Semi-Flush Bolted Marine Manhole Cover | ASTM F1142 Oiltight & Watertight Deck

Product Specification

Semi-Flush Bolted Marine Manhole Cover | ASTM F1142 Oiltight & Watertight Deck Access

Product Overview

The ASTM F1142 semi-flush bolted marine manhole cover is a non-hinged access closure for decks or bulkheads that require an oiltight and watertight boundary but do not require the cover assembly to be completely flush. The standard arrangement includes a cover plate, welded mounting ring, continuous gasket, welded studs, washers, and nuts. Handles are optional and should be specified in the inquiry when required.

Type I provides a 15 × 23 in. access opening, while Type II provides an 18 × 24 in. access opening. Each type is available in three cover-plate grades. The selected Type and Grade determine the access size, cover thickness, stud quantity, design pressure, and reference assembly weight. ASTM F1142 addresses lateral pressure such as hydrostatic pressure or vehicle loading; primary or cyclic structural loading and certain hazardous-cargo applications require separate engineering review.

Quick Specifications

• Current standard status: ASTM F1142-19, reapproved in 2024 → use the purchased current edition and approved drawing for production and inspection.
• Configuration: bolted, semi-flush, non-hinged assembly → suitable where a removable access cover is acceptable and a fully flush finish is not required.
• Type I opening: 15 × 23 in. (381 × 584 mm) → compact access with 22 welded studs.
• Type II opening: 18 × 24 in. (457 × 610 mm) → larger access with 24 welded studs.
• Cover grades: 1/4, 3/8, and 1/2 in. → increasing plate thickness corresponds to higher tabulated design pressure within each Type.
• Design pressure range in the supplied data: 8.9-47.9 psi (62.1-330.2 kPa) → this is a design basis and must not be treated as the test pressure.
• Complete assembly: cover, mounting ring, gasket, welded studs, washers, and nuts → handling devices are supplied only when specified.
• Application limit: lateral-pressure service in decks or bulkheads → primary loads, cyclic loads, structural deck loads, and restricted hazardous cargos need separate approval.

Main Technical Parameters

Selection & Inquiry Guide

Step 1: Confirm ASTM F1142 Type I or Type II and Grade 1, 2, or 3 according to the required clear opening, design lateral pressure, deck or bulkhead arrangement, and approved vessel drawing.

Step 2: State the installation position and loading: hydrostatic liquid head, deck traffic or vehicle loading, external pressure, and whether primary or cyclic structural loads can act on the assembly. Loads outside the ASTM F1142 scope require separate reinforcement and approval.

Step 3: Confirm the service medium, temperature, and cargo restrictions before selecting cover, mounting-ring, fastener, washer, and gasket materials. Certain hazardous-cargo applications are outside the standard scope.

Step 4: Provide the deck or bulkhead cutout, mounting-ring weld detail, surrounding plate thickness, reinforcement, available removal space, required semi-flush projection, and whether a handle or lifting feature is required.

Step 5: Confirm surface preparation and coating, gasket compound and hardness, stud and nut specification, corrosion-isolation requirements, tightening procedure, material traceability, and marking.

Step 6: Confirm pressure or tightness test method, test pressure and duration, acceptance criteria, class-survey scope, certificate requirements, quantity, destination, and delivery time.

Structure

Cover plate | Welded mounting ring | Continuous oiltight and watertight gasket | Welded studs | Washers and nuts | Optional handles or lifting feature | Protective coating or specified metallic finish

