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Power plant accessories special flange manhole, tank top manhole DN600 PN1.6 304 ASME manhole
Manhole refers to the opening structure used for personnel to enter and exit the equipment for installation, maintenance and safety inspection. It is mainly composed of short tube section (or short tube), flange and manhole cover with handle. From the perspective of safety inspection, the number of manholes required for pressure vessels and their minimum dimensions are shown in "Inspection Holes". The manhole materials are carbon steel and stainless steel. Manholes are divided into normal pressure and pressure manholes according to pressure conditions; manholes are divided into round, oval and rectangular manholes according to their shape. Rectangular manholes are only suitable for atmospheric equipment; manholes are divided into horizontal according to the installation position. And vertical installation manhole; the fixing method of manhole cover includes rotating cover and hanging cover; the speed after opening of the manhole has ordinary type and quick opening type, the structure and size of the manhole are generally standardized, please refer to the relevant manual for selection or design.
The manhole is a safety emergency ventilation device installed on
the top of the storage tank. It is usually used in conjunction with
fire extinguishers and mechanical breathing valves. It can not only
avoid accidents caused by sudden overpressure or vacuum in the tank
due to accidents, but also damage to the storage tank. It is a
safety device to protect the storage tank, and 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 the advantages of constant pressure discharge,
constant pressure suction, flexible opening and closing, safe fire
resistance, compact structure, good sealing performance, safety and
reliability.
Manholes are divided into emergency pressure relief manholes,
explosion-proof fire-resistance breathing manholes, tank top
manholes, tank wall manholes and cored manholes.
Manholes are generally made of 304, 316L stainless steel plate or
carbon steel.
Manholes have been shaped products, usually 600mm in diameter. The
center of the manhole is generally 750mm from the floor. It is
convenient for the staff to enter and exit the oil tank or
ventilate during installation, cleaning and maintenance.
The manhole of the non-metal oil tank is set on the top of the
tank, and the manhole of the metal oil tank is set on the bottom
plate of the tank wall. Most of them are round holes with a
diameter of 600mm, with a center distance of 750mm from the bottom
plate, which is used by oil tank cleaning or maintenance personnel
to enter and exit the oil tank. It is also called a door. Use
manholes for lighting and ventilation at all times during
maintenance and cleaning of oil tanks. Vertical oil tanks have 1 to
2 manholes when the capacity is below 5000m3, and 2 manholes for
those above 5000m3. The installation of the manhole should be no
more than 90° away from the oil inlet and outlet pipelines. When
only one manhole is provided, it should be placed on the opposite
side of the light-transmitting hole on the top of the tank; when
two manholes are provided, one of them is located on the opposite
side of the light-transmitting hole, and the other should be
separated from the first manhole by at least 90 °.
One manhole should be located near the right side of the oil inlet
and outlet pipes, and try to make the manhole face the closed door
of the tank chamber so as to facilitate the entry and exit of the
oil tank, the maintenance of the oil tank, and the ventilation
pipe.
Since the manhole is installed on the bottom ring of the oil tank,
leakage prevention is particularly important. It is required that
the joint surface of the two flanges must be flat and free of
twisting. Reinforcing plates and flanges should be cut on the whole
steel plate without splicing. The flange and cover plate are
processed with sealing rings, so special attention should be paid
to protection during construction. 3mm thick asbestos rubber gasket
is used for sealing, no cracks are allowed. When installing the
manhole cover to tighten the bolts, force evenly at diagonal angles
to prevent the manhole cover from deforming.