Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

API 12F vs. API 650 and anchors

API 12F vs. API 650 and anchors

API 12F vs. API 650 and anchors

Using a 210 BBL, design pressure of 16 oz. from Table 1 of API 12F, OD is 120" and height is 15'. Floor is 1/4" thick, shells are 3/16" and roof is 1:12 slope and also 3/16" thick. I chose a 210 BBL as the floor and shell thicknesses would be equivalent to an App. J tank of API 650.

I am well aware the that the roof geometry b/n these codes are different, but my issue is with F.4.2, which is independant of any roof compression areas and slope. Applying F.4.2 to a 12F tank provides a Pmax of around 0.5 ounces. API 650 wants this tank anchored.

Can anybody shed light on the mentality behind the formula of F.4.2? A positive pressure (increase in design P) is available due to shell weight, roof weight (0.08 * th) and is decreased due to the wind, which leads to anchorage.

Assuming the tank is fixed at the floor, call it liquid level which stops any deformation of the floor, the tank is essentially a cantilever with the wind as a load. Stress due to wind on the shell are minimal in this scenario.

Does J.3.9 intend to ignore F.4.2 and simply worry about overturning moment due to wind?

This issue pertains to purchasers specifying API 650 tanks when API 12F will work.

RE: API 12F vs. API 650 and anchors

If there is net uplift due to pressure against the roof balanced by the roof and shell weight only (ignoring for a moment some donut of liquid), the shell will lift off the foundation while the bottom is held there by the liquid weight.  This leads to bad stresses and strains at the corner weld.  Ergo, anchors.  You can use a thicker annular bottom ring so a larger donut of liquid is available to resist the uplift.  Wind and seismic add additional overturning loads that anchors must resist if the tank is unstable resisting these loads.  Note that wind acts horizontally and also vertically.  The vertical component adds to the internal pressure and tends to pick the shell off the foundation while leaving the bottom there.  Appendix J is not a design code - it is more of a cookbook for low stress, small tanks of very specific sizes.  Good engineering judgment should be used when these tanks are placed where wind and seismic forces could affect the tank.

RE: API 12F vs. API 650 and anchors

API-12F tanks are not designed per API-650.  What it really boils down to is that the API 12F/12D tanks are intended for oilfield service, and if one blows over, it's not the end of the world, whereas API-650 tanks are designed for more permanent use in more critical facilities.  If you check overturning on a 55 gallon drum, it'll probably calculate out to be inadequate also.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close