Raised Oval Bolted Marine Manhole Cover with Hinges | CB/T 4392-2014 Type EA

Product Specification

Raised Oval Bolted Marine Manhole Cover with Hinges | CB/T 4392-2014 Type EA

Product Overview

The CB/T 4392-2014 Type EA raised oval marine manhole cover is a hinged, multi-bolt access closure for steel ship structures. Its raised coaming keeps the sealing interface above the surrounding plating, while the oval opening provides personnel access to tanks, void spaces, cofferdams, double-bottom spaces, and other internal compartments where a bolted watertight or oiltight closure is specified.

The hinge supports controlled opening and closing of the cover, but the sealing performance is created by the gasket, the flatness and continuity of the sealing land, and the uniform compression produced by the perimeter bolts. For the supplied construction, the top sealing ring can be cut from one steel plate without a butt-weld joint across the gasket contact path, helping control distortion and removing a welded seam from the sealing surface. Final type designation, material, gasket compatibility, tightness class, test method, installation welding, and certificate scope should be confirmed against the approved vessel drawing.

Quick Specifications

• Product type: Raised-coaming oval bolted marine manhole cover with hinge → provides maintainable access while keeping the gasketed closure above the surrounding plating.
• Standard and type: CB/T 4392-2014 Type EA according to the supplied product name → the supplied specification line also states Type EB, so the final type code must be confirmed from the standard drawing or purchase specification.
• Nominal opening range: 450 × 350 to 800 × 600 mm → covers compact tank-access openings through larger oval personnel-access arrangements.
• Fastening arrangement: Multiple M20 bolts shown in the supplied data → perimeter tightening is used to develop distributed gasket compression; exact quantity follows nominal size and approved drawing.
• Raised coaming: 100 mm stated as the standard supply reference, with customized height available → installation height, surrounding structure, access clearance, and hinge swing must be checked before production.
• Construction options: Mild steel or stainless steel cover/coaming with stainless steel, bronze, or brass fasteners → material combinations require corrosion, galvanic compatibility, and class/project confirmation.
• Sealing and testing: Watertight and oiltight service can be specified; air or hydraulic leak testing is arranged according to the approved test procedure → gas-tight service is not assumed without project-specific design and acceptance criteria.
• Weight basis: 20.4 to 202.7 kg appears in the supplied detailed table, depending on nominal size and S/S1 combination → the separate summary limit of 165.2 kg requires reconciliation before final datasheet release.

Main Technical Parameters

Selection & Inquiry Guide

Step 1: Confirm the required standard and type. State CB/T 4392-2014 Type EA for a legacy or replacement design, and provide the drawing because the supplied specification contains an EA/EB designation conflict.

Step 2: Select the nominal opening size, S/S1 combination, raised coaming height, hinge orientation, and available opening clearance according to the vessel access arrangement.

Step 3: Confirm the service compartment and tightness requirement: seawater, freshwater, oil service, dry/void space, or other medium. State whether watertight, oiltight, or a project-defined gas-tight test is required.

Step 4: Confirm cover, coaming, bolt/nut, hinge, and gasket materials. Gasket compound must be compatible with the intended fluid, temperature range, cleaning chemicals, and service environment.

Step 5: Confirm installation details: deck/bulkhead plate thickness, opening cut-out, coaming welding detail, local reinforcement, sealing-land flatness, coating break area, and shipyard installation responsibility.

Step 6: State inspection and documentation scope, including material certificates, dimensional inspection, leak test method, class witnessing, maker certificate, marking, packing, and preservation.

Step 7: Provide quantity, vessel type, installation position, required delivery date, destination, approved drawing, and reference photos for replacement work.

Structure

Oval cover plate | Raised coaming | Continuous sealing land | Replaceable gasket | Multiple perimeter bolts and nuts | Hinged opening support | Lifting / handling grip as drawing | Welded ship-structure interface | Project-specified surface protection

