Dear Rajesh,
Support/ Nozzle deflections were considered in a static manner.
Regards
Rakesh Kumar
Engineers India Limited, Qatar
Manager, Piping
My e-mail ID: rakesh8193@yahoo.co.in
> Dear Rakesh,
> Coming to your point no.3
>
> 3) Deflection of all supports and nozzles due to Pitching, Rolling and
> vertical motion of ship for 100 or 50 year storm condition . Please note
> that for 100year storm condition consider only operating case and not
> design, upset cases etc. After certain rolling/ pitching angle plant will
> trip.
> In our case axial movent for flare line was -100mm and +100mm (i.e.
> 200mm).
> We reduced the factor "f" of stress range to 0.7 to take of fatigue cycle.
>
> Could you clarify whether the support deflections were considered in a
> static manner or dynamic displacements were considered??
> Regards,
> Rajesh Balapure
>
>
>
>
> rakeshkumar@eilqa
> tar.com.qa To:
> PipingDesign@yahoogroups.com
> Sent by: cc:
> AIpakchi@hanover-co.com, (bcc: Rajesh V Balapure/JAMNAGAR/RIL)
> PipingDesign@yaho Subject: Re: [PipingDesign]
> Stress Analysis of FPSO with Caesar II
> ogroups.com Importance: Normal Sender's OU:
> Reliance |------------------|
>
> | [ ] Confidential |
>
> |------------------|
> 07/16/2005 02:08
> PM
> Please respond to
> PipingDesign
>
>
>
>
>
>
> Dear Ali,
> This is the most difficult question in stress analysis for FPSO lines.
> Where
> is this FPSO situated (ambient temp. can also be -30C in some conditions)?
> Here are some factors; combination of which are to be done judiciously. In
> order to reduce the no. of cases to a minimum; discuss with team members
> and
> take collective decission. I am mentioning here some factors (matrics of
> these variable will give rise to some 250 cases of combination) which are
> to
> be cosidered while deciding stress analysis specifications/ methodology
> for
> your project. Some figures are taken just to show the range( figures are
> realistic). Eleminate the least sever cases. Make combination of worst
> cases.
>
> 1) Temperature: Operating (T1=55C), design hot (T2=65C ), design cold
> {could
> be -30C(T3) depending upon location of FPSO, as in case of Norway}, upset
> condition (T4=80C) and shut down condition(T3= -30C or 21C ambient temp).
>
> 2) Thermal Growth of Nozzles:Thermal Growth of nozzles are to be taken for
> above temteratures. Movement to be superimposed with movement of nozzles
> and
> supports due to pitiching, rolling and vertical movment of ship.
>
> 3) Deflection of all supports and nozzles due to Pitching, Rolling and
> vertical motion of ship for 100 or 50 year storm condition . Please note
> that for 100year storm condition consider only operating case and not
> design, upset cases etc. After certain rolling/ pitching angle plant will
> trip.
> In our case axial movent for flare line was -100mm and +100mm (i.e.
> 200mm).
> We reduced the factor "f" of stress range to 0.7 to take of fatigue cycle.
>
> 4) Wind load: Selection of direction of wind. It could be +X,-X, +Z, -Z. Y
> direction can be neglected for wind load.
>
> 5) Explosion load: In case of explosion application of wind load in all
> direction i.e. +x,-x, +y (-y can be neglected as it will be compressive
> load
> and is rare also) +z and -z. But in explosion load we can go for higher
> allowable loads and stress i.e. upto yield stress.
>
> 6) Acceleration: Acceleration is to be applied in different direction
> individually (x,y,z). Wind dierction and acceleration direction can be
> diffrent.
>
> 7) Snow load: Loading due to snow in addition to insulation is also to be
> considered by application of UDL. But this can be excluded by calculation
> of
> basic span for each spec. and schedule.
>
> So no. of cases will be:
> A) Operating: With operating temp., Design (hot) temp, design (cold) temp.
> and Upset temp. with combination of
> i) wind ii) without wind iii) acceleration iv) without acceleration vi)
> with movements due to pitching rolling yawing.
> B) Hydrotestig
> C) Explosion
>
> Dynamic analysis may be done only for lines with two phase flow and for
> compressor line (for crude injecting module).
>
> To take care of such extreme cases we indicated in MR itself (and also in
> stress analysis basis) for higher nozzle allowable loadings: 4 times of
> API610 for pumps and 8 times of API617 for compressors.
>
> Dear Ali my reply may not solve your problem rather may complicate it but
> may highlight some factors which you may be forgetting. I could have
> attached the stress analysis specification but now I am on foreign
> assignment to Qatar and all my refrence doc. are lying in India.
> I request you to email me the final methodology of analysis
> (rakesh8193@yahoo.co.in) of this job which will be interesting indeed.
> Dear Ali I attended one lecture on stress analysis and in that I cam to
> know
> that around 250 cases are analysed in nuclear power plant. However we were
> also not very sure about the no. of cases to be performed in our FPSO job.
> But every one was willing to analyse minimum no. of cases and min. no. of
> runs. After great arguments we land up for at least 3 no. of runs containg
> around 9 caeses each. Exact sequence and combination no of cases I dont
> know
> now as I did it in 1998.
> Please reply back to me and please write your reaction/ action on this
> issue.
>
> Regards
> Rakesh Kumar
> Engineers India Limited, Qatar
> Manager, Piping
>
> ----- Original Message -----
> From: "Ipakchi, Ali" <AIpakchi@hanover-co.com>
> To: <PipingDesign@yahoogroups.com>
> Sent: Friday, July 15, 2005 1:08 PM
> Subject: [PipingDesign] Stress Analysis of FPSO with Caesar II
>
>
>> Dear All,
>>
>> Can anyone cast a light on this:
>>
>> What are the most common load cases which to be considered for stress
>> analysis of piping systems on a FPSO and how normally we define these
>> loads for CII?
>>
>> Is it possible to just go for Static analysis with some Dynamic load
>> factors or Dynamic analysis is manentury.
>>
>>
>> Thanks
>>
>>
>>
>> Ali
>>
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Received on Mon Jul 18 02:02:00 2005
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