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

Thief Hatch Installation

Thief Hatch Installation

Thief Hatch Installation

Sorry for asking this silly question, but can somebody please tell me where I can find flange dimensional data for an API flange that has a bolt pattern API (16) 11/16 holes on a 10-3/8" circle?  I tried looking at API 6A but I get the funny feeling I'm looking at the wrong place.

Thank you for your help.

RE: Thief Hatch Installation

API-650 sends you to ASME B16.5 for all flange specifications.

Check out ASME B16.5. Flange dimensions start on page 64. You'll find all the information you can possibly need there.

Hope this helps.

RE: Thief Hatch Installation


Is this on a relatively small tank, and are you sure you have 11/16" holes and not 9/16"? Besides that discrepancy, your dimensions on bolt circle and number of bolts are in agreement with the Thief Hatch as called out in API 12F Figure 1 and API 12D Figure 3.

The references to B16.5 are for materials. Flange dimensions can vary, as most tanks don't need flanges capable of 285 psi pressure ratings.


RE: Thief Hatch Installation

Thank you guys/gals for all your posts.

I'm looking for a flange that would mate up to an Enardo Thief Hatch model 330.  I'm looking at their datasheet and it specifies a bolt pattern of 10-3/8" Circle API.  I've tried searching for other brand name thief hatch sizes but it appears that this bolt pattern is pretty standard.

I've tried to match this bolt pattern size with B16.5 flanges but could not find a match.

Have you guys installed one of these thief hatches before and how did you do it?

Thank you.

RE: Thief Hatch Installation

They are 1/2" bolts, likely to be 9/16" holes, do not match an ANSI 8" flange but will match the hole patterns jte mentioned above.  You will need a non-ANSI flange or an adapter, or bolt directly to the tank roof plate.

RE: Thief Hatch Installation

I believe API-12F has standard dimensions for a thief-hatch bolt pattern like this.  I assume the hatch bolts directly to the deck plate of the tank, not to a nozzle.

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