The Multi-claw Locking Structure And The Manhole Cover With Sight Glass Ensure Reliable Sealing And Rapid Opening And Closing
- Model:
- JOF-MHR006
- Brand:
- J&O
- Material:
- SS304/SS316L
- Connection:
- Weld
- Gasket:
- EPDM / Silicon / NBR / FKM
- Code:
- JOF-MHR006
- Payment:
- T/T, L/C, Western Union
A stainless steel manway opens safely under pressure through a four-step sequence: confirm zero gauge pressure, open the vent path, release claws in even increments, then swing the cover. SS304 or SS316L bodies with welded necks and EPDM, silicone, NBR, or FKM gaskets support this design. A multi-claw ring blocks cover ejection while the vessel stays pressurized.
How Multi-Claw Locking Blocks Accidental Release
The locking ring carries several claw segments around the cover circumference. Each claw engages a matching lug on the tank neck. One handwheel drives all claws at once.
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Claw count ranges from 4 to 12, based on vessel diameter.
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Even load keeps gasket compression uniform.
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Partial engagement shows at a glance.
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A safety vent opens before the final claw disengages.
This sequence stops the failure mode where one clamp releases under pressure and the cover lifts on one side.
Safety Interlock Logic for Pressurized Vessels
A stainless manway must not open while internal pressure exceeds atmospheric. Two methods cover this risk.
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Mechanical vent pin: a spring-loaded pin vents residual pressure before claws retract.
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Pressure switch: a sensor blocks release until pressure drops below a set threshold.
Vent Path Sizing
Both methods rely on a defined vent path. Vent diameter sizes to vessel volume and working pressure. A 10 bar vessel needs a larger vent than a 2 bar vessel to drop pressure in the same time.
Gasket Selection by Process Duty
Manways for steel tanks often specify the same seal grade as the vessel interior. This keeps the wetted boundary consistent from neck to cover.
| Gasket Material | Temperature Range | Media Resistance | Typical Duty |
|---|---|---|---|
| EPDM | -40°C to 130°C | Water, steam, mild CIP | Food and dairy |
| Silicone | -50°C to 200°C | Dry heat, cold | Pharma, dry powder |
| NBR | -30°C to 100°C | Oil, fuel, water | Non-aggressive media |
| FKM | -20°C to 200°C | Acid, solvent, steam | Chemical, aggressive fluids |
A gasket rated above the process temperature extends cover seal life. The seal grade must match the cleaning chemicals used in the tank.
Sight Glass Function and Seal Interface
A sight glass in the cover allows visual inspection without opening the tank. The glass seats against a PTFE or silicone gasket, held by a separate ring.
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Glass thickness matches rated pressure, typically 10 bar.
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The gasket compresses into a machined groove.
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A retaining ring isolates the glass from claw load.
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Borosilicate glass resists thermal shock during SIP cycles.
Sight Glass Seal
The sight glass seal is a second barrier. It must pass the same pressure test as the main cover seal.
Installation Checks for Stainless Steel Manway Lids
Stainless steel manway lids need a flat mounting flange and correct weld alignment. A warped neck flange prevents uniform gasket compression.
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Verify flange flatness before welding.
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Match the hinge arm to the tank radius.
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Check that the cover swings clear of nearby piping.
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Confirm the gasket groove is free of weld spatter.
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Pressure-test at the rated value before service.
These checks reduce leakage at the cover seal and extend gasket life.
Maintenance Points That Preserve Seal Life
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Replace the cover gasket at fixed intervals, not on failure.
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Inspect claw tips for wear or deformation.
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Check the vent path for blockage from product residue.
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Verify the sight glass ring torque after each cleaning cycle.
A worn claw tip reduces locking force. A blocked vent delays pressure release. Both conditions raise the risk of unsafe opening.
Verification Before Each Campaign
A documented pressure test confirms the interlock and gasket still meet the rated window. Record claw engagement depth and vent response time to track wear across service cycles.
Sanitary Stainess Steel Round Pressure Manhole With Sight Glass
- Manhole with a sight glass, it is convenient to observe the material inside the tank without opening the cover.
- It can be used for the control of water, gas, oil, and corrosive media in industries such as chemical, petroleum, plumbing, food, and pharmaceuticals.
- 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).
Technical Data
| Material: | SS304 or SS316L |
| Standard: | 3A, SMS, DIN, RJT, IDF |
| Size: | 8"-24" (200mm-600mm) |
| Height: | 100mm |
| Thickness: | 3mm |
| Handle Material : | Stainless steel and plastic |
| Handle number: | 4-8 pieces |
| Seal Material: | Silicone, EPDM, Viton, NBR |
| Surface Finishing: | Ra≤0.8 |
| Working Temperature: | -10 degree to +120 degree (EPDM) |
| Packing Details: | Carton box,plywood case or customized |
Product Parameter
Product Pictures
