An article on Strainers or Filters used in piping Industry

An article on Strainers used in piping Industry [With PDF]

What is Strainer?

Strainers (or filters) arrest debris such as scale, rust, jointing compound and weld metal in pipelines, protecting equipment and processes. A strainer is a device that provides a means of mechanically removing solids from a flowing fluid or gas in a pipeline by utilizing a perforated or mesh straining element. The following figure shows various types of strainers normally used in Pump Suction lines in the process piping industry.

Pump Strainers
Various types of Pump Strainers
Strainer
Fig.1: Example of a typical Strainer

To ensure against the 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 microns (0.00156 inches ).

Sensitive Static Equipment

Even though static equipment is normally not considered as that sensitive, still sometimes strainers are installed near the following equipment.

  • Heat exchanger
  • Meters
  • Steam trap
  • Spray nozzles

Sensitive Dynamic Equipment

For the following sensitive and vibration-prone equipment use of strainer is a must.

  • Pumps
  • Compressors
  • Turbines

Basic Strainer Types?

Permanent Strainers

This strainer will be installed permanently in the piping system.

  • Y type (Fig. 2)
  • Basket Type( Simplex & Duplex construction) (Fig. 3)
  • T type
Y-type Strainer
Fig. 2: Figure showing an example of a typical Y-type Strainer

Temporary Strainers

  • Cone type
  • Truncated Cone type

Design Codes for Strainers

Strainers or filters are normally designed following the below mentioned International Standards:

  • ANSI B 16.34
  • PED 97/23/EC: Pressure equipment design
  • BPV: ASME Boiler & Pressure vessel code, Section-VIII Div.1

Materials of Construction of Strainers:

Body

  • Forged
  • Casting( but flanges shall be an integral part of the body)
  • Fabricated

Internals

  • Stainless steel
  • Special care shall be taken for Produced water service
Basket type filters
Fig. 3: Example showing a figure of typical Basket type filters

End connections

  • Flanged
  • SW or Threaded

Construction terminology

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 multiple punches. These are relatively coarse screens and hole sizes typically range from 0.8 mm to 3.2 mm

Mesh screens

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 the 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 center line of the wire.
Example of Mesh Size
Fig. 4: Example of Mesh Size
  • 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

Strainer options

  • Magnetic inserts
  • Self-cleaning strainers
  • Mechanical type self-cleaning strainers
  • Backwashing type strainers
  • Temporary strainers

Temporary strainers (Fig. 5)

Typical Temporary Strainers
Fig. 5: Typical Temporary Strainers

Y type strainer on various fluid (Fig. 6)

Y type strainer on various fluid
Fig.6: Y type strainer on various fluid

Few more Resources for you..

Piping Design and Layout
Piping Stress Analysis
Piping Interface
Piping Materials

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5 thoughts on “An article on Strainers used in piping Industry [With PDF]”

  1. Kairi Gainsborough

    It’s really interesting how much variety you can find in strainer baskets. I would imagine that the hole size of the mesh you use should be determined by the location in the pipe. It would need to be small enough to catch any unwanted debris, while also not disrupting the flow of the pipe. Are there different types of strainers for fluid and gas pipelines?

  2. As explained in the post, there are two elements: the First one is perforated plate and the second one is the Mess.

    Now as per post, the Mess will be wrapped around the perforated plate. And perforated plate will provide support to the mesh.

    While purchasing the Strainers, I always came across the term “Perforation Ratio”.

    Can the Author or any other member of the portal explain the term “Perforation Ratio”?

  3. Post talk about the different types of Strainers.

    Can anybody explain:

    # Where to use “T- Type Strainers”?
    # Where to use “Y- Type of Strainers”?
    # Where to use “Basket Type Strainers”?
    # Where to use “Temporary Strainers”?

  4. Author presents exemplary outlook of the subject matter. expertise. no single stone is left to present its case.
    i was looking for selection criteria for different types of strainers.

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