3 replies to this topic

[Alex1]

Hello, 

 

As often on this forum I have 2 questions about the application of the 10/13 rule from API521.

The API considers taht following application of the 10/13 rule as unlikely the scenario pipe rupture, I understand a total rupture with the flow of 2 sections of pipes (to dimension the PSV) is not a credible scenario. However, a moderate rupture, for example due to corrosion because LP side is cooling water, cannot be excluded. In this case, is it assumed that the leakage will escape quietly through the cooling tower? and if it is a closed circuit with aerocoolers? 

 

My second question is more precisely about the key phrase: "including upstream and downstream system".

As an example, I take the case of a process gas cooler with a design pressure of 30 barg cooled by a cooling water system with a pressure of 10barg. 

For the shell and tube no problem I can increase the design pressure of the tubes to 10/13 of 30barg. 

For the upstream/downstream system, where is the limit? at the exchanger isolation valve? on the whole water network? 

If the cooling water header are low pressure, should they be protected by a PSV? 

 

Thank you for yours answers

 

Alex

[Bobby Strain]

There is no 10/13 rule. See the relative section of API 521. One must do a dynamic analysis to determine affected systems.

 

Bobby

[breizh]

Hi,

To add to the discussion, let you take a look at this link and comments:

https://www.linkedin...ting conditions.

 

https://www.youtube....h?v=qCE6D7jQVyU

 

Need to be cautious.

Breizh 

[seuenergy]

Hi Alex,

 

It seems that this is not an simple rule. The use of this rule should meets several conditions (please see Breizh's link).

And I am in China, the Chinese GB code requires pressure relief device for pressurized vessel. So the rule is not allowed by local government.

But thanks for this information.