4” x 24” Manhole Frame & Cover

The Amercast 4″ x 24″ Manhole Frame and Cover is one of the most widely used standard manhole assemblies in the country — and for good reason. With a 4-inch frame height, a 24-inch clear opening, and a solid cast iron cover, this assembly covers the full spectrum of municipal sewer, stormwater, and utility access applications where a proven, stock-ready, heavy duty casting is required.

Built from grey cast iron conforming to ASTM A48 Class 30B, the 4″ x 24″ frame and cover delivers a minimum 30,000 psi tensile strength, long-term corrosion resistance, and the structural rigidity that keeps roadway castings stable and quiet under continuous traffic loading. Rated AASHTO H-20 / AASHTO M-306 Heavy Duty, this assembly is proof-load tested to 40,000 lbs — meeting or exceeding the standard for every major municipal DOT specification in use today.

Amercast has supplied manhole frames and covers for infrastructure projects across New York City — including work for the NYC Department of Transportation, the MTA, JFK Airport, and LaGuardia Airport — and for leading regional contractors including Tully Construction and Perfetto Contracting. When your submittal calls for a standard 24-inch manhole frame and cover, this is the assembly that gets approved.

In stock. Domestic and import options available. Ready to ship.

Why the 4″ x 24″ Is the Municipal Standard

The 24-inch clear opening is the dominant standard for municipal sewer and utility access across New York, New Jersey, Connecticut, and the broader Northeast corridor. It provides sufficient clearance for safe confined-space entry per OSHA requirements while maintaining the structural mass and frame depth necessary for long-term roadway performance.

The 4-inch frame height is the workhorse depth of the Amercast manhole lineup. It provides greater frame mass and bearing surface than a 3-inch unit — distributing wheel loads more effectively across the surrounding pavement structure — while remaining compatible with standard precast concrete manhole cone sections used throughout the region.

Grey cast iron does not fatigue, corrode through, or degrade under UV exposure. Unlike polymer composite or lighter-duty alternatives, grey iron at this load class maintains its structural properties across decades of freeze-thaw cycling, de-icing chemical exposure, and continuous vehicular loading. The same material has been in continuous use in American roadways since the 19th century. ASTM A48 Class 30B is the standardized modern form of that same iron — controlled, tested, and documented for every submittal package your engineer or DOT contact will ask for.

Technical Specifications

Product Type — Manhole Frame and Cover, sold as a matched set Frame Height — 4 inches Clear Opening — 24 inches Outside Diameter (Frame) — approximately 33 inches Material — Grey Cast Iron Material Standard — ASTM A48, Class 30B Load Rating — AASHTO H-20 / AASHTO M-306 Load Class — Heavy Duty Proof Load — 40,000 lbs (per AASHTO M-306) Cover Style — Solid (non-vented) Finish — Black asphaltic coating (standard) Options — Domestic and import available Stock Status — In Stock

Key Features

• ASTM A48 Class 30B grey cast iron — 30,000 psi minimum tensile strength; the proven industry standard for load-bearing municipal street castings in sewer, stormwater, and utility applications
• AASHTO H-20 / AASHTO M-306 heavy duty rated — proof-load tested to 40,000 lbs; meets or exceeds NYC DOT, NYSDOT, NJDOT, ConnDOT, and municipal public works casting specifications throughout the Northeast
• 4-inch frame height — greater bearing surface and frame mass than 3-inch units; superior load distribution across pavement structure; compatible with standard precast manhole cone sections
• 24-inch clear opening — the dominant standard opening for municipal sewer and utility access in the Northeast; meets OSHA confined space entry clearance requirements
• Solid non-vented cover — prevents surface water, debris, and road materials from entering the manhole structure; appropriate for sanitary sewer, combined sewer, and utility vault applications
• Black asphaltic finish — standard corrosion-resistant coating meeting municipal aesthetics and DOT appearance specifications
• Factory-matched frame and cover set — dimensionally paired at the factory; eliminates field fit issues, rocking, and sourcing mismatches
• In-stock availability — same-day or next-business-day shipping from the Amercast distribution network; ready for fast-turnaround public works, emergency replacement, and infrastructure contracts

Application Guide

Ideal for:

• Municipal sanitary sewer access in roadway, shoulder, and median locations
• Combined sewer and stormwater access structures in standard vehicular traffic environments
• Water main and utility vault access covers in roadway pavement
• Public works infrastructure replacement programs where 24-inch standard clear opening is specified
• General contractor utility and drainage packages on municipal, commercial, and civil construction projects
• DOT and agency submittals requiring AASHTO H-20 / AASHTO M-306 compliance documentation

Need a locking or watertight version of this assembly? For installations where infiltration prevention, odor control, or security is required, see the  4×24 Manhole Frame and Cover Locking Watertight featuring a gasket seal and bolted cover for pressure-tight performance.

Need a bolted cover on this frame size? See the 4″ x 24″ Manhole Frame and Grate Bolted  for applications where a mechanically fastened cover is required by specification.

