- In PipingDesign@yahoogroups.com, Rajesh.Balapure@r... wrote:
>
> The query is not clear. Do you mean that there is a valve in the
line which has a spring support(variable load type)? Pipe spring
supports (variable load ones) are normally set in "cold load" in the
installed condition and the support carries the design "Hot" load in
the operating condition.Usualy the "hot" load is the operating
condition load and is arrived from the dead weight analysis. "Cold"
load is calculated from the 'Hot' load and the spring stiffness based
on the vertical displacement at the support point.This is an easy
enough procedure. Does this answer your query? The support carries
not only the dead weight of the valve but also that of the piping and
contents plus insulation, if any. Where large vertical displacements
are involved and the variation between hot and cold loads is more
than 20 to 25%, constant load supports are resorted to.
RVRamachandran
>
>
>
>
> Whether the operating load of spring which is closer to valve
should be
> lesser than the valve weight acting downwards
>
> => I mean to say that there should not be a large difference
between
> these two forces say valve weight is 2 tonne & spring force acting
upward
> is 8 tonne this will cause huge
> forces & moments on the valve flange especially when the geometry
is like
> spring---spool piece---valve immediately connecting to the header
of
> higher size through RF pad connection.
>
> Regards,
> Rajesh V Balapure
>
>
> |---------+---------------------------->
> | | <baskaran@idealtd|
> | | .com> |
> | | |
> | | 02/25/2005 10:16 |
> | | AM |
> | | Please respond to|
> | | PipingDesign |
> | | |
> |---------+---------------------------->
> >-----------------------------------------------------------------
----------------------------------------------|
>
|
|
> | To: <Rajesh.Balapure@r...>,
<PipingDesign@yahoogroups.com> |
> | cc: (bcc: Rajesh V
Balapure/JAMNAGAR/RIL)
|
> | Subject: RE: [PipingDesign] Digest Number
1424 |
> | Importance: Normal Sender's OU: Reliance |------------------
| |
> | | [ ] Confidential
| |
> | |------------------
| |
> >-----------------------------------------------------------------
----------------------------------------------|
>
>
>
>
>
> Dear Mr.Rajesh,
>
>
> as you said correctly the if the forces & moments at the valve
flanges is
> less then it will be easy for dismantling the valves in operating
> condition.
>
> i need some clarification on your point to design the spring
suitably near
> the valve
>
> In general we have to locate the supports closer to the
concentrated mass
> like valves...
>
> Whether the operating load of spring which is closer to valve
should be
> lesser than the valve weight acting downwards
>
> regards,
> A.R.Baskaran
>
>
__
>
> Message: 13
> Date: Thu, 24 Feb 2005 21:02:03 +0530
> From: Rajesh.Balapure@r...
> Subject: Re: Regarding Piping Stress Analysis
>
>
>
>
>
>
> If Forces & moments at valve flanges are less,it helps for the easy
> removal of the valve in operating position.
> For e.g. Any springs are located nearby valve ,the cold loads if
higher may
> introduce some forces & moments on the valve flange ,which may
cause the
> difficulty if that valve is leaking & want to replace the gasket .
> The spring force acting (say upward)on the valve flange can cause
the
> shearing of studs(valve weight acting downward) resulting in
locking of the
> bolt removal which may need the heavy force to be applied at that
existing
> position.
> To avoid such a position ,spring's, if located close to valve are
to be
> designed so that it will not transfer heavy forces & moments to the
valve
> flange.
> The allowable forces & moments at valve flange may be for the
abovesaid
> purpose.
