Spring Info 2

[Dj364]

Hello every one,
I have to perform stress analysis (insulated) HP steam line (750F,700Psig)and by pass steam line.
line 4" connecting to existing Air compressor/turbine, they want to re use one of the existing spring support.
I have in my hand iso's of existing dwg as well as new ones( tie in connection), existing spring support infos ( spring rate,size and type), insulation thick.

I asked for infos I need:
1-spring data sheets
2- vendor allowable loads on air compr/turbine
3- new valve (weight)

Three questions:
1- Shall I ask for more data?
2- how far I will go for modeling ie: shall I model all the existing spring supports or just stop at the first one?
3- Any tips for steam line (1" 750F,700Psig)
Thank for replying, I really need your help.
Your help will very well appreciated.
I hope I ve made it clear
Dj.

 

[DSB123]

Dj364,
I am sorry if this sounds negative but if you cannot answer the three questions yourself then I think you should not tackle the analysis and let a competent stress analyst provide the calculations for you. To ask such basic questions around "modelling" shows inexperience. If you get the "modelling" wrong then the results will not represent the actual situation. There are "Stress Engineers" who can use the software but do not understand the nuances around correct "modelling".

 

[Dj364]

Thanks DSB 123 for your reply...I am taking your reply in positive way!
Actually, may be you misunderstood...I just want some advices.
I know how to model, I ve done some stress work in the past, and now i am going back.
what I want is some tips,advices..from experience, if there s something I missed, some body to warn me . ( I ve never had the opprtunity to work on such High T lines).
"I think This is a forum where every one can ask questions...is there any minmum LEVEL required to enter the forum? may be if it s advantgeous for you to split it in diffrent categories Level 1,2,3,4 etc... in such a way high level talk to hight level"
Anyway, please reply if you have any comments on my queries above.
Thanks in advance.
Dj.

 

[MJCronin]

Dj..

I believe that this is the wrong forum for you.....

Post your Piping Stress Analysis questions on:

http://www.coade.com

-MJC

 

[JohnBreen]

Hello Dj364,

It may be useful to you to make yourself a “checklist” of all the data that you will need to perform a piping stress analysis. You could modify it by adding items as your experience grows. Perhaps at this point in your career you should try to get a copy of the excellent book by Dr. Charles Becht IV:

http://catalog.asme.org/books/PrintBook/Process_Piping_Complete_Guide.cfm

If you look at this book you will find Appendix II, Guidelines for Computer Flexibility Analysis and this is a good starting point for your “check list”. This book is an excellent reference for providing the background in theory and practice that the piping engineer will need.

Yes, to model the piping system at issue you will need the maximum allowable loading on the terminal equipment, the hanger detail sheet for the existing supports and hangers (and any guides or other boundary conditions) and the weights of all the in-line components (valves AND valve operators). You will need the drawings that show the details of the routing (geometry) of the piping. You will also need the expansion movements of the equipment that the piping is attached to. You need the insulation thickness and type (weight) the pipe material (allowable stresses), all dimensional data, and all the operating conditions (pressures and temperatures).

All piping engineers are student of the artful science. As I have said before ( thread378-189629 ): "Everything you need is not in print. You need to gain experience by working under a under a knowledgeable senior piping engineer to get where you want to be professionally. The “body of knowledge” required for competence in this field is huge and you should be prepared to devote the rest of your professional career in continuing to learn. The “student of piping engineering” (and I hope that includes all of us in this field) is “shooting at a moving target” – it is a dynamic discipline and it will continue to evolve – we must try to “keep up”." I wish you well.

Regards, John.

 

[JohnBreen]

Hello again Dj364,

One other thought. You must evaluate various modes of operation. Since you have a by-pass line, it is implicit that part of the system will run cooler that the operating temperature (out of service) at times. So be sure to determine what the temperatures and pressures are for all the various modes of operation and determine which valves are used to isolate the out of service portions.

Regards, John.

 

[Dj364]

Thanks very much John,You've really helped me to get a better overview.
The by pass line is only 1". for my understanding it does not affect very much the 4" small spool to suction nozzle and 8" line where the 1" is connected. I made sure that the 1" line is enough supported and flexible as well, to avoid any bending stress at the connecting point ( sockolet) due to sustained loads /thermal loads. And, Yes I will ask which valve isolate the out of service portions and run the analysis together hot/cold lines ( the cold line will act as anchor).
NB:
I am the only stress engineer in the office.I am trying to learn more by myself and from the forum.(Thankfully the forum does exist, very helpfull)
If I may; I hope one day you will decide to write a book, be sure that I will be the first one to buy it, you have this huge Body of knowledge as well as the Art of explaining (Pedagogy) .
Thanks again John.
Warm Regards
Dj364