9 replies to this topic

[navneet2109]

Respected Engineers,

 

I have some doubt regarding hydraulic calculation which i am mentioning point wise

 

1. Do we send Hydraulic calculation sheet as a document to the client?? Client asking for hydraulic calculation after that only they will approve line list!!!! 

 

2. Client is also asking for graphical representation and explanation of each operation of every line.!!! .

    I think Hydraulic calculation is on assumption basis right ???? 

 

2. To carry out Vapor density I have use this given formula:

 

         Density of vapor = PM/RT,         P-Pressure, M-Molecular weight, R-Gas Constant, T-Temperature.

         By doing this calculation I have Got 32kg/m3 of (20%propane+80%butane).

         I just wanted to know that my approach is correct or not and the density value is reasonable???

 

This is some question which i need on urgent basis but still there is more question is coming to this topic which i will include later. I am requested to all process engineers, please follow this topic.

 

With warm regards

Navneet

[J_Leo]

Navneet,

 

1. Do you have any agreement/contract with the client what are the deliverables? If the client insist, why not give the calculation to the client? Don't you have project manager to talk to about this?

 

2. If no isometrics, at least you should have a plot plan to obtain the line length for hydraulic calculation. Base on the equipment layout on the plot plan, you can get the approximate geographic location of each line.

 

3. For ideal gas, the equation you mentioned is right. Nowadays, we just use simulation softwares to get density.

Edited by J_Leo, 05 August 2016 - 04:47 PM.

[gegio1960]

Navneet,

J_Leo has already answered your questions but, if you want a "check" of your calculations at point 3, you should provide better data:

- temperature;

- pressure;

- type of composition (vol or mass).

[This is a general comment, that goes beyond this simple application] 

Moreover, better to include Z in your formula :-)

...and a final consideration: after 40 years of chemistry and chemical engineering, I have to make calculations like these w/o the simulator; for 2 reasons, basically:

- process simulators have costs not affordable by a single professional (and cracked copies are not legal);

- I prefer to use my brain and my knowledge instead ot the software, whenever I can.

Good luck!

[navneet2109]

Navneet,

 

1. Do you have any agreement/contract with the client what are the deliverables? If the client insist, why not give the calculation to the client? Don't you have project manager to talk to about this?

 

J_Leo, 

Actually problem is that my project manager does not know about document of hydraulic calculation. But still I have send the calculation of hydraulic in a excel sheet which consist only 1 page ( total 10 lines because project is not so big). client commented on my hydraulic calculation document, some comments are:

 

a) sources of values shall be listed

b)detail explanation of each operation

c)graphical representation of pipe network

d)distance consider required reference

 

My thoughts on this comments:

a.) density and viscosity are given by client so i used this. This is the main value in hydraulic calculation right?? vapour density i have          calculated from PM/RT formula which i will change by adding Z.

b.) Line is going from one equipment to another equipment How i explain differently?? I have submitted process flow diagram (pfd) and its approved, I submitted P&ID also

c.)Graphical representation means what?? Can't we use P&ID for that??

d.) I have assumed the length. How i give the reference for that. I have also mention in notes that The length is    assumption only.

 

I am sort of new in process engineer having 1 year of experience but have not even used any software. I am doing everything on manually or excel. That's Why i am asking questions.

Edited by navneet2109, 06 August 2016 - 04:24 AM.

[navneet2109]

 

2. If no isometrics, at least you should have a plot plan to obtain the line length for hydraulic calculation. Base on the equipment layout on the plot plan, you can get the approximate geographic location of each line.

 

J_Leo, 

 

I have assumed length on plot plan basis only. Is it not sufficient???

Edited by navneet2109, 06 August 2016 - 04:25 AM.

[navneet2109]

Moreover, better to include Z in your formula :-)

 

gegio1960, 

 

Thank you very much I will include z in my calculation.

[J_Leo]

Navneet,

Do you have a company calculation spreadsheet established already for the hydraulics calculation? What are the criteria for line sizing? Not sure what equation you have used.

