A few words to mechanical engineers

[frooboy]

I know most people here are mechanical engineers. I asked a question about structural design of downcomer; no answer yet. I don't konw if that question was too easy or too hard, or did not make any sense at all. What I am wondering if the mechanical engineers perform any sort of structural analysis at all other than following ASME rules, especially at such circumstances not covered by ASME. If a steam drum is supported by a lower drum through two long downcomer pipes, do you automatically assume the pipes won't buckle? the lower drum will work?

 

[SnTMan]

frooboy, I haven't designed such an arrangement, however:

I Would Not assume the downcomers would not buckle

I Would examine the loading on the both shells transferred by the downcomers

I Would consider any other external loadings in the design of such a system

Regards,

Mike

 

[metengr]

frooboy;
Are sure about the steam drum being supported by the downcomers? Is this for an industrial boiler or small power boiler? In addition to weight of the steam drum empty, you better factor in the full weight of water as well.

Most downcomers are designed using minimum ASME B&PV Code rules for pressure and additional thickness for structural loads. Also, downcomers serve to circulate water from the steam drum to the lower drum.

There is a lot here and unless you are familiar with boiler design and associated boiler structural loads, seek help from a qualified design organization.

 

[frooboy]

Thank you all for you replies. This arrangement (piggy back) is for a power boiler. Besides the gravity, pressure and thermal load, I will also design the vessels and pipes for seismic loads.

 

[MJCronin]

froo...

It sounds like you are designing a boiler by yourself and this is the first time you have done this.

Is this true ?

Is this some kind of boiler "repair"...?

What kind of stamp/certification do you hope to place on this boiler ?

Where are you located ?

-MJC

 

[insult2injury]

In my experience, the boiler is usually hung from the top, not supported from the bottom up.

What type of boiler is it? Manufacturer?

I2I