Appendix 2 Flange Strategy

[LOUDOG]

I have not done many designs on very large flanges and would like some advice. I have a customer who has requested that their vessel have a bolt on head. The vessel has a 36" ID, and a design pressure of 800 psi. What is the most economical type of flange to attach. I am using COMPRESS, but I dont have much expirience with these large flanges, so I dont how to make it economical.

 

[nickelkid]

Your ID rules out the most economical, which is to use a standard flange. Obtaining the Pressure Vessel Design Manual by Dennis Moss will provide you with a solid design strategy to start with.

 

[LOUDOG]

What if I switch to 36" OD

 

[nickelkid]

B16.47 has 36"-900# WN

I have used Texas Flange before, the following is note from them:

A Quick Note on B16.47
ASME has incorporated the MSS-SP44 specification into B16.47 Seiries A and the API 605 Specification into B16.47 series B. They have also added Blinds to these two specs. You may note that these specs include only Weld Necks and Blinds. For Slip-On’s over 24” you must refer to either Industry Standard (which are not automatically covered by ASME) or Boiler Code Flanges. If you need help deciding which flange best suits your application feel free to contact us.

 

[unclesyd]

You haven't mentioned your design temperature or process material to be contained. Both these numbers are needed to ascertain which type of flange might be more suitable.

 

[gr2vessels]

The most economical flange for your size, I believe is the custom design to ASME Appx 2, using Compress and the designer's experience. Missing any of the above is receipe for disaster. Using a massive oversized B16.47 flange might be a secure solution, but more expensive than otherwise. Perhaps use a compact flange (eg Norsok flange), you can buy it from the Vector International or other similar companies. Or perhaps get someone experienced to design it for you and you fabricate it.
cheers,
gr2vessels

 

[LOUDOG]

I came up with a custom one that was quite a bit smaller than the original one. I had some help from a QC guy that has been around forever.

However I would still like to do a cost comparison for machining the custom one I came up with, or ordering a 600# 36" Forged Flange.

I am not sure though to go with a slip-on or a weld neck. Especially since a head is being attached to the flange, it may be costly to order a head with a long straight flange in order to attach a slip-on.

 

[SnTMan]

LOUDOG, for 800 psi I'd go with a weld neck. Much better joint configuration.

Regards,

Mike