Flow induced vibrations in a vertical vessel

[Mech2325]

There is a vertical vessel supported on leg supports

This vessel is a tall vertical vessel and its height is about 11 ft – 8” diameter. This is made of 8” pipe. It is supported on 3 legs made of angle iron. (Total vessel height 3 meters and legs height 1.5 meters)
The vessel under strength conditions (when under static conditions, no flow) is balanced and strong enough to take care of its total load and design is OK.
However, I feel under flow conditions this vessel shall vibrate and flow induced vibrations may come when in operation.
One of the simple solution to above problem may be: Widen the support legs to 20” bolt circle dia (Flare the legs) and then bolt up to the structure/base under it. This was recommended to vendor but he is not willing to accept
The reason quoted by vendor being following
" 3 Legs be considered flared @ as 500BCD. This is in line with stability requirement as vessel legs are of same length as that of shell itself of (~200dia). Hand calculations are equally acceptable [BCD=500 has been respected by proposing a unique plate, Legs and the support plate has been statistically calculated, its not clear why you ask inclined legs. we can’t consider hand calculation since it is not accepted for a ASME U-stamp job]"

Any recommendations?

 

[SnTMan]

Mech2325, it is about impossible to make anything of your post. For starters, please avoid mixing / switching units of measure. You are setting traps for yourself and everybody else.

Second, make your concern clear. It appears you are worried about flow-induced vibration causing your vessel to overturn (I doubt it), am I reading your post correctly?

Third, if you are going to attach a sketch, attach a sketch.

Fourth I have no idea really what your vendor is talking about, except that to say that hand calculations are not accepted for U Stamp vessels is untrue.

If you can clarify your situation and concerns some useful advice might be offered.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Mech2325]

@snTMan:

No its its not about overturning of vessel. Its about the vibrations that will be generated.
Vibrations are not desired here actually

To avoid this, flare legs option was given to vendor but his reply is beyond my comprehension. The only thing i get is that the flare legs optiob is not acceptable to vendor since he doesnt want to perform hand calculations.

 

[SnTMan]

Huh

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

Legs should not be used to support vessels in high-vibration, shock, or cyclic service due to the high localized stresses at the attachments. Try with skirt

Try to consider additional support in the shell.

Regards
r6155