Sealing, Structural & Quality Advantages

• Twenty-two or twenty-four welded studs distribute clamping force around the gasket perimeter, helping maintain continuous compression when the nuts are tightened in the approved cross-pattern sequence.
• The semi-flush arrangement limits projection compared with a raised manhole cover while retaining a removable bolted assembly. It should not be described as completely flush unless the approved installation detail confirms the final finished level.
• The three Grade options provide a defined relationship between cover-plate thickness and tabulated lateral design pressure for each access-opening Type.
• The welded mounting ring establishes the sealing seat and transfers lateral pressure into the surrounding deck or bulkhead. Ring flatness, weld sequence, and structural reinforcement must be controlled by the approved installation drawing.
• Gasket contact surfaces and the stud pattern can be inspected during manufacture. Final sealing performance depends on surface condition, gasket compatibility, nut tightening, installation distortion, and the agreed pressure or leak test.
• The non-hinged cover can be fully removed for inspection and maintenance, providing unobstructed access through the opening. The owner should plan safe handling for the 35-64 kg reference assembly weights.
• Replaceable gasket, nuts, and washers support service maintenance, but substitute materials or fastener combinations should not be used without checking corrosion compatibility, strength, thread requirements, and class acceptance.

Custom Attributes

• Standard: ASTM F1142-19 (2024 reapproval) → current active reference; confirm the purchased edition and project drawing before production.
• Configuration: Semi-flush, bolted, non-hinged → removable oiltight and watertight access closure for decks or bulkheads.
• Type I: 15 × 23 in. access opening → 22-stud arrangement with Grades 1, 2, and 3.
• Type II: 18 × 24 in. access opening → 24-stud arrangement with Grades 1, 2, and 3.
• Cover Grade: 1/4 / 3/8 / 1/2 in. → select by Type and required tabulated lateral design pressure.
• Cover and Ring Material: Carbon shipbuilding steel or project-specified stainless steel → exact ASTM grade, weldability, and corrosion allowance to be confirmed.
• Fastener Material: Project-specified steel, stainless steel, bronze, or brass → strength, thread, galvanic compatibility, and approval must be verified.
• Gasket: Buna-N, neoprene, or project-specified compound → select for oil, water, temperature, cargo, cleaning chemical, and compression requirements.
• Surface Treatment: Near-white blast cleaning plus epoxy shop primer, galvanizing, polishing, or project coating → final system depends on material and installation welding.
• Testing and Certificates: According to the approved ITP and project requirement → available upon request and subject to class approval and survey scope.

How It Works

Cover is placed on the mounting-ring sealing seat → Continuous gasket is aligned → Nuts are tightened progressively in a cross pattern → Stud clamping compresses the gasket around the opening → The assembly resists the approved lateral design pressure → Nuts and cover are removed for access

Applications

Ship decks | Watertight or oiltight bulkheads | Ballast and service tanks | Fuel-oil and lubricating-oil spaces subject to gasket compatibility | Void-space access | Machinery-space tank access | Cargo and work vessels | Naval and government vessels | Newbuilding and replacement projects | Non-hazardous service within the approved ASTM F1142 scope

Certifications & Advantages

Material certificates, dimensional inspection records, welding documentation, coating records, pressure or tightness-test reports, and classification inspection can be arranged according to the approved drawing, purchase specification, and agreed survey scope.

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

Drawing & Photos

FAQ

Q1: What is the difference between Type I and Type II?

A1: Type I has a 15 × 23 in. access opening and uses 22 studs. Type II has an 18 × 24 in. access opening and uses 24 studs. The correct Type depends on access clearance, installation space, structural arrangement, and the approved vessel drawing.

Q2: Can the design pressure in the table be used as the test pressure?

A2: No. Design pressure is the tabulated lateral-pressure basis for the Type and Grade. The hydraulic, pneumatic, or leak-test pressure, duration, test medium, safety controls, and acceptance criteria must come from the current standard, approved drawing, class requirement, and project ITP.

Q3: Can ASTM F1142 be used for hazardous cargo or cyclic deck loading?

A3: Not automatically. The standard excludes certain hazardous-cargo applications and does not design the assembly for primary or cyclic loads. The vessel designer, cargo specialist, and classification society must review these conditions and specify any alternative cover, reinforcement, gasket, or testing requirements.