Flange gaskets are highly engineered products, and their performance depends on many factors. Of course, the design, manufacturing, installation and process conditions are all critical, but the same is true for storage before use. The gasket material is usually stored for a long time before it is put into use. Unfortunately, storage practices for gasket materials are often not optimal or well controlled. This article provides guidance on the storage of different gasket materials to maintain their integrity.

Gasket materials are divided into three categories: non-metal, semi-metal and metal. Non-metal gaskets or soft gaskets are made of materials such as rubber, fiber, polytetrafluoroethylene (PTFE) and graphite. The material properties make it ideal for low-pressure flat applications. The metal gasket is made of one or more metals. The semi-metal gasket is composed of metal and non-metal materials. Metal is designed to provide strength and elasticity, while non-metal parts provide consistency and tightness. These types of gaskets are used for higher pressure applications. The most common semi-metallic gasket is the spiral wound gasket.

The shelf life is defined as the period of time during which the material can remain applicable during storage. Although shelf life is a commonly discussed term about storage rather than service life, it is important to note that storage conditions affect service life. The shelf life varies with product specifications and compound design. The gasket material is usually stored for several months before use. Therefore, the shelf life is an important consideration for the end user. Gasket degradation may be the result of a combination of factors such as oxygen, ozone, light, heat, humidity, oil, water, solvents, acids, and steam.

Over time, materials with elastic adhesives will inevitably deteriorate. These gasket materials are widely used in many industries and have proven to provide reliable service in bolted flange connections. Elastomer-bonded fibrous materials can be made of complex materials. The main components include rubber (elastomer) adhesives, reinforcing fibers and filler components. The aging process of these types of gaskets involves an irreversible chemical process, and they are easily deteriorated due to increased ambient temperature. Direct sunlight usually accelerates degradation. Reinforcing fibers are generally considered to be the most stable ingredient, but modern fibers do gradually dry out, weather, and deteriorate.

Filler composition is usually the biggest factor in gasket deterioration. These ingredients come in many forms, come from many different chemical families, and are usually unique to each manufacturer. Select and combine them to optimize gasket performance. The speed at which this process occurs depends to a large extent on the material composition and its quality and storage conditions.

However, some gasket materials are basically inert and are not affected by long-term storage. For graphite and PTFE gaskets without binders, the shelf life of sheets and gaskets of these materials is almost unlimited.

For metal and semi-metal gaskets made of graphite or PTFE soft materials, the theoretical shelf life under ideal conditions is unlimited. However, in reality, too much dust may cause compatibility issues with the process, and exposure to a humid environment can cause metal parts to oxidize.

Poor storage conditions can lead to premature degradation of quality, especially in the presence of elevated temperatures, inappropriate humidity, and strong light.

The best storage conditions are defined as:

Without in-depth understanding of the many variables that affect the natural life of each component, it is difficult to determine the life of the gasket material when the storage environment is different from the recommended conditions. However, if storage guidelines are followed, there are some generally accepted storage periods for various materials. For example, Table 1 shows guidelines for some common elastomer compounds. Please consult the gasket manufacturer, as different adhesives and fibers may have special requirements.

In addition to the storage environment, physical storage conditions also affect the shelf life. For example, cut gaskets should be stored flat. This is especially suitable for large gaskets. When suspended from the smallest point, they may be stressed and permanently deformed, resulting in installation difficulties and material damage. If you choose to store the cut washers on the nail plate, they may become deformed if they are stored there for too long. Wear gloves when handling these materials to prevent oil deposits.

Please note that, especially for elastomer-bonded fiberboards, although boxes and cardboard tubes are approved coil transportation methods, they should not be used for long-term storage under any circumstances (see Figure 1). The reason is that these sheets will "solidify" into a roll and then cannot be flattened. This will result in an uneven corrugated shape when unfolded. When trying to flatten a sheet that has been rolled for a period of time, small cracks or cracks may appear, which may cause leakage in the future.

Spiral wound gaskets should be stored flat to avoid strain and warping. Encourage the use of gaskets to prevent possible damage to the sealing surface.

All gaskets need to be branded or labelled so that they can be clearly identified. In addition, the age/storage time in the warehouse needs to be tracked correctly. If possible, keep the gasket storage area away from large receiving doors. Install curtains around the area to avoid direct airflow. Cover the immediate top of the gasket to protect it from direct light and dust.

Following these simple guidelines can ensure that the storage time of the gasket does not affect its performance when it is put into use.

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Laverne Fernandes is a manufacturing and application engineer at Garlock Sealing Technologies. In this position, Fernandes is responsible for coordinating and leading a team that provides support in all aspects of product engineering, including applications, product development, and process improvement. Fernandes holds a degree in mechanical engineering from the University of Texas and is currently studying for an MBA at the University of Houston.