News and Information

　　Quick-opening manhole It belongs to the sanitary‑grade pressure manhole series and is a standard manhole rated for an internal pressure of 0.3 MPa. The primary materials used are stainless steels such as 304, 316, 321, and 316L. What are the applications of quick‑opening manholes? Let’s take a brief look below.

The quick‑opening manhole is a rapid‑access design, characterized by ease of operation, high safety, and an aesthetically pleasing, practical appearance. Typically, both the interior and exterior surfaces are finished with either mirror‑polished or matte finishes; the mirror polish achieves a surface roughness (Ra) of greater than 0.8 µm or equal to 0.8 µm. Quick‑access inspection hatches are usually installed at the bottom or top of storage tanks and are often used in conjunction with fire‑protection devices. This not only prevents tank damage and personnel injury caused by sudden pressure surges or vacuum spikes during accidents, but also enables these quick‑opening manholes to provide excellent fire‑safety protection, thereby maximizing tank integrity and safety.

　　To prevent tank leakage, the installation of quick‑opening manholes must be strictly controlled, and safety procedures and regulations should be implemented in a systematic manner. The same requirements apply to the fabrication of quick‑access inspection ports. The mating surfaces of the upper and lower flanges must be perfectly flat, with no unevenness or misalignment. When opening the quick‑access manhole, align the bolts evenly and tighten them uniformly to avoid deformation of the cover or uneven stress that could lead to oil leakage. Silicone rubber is typically used as the sealing material for quick‑opening manholes. Standard sizes range from 150 mm to 600 mm.

　 　Quick-opening manhole It is a quick‑opening manhole structure used in the pressure vessel industry, characterized by its openness, safety, and aesthetically pleasing appearance. Such quick‑opening manholes are typically installed on the bottom or top of tanks and water containers, facilitating personnel access and visual inspection of the vessel interior. They can be employed in both atmospheric‑pressure vessels and pressurized vessels. Traditionally, the flanges and cover plates of these quick‑opening manholes feature U‑shaped bolt holes oriented outward, enabling convenient installation via stud reversal. Currently, live‑joint bolts are commonly used; a headless pin serves as a support by passing through the bolt’s internal bore and the mounting block’s hole, thereby securing the live‑joint bolt during installation. However, because the diameter of the headless pin is smaller than the nominal size of the live bolt—taking GB 798 as an example, the secondary pin diameter for an M24 live bolt is only 18 mm—during bolt tightening, the headless pin experiences shear stress greater than that borne by the threaded portion of the live bolt. Improper pre‑tightening of the studs can induce tensile‑bending deformation in the headless pin, leading to uneven stress distribution at the flange seal and increasing the risk of leakage, thus posing a potential safety hazard.

　　 Quick-opening manhole It features a quick‑opening design, characterized by ease of operation, high safety, and an aesthetically pleasing, practical appearance. Typically, both the interior and exterior surfaces are finished with either mirror‑polished or matte finishes; the mirror polish achieves a surface roughness (Ra) greater than 0.8 µm or equal to 0.8 µm. Quick‑access inspection ports are usually installed at the bottom or top of the tank and are often used in conjunction with fire‑proof devices. In the event of a sudden pressure surge or vacuum buildup caused by an accident, such ports not only help prevent tank damage and protect personnel but also serve as effective fire‑safety barriers, providing limited yet valuable protection for the tank’s integrity.