Gauge Hatches & Manhole Covers

Vapor-tight access for gauging, sampling, and tank entry.

What It Is & How It Works

Gauge hatches and manhole covers are tank-mounted access fittings that provide vapor-tight openings for manual gauging, product sampling, visual inspection, and personnel entry while preventing fugitive emissions and protecting the tank vapor space from weather and contamination. They address the requirement that every tank opening must seal when closed and provide controlled access when opened.

A gauge hatch is a hinged or bolted cover over a small tank roof opening, typically 8 to 20 inches, that an operator opens briefly for manual gauging tapes, thermometers, or sampling equipment. When closed, the cover seals against a gasket or machined seat to contain vapors. A manhole cover seals a larger opening, typically 20 to 24 inches, sized for personnel entry during inspection, cleaning, and maintenance. The Expanda-Seal™ design provides a gas-tight closure that operators open and close without special tools.

Both device types mount to standard tank roof or shell nozzles and are available in carbon steel, stainless steel, aluminum, and FRP to match the stored product and vapor environment. Selection depends on the nozzle size, the stored product’s vapor pressure and corrosivity, and whether the access point serves gauging, sampling, inspection, or full personnel entry.

Gauge Hatch vs. Manhole Cover

Gauge hatches provide small-opening access for instruments and sampling equipment. Manhole covers provide large-opening access for personnel entry. Both seal the tank vapor space when closed. A tank may require both: a gauge hatch for daily operations and a manhole cover for periodic inspection and cleaning per API 653. Hatches measure and sample; manholes enter and inspect.

When to Specify Gauge Hatches & Manhole Covers

Gauge hatches and manhole covers are specified when a tank requires vapor-tight access for measurement, sampling, inspection, or personnel entry:

Petroleum and Chemical Storage Tanks Fixed-roof tanks storing crude oil, refined products, or chemicals where manual gauging and sampling must be performed without releasing vapors to atmosphere, and where EPA 40 CFR 60/63 requires vapor-tight closures on all tank openings.
Terminals and Tank Farms Requiring API 653 Compliance Multi-tank facilities where periodic internal inspection and cleaning require personnel access through manhole covers, and where daily inventory verification requires gauge hatch access for manual measurements.
Tanks with Manual Gauging as Primary or Backup Measurement Installations where manual tape gauging serves as the primary inventory method or as an independent check against automatic tank gauging systems per API 2350 and custody transfer verification requirements.
Corrosive Product Storage Tanks storing acids, caustics, bleach, or other corrosive liquids where FRP or stainless steel gauge hatches and manhole covers are required to resist chemical attack at the access opening.
Tanks Requiring Controlled Vapor Release During Access Any vessel where the access procedure must manage vapor release during opening, requiring self-closing or spring-assisted gauge hatch designs that minimize the duration the opening is unsealed.

Why Shand & Jurs Gauge Hatches & Manhole Covers Excel

Tanks Subject to Fugitive Emissions Regulations

Machined sealing surfaces and compression gaskets maintain a vapor-tight closure that satisfies EPA 40 CFR 60/63 requirements for sealed tank openings, reducing fugitive emissions at a common leak point on the tank roof.

Facilities Requiring Daily Manual Gauging or Sampling

Hinged and spring-assisted gauge hatch designs allow operators to open, gauge, and reseal the tank quickly during daily rounds, minimizing both vapor exposure time and operator effort.

Tanks Requiring Personnel Entry for Inspection and Cleaning

The Expanda-Seal™ manhole closure provides a gas-tight seal that operators open and close without special tools, reducing the time and complexity of confined space entry preparation per OSHA requirements.

Corrosive Vapor Environments That Degrade Standard Closures

Available in carbon steel, stainless steel, aluminum, and FRP construction to match the stored product’s corrosivity, preventing premature seal failure that would compromise both emissions containment and access safety.

Multi-Product Terminals with Varied Access Requirements

A range of sizes (8–24 inches), materials, and closure mechanisms allows each tank in a terminal to be fitted with the gauge hatch or manhole cover matched to its specific product, vapor pressure, and access frequency.

Gauge Hatches vs. Manhole Covers — Selection Guide

Attribute	Gauge Hatches	Manhole Covers
Primary Function	Small-opening access for manual gauging, sampling, and thermometer insertion	Large-opening access for personnel entry, internal inspection, and cleaning
Typical Opening Size	8 to 20 inches	20 to 24 inches
Access Frequency	Daily to weekly during routine operator rounds	Periodic: scheduled inspections, cleaning, and maintenance events
Operating Mode	Hinged or spring-assisted; opened briefly then resealed	Bolted or Expanda-Seal™ closure; opened for extended entry periods
Regulatory Driver	EPA 40 CFR 60/63 (vapor-tight closure), API 2350 (manual verification)	API 653 (internal inspection access), OSHA confined space entry
Material Options	Carbon steel, stainless steel, aluminum, FRP	Carbon steel, stainless steel, aluminum, FRP
Recommendation	Specify for every tank requiring manual gauging, sampling, or thermometer access with vapor containment	Specify for every tank requiring periodic personnel entry for internal inspection and maintenance per API 653

What to Consider Alongside Gauge Hatches & Manhole Covers

Emergency Overpressure Relief With Personnel Access You need a manhole cover that also functions as a fire-case emergency vent, providing both access and overpressure protection at a single opening. See Emergency Vents & Manhole Covers.
Corrosive Service Requiring Full FRP Construction The vapor environment requires fiberglass-reinforced polyester construction throughout, including both vent and access devices. See FRP Vents & Hatches.
Biogas Digester Cover Access You need gas-tight personnel and inspection access at an anaerobic digester cover rather than a petroleum or chemical storage tank. See Biogas Cover Equipment.
Complete Tank Roof Fitting Assembly Pair gauge hatches and manhole covers with conservation vents and flame arresters to ensure every opening in the tank roof provides both its intended function and vapor containment. See Conservation Vents & Seals and Flame & Detonation Arresters.
Automated Gauging With Manual Verification Combine gauge hatch access for manual tape measurements with L&J Technologies automatic tank gauging to provide independent level verification for custody transfer and API 2350 overfill prevention compliance. See Clairvoyance.