Strainers (Fig. 1) arrest debris such as scale, rust, jointing compound and weld metal in pipelines, protecting equipment and processes. A strainer is a device which provides a means of mechanically removing solids from a flowing fluid or gas in a pipeline by utilizing a perforated or mesh straining element.
To ensure against untimely shutdown of equipment, strainers should be installed ahead of pumps, loading valves, control valves, meters, steam traps, turbines, compressors, solenoid valves, nozzles, pressure regulators, burners, unit heaters and other sensitive equipment. The most common range of strainer particle retention is 1 inch to 40 micron (.00156 inch ).
Sensitive Equipments: Static
- Heat exchanger
- Steam trap
- Spray nozzles
Sensitive Equipments: Dynamic
What are Basic Types?
- Y type (Fig. 2)
- Basket Type( Simplex & Duplex construction) (Fig. 3)
- T type
- Cone type
- Truncated Cone type
Design to following International Standards:
- ANSI B 16.34
- PED 97/23/EC: Pressure equipment design
- BPV: ASME Boiler & Pressure vessel code, Section-VIII Div.1
Material of Construction:
- Casting( but flanges shall be integral part of body)
- Stainless steel
- Special care shall be taken for Produced water service
- SW or Threaded
Two types of screens used in strainers :
- Perforated screens
- Mesh screens
Perforated screens :
– These are formed by punching a large number of holes in a flat sheet of the required material using a multiple punch. These are relatively coarse screens and hole sizes typically range from 0.8 mm to 3.2 mm
– Fine wire is formed into a grid or mesh arrangement. This is then commonly layered over a perforated screen, which acts as a support cage for the mesh.
- Mesh Screen terminology : e.g. 3 mesh screen
- We shall always ask process to give Max.allowable pressure drop at % clogged condition.
- Mesh screens are usually specified in terms of ‘mesh’; which represents the number of openings per linear inch of screen, measured from the centre line of the wire.
- Mesh is not the only thing to be asked for but hole size is also important.
- Corresponding hole size in the mesh screen is determined from knowledge of the wire diameter and the mesh size
- Magnetic inserts
- Self-cleaning strainers
- Mechanical type self-cleaning strainers
- Backwashing type strainers
- Temporary strainers
Temporary strainers (Fig. 5): –
Y type strainer on various fluid (Fig. 6):-