October 2019

How to Install a Gasket

The costs of gasket failure are far greater than the price of the gasket itself. A leaking joint means wasted gas or liquid, and that can have safety and environmental implications. Unplanned downtime cuts into production, reducing output and perhaps needing expensive overtime working to make good the shortfall. Then there’s the actual time and effort involved in opening up the joint, cleaning the faces and installing a new gasket.

Bottom line: you only want to do the job once, so do it right. Here’s what and what not to do.

Don’t reuse an old gasket. It’s a false economy. The material has been compressed and creep has taken place. It won’t have the recovery of a new gasket so it won’t seal as well.

Do clean the mating faces thoroughly. Residual gasket material or adhesives will reduce the ability of the new gasket to make a good seal.

Don’t use a gasket that’s thicker than what the flanges need. Remember, the purpose of the gasket is just to take up surface imperfections and misalignment and to handle expansion and contraction. An unnecessarily thick gasket is more likely to fail.

Do choose a gasket that’s appropriate for the joint TEMP – that’s Temperature, Environment, Media and Pressure. Soft gaskets – those made from materials like neoprene, graphite, fiber or cork – should not be used in high-pressure applications. Ask your gasket material supplier if they can provide pressure-versus-temperature (PxT) charts for your preferred material.

Don’t overtighten a soft gasket joint. Once the gasket has been crushed the material loses its ability to recover as the joint opens up. That leads to leaks.

Do follow the correct bolt tightening procedure. See “How To Bolt Flanges” for details.

Don’t glue thin gaskets together to make one thick enough for the joint. It won’t behave like a gasket of the right thickness and will almost certainly fail prematurely.

Do it right

Replacing a gasket outside of scheduled maintenance periods is often awkward and expensive. Achieving a long life is a function of gasket selection and installation, and these dos and don’ts will help.

White Nitrile Rubber

Gaskets made from white nitrile rubber won’t impart any taste to food. That’s one reason they’re used in food and beverage production but it’s not the material’s only useful property. Here’s a look.

Understanding White Nitrile Rubber

White nitrile rubber chemical name Acrylonitrile Butadiene carries the ASTM designation NBR and is sometimes referred to as white Buna-N. A blend of neoprene and SBR, white nitrile rubber is an abrasion-resistant elastomer. Shore hardness is around 60, putting it somewhere between tire tread and a pencil eraser, making it firm yet flexible.

White nitrile is usable over temperatures from around -40°F to 220°F (-40 to 105°C.) It resists attack by oils, fats, greases and hydraulic fluids although it is vulnerable to ozone, ketones, esters and aldehydes. (These were explained in a previous blog post, “Ketones and Gasket Materials”.)

Nitrile rubber is produced in a range of colors, but white nitrile is, as the name suggests, white. This gives it some useful applications.

Applications for White Nitrile Rubber Gaskets

As it doesn’t mark surfaces or impart a taint, white nitrile is available in grades approved by the FDA for food use. It’s also non-allergenic. Consequently, white nitrile gaskets are common in food and beverage production as well as pharmaceuticals.

White nitrile rubber is also used in applications where appearance matters. The smooth white finish is often desirable, especially in medical applications, and has a secondary benefit: it shows up leaks that would be unseen against dark materials.

In addition to sealing and gasketing applications, white nitrile is used for cushioning and protection. You may see it as liner in food processing equipment and also as bumper protection strips. A less obvious, though still common application, is for food grade rubber scrapers.

Talk to Hennig Gaskets & Seals

Gaskets for food and pharma use must comply with FDA requirements. White nitrile is often a good choice for such applications, although it has other uses too. As an attractive, non-marking material it works well in situations where appearance matters. Learn more by talking to our specialists.