Applications for Temporary Strainers

Introduction

Temporary strainers (also called startup strainers) protect pumps, valves, meters and other downstream equipment during the commissioning of new or revamped pipelines. They capture welding slag, pipe scale and other debris, then are removed once the system is flushed clean. They are essential in oil & gas, chemical processing, water treatment and similar industries.

 

Types of Temporary Strainers

There are three primary styles: cone, temporary basket, and plate. Each suits different space constraints and flow requirements.

 

Cone Strainers

Cone strainers (also called conical or “witch’s hat” strainers) are installed between flanges. They can be oriented with the tip facing upstream or downstream:

 

• Tip facing upstream (preferred) — Fluid flows outside-to-inside. Debris collects on the stronger outer surface, reducing the risk of tearing. Best for high-velocity flows.
• Tip facing downstream — Fluid flows inside-to-outside. Debris collects inside the cone, making cleaning easier, but the tip is more vulnerable under heavy loads.

 

Cone strainers offer low pressure drop when space allows and are widely used in oil, gas, chemical and water applications.

 

Temporary Basket Strainers

These are shorter cylindrical designs installed with the open end facing upstream so debris collects inside. They have a slightly higher pressure drop than cone strainers but work well where axial space is limited.

 

Plate Strainers

Flat perforated discs installed between flanges. They are the most compact option and the only style that easily allows bi-directional flow, but they produce the highest pressure drop because of limited open area. Used mainly when space is extremely restricted.

 

Applications Summary

Type	Typical Applications	Key Considerations
Cone	Oil, gas, water, chemical processing	Low pressure drop, requires more length
Basket (Temporary)	Similar services in compact spaces	Moderate pressure drop, shorter length
Plate	Small pipelines, tight access, bi-directional flow	Highest pressure drop, minimal space needed

Sizing Methodology – Open Area Ratio (OAR)

The primary sizing metric is the Open Area Ratio — the strainer’s open area divided by the pipeline’s cross-sectional area (expressed as 100 %, 150 %, 200 %, etc.). Higher expected debris loads and tighter pressure-drop limits call for higher OARs. Perforation or mesh size is selected according to the smallest particle that must be retained (commonly 1/8" perforations or 20–100 mesh).

 

Material Selection

Most temporary strainers are made from stainless steel (304 or 316), carbon steel, or specialty alloys such as Monel, chosen for fluid compatibility. Stainless steel is preferred for water and many chemical services.

 

Temporary vs Permanent Basket Strainers

Feature	Temporary Strainers	Permanent Basket Strainers
Cost	Lower, cost-effective	Higher initial cost
Installation	Simple – between flanges	Requires more space and piping
Maintenance	Removed after startup	Cleanable without pipeline disassembly
Pressure Drop	Can be higher if undersized	Generally lower
Use Duration	Short-term (startup only)	Long-term continuous service

Temporary strainers are the practical choice for initial system flushing. Permanent basket strainers are the better long-term solution when continuous filtration is required.

Conclusion

Proper selection of cone, temporary basket or plate strainers — sized with the correct Open Area Ratio and installed in the preferred orientation — protects critical equipment during pipeline commissioning and helps ensure a smooth, debris-free startup.