An analysis of a system supplying steam to boiler sootblowers is being conducted. The lines will be supported with spring hangers. Although the lines will be hydrotested elsewhere, once a year the boiler is “water washed” by connecting the steam lines to a water supply. To cover this case, a “modified” hydrotest case is being considered. This will be added to the existing load cases (HRG, HGR, OPE, SUS, and EXE) by defining a hydrotest pressure, changing the configuration file to include insulation for the hydrotest case, and defining hanger stiffness for this new case as “As Designed”, since the hangers will not be locked as they would be for a normal hydrotest.

Does this approach sound valid? Are there better ways of doing it?

How about WW+P2 (SUS) ?

Or use the following:

Use water density in the input, but for all "normal cases" use WNC

L1 (HGR) WNC+H
L2 (HGR) WNC+T1+P1+H
L3 (OPE) WNC+T1+P1+H
L4 (SUS) WNC+P1+H
L5 (SUS) W+P2+H
L6 (EXP) L3-L4

Regards,

Dan - Yes that would be more straightforward now wouldn't it? Thanks much for your help!

Dan - Now that I look at your cases more closely I'm wondering about the first two. I'm thinking they should be as shown below so that the hangers get selected properly?

L1 (HGR) W
L2 (HGR) WNC+T1+P1

My opinion is that springs are sized ok since their purpose is to be used for the normal operating mode and it make sense to be used. It is indeed a problem because you will use them also when the line is full of water, therefore you should always keep an eye on what is going on. You can add some sort of travel limits pending on the orientation of the movement (when the line will move down more when is full of water) or you can try to gain a compromise between full and empty. You can try to go to Hanger Design Control Data and to specify that you want to design for two Load cases, then to alter the loadcase as you wish. Problem is that you will have only one L1 (HGR) WNC, or L1 (HGR) W so I think that Ceasar will not be able to know what you try to do. Alternatively you can try to alter manually the operating load until you obtain something in between, but also this is dangerous. It will work only for small size lines where the difference is not so big.

It is a similar problem with the one when you have spring hangers on big liquid lines and you must think also if the lines will be drained.

Dan - Thanks so much for your help - very generous of you.

Rod

Thank you

Rod,

Is there a possibility to lock the springs during "washout"?Or replace the springs with temporary support during wash-out?

The former may need travel-stops which the vendor may or may not agree (depends on the status of the spring delivery).But the latter seems to be a good option.

If yes, then this may be a good-deal.

Then , you can retain the same springs which are good for normal operation & also, there won't be any need to alter spring design for wash-out case.

Consult Construction & Operations for using temporary support & if they agree, put a note on ISO & on spring can that says " replace spring with temporary support during Wash-out"