1.self drain only the way,because if you give slope,normaly the
downstram is different rating than upstrem side so their will be a
reduced flange.
- In PipingDesign@yahoogroups.com, Paul Bowers <pbowers@...> wrote:
>
> What is the difference between these terms on a P&ID:
>
> -Free draining
> -No pockets
> -Slope
>
> All of these refer to the concept of preventing (via piping
> configuration) liquid build-up (possibly due to condensation)
downstream
> of the safety valve in order to avoid backpressure on the PSV
spring,
> possible freezing of liquids or waterhammer effects. Typically the
> discharge piping is fairly short, so "powerlining" is not usually
an issue.
>
> Of the three, sloping the discharge line is the best process
design
> solution, but it is also the most labour-intensive for
> fabrication/construction due to elbow cut-backs/non-parallel butt
welds
> and the sometimes need to trim pipe shoes progressively to
maintain the
> slope. Also, Isogen tends to barf and do odd things with sloped
piping,
> making isos sometimes really bizarre-looking.
>
> "No pockets" is pretty self-explanatory.
>
> "Free draining" is the ambiguous one. Does this imply that a slope
is
> necessary or does it refer to no internal obstruction (say, a FOT
> reducer, flow orifice, etc.).
>
> Paul
>
Received on Sun Jan 28 10:03:00 2007