Re: [PipingDesign] Stress Analysis of FPSO with Caesar II

From: <Rajesh.Balapure@ril.com>
Date: Mon Jul 18 2005 - 03:20:00 EDT

Thanks Rakesh,
For your supports or end connections which are affected by vessel movements(Rolling ,Pitching etc) due to tide ,was there any guideline for asserting the displacements as static one or dynamic one?In your offshore project ,did you come across any criterion for classifying static & dynamic displacements.

Regards,
Rajesh V Balapure

                       rakeshkumar@eilqa
                       tar.com.qa               To:      
PipingDesign@yahoogroups.com
                       Sent by:                 cc:       (bcc: Rajesh V
Balapure/JAMNAGAR/RIL)
                       PipingDesign@yaho        Subject:  Re: [PipingDesign]
Stress Analysis of FPSO with Caesar II
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                       07/18/2005 11:32
                       AM
                       Please respond to
                       PipingDesign






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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[Non-text portions of this message have been removed] Received on Mon Jul 18 03:20:00 2005

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