Markings and Custom Identification

Municipal specifications frequently require cast-in markings on the cover face to identify the utility served — SEWER, STORM, WATER, ELECTRIC, or a municipality name. Amercast offers marked variants of the 4″ x 24″ cover to meet these requirements without the lead time of a fully custom casting.

4″ x 24″ Manhole Frame and Cover with Markings  — standard utility identification cast into the cover face.

4″ x 24″ Manhole Frame and Cover Marked Storm — pre-marked STORM for stormwater drainage applications; satisfies MS4 stormwater permit marking requirements in many municipalities.

Need a logo, municipal seal, or fully custom cover design? Visit our  Custom Manhole Covers page for decorative and municipality-branded options.

Explore the Complete 24-Inch Manhole Lineup

Amercast stocks the full range of 24-inch manhole frame and cover configurations. Select the assembly that matches your project specification:

3″ x 24″ Manhole Frame and Cover () — standard depth option for lower-profile installations and residential applications.

4″ x 24″ Manhole Frame and Cover — this page; the standard heavy duty municipal depth.

6″ x 24″ Manhole Frame and Cover () — maximum frame height for deep-set installations and high-traffic roadway applications requiring maximum bearing depth.

4″ x 24″ Manhole Frame and Cover Locking Watertight () — gasket sealed, bolted cover for infiltration prevention and odor control.

6″ x 24″ Manhole Frame and Cover Locking Watertight () — maximum depth locking assembly for high-specification watertight installations.

4″ x 24″ Manhole Frame and Cover with Markings () — utility-identified cover face for DOT and municipal marking requirements.

4″ x 24″ Manhole Frame and Cover Marked Storm () — MS4-compliant storm marking for stormwater access structures.

4″ x 24″ Manhole Frame and Grate Bolted () — mechanically fastened cover for security and containment applications.

4″ x 24″ Manhole Frame and Grate () — open grate cover for ventilation or drainage on a 24-inch frame.

Browse the complete Manhole Frames and Covers catalog

Browse Manhole Frames and Grates

Related Products for Your Project

one type of casting. Amercast stocks everything your job needs from a single source.

Catch Basin Frames and Grates () — stormwater inlet castings in 12″, 14″, 16″, 18″, and 24″ sizes with standard, square-hole, and ADA grate options.

Inlet Frames and Grates () — curb and combination inlet castings for roadway stormwater collection.

Manhole Risers () — cast iron grade rings for adjusting manhole frame elevation during paving and reconstruction.

Valve Boxes () — cast iron valve access boxes for water main and gas distribution infrastructure.

Custom Manhole Covers ()— municipality-branded, decorative, and specialty cover designs for unique project requirements.

Engineering and Material Standards (https://amercast.com/engineering/) — Amercast’s complete ASTM and AASHTO compliance reference for submittals and specifications.

About Amercast

American Cast Iron Products, Inc. has served the sewer, waterworks, and construction industries for over 27 years. With more than 1,000 specifications stocked across manhole covers, catch basins, inlet grates, valve boxes, trench drains, and more, Amercast is the single-source supplier trusted by contractors and engineers throughout the Northeast. We carry both domestic and import grey iron and ductile iron castings, giving you flexible options for Buy American compliance and project budget requirements.

Whether you are pulling permits on a DOT contract, sourcing emergency replacements for a failed casting in the field, or building out a full drainage submittal package, the Amercast team has the product knowledge and inventory depth to get your project moving.

Questions about specifications, availability, or project submittals? Call 646-227-0910 or 516-624-8543

Request a Quote (https://amercast.com/contact/) — same-day response for in-stock items.

The Gold Standard for 4” x 24” for 38 years and counting

The 4” x 24” Manhole Frame & Cover is engineered to provide secure access to underground utility infrastructure while delivering the structural performance required for municipal, commercial, industrial, and public works applications. Manufactured from premium gray iron conforming to ASTM A48 Class 30B specifications, this heavy-duty casting assembly is designed to protect critical underground assets while providing dependable long-term service in demanding environments.

Designed to meet Class C and H-20 loading requirements, this cast iron manhole frame and cover assembly is capable of supporting vehicular traffic and infrastructure loading conditions commonly encountered in municipal streets, parking facilities, utility corridors, industrial developments, and transportation projects. The robust frame and cover design helps distribute imposed loads effectively while maintaining safe and reliable access to underground systems.

Manholes serve as critical access points throughout modern infrastructure networks, allowing maintenance personnel and utility operators to inspect, maintain, and service underground assets. The 24-inch opening size is one of the most widely specified dimensions throughout North America and is commonly utilized for sanitary sewer systems, stormwater drainage networks, septic systems, water distribution systems, telecommunications infrastructure, electrical vaults, and utility access chambers.

Manufactured from ASTM A48 Class 30B gray iron, this manhole frame and cover provides exceptional compressive strength, dimensional stability, wear resistance, and long-term durability. Gray iron continues to be one of the most trusted materials for underground infrastructure because of its proven ability to perform reliably under continuous loading, changing weather conditions, and decades of field exposure.

