Studies have shown that strainers are essential to protect pumps, compressors, turbines, burner nozzles, steam traps and various other pipe equipments. When strainers are used properly, they provide invaluable service. This article provides essential information of strainers so that engineers can make the right decision in the specification of pipeline strainers.
What is a pipeline strainer?
Pipeline strainer is an equipment to provide a way to remove solids from flowing fluid. It is performed by using woven mesh or perforated metal. A commonly used strainer holds a particle range of 1 to 40 micron.
Strainers are widely used in pipelines to secure the downstream systems for example condensers, heat exchangers, compressors, turbines and steam traps from the severe effect of rust, pipe scale and other unwanted particles.
Mesh screen based strainers are very important for vertical pipes. Most basket strainers are designed for horizontal or somewhat inclined pipes. More attention is required to the orientation of the debris collection and chamber and the drain connection of the screen. The mesh screen should be installed such that it is configured at the lowest feasible position. The screen in the vertical pipes should be located with its screens in the downward position to hold the sediment in the debris collection container.
The strainers used for suction diffusers can also be used in a perpendicular direction flow based application. These strainers can be self-cleaning. By adding blowdown valve and with some modification of the straining screens, the mesh can be cleaned by opening and closing the blowdown valve. It can be performed without shutting down the system or disassembling the pipe.
When the debris size is above 4 inch, a single basket strainer usually develop lower pressure drop than a perpendicular strainer. The basket strainers are usually used in a horizontal pipe system with a shield over the basket. The cleaning of strainer is usually simple and does not need any draining. Cover flanges for basket strainers are somehow easy to prevent and service is simple. The shield can be replaced by using stud instead of bolts, to align the cover during the replacement easily.
In most cases, the basket and perpendicular strainers provide the same service in steam applications. Whilst in other cases, they perform variably. It is important to get proper advice of your strainer. In some cases high pressure applications involve the use of basket strainers for their high thickness. Basket strainers made of Incoloy mesh are used in severe applications.
The applications which demand continuous operation and system cannot be shutdown, dual or duplex strainers are required. Automatic strainers are recommended for use in continuous applications such as fuel oil strainers for industrial and marine oil burners, lubricating lines on ships, cooling systems, chemical operations and various industrial water lines. Once a basket is full, the flow turns to other basket. Then the filled basket is removed, cleaned and placed again. In this way, the operation keeps going on and the baskets are maintained. It helps in making the operation cost-effective and timely.