A speciality manhole is the hygienic access opening on process vessels, reactors, silos, and tanks, made up of a neck, cover, gasket, hinge, and locking system. Supplied from ID 100 to ID 500 in 50 mm steps, JBM manholes cover atmospheric, pressure, quick-access, aseptic, and functional designs in SS316L with crevice-free welds, FDA-grade gaskets, and Ra <0.4 µm internal finish.
The neck is welded flush into the vessel shell or dish, and the cover seats on a gasket held in a machined groove. Atmospheric covers close with hinges and swing clamps; pressure covers use bolts or swing bolts sized to ASME Section VIII. Quick-opening, spring-assisted, and pneumatic versions reduce handling effort and add limit-switch interlocks. Functional covers carry sight glasses, lights, CIP devices, and charging nozzles, reducing shell penetrations.
Challenges
Gasket Groove Contamination
Product trapped in grooves harbours microbes after cleaning.
Leakage Under Pressure or Vacuum
Uneven clamp load distorts gaskets and breaks the seal.
Heavy Cover Handling
Large-ID covers create ergonomic and safety risks.
Unsafe Opening
Opening under residual pressure or during agitation injures operators.
Condensation and Heat Loss
Uninsulated covers on heated vessels form condensate and hot spots.
Solutions
- Hygienic Flush Groove: Radiused, drainable groove with profiled FDA silicone or EPDM gasket.
- Engineered Bolting and Clamps: Clamp and bolt load calculated per ASME for uniform compression.
- Spring or Counterweight Assist: Reduces lifting effort to under 15 kg.
- Limit Switch and Pressure Interlock: PLC blocks opening and agitation while pressurized.
- Jacketed or Insulated Cover: Double-skin cover holds temperature and stops condensate drip.
Applications
- Pharmaceutical: Reactors, fermenters, and sterile holding tanks.
- Food & Dairy: Milk silos, syrup tanks, and process vessels.
- Cosmetics: Emulsion and cream vessels.
- Chemical: Pressure reactors, storage tanks, and hoppers.
Types & Configurations
| Type | Code | Design & Operation | ID Range [mm] | Rating | Typical Use |
|---|---|---|---|---|---|
| Standard Access | |||||
| Round Non-Pressure | MH-RN | Hinged dished cover, swing clamps, lifting handle | 100–500 | ATM, ±0.1 bar | Atmospheric tanks, mixers |
| Round Pressure | MH-RP | Flat or dished bolted cover on raised-face neck flange | 100–500 | 3 / 6 / 10 bar, FV | Reactors, pressure vessels |
| Oval / Elliptical | MH-OV | Inward-opening cover with yoke; pressure assists sealing | 300×400 to 450×550 | Up to 10 bar | Vessels with limited dish space |
| Rectangular / Square | MH-RC | Hinged flat cover, radiused corners, multi-point clamps | 300×300 to 500×500 | ATM | Silos, hoppers, troughs |
| Quick Access | |||||
| Quick-Opening Clamp | MH-QO | Wing nut or toggle clamps, captive hinge, tool-free | 100–500 | ATM to 3 bar | Frequent charging |
| Spring-Assisted / Counterbalanced | MH-SA | Gas spring or counterweight lifts the cover | 350–500 | ATM to 6 bar | Large, heavy covers |
| Pneumatic / Automatic Locking | MH-PN | Pneumatic opening, auto-lock, limit switches | 300–500 | ATM to 6 bar | Automated process lines |
| Tri-Clamp Hand Hole / Inspection Port | MH-HH | Tri-clamp ferrule with blind or glass cover | 100–200 | Up to 6 bar | Inspection, sampling |
| Functional & Process | |||||
| Sight Glass Manhole | MH-SG | Borosilicate glass in cover with protective frame | 150–500 | ATM to 6 bar | Visual process monitoring |
| Multi-Port Manhole | MH-MP | Cover with sight glass, light glass, CIP port, charging nozzle | 300–500 | ATM to 6 bar | Mixing vessels |
| Aseptic / Sterile | MH-AS | Hygienic O-ring, crevice-free, SIP rated | 100–500 | FV to 3 bar, 140°C | Fermenters, sterile tanks |
| Jacketed / Insulated | MH-JK | Double-skin cover for heating, cooling, or insulation | 300–500 | ATM to 6 bar | Heated and chilled vessels |
| Pressure-Relief | MH-PR | Weighted lifting cover or rupture disc insert | 300–500 | Set 0.05–0.5 bar | Storage tanks, venting |
Models & Sizes: ID 100 to ID 500
| Model | ID [mm] | Cover OD [mm] | Neck Ht [mm] | Neck Thk ATM / Press. [mm] | Cover Thk ATM [mm] | Cover Thk 6 bar [mm] | Cover Thk 10 bar [mm] | Clamps ATM [nos] | Bolts Press. [nos×size] | Weight ATM [kg] | Weight 10 bar [kg] |
|---|---|---|---|---|---|---|---|---|---|---|---|
| MH-100 | 100 | 180 | 100 | 3 / 5 | 3 | 5 | 8 | 2 | 4×M12 | 4 | 7 |
| MH-150 | 150 | 230 | 100 | 3 / 5 | 3 | 8 | 10 | 2 | 8×M12 | 5 | 11 |
| MH-200 | 200 | 280 | 100 | 3 / 5 | 3 | 10 | 12 | 2 | 8×M12 | 6 | 17 |
| MH-250 | 250 | 350 | 100 | 3 / 5 | 4 | 12 | 16 | 3 | 8×M16 | 8.5 | 31 |
| MH-300 | 300 | 400 | 150 | 4 / 6 | 4 | 16 | 20 | 3 | 12×M16 | 12 | 51 |
| MH-350 | 350 | 450 | 150 | 4 / 6 | 4 | 16 | 20 | 3 | 12×M16 | 14 | 63 |
| MH-400 | 400 | 520 | 150 | 4 / 6 | 5 | 20 | 22 | 4 | 16×M16 | 20 | 88 |
| MH-450 | 450 | 570 | 150 | 5 / 8 | 5 | 20 | 25 | 4 | 16×M20 | 24 | 122 |
| MH-500 | 500 | 620 | 150 | 5 / 8 | 5 | 22 | 28 | 4 | 20×M20 | 27 | 158 |