In oil & gas drilling, shaker screens are used on not only shale shaker which is the first grade of solids control equipment, but also desander, desilter and mud cleaner to separate the solids in the drilling fluids. In different period, people invented different types of shaker screens, such as conventional flat screen, corrugation screens, and with square meshes, hexagonal meshes, diamond meshes, etc. And different geological condition may require different ability and type of shaker screens. But in different times, people used different ways to describe the ability of screens.

Ⅰ. How to Describe Shaker Screen Before?

Initially it is easy to describe and identify the shaker screens. The previous screens are made of steel wires with square meshes, so the screens are defined basing on the number of the meshes per square inch. For example, people use a number plus mesh to describe the type of screen. In this way, the sizes of solids that are separated by the screens would depend on the mesh sizes and the diameter of wires. The smaller the wire diameter, the larger of the meshes, so the larger of the solids that can pass through the screen. Thus, even though two screens may have same number of mesh per square inch, but the mud flow capacities and the sizes and amount of solids that return to the mud tank may be the same. So the concept of mesh can not definitely identify the ability of the screens to purify the solids in drilling fluids. But before new API standard was issued, the concept of mesh was generally accepted as the screen descriptor.

Shaker screens

1. KOSUN’s shale shaker

Ⅱ. API Standard to Identify Shaker Screen.

Nowadays the concept of mesh was no longer appropriate because the type of meshes are different so much, such as diamond meshes, hexagonal meshes, conventional flat screen, corrugation screen, etc. So we must use metric units (international unit of system ) to describe the ability of the shaker screens. So API standards was issued to identify different screens.

(Ⅰ) The new method is physically developed by comparing the screens that to be tested with standard screens of American Society of Testing and Materials (ASTM). Solids can be sieved and sorted through a stack of standard ASTM screens. These solids, when placed on a test screen, will be sorted by the test screens into sizes equivalent to some ASTM designation. The designation will be used as the API number. For example, when we descibe a screen, we may say it as API 200, API 150, etc.

(Ⅱ) The quickest method is called the “finder’s method.” In this method, small amounts of different aluminum oxide grit are placed on a test screen and shaken on a RO-TAP for 10 minutes. The weight of the grit remaining on the screen can be used to determine the size of grit that could not go through the screen to efficiently measure the test screen’s equivalent opening size.