When building a new pipeline there is always a chance that items, such as weld beads and slag, did not get completely cleaned out of the pipeline. A weld bead (ball) moving down a gas pipeline at a high velocity would act like a bullet being shot from a gun.
Temporary strainers act like a safety net in the design. Over the past 40 years that our engineers have been involved with designing or selling this type of equipment, they have heard of chipping hammers, hard hats, and lunch boxes being left in the lines.
One particle of scale, weld bead, dirt, or other entrainments can cause sever damage to expensive equipment. To prevent damage, temporary strainers are used and must be designed of durable corrosion-resistant materials.
Fluid Engineering has started an intensive redesign study to improve the structural integrity of the conical and basket strainers. This study is looking at general conditions as well as when the strainer is subjected to reverse flows found in high-pressure natural gas pipelines.
Extreme loading that can be introduced on the surface of the strainer causes the open area ratio to decrease as the debris builds up. Therefore, it is necessary to add a support cage structure to insure a higher safety factor. This support cage is highly recommended in reverse flow, high-pressure applications.
The temporary strainer is usually installed in a spool piece equal or longer in length with the gasket end of the temporary strainer located between a matching pair of flanges.
By removing the bolts on both ends of the spool piece, the assembly can easily be removed from the pipeline for cleaning.