Steam lines (example in Power plant applications) definitely need a high
constant slope to avoid collection of any condensate whatsoever -
otherwise the result could prove to be extremely counterproductive eg.
Hammer, water ingress into the turbine etc.
I would suggest a slope of at least 2% - not only to ensure proper
drainage, or the sag factor as mentioned by Ben below, but also to avoid
counter-slope created in the line due to the differential thermal
expansion of the pipe.
Go through the ASME code TDP1 (Turbine Damage Protection) for further
recommendations.
Regards,
Jaydeep Naha.
Manager - Mechanical Engineering
Siemens AG
Cell : + 91-9811185519
From: PipingDesign@yahoogroups.com [mailto:PipingDesign@yahoogroups.com]
On Behalf Of Ben Nottingham
Sent: 10 January 2007 03:05
To: PipingDesign@yahoogroups.com
Subject: RE: [PipingDesign] Slope in Steam lines
I think the question was about any pipe requiring complete drainage.
Per document EM 1110-1-4008, 5 May 99, pp.3-27 (internet pdf): "The
elevation of the down-slope pipe support should be lower than the
elevation
of the lowest point of the sag in the pipe. This is determined by
calculating the amount of sag and geometrically determining the
difference
in height required.
h = (L / n)^2 y / (0.25 (L / n)^2 - y^2)
where:
h = difference in elevation of span ends, mm, (in) L = span, m (ft) n = conversion factor, 10^-3 m / mm (1 ft / 12 in) y = deflection, mm (in) "
Ben
From: PipingDesign@yahoogroups.com
<mailto:PipingDesign%40yahoogroups.com>
Subject: Re: [PipingDesign] Slope in Steam lines
Hi,
Well it is not common to see Sloping steam line. May be it would have
been
done in order to catch condensate. You can do away with slope if this is
the
reason by intoducing drip legs and steam traps at low points. The drip
legs
location should be at lowest point in that pocket and nos depend upon
the
capacity required to remove the valuable condesate which in turn depends
upon primirarily on pressue (i.e L.P, M.P., H.P. and HHP).
Sloping lines have thier own problem so try not to see them on p&id`s
untill
and unless really warranted.
As to ur last qs I feel it is process designer responsibility to
indicate
any such reqt.
best regards
Hi all,
The Slope in steam lines is different (exp 0.5%, 1%, 2% <---- as I see
in
some projects).
But Generally who should decide about the amount of slope (piping or
process
designer) and how the suffiecient slope is calculated? does any criteria
exist to select the piping slope or related to experience?
Regards,
Mehdi Orojlu
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Received on Wed Jan 10 00:04:00 2007
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