4 replies to this topic

[Olidin]

Hello,

I have been using the forum for quite some time and it has been quite helpful. Thanks to many that posted on the forum. I just recently graduated in Dec 2011 with a chemical engineering degree and started as a process engineer in refining business.

My focus however, has been relief devices. And I have a few questions hopefully members here can share their views and experience on:

1. How did you remember all the standards? Are there any tricks/methods to remember the guidelines and standards such as API 520/521. I tend to forget some details here and there.

2. The most time consuming part of my work is not the engineering but more of finding and gathering information and documentation. What is the equipment MAWP, what is the flow rate in a particular line, how are the valves operated (are they open and closed in any combination)? what are the valves Cv and K? exchanger heat dutym, dimensions....

That part of my work is particularly time consuming (about 60-80% of total time on any relief valves) and added less value to my technical skills. Do you have to face the same issue? If so, what did you do to overcome such challenge (beside just dealing with it and go ask everyone you know for the documents)?

3. When performing calculations for required relief rates and valve capacity, did you do so by hand or did you use a software of some sort?

4. I feel that identifying applicable scenarios and taking credit for certain items when calculating the required relief rate depend heavily if not solely on experience. Is that correct? How long should it take to be competent at such skill?

5. What are the books and material that I should/must read or know to be competent at relief device sizing?

Overall, I seek to quickly learn this area as well as the industry overall. Once mastering this skill, I can expand my focus elsewhere.

Thank you for your help.

[Dacs]

You ask those questions with 100 engineers and I think you'll never get the same answer twice (apart from API stuff of course)

Anyway, I'll try to answer your questions strictly based on my perspective as a process engineer:

1. How did you remember all the standards? Are there any tricks/methods to remember the guidelines and standards such as API 520/521. I tend to forget some details here and there.

I personally don't know which section to find a certain information so I keep a copy of API 520/521 in handy. What I can tell though is after you've done this calculation on a regular basis, some of the more important stuff will stick to your head. That said, I still refer to my copy at times if I need some clarifications at hand (or ask here!)

2. The most time consuming part of my work is not the engineering but more of finding and gathering information and documentation. What is the equipment MAWP, what is the flow rate in a particular line, how are the valves operated (are they open and closed in any combination)? what are the valves Cv and K? exchanger heat dutym, dimensions....

I was in your shoes before thinking that all those collating information is something not worth "my time" (whatever that means LOL) in doing my work, I came to realize that this is just as important as the actual number crunching itself. The information you collect serve as a basis for whatever engineering judgment you have to undertake and if you don't have the whole picture at hand, it's easy to imagine that you're may end up making a critical mistake in your judgment simply because you skirted out your way in collecting the right data.

Over time I guess you'll learn how to optimize your time and look for relevant data in the right places at a faster pace as you get to do this on a regular basis. I believe however that this is something every engineer should experience since this will basically develop his/her skills over time.

Take your time on this particular work. While you have to give your 100% on all what you're doing, I have to emphasize to take a very special attention on everything that has something to do with safety (and lives of operator that depends on your skill in designing a safety device properly).

That I can't stress enough

3. When performing calculations for required relief rates and valve capacity, did you do so by hand or did you use a software of some sort?

Some will do by hand (or Excel), some companies would have their own in-house templates. I personally do it by Excel.

4. I feel that identifying applicable scenarios and taking credit for certain items when calculating the required relief rate depend heavily if not solely on experience. Is that correct? How long should it take to be competent at such skill?

While experience takes a lot of credit in this cases, you're trained to be an engineer. You have what it takes to analyze the scenario and give your judgment based on your training.

In this particular exercise, use API as your guide to go through your analysis.

Learning is a continuous process. I still feel that I have lots of things to learn even though I've been doing this stuff for 7 years.

5. What are the books and material that I should/must read or know to be competent at relief device sizing?

I can't speak out a particular book but some references on relief sizing on your past projects in your company is a good tool to at least learn the ropes of this job.

All that said, it's very beneficial to seek out help from your more senior colleagues, since they're in the best place to nudge you to the ways of doing this work. Ask them questions and do your work right. If in doubt, let them check your work.

That's how you'll learn how things are done.

Good luck

Edited by Dacs, 24 September 2012 - 07:53 PM.

[RoyenG]

Hi Olidin,

i'm not an expert in the relief system, just want to share my little experience in that area.


1. How did you remember all the standards? Are there any tricks/methods to remember the guidelines and standards such as API 520/521. I tend to forget some details here and there.

i personally agree with Dacs, important things will stuck in to the head after doing relief sizing many times, eventhough do not know exactly in with chapters are those written in API 520/521.


2. The most time consuming part of my work is not the engineering but more of finding and gathering information and documentation. What is the equipment MAWP, what is the flow rate in a particular line, how are the valves operated (are they open and closed in any combination)? what are the valves Cv and K? exchanger heat dutym, dimensions....


That part of my work is particularly time consuming (about 60-80% of total time on any relief valves) and added less value to my technical skills. Do you have to face the same issue? If so, what did you do to overcome such challenge (beside just dealing with it and go ask everyone you know for the documents)?

To safe the time in gathering required information, in my opinion, related P&IDs and equipment datasheet have given big contribution in relief sizing. Other documents may be come later if required and sometimes not.

3. When performing calculations for required relief rates and valve capacity, did you do so by hand or did you use a software of some sort?

For relief load and size, usually company have their own spreadsheet, while for the fluid properties i use process software.

4. I feel that identifying applicable scenarios and taking credit for certain items when calculating the required relief rate depend heavily if not solely on experience. Is that correct? How long should it take to be competent at such skill?

in my opinion, in identifying applicable scenarios and governing scenario, experience will give big contribution, especially in determining other cases ("hidden cases") that could happen.

5. What are the books and material that I should/must read or know to be competent at relief device sizing?

In my opinion, reading articles such as Hydrocarbon Processing or other articles will tell more than reading a book (without reducing my respect to the book writer).

Overall, I seek to quickly learn this area as well as the industry overall. Once mastering this skill, I can expand my focus elsewhere.


Good luck and have a good time

[paulhorth]

The subject of relief system design and relief valve sizing is covered in depth in this publication: "Guidelines for the Safe and Optimum design of Hydrocarbon Pressure Relief and Blowdown systems" published by the Institute of Petroleum (UK) in 2001. I participated in writing parts of this document which was produced and reviewed by a committee of representatives of major oil producing companies.

If you can get a copy of this publication, it will provide you with a great deal of background and design principles.

Paul

[Olidin]

Thank you everyone for responding. For such a small device in a large refinery, there is so much. I'll keep chugging along