How to install temporary strainer (cone type) 1

[Redpipe]

Hi!

I know that temporary strainer (cone type) can be installed 2 direction as follow:

1 fluid flow from outside of strainer to inside.
2 fluid flow from inside of strainer to outside.

Can you please tell me how we decide to install temporary strainer?

Gas flow is difference from fluid flow?

Thanks and regards,

Big.

 

[CRG]

http://www.standard.no/pronorm-3/data/f/0/01/35/7_10704_0/L-003-CR.pdf

 

[Montemayor]

11000:

Contrary to what some engineers think, a cone strainer is designed to do its work with the tip of the cone FACING the direction of flow (facing upstream). In other words, this strainer is designed to collect debris and trash around the outer edges of the cone because this is a mechanically stronger orientation. If you place the cone with the tip facing downstream, debris will collect in the tip and rip the cone apart due to the heavier strain on the mesh and it's construction. This type of strainer should use a wire re-inforcement to ensure its mechanical stability.

My Mechanical Engineering mentor, Alf Newton, taught me this and proved it out in the field when I entered my first plant engineering job 44 ago. Ever since that time, that's the only way that I have ever installed cone strainers during startups and it's the way I have taught all engineers that I have mentored or supervised since then. I'll bet his logic and design still work.

I don't know how ya'll decide to install a temporary strainer. I do it routinely when starting up new or rebuilt equipment.

Gas flow is fluid flow. There is no difference.


Art Montemayor
Spring, TX

 

[CRG]

The link I posted above is the Norsok Standard Piping Detail. It shows a conical strainer installation on page 34. Years ago, I have been given the same advice that Art has discussed above, and in contrast, the Norsok Detail indicates flow in either direction. I believe one must decide which failure mechanism is prevalent with a given strainer. If the strainer is stronger in tension (pointed end towards direction of flow) then it will rip apart as Art described above. If the strainer is installed as Art recommends above, the failure mechanism will be from collapse. Either case is undesirable so if practicable install a differential pressure gauge as shown in the Norsok detail. The manufacturer may be able to add some insight as to the most likely failure mode. Startup strainers are not always removed (what is intended to be temporary becomes permanent.) If the conical strainer is used only for startup, dp gauge may not be practical.

11000, if you contact the manufacturer to get their installation guidelines, I would like to know what they say.

 

[donf]

My experience is the same as Art's (posted above)- strainer tip pointed upstream. Another possible advantage of this orientation might be that it could accommodate more and provide a better distribution of debris. Perhaps someone with a penchant for geometry would like to compare the two orientations and determine the strainer free area after a given quantity of "debris" is trapped??

By the way, we refer to this conical style of start-up screen as a "witch's hat".

Regards,

donf

 

[btrueblood]

The volume of the cone is 1/3*pi*r*h, the volume of the pipe minus the cone is 2/3*pi*r*h; the pointy end should face into the flow.

 

[btrueblood]

Whoops. I'm going to go back on what I said, after plugging some numbers into a spreadsheet. While the "up" (cone pointing into flow) configuration can absorb a greater total volume than the "down" configuration, the "up" config. also plugs faster early on, for the same volume of trapped debris. After the two configurations have absorbed about 60% to 70% of the cone volume, the "up" config. becomes less of a restriction, and can go on to absorb about 2x the volume of the "down" config. However, the crossover point occurs when the flow area is restricted to 25% of the original pipe area(!).

 

[CRG]

11000,

http://www.weamco.com/cone.htm

is an informative web site showing four different conical strainers that Weamco manufactures. Two of the four are bidirectional, one shows flow opposite of the pointed end of the cone, and the last show flow in the direction of the pointed end of the cone. So the bottom line is that you should install the conical strainer per the manufacturer’s instruction.

CRG

 

[CRG]

Oops
The web address did not print a planned, see below:

http://www.weamco.com/cone.htm