>
> Regards,
> Rajesh V Balapure
> ----- Forwarded by Rajesh V Balapure/JAMNAGAR/RIL on 02/24/2005
08:49 PM
> -----
> |---------+---------------------------->
> | | Rajesh.Balapure@r|
> | | il.com |
> | | |
> | | 02/24/2005 08:25 |
> | | PM |
> | | Please respond to|
> | | PipingDesign |
> | | |
> |---------+---------------------------->
> >-----------------------------------------------------------------
----------------------------------------------|
>
> |
> |
> | To: PipingDesign@yahoogroups.com
> |
> | cc: (bcc: Rajesh V Balapure/JAMNAGAR/RIL)
> |
> | Subject: Re: [PipingDesign] Regarding Piping Stress
Analysis
> |
> | Importance: Normal Sender's OU: Reliance |------------------|
> |
> | | [ ] Confidential |
> |
> | |------------------|
> |
> >-----------------------------------------------------------------
----------------------------------------------|
>
>
>
>
>
>
>
>
>
>
> What you did is correct ,but What did you mean by allowable forces &
> moments for valve?
> Vendor might want you to check allowable forces & moments for flange
> leakage analysis point of view.
> The Allowable nozzle loads may affect in case the valve weight is
different
> from earlier??
> Also you have not mentioned the pipie size & valve size ??higher
sizes
> critical lines requires flange leakage analysis.
>
> Regards,
> Rajesh V Balapure
>
>
> |---------+---------------------------->
> | | sathish babu |
> | | <togsb@y...|
> | | n> |
> | | |
> | | 02/24/2005 10:22 |
> | | AM |
> | | Please respond to|
> | | PipingDesign |
> | | |
> |---------+---------------------------->
> >-----------------------------------------------------------------
----------------------------------------------|
>
>
> |
> |
> | To: PipingDesign@yahoogroups.com
> |
> | cc: (bcc: Rajesh V Balapure/JAMNAGAR/RIL)
> |
> | Subject: [PipingDesign] Regarding Piping Stress Analysis
> |
> | Importance: Normal Sender's OU: Reliance |------------------|
> |
> | | [ ] Confidential |
> |
> | |------------------|
> |
> >-----------------------------------------------------------------
----------------------------------------------|
>
>
>
>
>
>
> Hello Everybody,
> I will introduce myself to the group, i
am
> sathish babu working in ASLTOM Projects
india
> Ltd in piping department of plant
engineering
> section.
>
> I am a Graduate Engineer and having a experience of three and Half
Years.
>
> Now i am working in CAESAR II stress analysis
>
> When a Forces and moments to be checked ?
> to my Idea i usually check on Equipment Nozzles where the piping
is to be
> connected for that i will be defining the nozzle node to have
displacement
> and check in the Restraints Summary for all operating and sustained
> condition.
>
> Now i faced a small problem , i have angle valve ( Main steam
bypass valve
> dumped to condenser ) while doing analysis i have defined it as
rigid
> component and finished the analysis.
>
> After that the valve manufacturer produced the drawing and asked me
to
> check the allowable forces and moments on the valve.
>
> What i did was went to local element forces and moments and checked
the
> allowable forces and moments on the corresponding node to be OK -
Whether
> This is Right or I have to do anything more
>
> If anyone have any Idea about when this forces and mon=ments to be
checked
> and the basis please explain
>
>
> Thanking you
>
> Sathish Babu
>
>
>
>
> Steve McKenzie <mechproj@x...> wrote:
>
> Paul
>
> I have already given myself a stern warning about this, and any
further
> outbursts on my part will, regrettably result in me requesting my
> resignation. This has been conveyed to me in a formal letter as a
first
> and final warning, so I will not accept any excuses from myself.
> Sometimes I hate being my own boss.
>
> It sure would be nice to leave this whole national/language mess
alone.
>
> If you agree please indicate by not replying.
>
> Cheers
>
> Steve
>
> -----Original Message-----
> From: Paul Bowers [mailto:pbowers@p...]
> Sent: Thursday, February 24, 2005 3:58 PM
> To: PipingDesign@yahoogroups.com
> Subject: Re: [PipingDesign] Metallized valve
>
>
>
> Sajit Viswan wrote:
>
> > Paul,
> >
> > I haven't understood your giberrish. Didn't bother to
> > try to understand either.
> >
> > Sajit
>
>
> Maybe all the recent discussion has served to bring out unsaid,
possibly
>
> pent-up thoughts and attitudes - it wasn't planned to do so.
>
> I remind everyone that you are all free to unsubscribe at any time.
