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The DF-450 Raised Watertight Expansion Dome addresses a specialized challenge in marine engineering: providing pressure-compensating access to closed fluid systems.
| Quantity: | |
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DF-450-3624
DF-450-3026/3624/4224 RAISED WATERTIGHT EXPANSION DOME
MODEL NO. | ΦA | B | C | ΦD | WT.(lbs) |
| DF-450-3026 | 30" | 26" | 50" | 8" | 750 |
| DF-450-3624 | 36" | 24" | 48 1/2" | 8" | 860 |
| DF-450-4224 | 42" | 24" | 49" | 8" | 950 |
| NO. | Name & Specifications | Qty | Material |
| 1 | HATCH COVER ASSEMBLY | 1 | STEEL |
| 2 | UPPER COAMING RING | 1 | STAINLESS |
| 3 | COAMING ASSEMBLY | 1 | STEEL |
| 4 | HATCH GASKET | 1 | NEOPRENE |
| 5 | CENTER SHAFT | 1 | STAINLESS |
| 6 | I-BEAM SWIVEL ARM | 1 | STEEL |
| 7 | 8"ULLAGE HATCH | 1 | ASSEMBLY |
Leakage test: Pressure 0.04MPa
Other optional extras include: hot dipped galvanized, stainless steel construction, and customing heights
Product Overview
This marine quick-opening pressure manhole cover (deck cover) is a high-reliability sealing and opening device specifically designed for ships, marine engineering, and industrial pressure vessels. Featuring a mature spun-quick-opening structure, it combines high-pressure resistance and convenient operation, serving as a core sealing component for ship cabins, pressure tanks, reactors, and similar equipment. Widely used in various vessels, offshore platforms, and industrial pressure systems, it meets stringent safety sealing requirements under harsh operating conditions.
Core application scenarios
◎Ship and Offshore Engineering Field
1. Various types of ship compartments: Suitable for all types of vessels such as cargo ships, oil tankers, bulk carriers, engineering ships, fishing boats, and passenger ships. It is used for manhole openings in compartments requiring pressure resistance and sealing, such as ballast tanks, fuel tanks, fresh water tanks, cargo holds, and engine rooms, ensuring convenient opening and closing for personnel maintenance and reliable sealing.
2. Offshore Engineering Equipment: Designed for offshore drilling platforms, FPSOs (Floating Production Storage and Offloading vessels), oceanographic research vessels, wind turbine installation vessels, etc., it is used for sealing cabins, liquid storage tanks, and equipment compartments to withstand harsh marine environments with high salinity, humidity, and strong winds and waves.
3. Ship auxiliary systems: Used for sealing inspection ports of supporting equipment such as ship sewage treatment plants, ballast water treatment systems, boilers, and heat exchangers.
◎ Industrial Pressure Equipment Sector
1.Pressure vessels / Reactors: Inspection manholes for pressure tanks, reactors, and storage tanks used in the petrochemical, pharmaceutical, and food processing industries, meeting the requirements for pressure-bearing and sealing.
2. Municipal/Industrial Pipelines: Suitable for sealing inspection wells and maintenance wells in large water supply and drainage pipelines, thermal pipelines, and gas pipelines.
3. Special Industrial Equipment: Customizable sealing manholes for special working conditions such as vacuum equipment, high-temperature and high-pressure equipment, and nuclear power auxiliary equipment.
Core product features
★Quick-opening for convenient operation
The manual spin-type opening and closing mechanism allows for quick locking/unlocking via the top handwheel, requiring no complex tools and enabling single-person operation, significantly improving maintenance efficiency. Optional hydraulic or electric drive systems are available to meet automation requirements.
★High-reliability sealing performance
Equipped with a dual sealing design featuring an inclined surface seal and a sealing ring, it can withstand internal and external pressure differentials of 0.1~1.6MPa (customizable for higher pressures). Fully compliant with IMO standards for watertightness and weathertightness in marine applications, it effectively prevents seawater, oil, and medium leakage, ensuring cabin safety.
★High-Strength Structural Design
Integrated reinforced bracket + thickened cover plate structure, evenly distributing pressure loads, resistant to impact and deformation, capable of withstanding wave impacts and equipment vibrations during ship navigation, compliant with global classification society standards such as CCS, ABS, LR, and DNV.
★Full-scenario customization
Customizable dimensions (full range of diameters from 300mm to 1500mm), structural customization (with small inspection ports, observation windows, and pressure relief valves), material customization, and pressure rating customization, perfectly suited for installation requirements of various ships and industrial equipment.
★Long lifespan and maintenance-free
All-metal construction + high-standard anti-corrosion process, with a service life exceeding 15 years under normal operating conditions; modular design allows for easy replacement of wear-prone components (seals, bolts), reducing maintenance costs.
Expansion domes accommodate volumetric changes in closed fluid systems caused by temperature variations, pressure fluctuations, and filling/draining operations . They prevent pressure buildup and vacuum formation that could damage tanks, pipes, or fittings, while providing watertight access for inspection and maintenance.
The reinforced bellows features convolutions designed to flex while maintaining constant compression on the sealing gaskets . The PTFE coating reduces friction during movement and prevents gasket adhesion, ensuring consistent sealing performance through thousands of expansion cycles.
The standard configuration is compatible with fuel oils, diesel, freshwater, and saltwater . For chemical applications, optional Viton gaskets and specialized coatings are available to handle aggressive substances like acids, alkalis, and hydrocarbon solvents.
The bellows and seals should be inspected annually for signs of cracking or degradation . The movement mechanism requires no lubrication, as the PTFE coating provides self-lubricating properties. In high-cycle applications, a complete seal replacement is recommended every 5 years.
Yes, the DF-450 is designed for both above-deck and submerged installations up to a maximum depth of 30 feet (10 meters) when properly installed with the optional deep-water flange kit . The structural design withstands external hydrostatic pressure at this depth while maintaining internal pressure compensation capabilities.
