Issues regarding the selection and use of gaskets

(1) Asbestos rubber gaskets belong to non-metallic gaskets and are widely used in pipelines carrying media such as air, steam, gas, brine, acids, and alkalis. Metal wound gaskets are simple to manufacture, inexpensive, and have a high material utilization rate. They require little attention to the surface roughness of the flange sealing surfaces, offer multiple layers of sealing, and provide good sealing performance, making them an ideal gasket for medium-pressure applications. It is widely used in pipelines for general process materials under high temperature and pressure conditions. (2) Asbestos does contain carcinogens, and its use has been banned abroad; however, it is still used in some pipes in China, mainly in situations where no harm is expected to occur. But it’s best to avoid choosing them (from a personal perspective). (3) Regarding the selection of gaskets, it generally involves accumulating more experience. You can look at the relevant standards for gasket products, such as GB/T4622.1, HG20610, GB/T9126, and so on. There are many other standards related to gaskets as well; please read more information and explanations on these standards, and you will gradually understand them better.

The reasons we don’t use graphite gaskets are, first, their pressure resistance is not very high; second, they stick to the flange surface after use and are difficult to clean. Therefore, we usually use graphite wound gaskets

But use non-asbestos gaskets

We use only metal gaskets and PTFE gaskets; the steam pipes are made of metal, while everything else uses PTFE gaskets. However, I’ve heard that metal gaskets are quite expensive. Generally, metal gaskets are used in high-temperature applications, and for high-pressure systems, flange connections with male and female surfaces are used. It’s not clear how to replace these gaskets

We rarely use asbestos gaskets these days; metal wound gaskets are generally used instead. Easy to use and effective. Generally, it is best to standardize the gaskets for a given device, as this facilitates material procurement and management.

I thought it should be chosen based on pressure, pipe material, and the corrosivity of the medium. At a temperature of 150 degrees, F4 gaskets can be used, while for plastic pipes (PVC, PP), PP soft gaskets can be employed. Metal winding can be used in high temperatures, while for graphite winding it is important to ensure that the medium is not highly oxidizing.

Our factory mainly uses reinforced graphite gaskets, with a small amount of wound gaskets and serrated gaskets being used as well

Rubber gaskets are generally used for water pipes, while PTFE gaskets are used for hot water pipes. Metal-wound graphite gaskets are used for steam pipes. The process pipe is selected based on factors such as the material, as well as temperature and pressure; for example, at room temperature, soft PVC gaskets or acid-resistant rubber gaskets can be used for acids. Tetrafluoro gaskets are commonly used for organic applications. High temperature and pressure conditions can be handled using metal gaskets such as steel or aluminum gaskets. Copper gaskets are used on the oil lines. Teflon-coated gasket for enamel pipes.

You can check the GB20801-2006 pipeline standards to find out which type of gasket should be used in different applications.

The experienced engineers in our design institute generally recommend using flexible composite graphite gaskets, as these gaskets can meet the needs of most applications; for pure water, we use PTFE gaskets. It is best to consult the specification for specific usage scenarios.