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How To Start Hydraulics

hydraulics line sizing

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#1 PKS

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Posted 27 December 2015 - 01:36 AM

Dear Members,

 

For a Process Engineer, what is the ideal way of carrying out hydraulics (line sizing, Control Valve sizing, Compressor circuit sizing, pump circuit sizing etc). What is the best and time efficient sequence of doing this? Please see below:

 

Line sizing referring to PFD 

1. Start line sizing referring to PFD (without using any line lengths) to get an initial estimate of line sizes based on recommended pressure drop and velocity considerations. So, we will be ready with initial estimate of line sizes.

 

Next w.r.t. to P&IDs (considering total equivalent pipe lengths)

2. Do control valve sizing, pump circuit hydraulics, Compressor circuit hydraulics to finalize the line sizes.This will cover most of the piping in a unit.

 

3. Then for remaining lines (which do not come under above circuits), check and finalize the line size based on equivalent lengths.

 

Is the above an ideal way of carrying out hydraulics to fix line sizes.

 

Request your suggestions/comments on above. 

 

As a Process Engineer, one have to carry out activities like Process Simulation, preparing H&MB, P&IDs, Equipment sizing, line sizing etc. My concern is to get a way to do the things in proper sequence so as to remove any rework etc. Since, the project schedules are very tight.

 

So, I have raised above question w.r.t. sequence of hydraulics only. Request members to focus on that only otherwise the discussion may lead to numerous directions without satisfying the response to question in principal

 

Regards,

PKS


Edited by PKS, 27 December 2015 - 02:28 AM.


#2 ankur2061

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Posted 27 December 2015 - 02:03 AM

PKS,

 

You cannot correctly establish, pipe fittings (elbows, tees, reducers / expanders) from P&IDs. When doing hydraulics for critical lines, you need piping GADs and / or piping isometric drawings indicating exact line lengths and number of fittings. An example would be reboiler piping.

 

Hope this helps.

 

Regards,

Ankur.



#3 PKS

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Posted 27 December 2015 - 02:17 AM

@Breizh: I will review ur link.

@Ankur: You are correct that P&IDs cannot give full picture of piping fittings etc. That is not a problem. However, I request you to comment on above mentioned way/sequence of carrying out hydraulics. 

 

Regards,

PKS



#4 PKS

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Posted 27 December 2015 - 02:27 AM

@Breizh: I have gone through the link u suggested. This page gives basic fundamentals to be followed for line sizing. That's ok for me. However, I request you to comment on above mentioned way/sequence of carrying out hydraulics. 

 

As a Process Engineer, one have to carry out activities like Process Simulation, preparing H&MB, P&IDs, Equipment sizing, line sizing etc. My concern is to get a way to do the things in proper sequence so as to remove any rework etc. Since, the project schedules are very tight.

 

So, I have raised above question w.r.t. hydraulics only. Request members to focus on that only otherwise the discussion may lead to numerous directions without satisfying the response to question in principal.

 

Regards,

PKS



#5 ankur2061

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Posted 27 December 2015 - 02:59 AM   Best Answer

PKS,

 

Sequence depends on what type of project it is. If it is a Pre-FEED project, then tentative line sizes based on flow and velocity considerations will suffice based on the H&MB and PFDs. If it is a FEED project with multi-disclipinary engineering you need to perform the hydraulics for all major process and utility lines using at least preliminary piping GADs prepared by piping discipline. If the project requirement is to perform detail engineering, you need to re-verify the hydraulics done during FEED based on equipment / instrumentation vendor data as well as check hydraulics based on "Issued for Construction" piping isometrics for critical lines.

 

Thus there is no straight forward sequence for performing engineering calculations. It depends on the type of engineering work (Pre-FEED, FEED, Detail Design), the client's understanding and visualization of engineering design and the prior experience of the engineering contractor for doing a particular type of project.

 

To give an example, in one of the companies where I worked, and which was also a technology licensor, I have issued process specifications even before preparing the H&MB and PFD. Sounds strange, but it is true, since we were doing repetitive projects of the same technology with increased capacities and based on experience and judgement acquired in the past, we could issue RFQ specifications despite not having prepared the H&MB and PFDs.

 

Hope this helps.

 

Regards,

Ankur.



#6 PKS

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Posted 27 December 2015 - 03:17 AM

@Ankur: Your reply is like hitting the bulls eye. Very nice explanation. Thanks!!

 

Assume Detailed Engineering phase and assume one is doing the unit for first time:

 

In that case after we receive the FEED Package, we shall directly identify the circuits and start verifying line sizes (off course with piping and other deptt inputs, if required) instead of doing the line sizes based on PFD. This will save time. 

 

Regards,

PKS






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