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API 610 vs. API 6AF

API 610 vs. API 6AF

API 610 vs. API 6AF

Can someone please explain to me API 610.

API 6AF shows graphs where a pipe flange limitation can be read out. One can determine under a specific set of bore pressure and tension load a maximum bending moment or visa versa depending on how one like to read the charts. This is understandable and easy to follow.
If I have to select the flanges directly at a pump I am forced to consider API 610. In API 610 there is only a table of maximum allowable forces and moments for the suction and discharge side of a pump. These numbers are only a fraction compared to API 6AF. I was told that API 610 is already including pump-off forces (tension loads) which could explain the offset in values.

My questions still is: How can someone setup an API, limiting the allowable forces and moments without knowing the pressure regime or geometric form, properties and thickness of material?

Any comment that brings some light to this is highly appreciated!

RE: API 610 vs. API 6AF

The allowable forces and moments in API 610 are much lower because they are limited to prevent misalignment and/or distortion of the pump casing that could lead to bearing and/or seal failures, not flange leaks.  You will need to know what pipe size and wall thickness are required for your pressure design first.  Then the detailed piping design must include adequate flexibility to keep the forces and moments within the allowable range.  This will generally require a detailed FEA stress analysis of the piping using a program such as CAESAR II.  It is greatly preferred to design the piping with adequate flexibility than to use expansion joints, as they are weak points in the system and can be subject to catastrophic failure.

RE: API 610 vs. API 6AF

I would recommend that you look into getting a copy of a recently issued Welding Research Council document:

Title: Guidelines for the Design and Installation of Pump Piping Systems.
V. A. Carucci and J. A. Payne
Welding Research Council Bulletin 449

This is a guide to designing piping systems so that the pumps will have a long and happy (bearing) life.

Look here for WRC publications


Best regards, John.

RE: API 610 vs. API 6AF


I believe it is important to point out the intent in the development of API-610. This standard, with it's requirements for forces and moments on pump flanges, was set up to enable a purchaser to procure a "robust" pump.... one suitable for refinery service.

Contrast the physical construction of an API-610 design with that of a similar ANSI B73 series pump and you will notice the difference. The API pump is bigger and more rugged and, typically used at a higher temperature.

I don't believe that the industry has set a position on allowable loads for ANSI pumps ( I think that the Hydraulic Institute has been looking at this for some time) However, you can be sure that the allowable loads, if stated by the manufacturer will be much lower..

Anyway, John Breen (above) makes an excellent suggestion in the purchase of the WRC document.....

Hope this helps....


RE: API 610 vs. API 6AF

Thanks to all of you for your input. I will purchase the guidelines.

RE: API 610 vs. API 6AF

I think the main intent on API-610 is to prevent refinery fires and they seek to accomplish this by making the pump bigger, better, and meaner..and oh yeah, the mech seal and seal chamber/gland also...


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