A properly designed manhole assembly does more than simply cover an opening. It serves as a critical component within the infrastructure network, helping protect public safety, prevent unauthorized access, safeguard underground utilities, and support long-term asset management objectives. Municipal engineers and utility authorities frequently specify cast iron manhole covers because of their ability to deliver predictable performance and extended service life.

This 24” Manhole Frame & Cover is available with a variety of cast-in identification markings to assist with utility asset management and infrastructure identification. Standard markings include SEWER, STORM, and SEPTIC designations. Amercast also offers custom cast lettering, municipal seals, utility authority logos, contractor branding, project-specific identification, and proprietary customer logos directly cast into the cover.

Custom casting capabilities provide municipalities, utility authorities, developers, and contractors with enhanced asset identification while creating a professional and permanent infrastructure solution. Custom logos and markings also help reduce field confusion, simplify utility management, and support long-term operational efficiency.

Whether specified for municipal wastewater systems, stormwater infrastructure, utility networks, residential developments, commercial construction, industrial facilities, or transportation projects, the 24” Manhole Frame & Cover delivers dependable performance, engineering reliability, and long-term infrastructure value.

Features & Benefits

• Manufactured from ASTM A48 Class 30B gray iron
• Class C and H-20 load rated
• Heavy-duty cast iron construction for long service life
• Designed for municipal, commercial, and industrial infrastructure
• 24-inch opening accommodates a wide variety of utility access applications
• Excellent compressive strength and structural stability
• Resistant to impact, wear, and environmental exposure
• Precision-cast frame and cover assembly for proper seating and fit
• Supports underground utility asset protection
• Helps prevent unauthorized access to critical infrastructure
• Available with SEWER, STORM, and SEPTIC cast-in markings
• Custom names, municipal logos, utility identifiers, and branding available
• Suitable for roadway, parking lot, and utility corridor applications
• Proven long-term performance in demanding infrastructure environments

Applications

This 24” Manhole Frame & Cover is commonly specified for:

• Municipal sanitary sewer systems
• Stormwater collection networks
• Septic system infrastructure
• Wastewater treatment facilities
• Water distribution systems
• Utility access vaults
• Electrical infrastructure
• Telecommunications systems
• Transportation infrastructure projects
• Public works construction
• Commercial developments
• Industrial facilities
• Residential subdivisions
• Utility corridor installations
• Municipal reconstruction projects

Product Specifications

Engineered for Utility Access and Infrastructure Protection

Underground utility infrastructure represents a significant public investment and requires reliable access solutions capable of performing for decades. Manhole frame and cover assemblies serve as the interface between surface infrastructure and critical underground systems, making durability, safety, and performance essential design considerations.

The 24” Manhole Frame & Cover is engineered to provide secure access while protecting underground assets from unauthorized entry, debris infiltration, and external loading conditions. The heavy-duty cast iron construction distributes traffic loads efficiently while maintaining structural integrity under demanding service conditions.

Unlike lightweight alternatives, cast iron manhole assemblies provide proven lifecycle performance and remain the preferred solution for municipal infrastructure applications throughout North America. Their combination of strength, durability, dimensional stability, and serviceability continues to make cast iron the industry standard for utility access products.

For municipalities and utility owners, custom cast markings offer an additional layer of asset identification and infrastructure management. Utility-specific markings help maintenance personnel quickly identify system ownership and application type while improving operational efficiency in the field.

Frequently Asked Questions

What does H-20 load rated mean?

H-20 is an industry-recognized loading designation commonly used for municipal infrastructure applications exposed to vehicular traffic. H-20 rated castings are designed to withstand roadway and transportation-related loading conditions.

What is ASTM A48 Class 30B gray iron?

ASTM A48 Class 30B is a widely specified gray iron grade known for its strength, durability, machinability, and long-term performance in municipal and utility infrastructure applications.

What markings are available on the manhole cover?

Standard cast-in markings include SEWER, STORM, and SEPTIC. Amercast can also manufacture covers with custom utility names, municipal seals, project identifiers, and customer logos.

Why are cast iron manhole covers preferred for municipal infrastructure?

Cast iron provides exceptional compressive strength, durability, wear resistance, and long service life, making it ideal for utility access and infrastructure protection applications.

Can custom logos be cast directly into the cover?

Yes. Amercast offers custom casting services that allow municipal logos, company branding, utility identifiers, and project-specific lettering to be permanently incorporated into the casting.

What industries commonly use 24-inch manhole covers?

These products are widely utilized by municipalities, utility authorities, contractors, developers, engineering firms, wastewater facilities, transportation agencies, and industrial infrastructure owners.

Amercast manufactures specification-ready manhole frames and covers for municipalities, utility authorities, engineers, contractors, developers, and infrastructure professionals seeking dependable utility access solutions and long-lasting cast iron infrastructure products.

Contact our team for pricing, lead times, custom logos, municipal castings, and project-specific manhole cover solutions.

Request a Quote Today.