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Manholes can be made from the following materials:
• A36 mild (carbon) steel with these finishes:

Shop cleaned (SP3) and red-oxide primed. This is our standard finish.
Sandblasted to white metal (SP10) and primed with an inorganic zinc primer. Cathacoat 302 (also known as Devoe 302) is the primary inorganic zinc primer we use. This is a premium finish available at an additional cost.
Specialized paint / primer finishes are available at an additional cost. Custom paints may significantly increase the product price, since the paint systems cannot be re-used on other jobs.
Galvanizing is another premium finish available at an additional cost. This finish option also adds at least two weeks to the lead time.

• Grade 5000 series Aluminum

• 304 Stainless Steel

• 316 Stainless Steel

Manhole cover thickness: (any material)
• 3/8” thick = ABS Grade (standard thickness)

• Can get a thicker cover if needed

Deck ring dimensions

• 2-1/2” x 2-1/2” x 1/4” thick = Steel, Aluminum, or Stainless Steel

• Custom options, such as making deck ring taller than 2-1/2” are available

Standard outside diameter sizes:

• 15” x 23”

• 16” x 23”

• 18” x 24”

Oval radius:

• Width of manhole clear opening divided by 2

• Example of measurements for 18” wide by 24” long hatch:

Take 18” / 2 = 9” radius for oval ends of hatch
Remaining straight section of hatch between curved ends of hatch cover = 24” - 9” - 9” = 6” straight section

Gaskets:

• 1/8” thick flat gasket with 21 holes

• Available in Neoprene or Buna-N

Fasteners:

• Standard: plated bolts, washers, and nuts

• Optional (for additional cost): stainless steel bolts and washers, with brass or bronze nuts

Optional features:

• NPT plugs installed in cover

• Custom sizes available

ABS Type Approval / Classing Agency Approval:

• All manholes are built to standards generally accepted by ABS, USCG, and other classing agencies. See link to ABS Explanation

• Manholes do NOT carry ABS “Type” approval. For further explanation, click here.

• Drawings and release letters are available for submission for classing agency review.

• It is the responsibility of the customer to verify which certification requirements (i.e. ABS, USCG, DNV, SOLAS) apply to their vessel, and to check with their local governing agency as to the requirements for certifications for all of the items quoted, based on the use for each item on the vessel, and the location of each item as installed on the vessel. Depending on the requirements of the governing agency, additional testing at the manufacturing plant may be required. A separate fee will be charged for any testing.

• Manholes conform to C-class fire rating - they are made of non-combustible materials, however, they are NOT designed or certified to resist the passage of fire from one space to another.

manhole #302

Raised Watertight and Oiltight Multibolt, Oval

For additional information download our pdfs and watch our videos

CEN-TEX spare parts