Dear all,

I am doing cryogenic piping analysis first time, for that I had following queries.
1) which data I required to modeled system(temp,pr,heat transfer,density,E,expansion,material etc)
2)How to modeled in caesar
3)how to analyse system
5)what will be the load cases
6)Type of support & its materials
7)What else we have to check-other information

PLz give your valuable reply asap.
Thanks

My sugegstion will be :

1) Understand the process first.Through pipes, the actual process is carried out. Hence understanding the process is must. Talk to your process group.

2) If it is an LNG, some LNG systems ( like Loading or Unloading lines ) are subjected to Fluid Hammer and have to be designed accordingly.

3) Cryogenic supports are different types ( usually the shoes will have a PUFA or Micarta Block the base will have heights higher than conventional pipe shoes).

4) Material will be SS (Typically dual grade 304/304L)

5)Minimum to max. Temperature range should be checked. In case of problem, talk to process group to find out the anticipated no. of cycles at this range.

6)Modelling is same in CAESAR II. The line contracts instead of expanding.

7) Check for hot cold philosophy of different segments of piping systems.

8) Check for correct information of insulation density.

9) LNG loading and unloading lines ( even when they are running on pipe racks) should best be supported on anti-friction pads.

10) Lines connecetd to LNG tanks ( as they drop down from the tank and enter piperack) will have substatntial upward displacement and constant springs may be needed at the first support on rack. Chheck for amount of clearance required.

11) Lines connected to BOG compressors( again considering an LNG Project)should be analyzed for pulsation study by vendor/third party.

12) Check for low allowable loads on some equipment connections.

13) Check for clear demarkation between some vendor and your company's scope of work ( this happens typically on lines connecetd to LNG tanks)

14) Some LNG systems like PSVs, Flare header,Compressor Hot GAs bypass and Recycle lines are subjected to Acoustic induced vibration ( AIV)and it is best that the wall thicknesses for these systems should best be computed ( this is primarily responsibility of a noise specialist) before these pipes are procured. Consult your noise specialist for details of AIV and special fitting and supporting realted to AIV.

These are the points I could come out with. If I come out with more, I will let you know.

Regards

Thanks Anindya,

Can u give some lights on Load cases (with H,F,wind,sismic,steamout & two phase)

If design temp= 120F
Op. temp = -100F
Ambient temp = 50F
What will be my T1 & T2 & give me load cases.(with considering H,F,wind,sismic,steamout & two phase)


Regards,
CAS

You might also want to take a look at B31.3 para' 323.2.2 for the eventual further implications.

DEAR

HOW I CAN START CAESAR II BASICS

HELP ME

Your stress range should be 120- (-100)

There is no change in wind and seismic load cases with respect to HOT LINES ( only thing, you may have to use cases like W+T+P+WIN-W+P+T where T will be design max. and design min. to extract the WIN, U loads etc). There are no of discussions in the forum on generation of load cases for wind and seismic, similar thing is applicabke for streamout.


Furher, many SS systems may be having D/T close or exceeding 100 ( specially for flare systems). Read the note in B31.3 for SIF/Flexibility for such cases.FEA is recommended to compute SIF/Flexibility for D/T>100.

Anindya,
Why the stress range you have chosen 120F - (-100F)? The user is saying the design temp as 120F and Operating Temp as -100F, he should look into the cold design temp. I understand the expansion range will be from maximum hot to maximum cold and user should look into the cold design temperature.