Requirement of seismic calculations for small pressure vessels 3

[GD_P]

Hello Forum,

I have questions, regarding requirement of seismic calculations for small horizontal pressure vessel supported using lugs (since saddle supports are not feasible). The vessel weights during operation (flooded) are around 50kg & 100kg respectively for 2 vessels. The vessels governed design external pressure is 6 bar.
My question is that, is it necessary to perform the seismic calculations for these vessels, which are very light weight. Force evaluation calculations are performed as per ASCE 7-16.
Site is located in CA, USA.

I am eager to know how other experts handle these conditions.

GD_P

 

[SnTMan]

GD_P, several facets to the problem.

Contractural Facet: Are such calculations required by contract (if any)?

Legal Facet: Are such calculations required by jurisdiction, insurance carrier, etc. (if any)? What are consequences of various types of failure possible during a seismic event?

Engineering Facet: Assuming no particular unusual features to the vessels, the necessary considerations would seem to be: Anchorage of vessels to the world, structural integrity of the lugs themselves, structural integrity of the shell-lug junction under the loading.

Presumably, performing the calculations is no great burden, but then you are kind of obligated to act on the results.

Regards,

Mike

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

 

[JStephen]

I think you could work it several ways.
It's not unreasonable to say "Seismic design won't affect this item and need not be calculated" if that's the case. Just because something can be calculated, doesn't mean it needs to be calculated.
The seismic design could consist basically of taking an acceleration from the customer and multiplying by the weight and there you are.
Note the provisions in ASCE 7 for "rigid" tanks, etc., also for tanks supported by other structures.
With those weights, it could be something like a 1 hp air compressor tank, and that likely wouldn't have any seismic design done.

 

[DriveMeNuts]

UG-22 says that a series of loadings such as Wind, Seismic and fatigue only need to be 'considered'. It doesn't say that a calculation needs to be carried out.
A page at the front of the design report should list all of the loadings mentioned in UG-22 and provide a considered status for each (i.e. Seismic: Insignificant, Wind: Not Applicable, Fatigue: Yes, included in report, etc)

 

[r6155]

The calculation requires less time than the time taken by SnTMan,JStephen,DriveMeNuts and I to answer your question.

Regards

 

[mk3223]

What's the consequence if the vessel damaged in the earthquake which is much alive in many areas of the great CA? Although the vessel size is kind of small, the impact of the failure may be big depending on the type of service, operation condition, location, etc.

Agreed with R6155 statement.

 

[SnTMan]

r6155, Agreed

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

 

[GD_P]

Thank you all for the response.
For your info. vessel will carry non lethal fluid and will be mounted on steel structure at height of 1500 mm above ground.
I totally agree with you r6155. I will perform the calculations rather than speculating "required or not required".
Thank you.

GD_P