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　　Functions of sanitary manholes:

　　 Hygienic manhole Also known as a stainless steel sanitary manway, it meets the specific requirements of various media in the food and biopharmaceutical industries. Types include: atmospheric-pressure, sight-glass with pressure seal, handwheel‑type, rectangular, elliptical, elliptical with sight glass, and square, among others.

　　Applications: Suitable for stainless steel storage tanks and vessels that require internal locking. Pressure is a critical parameter for sanitary fittings. When purchasing such components, careful selection is essential. As we all know, 304 stainless steel offers corrosion resistance two grades higher than 201 stainless steel, with 301 stainless steel falling in between. The statement “pressure resistance depends solely on the wall thickness of the sanitary fitting” is correct—thicker walls provide greater strength. So, do you know how the pressure rating of sanitary fittings is calculated?

        Hygienic manhole It is a negative-pressure manhole; typical manholes can withstand pressures up to 0.3 MPa. The primary materials used are stainless steels such as 304, 316, 321, and 316L. These manholes are generally installed on large‑capacity cans and larger vessels in industries like dairy, brewing, beverage production, pharmaceuticals, and bioengineering. Because the application areas impose stringent pressure‑resistance requirements, selecting appropriate stainless steel plate grades and thicknesses for quick‑opening manholes, along with ensuring the structural strength and sealing integrity of the manhole itself, constitutes the key technical challenges. A standardized process flow for sanitary fittings should be established, accompanied by complete, consistent, and clearly defined process documentation. Process equipment must be rationally designed, easy to operate, and reliably high‑quality, thereby ensuring robust reproducibility of manufacturing processes. During the production of sanitary fittings, process engineers should actively participate in or collaborate on process design and modifications, fostering integrated management that spans from process formulation through execution to ongoing refinement. While strengthening preparatory work on process technology, continuous attention should be paid to revising and improving these technologies. Whenever changes occur in the process flows or production rhythms for sanitary fittings or three‑piece ball valves, the corresponding process technical requirements must be promptly updated.

　　 Hygienic manhole The opening mechanism is characterized by convenience, high safety, and an aesthetically pleasing appearance. Typically, both the inner and outer mirror surfaces are polished or finished with a matte coating, achieving a surface roughness of Ra ≥ 0.8 µm. Quick‑opening manholes are generally installed at the bottom or top of the vessel and are equipped with flame arrestors and other safety devices. This design not only prevents vacuum‑induced damage to the vessel and potential casualties caused by sudden pressure surges or emergency situations, but also provides excellent fire‑safety protection, thereby maximizing the vessel’s overall safety. To prevent leakage, strict installation requirements must be followed for sanitary‑grade manholes, with adherence to step‑by‑step safety procedures. The same standards apply to production needs: the mating surfaces of the upper and lower flanges must be perfectly flat, with no wobbling or misalignment. When installing a quick‑opening manhole, ensure proper alignment and tighten the bolts evenly to avoid deformation of the cover plate or uneven stress that could lead to oil leakage.