Critical - Subcritical

Hi my friend, how are you today? I am sorry, It’s been a while my blog has not been updated. I was very busy this week; therefore I had no time to write a new article. Ok, Let's continue the discussion about back pressure. Now, by this article I will explain you that the critical and subcritical condition depend on the back pressure.

Back Pressure Effect

In the previous article, two kinds of back pressure have been discussed. We have already understood that back pressure has several impacts to PSV performance. In this article, we will learn the impact of back pressure on the relief valve opening, operation and flow capacity.

Built Up and Superimpossed Back Pressure

Back pressure is defined as pressure that exists at PSV’s outlet. It has impact to performance of PSV, hence its value should be informed to vendor therefore shall be stated in the datasheet. Good concept understanding of the back pressure is helpful when calculates its value.

PSV Calculation - Kd,Kc,Kb factor

Hi friends, how are you today? Hopefully, you are not already bored with my articles. Now, we will learn the concept of relief valve calculation. The spreadsheets not tell you anything, but we should know what really it does. After read this fully article, I hope you get a better understanding of the relief valve calculation concept, and then know well with your spreadsheet.

The Art of Line Sizing

As process engineer, we have responsibility in determining the pipe size. Both at proposal and project stage, the adequacy of line size shall be reviewed by process team. I am really sure all of us already familiar with line sizing. We know well both the methods and criteria. Here, we will learn together that actually, the understanding of line sizing philosophy is very important. Line sizing is not just about GOOD and NOT GOOD as we can show in the spreadsheet.

LINE LIST – Input data temperature carefully!

All of us already know that line list is one of deliverable documents provided by process engineer. It is our important product document as a process engineer at IKPT. Many important data will be covered in this document.

Dry and Wet Gas

Wednesday, 11 January 2011, DEGC project team conducts regularly meeting. When the issue of PWHT -Post Weld Heat Treatment- requirement for some pipe is raised up on that meeting, piping engineer ask me what the service for and whether the condition is wet or dry.


In my understanding, good Process Engineer has capability in designing the process, developing the system and also capable of designing involved equipment which compliance both with the codes and standards. The capability in those wide areas can be obtained either by self-learning from handbook and literature or from experience in a real project. I do sure, all of us agreed that the experience is much better.