Hanging Vessel Saddle Analysis

[ting123]

WE have a project from Aramco where the vessel is hanged from the floor.Attached is the data sheet for the same. My query how can we perform the saddle analysis for this vessel. (WIND, Seismic, ZICK)

 

[saplanti]

If you use a full circumferantial ring for each hanger location and provide two ceiling supports for each hanger, you can solve the problem a lot easier without going into local stress calculation on the shell. You can use Roark's Formulas for Strain and Stress for the ring analysis under several type of support which can be considered.

However you use three instead of two hanger location, this will make the structure indeterminate. Depending on the stiffness of the ceiling the support can have different loads than the considered.

Hope it helps.

Ibrahim Demir

 

[ting123]

Using a full ring will definitely be helpful to eliminate zick as zick analysis is not applicable for saddle angle greater than 180 deg. But how about wind and seismic.Will it be correct to use the same wind and seismic report from compress considering the vessel resting on ground.

 

[saplanti]

I think you need to do wind and seismic calculation by hand, you do not need compres or other analysis software.

Using the analysis for vessels resting on ground will not be correct. The support will be in tension in your application under the gravity loads.

You can use approximation to solve the vessel:

1. Design each ring to take half the vessel gravity load due to the expected deflections on the ceiling under the center hanger.

2. Consider static force due to the wind and seismic forces in two horizontal directions separately.

3. Add the actions due to wind/seismic onto the gravity load on the largest loaded ring, and solve the ring under the combined loading using Roark's Formulas or equations taken from other sources. You may need to solve the actions separately and add them later on the ring.

4. Design the ring section for the combined loading and support conditions considered.

 

[LSThill]

ting123 (Mechanical)

PAULIN RESEARCH GROUP has completed simlar desing in mid 90 using FE/PIPE SOFTWARE for offshore phatform.

Stephen

 

[chicopee]

Get a copy of Pressure Vessel Design Handbook by Bednard. You'll have a whole section on the subject but instead of the tank being suspended, the analysis deals with a tank being supported by two piers.

 

[ting123]

I do have copy of the "Pressure vessel design by Bednar" and i visited the chapter 6 which explains the "Design of saddle supports for large horizontal cylindrical pressure vessel" But i could not find the one that Mr.chicopee is addressing. If possible can you please provide me the page numbers. It will be very helpful.

 

[saplanti]

There is no such a thing in that book. The address was incorrect.

 

[chicopee]

I am looking at chapter six, Sects.6.2,6.3,6.4,6.6,6.8 are the sections that I though might have been of interest in your query. If not than I am misunderstanding your OP.
You indicated that the tank is to hang from the floor, therefore, you are looking for steel straps around the tank. Basic engineering calculations for tension and elongation as well as analysis of the attachments of their ends to the floor should suffice.

 

[LSThill]

ting123 (Mechanical

GOOGLE SEARCH: Design, Analysis and Testing of Saddle Supports

http://www.google.com/#hl=en&cp=47&...w.,cf.osb&fp=2f0b188327e19041&biw=949&bih=857

[PDF]
Design, Analysis and Testing of Saddle Supported Pipes and Vessels
files.engineering.com/download.aspx?folder...7cef...saddleppt...File Format: PDF/Adobe Acrobat - Quick View
Design, Analysis and Testing of. Saddle Supported Pipes and Vessels. Paulin Research Group. 11211 Richmond Ave. Suite 109. Houston, Texas 77082 ...

 

[ting123]

Thankyou Mr.LSthill for providing such a useful link. Today we received the formal order for the above stated vessels.

 

[LSThill]

ting123 (Mechanical)

ALSO: DO GET THESE DOCUMENT:

1) API 579 & A S M E FFS 2 (2009) Fitness for Service Example Problem

2) ASME PTB-3 VIII-Division 2 Example Problem Manual American Society of Mechanical Engineers

3) PLEASE CUT & PASTE IN ADDRESS LINK: AMERICAN SOCIETY OF MECHANICAL ENGINEER'S ASME:

http://dl.ebmcdn.net/asme/flash/CS/ASME-FFS_6-09_v3.swf

best regards
LEONARD S. THILL

L S THILL