Square Quick-Acting Watertight Hatch Cover with Handwheel for Ship Access Openings | CB/T 3842 Type B

Product Overview

The CB/T 3842-2000 Type B quick-acting watertight hatch cover is a square hinged closure for ship access openings where reliable water containment and frequent manual operation are required. A handwheel-operated central clamping arrangement compresses the gasket against the coaming, while the spring balancing device assists opening and closing. The standard series covers nominal clear openings of 600 × 600, 700 × 700, and 800 × 800 mm.

The supplied configuration is based on a 0.2 MPa hydraulic pressure requirement and a standard 200 mm coaming height. Selection should be coordinated with the watertight boundary, installation position, deck or bulkhead opening, operating clearance, gasket medium compatibility, structural welding, and class inspection scope. Higher pressure, increased coaming height, gas-tight duty, stainless steel construction, or non-standard dimensions require project-specific engineering and approval.

Quick Specifications

• Product type: Type B square quick-acting watertight hatch cover → compact hinged access closure for watertight ship structures.
• Standard: CB/T 3842-2000 → public standard records list it as the current Chinese shipbuilding industry standard for quick-acting watertight hatch covers.
• Nominal clear opening: 600 × 600 to 800 × 800 mm → select according to personnel access, equipment passage, and the approved vessel arrangement.
• Pressure basis: 0.2 MPa hydraulic pressure according to the supplied product data → higher pressure must be recalculated, tested, and accepted for the project.
• Operating arrangement: handwheel quick operation with central clamping and spring balancing → supports repeated manual opening while maintaining controlled gasket compression.
• Standard coaming height: 200 mm → increased height affects plate scantlings, stiffness, installation clearance, and the approved welding arrangement.
• Material options: mild steel or stainless steel → final grade, corrosion allowance, welding consumables, and dissimilar-metal isolation are to be confirmed.
• Seal and finish: neoprene, NBR, or high-nitrile gasket with Sa 2.5 blasting and epoxy shop primer as reference → compatibility and final coating follow the service environment.

Main Technical Parameters

Selection & Inquiry Guide

Step 1: Confirm CB/T 3842-2000 Type B, the nominal clear opening, required passage size, and whether the hatch is for newbuilding or replacement.

Step 2: State the installation position and watertight boundary, design pressure or water head, opening direction, hinge side, available operating clearance, and access from one or both sides.

Step 3: Confirm deck or bulkhead cutout, coaming height, surrounding reinforcement, welding interface, structural material, and whether the supplied hatch includes loose installation parts.

Step 4: Confirm mild steel or stainless steel construction, gasket material and service medium, operating temperature, oil exposure, corrosion environment, and final coating system.

Step 5: Define the required test and inspection scope: dimensional inspection, operation test, hydraulic pressure or leakage test, material traceability, NDT, class witnessing, and certificate type.

Step 6: Provide quantity, vessel type, classification society, approved drawing or replacement sample, delivery destination, required delivery time, and packing requirement.

Structure

Square cover plate | Hinged connection | Spring balancing device | Handwheel-operated central clamping mechanism | Replaceable gasket | Welded coaming | Structural stiffening | Opening and securing components | Shop-primer or specified finish

Watertight Design, Operation & Quality Advantages

• The central handwheel operating arrangement applies coordinated closing force to the sealing system, reducing the need to tighten multiple independent cleats during routine access.
• The spring balancing device assists the operator by offsetting part of the cover weight. Spring setting, hinge alignment, and opening travel should be checked during assembly and commissioning.
• A continuous, correctly compressed gasket forms the primary water barrier. Gasket cross-section, hardness, jointing method, compression allowance, and seating-surface flatness directly affect leakage performance.
• The cover plate, coaming, hinge supports, and clamping mechanism transfer hydrostatic pressure into the surrounding ship structure. The deck or bulkhead reinforcement remains part of the vessel design and should not be assumed from the hatch-cover supply alone.
• Both-side operation can be arranged according to the standard or approved drawing. Where the opening forms part of an access or escape route, operating direction, locking prevention, clear opening, and onboard safety requirements must be confirmed.
• For stainless steel construction, welding procedure, distortion control, surface finishing, and isolation from carbon-steel ship structure should be agreed before production to reduce corrosion and fit-up risks.
• Hydraulic pressure and operational testing should verify leakage, permanent deformation, smooth handwheel movement, clamping engagement, hinge function, and spring balance. The final pressure, holding time, acceptance criteria, and witness scope follow the approved test procedure.
• Higher pressure, increased coaming height, modified opening dimensions, or alternative materials can be reviewed by structural calculation or finite element analysis when required, subject to project and class approval.

Custom Attributes

• Standard: CB/T 3842-2000 → quick-acting watertight hatch-cover standard for ship access openings.
• Type: Type B square configuration → suitable where a square clear opening is specified by the vessel arrangement.
• Nominal Size: 600 × 600 / 700 × 700 / 800 × 800 mm → select by required access and approved structural opening.
• Pressure Basis: 0.2 MPa according to supplied data → not automatically applicable to higher pressure or deeper water-head duty.
• Operation: Handwheel quick action → central clamping and spring assistance should be checked on the approved drawing.
• Opening Access: Both-side operation stated in supplied data → exact handle arrangement and emergency-access function are to be confirmed.
• Material: Mild steel or stainless steel → exact grade and material certificates follow the order specification.
• Packing Material: Neoprene / NBR / high-nitrile rubber → select according to water, oil, temperature, ageing, and fire-performance requirements.
• Surface Treatment: Sa 2.5 blasting + epoxy shop primer as reference → final paint system, galvanizing feasibility, or stainless finish must be specified.
• Tightness Scope: Watertight as standard product intent → gas-tight, fire-rated, or Load Line weathertight compliance is not assumed without separate approval and testing.

How It Works

Operator closes the hinged cover → Handwheel drives the central clamping arrangement → Closing components compress the gasket evenly against the coaming seat → The gasket and structural cover resist the specified water pressure → Handwheel is released for opening and the spring balancing device assists cover movement

Applications

Watertight ship access openings | Machinery-space access | Inspection openings | Service compartments | Deck or bulkhead penetrations according to approved arrangement | Newbuilding projects | Replacement and retrofit projects

Certifications & Advantages

Certificates and inspection can be arranged according to the project specification, material traceability requirement, approved test plan, and classification society procedure. Type approval, class product certification, or witness testing is not included by default and should be confirmed before quotation.

Certification: CCS, NK, BV, ABS, DNV, LR, KR, IRS, RS, RINA, CRS, Makers Test Certificate.

Drawing & Photos

FAQ

Q1: Is this hatch cover automatically suitable for an exposed freeboard or weather deck?

A1: Not automatically. CB/T 3842 Type B defines a quick-acting watertight hatch-cover product, but the installation position must also satisfy the vessel’s applicable Load Line, flag, and class requirements. Coaming height, structural strength, closing arrangement, accessibility, and required weathertight or watertight test must be confirmed for the actual location.

Q2: Can the hatch cover be supplied for pressure higher than 0.2 MPa?

A2: A higher-pressure design can be considered case by case. The cover plate, coaming, stiffeners, hinge supports, clamping mechanism, gasket compression, surrounding ship structure, and test pressure must be recalculated and submitted for project or class approval.

Q3: Does a watertight hatch cover also qualify as gas-tight or fire-rated?

A3: No. Gas-tightness and fire rating are separate performance requirements involving specific materials, sealing details, test procedures, and approvals. They should only be stated when the ordered configuration has been designed, tested, and certified for that duty.