What Is a Sanitary Tank Manway
A manway (also called manhole or access door) is an opening in a tank or vessel that allows personnel to enter for cleaning, inspection, and maintenance. In sanitary processing, manways must seal completely, be easy to open from both sides, and have a crevice-free interior surface.
We manufacture manways at our facility in Wenzhou, China in elliptical and rectangular shapes, in SS304 and SS316L. Surface finish: Ra ≤ 0.8 μm standard, Ra ≤ 0.4 μm for pharma.
Elliptical Manways
Most common type. Elliptical shape (typically 11″x15″ or 16″x22″) provides enough space for an operator to enter while maintaining structural integrity of the vessel wall. Hinged lid with swing bolts. Standard pressure rating: up to 10 bar. Optional: sight glass window in the lid, spring-assist for heavy lids.
Rectangular Manways
For tanks where headroom is limited. Rectangular shape (typically 12″x16″ or 14″x18″). Same sealing mechanism as elliptical. Lower pressure rating — typically up to 3 bar due to stress concentration at corners. Used for atmospheric and low-pressure storage tanks.
Key Selection Factors
Vessel pressure — determine if the manway needs to be pressure-rated or atmospheric only. Tank wall thickness — manway flange must match the vessel wall for proper welding. Frequency of access — if opened daily, choose a hinged design with spring-assist. Cleaning requirements — for CIP/SIP, the interior surface must match the vessel finish.
FAQ
Q: What size manway is standard? Elliptical 11″x15″ is most common for sanitary vessels. Rectangular 12″x16″ for atmospheric tanks.
Q: Can you add a sight glass to the manway lid? Yes — we offer manways with an integrated sight glass for visual inspection without opening the lid.
Q: What gasket material? EPDM standard. Silicone for SIP applications. FPM for chemical resistance.
Technical Review
Zhang Wei, Senior Engineer. onemo@onemoss.com