>
> This discussion list is at about 1100 members now; well over 75% do
not
> ever contribute to the technical discussion. I don't think that 750
> sudden unsubscriptions would hurt the quality of the technical
> discussion.
>
> Then again, it seems to be a free-for-all at the moment and the best
> move might be to just let it play itself out without possibly
> heavy-handed intervention.
>
> Paul
>
>
>
> =========================================
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> http://www.pipingoffice.us/
> Main site: http://www.pipingdesign.com
>
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>
>
>
>
>
>
>
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> =========================================
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> Yahoo! India Matrimony: Find your life partneronline.
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>
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> =========================================
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> http://www.pipingoffice.us/
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> http://www.pipingoffice.us/
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>
__
>
__
>
> Message: 14
> Date: Thu, 24 Feb 2005 11:29:55 -0600
> From: Christopher Wright <chrisw@s...>
> Subject: Re: Regarding Piping Stress Analysis
>
>
> On Feb 23, 2005, at 10:52 PM, sathish babu wrote:
>
> > When a Forces and moments to be checked ?
> The short answer is 'always.' Piping system stress must be kept
within
> code limits for all loadings and all service conditions.
Verification
> that you have not exceeded code limits is your responsibility as an
> engineer. You need not always do a complete stress analysis of every
> last detail, but you must be able to satisfy yourself, using
judgement
> based on experience, that all the details will meet the code. CAESAR
> isn't enough by itself, because it provides results based on
> idealizations with limited validity.
>
> In your case you idealized the valve as rigid, which it is with
respect
> to the piping network, but the valve body isn't absolutely rigid.
Loads
> applied to the valve cause deformations and stresses which must also
> meet code requirements. Normally design of the valve is the
> responsibility of the valve manufacturer, but the manufacturer can't
> possibly anticipate every possible service condition the valve might
> see, and it sounds like he asked you for an assessment of the valve
> under your particular service. Did I guess right? If so, do you have
> reason to believe that your service is such that the valve body
might
> be over-stressed?
>
> Again, guessing, I suspect that what you call 'allowable moments'
are
> in fact calculated moments from CAESAR which turn out to be
allowable
> because they don't exceed the maximums allowed by the code for your
> loading. In that case they'd be allowable moments for the pipe, but
> not necessarily allowable moments for the valve. To know that you'd
> need to do a stress analysis of the valve body. Presumably that's
why
> the manufacturer 'produced the drawing,' by which I presume that he
> produced a drawing of the valve body.
>
> In fact you should probably be asking the manufacturer for guidance,
> and be prepared to help out the some extent, at least with an
estimate
> of valve body stress caused by your particular combination of forces
> and moments. Doing a complete job of it may be beyond your scope of
> work, because it could be expensive, but you may have to do
something
> if you want to use that particular valve. This is your piping
system,
> not the valve manufacturer's, so you have the major responsibility
and
> interest for insuring that the valve provides satisfactory service.
The
> valve manufacturer's customer support should be willing to help to a
> degree--if he isn't interested in helping, maybe it's time to tell
him
> you're shopping elsewhere for valves.
>
> (As an aside, here's one of those engineering issues which demands
> accurate written communication, whether in English or Hindi or
> whatever. You can't do it with a picture. I've guessed at a lot of
the
> issues Satish is facing, and I may have gotten it totally wrong.
> Satish's English is good, and what I said is correct, but I might
not
> have answered the question or my answer might be the answer to the
> question as posed, but the question posed might not be the question
he
> meant to ask. Or it might be the question he meant to ask but not
the
> question he should have asked so that I might infer the intended
> question and thus give him the answer he needed, which of course
might
> not be the answer he expected. That's perfectly clear, isn't it? ;-
>)
>
> Christopher Wright P.E. |"They couldn't hit an elephant at
> chrisw@s... | this distance" (last words of Gen.
> .......................................| John Sedgwick, Spotsylvania
> 1864)
> http://www.skypoint.com/~chrisw/
>
>
>
>
__
>
__
>
>
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> =========================================
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>
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>
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Received on Fri Feb 25 05:18:00 2005
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