Re: Moment calculation

From: <Gang>
Date: Fri Jul 02 2004 - 01:16:00 EDT

Gordon,
I hope that I am right in addressing like that. Pardon me if I am wrong.
Thanks for the well-drafted reply. My salutations! Now, coming to the technical matter: I had been closely following all the stuff mailed in to the group. The reason I did not respond for the last couple of months was that I was too much preoccupied in the project jobs. I feel a little relaxed now, and so, I thought of sharing my views with the group. Thanks for enlightening about the code basics regarding the elbows and tees. Your assessment about friction, appears to be in order.
Keep mailing such enlightening views.
Regards.
C. V. Gangadharan.
--- Gordon.Reddek@Alcan.com wrote:
> Dear Gangadharan,
>
> Firstly concerning the name. I am fully aware that
> this is an
> international site and should by now have learned to
> be more careful with
> the terms I use to address the group. The fact is I
> was not addressing
> you personally but the GROUP, who I called a"gang".
> Like a gang of
> workers, or thieves, or thugs. We in the west would
> take that address in
> good humour and see it a s a joke. I was in fact
> reacting to the reply by
> Mr Tony Paulin, and not to your original query.
> Never the less, the
> remark has obviously hit a raw nerve, so please
> accept my apologies.
> As it so happens I have worked with Indians in the
> past and have more than
> a passing interest in Indian English and customs.
> One of them that has
> always fascinated me is that Indians will address a
> westerner by putting
> the address Mr, Mrs or Miss in front of the first
> name. So one gets Mr
> John and Miss Susan etc. In the west the Mr, Miss
> and Mrs are used only
> in front of the last name like Mr Jones, Mrs Jones
> and Miss Jones. We
> never put the Mr, Mrs or Miss in front of the first
> name which always
> stands alone. Also, in some countries, like
> Germany, the use of the first
> name is reserved for very personal friends, and
> family. In those
> countries it is considered an insult to use a
> persons first name without
> their express consent. So, on the subject of names
> then, if you wish to
> address a westerner in a way that makes them feel at
> home I suggest you
> use the first name on its own (like Gordon) or the
> second with the prefix
> like Mr Reddek. If you leave the prefix off the
> second name it is
> generally taken badly in the west because school
> children and minions are
> addressed that way.
> I have noticed that Indians tend to have lots of
> names and they do not in
> general seem to mind which one one uses. We in the
> west have a little
> difficulty with that because the way we address
> people follows fairly
> strictly predefined rules.
>
> Now to the technical matters addressed. I
> successfully generated a fire
> storm of replies on this one and will add only the
> following:
> In your discourse you referred to three connecting
> pipes in different
> vector directions. The origin of the in-plane and
> out-of -plane
> terminology seems to be the ANSI pipe specifications
> and they use the
> terminology only for tee's and elbows, so the
> complications of the third
> leg at right angles to the plane are not an issue.
> The calculations
> relate to the Tee and Elbow only.
> Regarding friction. When a pipe is cold and at
> rests on a rack friction
> plays no part. As the pipe heats up it expands and
> so it must slide over
> the rack. If one end is attached to an anchor, that
> anchor will have to
> bear the full force of the pipe sliding over the
> rack, and that force will
> occur only while the expansion is taking place, but
> it will occur. When
> the pipe has heated up, the friction force will
> vanish as you correctly
> mention.
> Now for the next fire storm:
> You mention the coefficient of friction as being
> 0.3. Have a look in
> Marks Mechanical Engineering Handbook and you will
> find it is greater than
> 0.7. I have a theory that 0.3 is commonly used
> because structural
> engineers use that value however I consider it to be
> an inappropriate
> figure for pipe stress analysis despite the fact
> that most of the world
> uses it.
>
> Cheers,
>
> Gordon Reddek
>
>
>
>
> Gordon Reddek
> Specialist Mechanical Engineer
> Alcan Engineering, Level 3, 443 Queen St, Brisbane,
> Qld 4001, Australia.
> Tel: +61 7 3328 6424
> Fax: +61 7 3328 6990
> Email: gordon.reddek@alcan.com
>
>
>
>
> Gang Cvg <cvg_gang@yahoo.com>
> 01/07/2004 06:58 PM
> Please respond to
> PipingDesign@yahoogroups.com
>
>
> To
> PipingDesign@yahoogroups.com
> cc
>
> Subject
> Re: [PipingDesign] Moment calculation
>
>
>
>
>
>
> Dear Reddek,
> Please do not address me as Gang. It happens to be
> just an abbreviation in my E-mail id. My name is
> Gangadharan. If you feel it is too difficult, you
> may
> cut it short to Ganga. (Ganga is the name of a river
> in India.) It might be easier for you to handle it.
> Let us come to the subject! It is a tricky
> situation:
> Imagine a three-element piping configuration, with
> say
> 10 m pipe towards North, then 10 m pipe towards East
> and the next 10 m upwards. I call the plane
> constituted by the first two as H-plane. The other
> on
> is V-plane. Now, the 10 m East-West segment is
> common
> to H-plane as well as V-plane.
> If we consider the effect of “out-of-plane
> vector”
> from the H-plane on it; the same vector is
> “in-plane”
> for it in the V-plane. It has got its own
> “in-plane
> vector” due to the V-plane as well.
> Now the next question: Can these vectors be added
> together? If yes, is the addition algebraic or
> vectorial? We resolve all the forces and reactions
> into X, Y and Z components. It is from this
> standpoint, the possibility of algebraic addition
> comes into the picture. This is my curiosity. Can
> anyone give a convincing explanation to the concept
> of
> the forces and reactions with reference to the
> stress
> analysis softwares?
> The effect of combined reactions in a complex pipe
> run
> cannot probably be broken down into simplified
> sectors
> of pipes where we consider the forces act in the
> most
> simplistic way, resolvable by elementary rules of
> “Strength of Materials”. What the FEM does is
> precisely this. The results could be taken as the
> solutions, which justify the many observed
> phenomena.
> And to that extent, we have to be content also. The
> “real” values still remain elusive. We work
> within the
> limits “safely” due to the built-in safety
> margins
> attributed and accumulated over various successive
> steps. This avoids catastrophic failures, within the
> expected plant lives. Luckily, there are not many
> accidents due to pipe failures! We have to be
> “happy”
> about this, and hope for the (still) better. If one
> takes a set procedure of checks of the checklist, in
> the context of HOT and CRITICALl lines, the outcome
> generally turns out to be SAFE.
> There is another fallacy in the stress analysis
> programmes. That is regarding the friction factor.
> Friction, as we all know, is associated with motion.
> The pipe (the support point) does move from cold to
> hot condition, DURING THE WARMING UP period. Once it
> attains the HOT / OPERATING condition it is
> STATIONARY
>

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New and Improved Yahoo! Mail - 100MB free storage! http://promotions.yahoo.com/new_mail Received on Fri Jul 02 01:16:00 2004