Identifying and Measuring Tank Manway Gaskets

A Step-by-Step Technical Guide to Precision Sizing and Identification

In any food manufacturing or dairy processing facility, tanks, silos, and process vessels are key components of the production line. However, there is another key component that can be overlooked that keeps these critical operations running smoothly, safely, and contamination-free: the manway gasket.

Manway gaskets play a crucial role in protecting product purity and preventing leaks of valuable ingredients or chemical solutions. If a gasket fails to fit or seal properly, it can lead to product spoilage, downtime, or safety hazards. Because every vessel's manway has a unique design, size, and pattern, selecting the exact replacement gasket is crucial.

Getting the Right Manway Gaskets

Prevent product spoilage with the perfect, reliable sanitary seal.

get a custom quote

A Smarter Approach to Tank Integrity

Protecting product purity and preventing leaks of valuable ingredients or chemical solutions starts with selecting the right gasket material and dimensions. Nelson-Jameson offers three methods to identify your gasket:

Method 1: The Preferred Way - Nameplate Identification

The fastest and most reliable path to find the correct replacement gasket is to check the tank's original manufacturing nameplate. Most manufactured tanks feature a stainless steel tag welded or riveted to the exterior. If you can provide the following three elements straight away, Nelson-Jameson can trace the manufacturer's records without requiring manual measurements:

1. Manufacturer (Brand): Common manufacturers include Walker Stainless, Heil, Paul Mueller Company, DCI Inc, Cherry Burrell, Alfa Laval, Tetra-Pak, Damrow, Rubber Fab, Custom Fabricating & Repair, Flowtrend, and Sani-Matic.
2. Serial Number: The unique registration number for the specific vessel build.
3. Model Number & Capacity: Identifies the product series and capacity (e.g., 800 gallons). This defines the standard dimensions for manway doors.

Pro Tip: If you can provide the manufacturer, serial number, and model straight away, Nelson-Jameson can trace the exact part number for your gasket without needing any additional measurements! Even if you only have a model number from an old gasket, this can often be traced back to the manufacturer and the tank.

Method 2: The Backup – Contact the Original Installer

If the nameplate is unreadable or missing, try contacting the mechanical contractor or engineering firm that originally installed the tank or completed your plant commissioning. Most will usually keep detailed spare parts lists, system schematics, and purchase invoices in their records, which can quickly reveal information about the installed manway.

Method 3: Measuring & Identifying from Scratch

When no manufacturer records are available, you will need to identify the material and measure the physical dimensions. Selecting the correct rubber compound is critical for withstanding operational temperatures, sanitizing chemicals, and product contact.

Step 1: Identify the Correct Gasket Material

Different processing applications require different gasket materials to handle temperature, chemical cleaning cycles, and product contact.

Material & Key Performance Properties

• EPDM: Excellent resistance to heat, weather, and sanitizing chemicals. Best general-purpose utility compound.
• Silicone: Renowned for outstanding high-temperature resistance and extreme flexibility in low-pressure sanitary lines.
• Viton: Provides superior, chemical-proof resistance. Ideal for harsh processes, high temperatures, and aggressive chemicals.
• Buna: Excellent resistance to fats, oils, fuels, and petroleum-based dairy/food ingredients—with a high-wear resistance.

Select the material that matches your product and cleaning cycles. If you are unsure what your old gasket was made of, Nelson-Jameson can help you select the ideal material for your specific application.

Service & Repair by Nelson-Jameson

Supplement your maintenance team with in-plant services performed by our seasoned, expert technicians.

Get Started

Step 2: Gather Your Measurement Tools

Before measuring, gather the appropriate tools. To ensure an airtight, sanitary seal, measurements must be precise. Do not rely on loose estimates or standard construction tape measures for small details.

• Digital Caliper: Used for small crevices, groove depths, and gasket thickness.
• Gasket Thickness Gauge: Ensures precise thickness measurements to prevent compression leak paths.
• Flexible Measuring Tape: Such as a tailor's tape, to wrap around and capture the outer circumference.
• Piece of String: An alternative tool to wrap around, mark, and measure on a ruler.
• Steel Ruler or Square: Best for flat sides, square manway gates, and outer dimensions.
• Sketch/Template Sheet: To sketch the profile and record dimensions for our specialists.

Step 3: Measure the Gasket’s Key Dimensions

Follow these structured procedures to measure either your existing, non-distorted gasket or the actual metal seating groove on the manway door:

1. Outer Diameter (OD) & Inner Diameter (ID): Measure the absolute end-to-end dimension across the outside edge for Outer Diameter (OD), and from inside edge to inside edge for Inner Diameter (ID).
   1. Conversion Formula: Circumference = π × Outside Diameter (Example: A 20" OD Gasket has an outer circumference of 3.1415 × 20 ≈ 62.83 inches.)
2. Outer Circumference: Wrap a flexible tailor's tape directly around the outer sealing edge. If unavailable, wrap a non-elastic string around the edge, mark the overlap point with a pen, and lay the string flat against a tape measure to record length.
3. Cross-Section (Long Leg / Flange Width): The cross-section is the primary sealing surface of the rubber between the door and the tank wall. You can measure this directly off the long leg of your old gasket, or by calculating [ Math Shortcut: Cross-Section = (Outside Diameter - Inside Diameter) / 2 ]
4. Thickness: Essential for pressure-tight sealing. Use a digital caliper rather than a ruler to ensure millimeter-level accuracy, as minor discrepancies can cause over-compression or bypass leaks.
5. Bolt Holes (If Applicable): Some gaskets feature integrated mounting bolt holes. If applicable, record: (1) total hole count, (2) exact diameter of the holes, and (3) center-to-center distance between two directly opposite bolt holes.

Step 4: Capture Clear Technical Photos

Visual profiles are extremely helpful for our technical team in verifying your gasket's exact cross-section. Take four high-resolution photos: (1) Front Profile, (2) Back Profile, (3) Side Profile (to show the long-leg or cross-section thickness), and (4) The Tank Opening itself showing the metal seating groove.

Ready to Order? Contact Nelson-Jameson

Our Sanitation and Process Component Specialists are ready to assist. Contact us with your information and get an accurate quote today!

1. Contact Us: Email sales@nelsonjameson.com or call 800-826-8302.
2. Provide Tank Data: Share the brand name, model number, and serial number (or your physical measurements).
3. Get A Quote: Our product specialists will verify the fit and send you a custom quote immediately.