Obviously P&ID alone is not sufficient for hydraulics calculation. It cannot give you the line length and all the fittings required. If for liquid, line elevation has to be considered as well. Remember pressure drop through fittings are pretty significant and it can be dorminant for short lines. Fittings include pipe entrance, exit, block valves, check valves, elbows, tees.... If you want to make it simple, you may apply equivalent length factors to your straight lines to cover fittings. Generally speaking, the longer the line, the smaller factor you may use.

I do not know what kind of plot plan you got and location of equipment between your lines. It the equipment are far away apart, the line need to go through pipe rack. If you have a piping designer available, you can seek help from him.

Anyway, you have to convince the client your calculations are solid and your assumptions are reasonable.

[navneet2109]

Navneet,

Do you have a company calculation spreadsheet established already for the hydraulics calculation? What are the criteria for line sizing? Not sure what equation you have used.

Obviously P&ID alone is not sufficient for hydraulics calculation. It cannot give you the line length and all the fittings required. If for liquid, line elevation has to be considered as well. Remember pressure drop through fittings are pretty significant and it can be dorminant for short lines. Fittings include pipe entrance, exit, block valves, check valves, elbows, tees.... If you want to make it simple, you may apply equivalent length factors to your straight lines to cover fittings. Generally speaking, the longer the line, the smaller factor you may use.

I do not know what kind of plot plan you got and location of equipment between your lines. It the equipment are far away apart, the line need to go through pipe rack. If you have a piping designer available, you can seek help from him.

Anyway, you have to convince the client your calculations are solid and your assumptions are reasonable.

J_Leo,

 

Yes I have calculation spreadsheet.

But I think hydraulic calculation is depend on mass balance, PFD, Assumption of length, Equivalent length of valves and fitting, so that we can calculate the diameter of pipe as you say.

 

But question is only that anyone who is process engineer here can tell me that what content in hydraulic calculation document we've to send to client ??

Edited by navneet2109, 10 August 2016 - 04:27 AM.

[senthil13]

If you can calculate velocity & pressure drop per 100 ft considering all the process input and using the correct equation whether it is gas or liquid (two phase is another level of detail). you should be able to provide the calculation to your client. if you are in the early stage of project you might not have isometrics to input all the components in the pipeline . but you should know the basic valves and instruments that are inline so that you can assume the equivalent length. If you can do that , most of the time in detailed engineering when you develop the Isometrics you should be able to fine tune the calculation for final sizes.

 

I'm a client currently on a project. Our EPC contractor gives us the calculation in PDF format since the excel is their internal proprietary calc. I check it for all inputs based on my operating and design experience. there is no hidden mystery or intellectual property in a hydraulic calculation. Clients like to verify all the input data has validity and reasonable to that they dont run into issues when they start the process.

 

Hope this helps

Senthil

[navneet2109]

If you can calculate velocity & pressure drop per 100 ft considering all the process input and using the correct equation whether it is gas or liquid (two phase is another level of detail). you should be able to provide the calculation to your client. if you are in the early stage of project you might not have isometrics to input all the components in the pipeline . but you should know the basic valves and instruments that are inline so that you can assume the equivalent length. If you can do that , most of the time in detailed engineering when you develop the Isometrics you should be able to fine tune the calculation for final sizes.

 

I'm a client currently on a project. Our EPC contractor gives us the calculation in PDF format since the excel is their internal proprietary calc. I check it for all inputs based on my operating and design experience. there is no hidden mystery or intellectual property in a hydraulic calculation. Clients like to verify all the input data has validity and reasonable to that they dont run into issues when they start the process.

 

Hope this helps

Senthil

Respect Senthil,

 

Thank you for giving me reply which gave me the confidence to talk to senior and client. I have sent my calculation as i wanted to. Actually I have not much experience ( 1.5 years ) so sometime i m in confusing state that whatever i am doing is correct or not.