Sealing, Fabrication & Installation Advantages

• The raised coaming positions the gasketed joint above the surrounding plating and creates a defined welding interface for installation in deck, tank-top, or internal ship structures.
• A one-piece plate-cut top sealing ring, when supplied without a butt joint across the gasket contact area, avoids a weld seam in the sealing path and helps control local distortion. Final tightness still depends on machining or dressing, flatness, gasket condition, bolt preload, and installation quality.
• The oval shape provides a practical personnel-access opening while controlling the overall width of the surrounding frame. Clear opening and body clearance should be checked together with adjacent stiffeners, piping, insulation, and hinge swing.
• Multiple bolts distribute compression around the gasket. Bolts should be tightened progressively in a cross-pattern according to the approved procedure to reduce uneven gasket loading and cover distortion.
• The hinge supports handling of the cover and reduces the need to remove the plate completely during inspection. It is not a substitute for the full bolting arrangement and should not be used as an uncontrolled lifting point unless specifically designed for that purpose.
• Material combinations should be selected for the compartment environment. Stainless steel, bronze, or brass fasteners may improve corrosion resistance, but galvanic compatibility, anti-seize practice, thread protection, and future maintenance must be considered.
• The coaming weld and surrounding ship structure can distort the sealing land if welding sequence and heat input are not controlled. Flatness and leak testing should therefore be checked after fabrication and, where specified, after shipboard installation.
• Surface preparation may use blast-cleaning to Sa 2½ with epoxy shop primer as a project reference. Final coating, galvanized finish, or polished stainless finish must match the vessel coating schedule and must not impair gasket contact or fastener operation.

Custom Attributes

• Standard Basis: CB/T 4392-2014 → suitable for projects, replacements, or vessel drawings that specifically call for this legacy Chinese marine manhole-cover series.
• Type Designation: EA according to supplied title → supplied specification also states EB, so approved drawing confirmation is mandatory before quotation and production.
• Shape: Raised oval / elliptical → provides personnel-access geometry with a raised sealing interface.
• Nominal Sizes: 450 × 350 / 500 × 400 / 600 × 400 / 600 × 450 / 800 × 400 / 800 × 600 mm → select according to clear access requirement and surrounding structure.
• Cover and Coaming Material: Mild steel or stainless steel → exact grade, minimum mechanical properties, and material certificate scope to be confirmed.
• Fasteners: Stainless steel, bronze, or brass options → size, property grade, corrosion compatibility, locking method, and lubrication / anti-seize requirement to be specified.
• Gasket: Neoprene or project-specified material → compatibility with seawater, freshwater, oil, temperature, and service medium must be verified.
• Tightness: Watertight / oiltight according to approved design and test scope → gas-tight classification requires separate project confirmation and acceptance criteria.
• Test Method: Air leak test or hydraulic pressure test according to project procedure → test pressure, duration, acceptance criteria, and witnessing are to be confirmed.
• Surface Treatment: Sa 2½ blast-cleaning plus epoxy shop primer as reference → final coating, galvanizing, or stainless polishing follows the approved coating specification.
• Certificate Scope: Available according to project requirement → class approval, witness points, material traceability, and final certificate type must be agreed before order.

How It Works

Ship structure opening and raised coaming are aligned → Gasket is seated on the continuous sealing land → Cover swings into position on the hinge → Perimeter bolts are tightened progressively in a cross-pattern → Uniform gasket compression forms the specified watertight or oiltight seal → Final inspection and agreed leak test confirm acceptance

Applications

Ballast tank access | Freshwater tank access | Oil tank access subject to gasket compatibility | Double-bottom spaces | Void spaces | Cofferdams | Tank tops | Internal deck and bulkhead access | Merchant vessel newbuilding and replacement projects

Certifications & Advantages

Certificates and inspection can be arranged according to the approved project specification, material traceability scope, test procedure, and classification society requirements. Availability is subject to class approval and order confirmation.

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

Drawing & Photos

FAQ

Q1: Is this product Type EA or Type EB under CB/T 4392-2014?

A1: The supplied page title identifies Type EA, while the supplied technical specification line identifies Type EB. The page is prepared for Type EA, but the final designation must be verified against the original standard figure, approved vessel drawing, or purchase specification before quotation and production.

Q2: Can the cover be described as watertight, oiltight, and gas-tight?

A2: Watertight and oiltight bolted manhole-cover service is consistent with the general scope of current marine manhole-cover standards when the design, gasket, installation, bolt compression, and test procedure are suitable. Gas-tight service should only be stated when a project-specific leakage criterion, test pressure, duration, and acceptance method have been approved.

Q3: Why is a one-piece sealing ring useful?

A3: A sealing ring cut from one plate can remove a butt-weld seam from the gasket contact path and help reduce local distortion. It does not by itself guarantee tightness; sealing-land flatness, surface finish, gasket selection, bolt tightening, coaming welding, and final leak testing remain essential.