1 reply to this topic

[dmin0307]

Dear Sir:

 

I am a young engineering working at an engineering company from last year.

 

I have given a task to study depressurization to be applied in our project.

 

So, I have been recently looking over API 521, and have one question from API.

 

API 521 states that depressurization should be done in 15 minutes to 50% of vessel pressure or 690 kPa (100psi)

 

My question is that why are those numbers?

 

1. 15 minutes is like the experimental result? Or is there any standard to set this number. I would like to know issues I would have if I increase the depressuring time from 15 minutes say about 20 minutes for a vessel with 1 inch thickness. I tried to understand this 15 minutes from the graph, but I could not get to the point.

 

2. Why 100 psi? Is this any experimental result as well as 15 minutes? Or is it because its 100 psi (I mean hundred)? I tried to find why 100 psi from all resources I have, but I could not have found any. I think this is somewhat stupid question but why not 120 psi or 150 psi? 

 

I am eagerly wating for your answers.

I always appreciate your smartness and knowledge you have. I always get help from this forum.

 

Thank You

 

[fallah]

Hi,

 

Below links can help you out. If you need more clarifications let's know...

 

http://www.cheresour...c-blowdown-time

http://www.cheresour...psig-in-api-521