Applications Of Stainless Steel Manholes In Various Fields

A stainless steel manway is a circular or oval access portal on tanks and vessels for cleaning, inspection, and maintenance. From dairy silos to fermentation vessels, these access points ensure hygienic operations. The cover seals with gaskets and clamps, maintaining tank integrity while allowing personnel or equipment entry.

How to select a stainless steel manway for your tank?

1. Choose material: 304 for food/beverage, 316L for pharma/biotech.

2. Select surface finish: Ra ≤ 0.8 μm for sanitary, Ra ≤ 0.4 μm for pharmaceutical.

3. Specify gasket: EPDM for food/dairy, PTFE for aggressive chemicals.

4. Verify pressure rating: atmospheric for storage, ASME-rated for pressure vessels.

Common Selection Pitfalls – Why and How to Avoid

• ⛔ Non-sanitary gaskets: Harbor bacteria, fail FDA inspection. → Specify FDA-compliant EPDM or silicone.

• 🔴 Incorrect size: Under DN400 restricts personnel entry. → Minimum DN400 for personnel access.

• ❗ Rough finish: Traps residue, fails CIP. → Specify Ra ≤ 0.8 μm sanitary, Ra ≤ 0.4 μm pharma.

• ⬇️ No pressure rating: Collapses under vacuum or blows out. → Verify ASME/PED rating matches tank design.

Application-Specific Requirements

Dairy Processing: Milk silos, cheese vats. 304/316L, Ra ≤ 0.8 μm, EPDM (FDA 21 CFR 177.2600). CIP to 85°C. Stainless steel manways for tanks in dairy service require 3-A Sanitary compliance.

Beverage Production: Beer, wine storage. 304/316L, Ra ≤ 0.8 μm, EPDM. 3-A Sanitary. Atmospheric to 3 bar. Stainless manway designs for beverage tanks often include sample ports.

Pharmaceutical: API reactors, sterile water. 316L, Ra ≤ 0.4 μm electropolished (ASME BPE SF4), PTFE/silicone (USP Class VI). SIP to 150°C, ASME rated. Sanitary tank manways in pharma service require full material traceability.

Biotech Fermentation: Bioreactors, cell culture. 316L, Ra ≤ 0.4 μm electropolished, PTFE/silicone. Lift assists for safe operation. Manways for steel tanks in biotech are often specified with pressure-rated closures.

Manway Design Features

Selection Criteria

Material: 304 for food/beverage; 316L for pharma/biotech.

Finish: Ra ≤ 0.8 μm (food/dairy); Ra ≤ 0.4 μm electropolished (pharma/biotech per ASME BPE SF4).

Gasket: EPDM (food, FDA 21 CFR 177.2600, CIP to 85°C); Silicone (pharma USP Class VI, SIP to 150°C); FKM (oils to 200°C); PTFE (chemicals to 260°C).

Pressure: Atmospheric for storage; ASME/PED for pressure vessels. Minimum DN400 for personnel entry.

Safety Features

• Spring-assist: Reduces opening effort for covers > DN400

• Safety grid: Prevents falls

• Locking devices: Padlockable handles for security

• Inward-opening: Preferred for pressure applications

Sanitary Tank Manways

For dairy and food: 304/316L, EPDM, Ra ≤ 0.8 μm, 3-A Sanitary, CIP to 85°C. Stainless steel manways for tanks in this category often include CIP spray ball mounting brackets.

For pharma and biotech: 316L, PTFE/silicone, Ra ≤ 0.4 μm electropolished (ASME BPE SF4), SIP to 150°C, ASME rated. Sanitary tank manways with electropolished finishes meet ASME BPE requirements.

For personnel entry: Minimum DN400 (16"). Spring assists and safety grids recommended. Stainless manway covers with inward-opening design suit pressure applications where internal pressure assists sealing.

ASME BPE SF4 defines electropolished finish. FDA 21 CFR 177.2600 applies to EPDM. 3-A Sanitary covers dairy and food. Manways for steel tanks are available in round, oval, and rectangular configurations. Sanitary tank manways with inward-opening covers suit pressure applications.

Sanitary Stainless Steel Round Manhole Without Pressure

• We can supply Hygienic Circular Manway Cover, Sanitary Oval Manhole, Hygienic Square Manhole, Sanitary Pressure Manway, Sanitary Stainless Steel Manhole with Sight Glass.
• Manhole cover is mainly used for pressure vessel in the fields of food, beverage, chemical, etc.
• All Stainless steel manhole cover are produced in both AISI 304L and AISI 316L stainless steel and can be supplied with the gasket in several different food grade materials (natural rubber, NBR, EPDM, silicone, viton & FEP/PFA-encapsulated). 
• Compared with the ordinary atmospheric manholes, the cover design of the sanitary ribbed manholes is unique. The cover is easy to open, and it can be opened 180 degrees and rotated 360 degrees. The sealing ring is installed on the cover, which can meet the hygienic requirements of food tanks and other ordinary tanks. Due to limited pressure resistance, this manhole can only be installed on the top of the tank.

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