manhole is generally made of 304,316L stainless steel plate or carbon steel. The manhole has been formed products, usually 600mm in diameter, and the center of the manhole is generally 750mm from the floor, making it easy for personnel to enter and exit the tank or ventilate it during installation, cleaning and maintenance.
The manhole of non-metallic tank is located on the top of the tank, and the manhole of metal tank is located on the lowermost ring plate of the tank wall. Most of them are 600mm diameter round holes, the center of which is 750mm from the bottom plate, for tank cleaning or maintenance personnel to enter and exit the tank, also known as the door. Inspection and cleaning of the tank at the time to use the manhole for light and ventilation. The capacity of vertical tanks in 5000m?3; below set 1 ~ 2 manholes, 5000m?3; above set 2 manholes. The installation of the manhole should be separated from the inlet and outlet pipelines by no more than 90°. When there is only one manhole, it should be placed on the opposite side of the tank roof light; when there are two manholes, one of them is located on the opposite side of the light hole, and the other should be at least 90 ° from the first manhole. One manhole should be located near the right side of the inlet and outlet pipe, and try to make the manhole facing the closed door of the tank room, so that personnel can enter and exit, repair the tank and ventilation take over with.
As the manhole is installed in the tank’s lowermost body circle, leakage prevention is particularly important. It is required that the joint surface of the two flanges must ensure their straightness and no drifting and twisting phenomenon. The reinforcement plate and flange should be cut on the whole steel plate as far as possible without splicing. The flange and cover plate are processed with sealing rings, which should be protected with extra attention during construction. Seal with 3mm thick asbestos rubber gasket, no fracture is allowed. When installing the manhole cover plate tightening bolts, it should be diagonal and even force to prevent the hole cover from deformation.
Manhole is a safety emergency ventilation device installed on the top of the tank, usually used in conjunction with the fire arrester, mechanical breathing valve, not only to avoid accidents due to accidental causes of acute overpressure or vacuum in the tank, damage to the tank, but also to play a role in the safety of fire, is a safety device to protect the tank, especially for storage materials to nitrogen capped vaulted atmospheric pressure tank. It has the advantages of constant pressure discharge, constant pressure inhalation, flexible opening and closing, safe fire stopping, compact structure, good sealing performance, safety and reliability, etc.
Manhole is divided into emergency pressure relief manhole, explosion-proof fireproof breathing manhole, tank roof manhole, tank wall manhole and manhole with core, etc.. Manhole is generally made of 304,316L stainless steel plate or carbon steel. The manhole has been formed products, usually 600mm in diameter, and the center of the manhole is generally 750mm from the floor, making it easy for personnel to enter and exit the tank or ventilate it during installation, cleaning and maintenance.
The manhole of non-metallic tank is located on the top of the tank, and the manhole of metal tank is located on the lowermost ring plate of the tank wall. Most of them are 600mm diameter round holes, the center of which is 750mm from the bottom plate, for tank cleaning or maintenance personnel to enter and exit the tank, also known as the door. Inspection and cleaning of the tank at the time to use the manhole for light and ventilation. The capacity of vertical tanks in 5000m?3; below set 1 ~ 2 manholes, 5000m?3; above set 2 manholes.
The installation of the manhole should be separated from the inlet and outlet pipelines by no more than 90°. When there is only one manhole, it should be placed on the opposite side of the tank roof light; when there are two manholes, one of them is located on the opposite side of the light-transmitting hole, and the other one should be at least 90 ° from the first manhole.