So you all know that I am a fan of Gleason Steam's shop training programs and I like to pass on to you some of the really cool things that I have picked up from them. Here is one that I think you will find interesting and after reading this, go ahead and do a walk through your plant and see if you have this problem.
What's wrong here?
In reviewing a system recently, we found a Y-strainer installed upstream of a pressure-reducing valve (PRV) with the strainer screen portion in the vertical plane. The PRV was operating properly...so why is this incorrect? Very simply:
The purpose of the Y-strainer is to protect the PRV from damage, pluggage, or partial pluggage.
Steam that is destined to pass through the PRV must first pass through the Y-strainer, whose job it is to collect (strain out) corrosion materials, pipe scale, weld slag, etc.
Why, in this scenario, is the piping incorrect?
When installed with the screen portion in either the vertical or horizontal plane, the Y-strainer can effectively do its job of removing unwanted debris. However, when it is installed in the vertical plane, water (condensate) will collect at the low point. The condensate that collects
here can be picked up by the steam and carried through the valve, damaging the valve's seating surfaces by way of erosion. This can significantly reduce the lifespan of your regulator or control valve. Flashing condensate and the resulting volume expansion can also negatively affect the valve's flow characteristics.
How is this corrected?
Proper installation of the Y-strainer should have the strainer screen portion situated in the horizontal plane. This practice allows the strainer to accomplish its objective while eliminating the low point where water (condensate) will collect.
Pertinent Steam System Best Practices:
A Y-strainer (with a blowdown valve) is to be installed upstream of the PRV. (Many PRV manufacturers will not honor their warranties if a Y-strainer is not installed.)
The Y-strainer is to be installed with the screen portion in the horizontal plane.
Provide regular, recurring steam system training for personnel.
Specify continuous, at-a-glance monitoring of steam temperature vs. expected saturated temperature at the system's saturated pressure.
"Steam knowledge is evaporating."
Remember for Gleason Steam for your training needs. Give them a call for an on site training class.
This is Mike at SiteWorks Mechanical wishing you all a safe day.
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