How to choose the right manway gasket?

Manway gaskets may seem like a small detail, but the wrong choice can lead to serious leaks, contamination, or production downtime. If you’re working with tanks, vessels or processing equipment, choosing the right seal is essential. In this article, you’ll learn what to look for and how to avoid the most common mistakes.

What are manway gaskets used for?

Manway gaskets are sealing elements installed between a tank or vessel opening and its cover – usually in food, beverage, pharmaceutical, or chemical industries. Their job is simple but critical: keep the contents inside and external contaminants out, even under pressure, heat, or during cleaning.

They’re found in stainless steel tanks, pressure vessels, and sanitary equipment, typically where regular access is needed for cleaning, inspection, or maintenance. Without a reliable gasket, even the best-designed system can leak or fail under operating conditions.

Because manway gaskets often work in direct contact with sensitive products, they must meet strict hygiene and safety requirements.

Shapes and types of manway gaskets

Manway gaskets come in several shapes, depending on the construction of the manway and the sealing surface:

• Flat gaskets – most commonly used for standard, smooth manway flanges.
• Profiled gaskets – shaped to fit grooves or specific lid designs, offering better sealing under pressure.
• Inflatable gaskets – used where the seal needs to expand after closure, ensuring tight fit in high-demand applications.

Materials used in manway gaskets

The material of the gasket matters just as much as its shape. It must resist whatever passes through the tank – temperature, pressure, or aggressive chemicals. The most commonly used materials are:

• EPDM – good for steam, hot water, and common cleaning agents; widely used in food processing.
• Silicone – very flexible, handles high and low temperatures well; ideal for hygienic environments.
• PTFE (Teflon) – chemically inert, non-stick, and easy to clean; great for pharmaceutical and chemical use.
• FKM (Viton) – designed for high temperatures and resistance to oils, fuels, and aggressive fluids.

Common mistakes when choosing manway gaskets

Even high-quality gaskets can fail if they’re chosen or used incorrectly. Some of the most common mistakes include:

• Using the wrong material – not every gasket resists the same chemicals, temperatures, or cleaning cycles.
• Wrong size or shape – a gasket that doesn’t fit exactly can shift, leak, or compress unevenly.
• Reusing old gaskets – even if they look intact, gaskets lose flexibility over time and can fail suddenly.
• Ignoring compatibility with cleaning agents – CIP and SIP systems often involve strong detergents or steam, which can damage unsuitable materials.

How to make the right choice?

Choosing the right manway gasket always starts with understanding your process. You need to know what flows through the tank, how often cleaning takes place, what chemicals are used, and what kind of pressure or temperature the gasket will need to handle. It’s not just about fitting the lid – it’s about long-term performance, hygiene, and safety.

A gasket that performs well in one setup may completely fail in another, even if the dimensions are identical. That’s why it’s worth consulting technical specifications, getting clear answers before ordering, and choosing suppliers who know your industry. Spending a few extra minutes early on often saves hours of repairs and downtime later.