Guys:
From my experience in gas compression industry, strainers need care and
attention. At a typical "best practices" installation, we would have an inlet
filter/scrubber to catch water/dirt/trash which is a normal part of the stream.
But you will still have piping from this unit over to the pump/compressor. This
will have slag, rust, rags, dead cats...which need to be removed before they
pass through the unit. This is the real purpose of an inlet strainer. Agreed,
in some cases, particularly with a liquid pump, a strainer is used instead of a
filter. Then, in that case, it needs to be a permanent fixture. But as the
question was phrased, a start up strainer is normally used to catch trash left
in the piping. If you leave it in permanently, and if the screen is effective,
sooner or later it will get clogged with pipeline rouge, dust, oil and other
materials. If differential across the strainer is not checked, it can either
degrade performance of the pump, or as a worst case, fail, dumping all the trash
and the screen into the pump inlet. I have seen a 14,000 Hp centrifugal
compressor impeller destroyed when a "start up" strainer was left in place and
failed.
To totally beat this horse: if you need permanent cleaning, you should have a filter/separator/scrubber. These are designed to remove quantities of contaminants, and to be easily maintained/cleaned. A strainer should either be for startup - definitely temporary, or a very non-restrictive protection against large items, or failure of the filter.
George McKinney
Although it is called temporary strainer but mostly people do not remove it. May be a permanently temporary strainer.
-----Original Message-----
From: <a href="/group/PipingDesign/post?postID=rb8FD_MdpvTFlvdKMmCXXl1T8XxzEkpC-rPKjhIQhsS5MtXh6FnK6SxprhfbxeS8u0ljYBtqC3EgndPQe78H2weL5ik">PipingDesign@yahoogroups.com</a> [mailto:<a href="/group/PipingDesign/post?postID=rb8FD_MdpvTFlvdKMmCXXl1T8XxzEkpC-rPKjhIQhsS5MtXh6FnK6SxprhfbxeS8u0ljYBtqC3EgndPQe78H2weL5ik">PipingDesign@yahoogroups.com</a>]
On Behalf Of George McKinney
Sent: Tuesday, August 30, 2005 6:32 PM
To: <a href="/group/PipingDesign/post?postID=rb8FD_MdpvTFlvdKMmCXXl1T8XxzEkpC-rPKjhIQhsS5MtXh6FnK6SxprhfbxeS8u0ljYBtqC3EgndPQe78H2weL5ik">PipingDesign@yahoogroups.com</a>
Subject: Re: [PipingDesign] temporary strainer removal
Hello Pipe Design (Somebody is writing anonymously, maybe as a result of
recent flaming on this site?)
You are correct on the spacing. You could have just a spacer ring, but
I would recommend an alternate strainer with large holes - something
that would stop large pieces of trash but not clog.
George McKinney
Hello everybody
Temporary strainers are specified on piping connected to pumps and
compressors during commissioning.They are placed between two flanges, so
there is a gasket specified on both sides of the strainer.If the
thickness of the strainer plate is 't' mm , then the total space between
the two flanges is (6 + t )mm .(taking gasket thickness = 3mm ).The same
is reflected on the isometrics.
Now , after commissioning , when this strainer is removed , how is the
gap created by removal of the strainer ( 3+t )mm compensated for ?
Is a spacer ring of thickness 't' installed in place of the
strainer.? If this is not the case , then strain is being imposed on the
equipment nozzle for which there is no accounting during stress
analysis.
Regards,
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[Non-text portions of this message have been removed] Received on Tue Aug 30 11:20:00 2005
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