#  > Petroleum Industry Zone >  > Petroleum Refining >  >  >  Difference between Front End Engineering Design (FEED) and fabrication/construction?

## cxcxcx0505

Can anyone explain the difference between Front End Engineering Design (FEED) and fabrication/construction in oil and gas sector? And also, what do Front End Engineering actually do? Thanks.

See More: Difference between Front End Engineering Design (FEED) and fabrication/construction?

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## feune111962

The FEED takes place upstream the detailed engineering studies. It covers all the process engineering studies for a given project. Typical documents produced during the FEED are:
- PFD & Block diagram
- P&ID and line list
- Utilities & general facilities distribution and line list
- Equipment data sheet
- Control valves datasheet
- Cause an effect chart

I hope that this clear enough.

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## mrkssastry

FEED:  Front End Engineering & Design

This the first stage of Engineering for any Project (Chemical / Petrochemical / Oil & Gas / Refinery etc) where the following discussed & decided.  

1. Technical / Process Wise:
a.  Material Balance (Mass & Heat)
b.  Process Flow - How the various raw materials flow from start to end & in what form
c.  Major equipments of the process - pumps, vessels, heat exchangers, filters, etc
d.  Safety Systems requirement for process

Engineering Wise: 

1.  Approximate Load List - for motors, transformers, drives, High Voltage Switchgear, UPS size, Diesel Genertor requirements etc
2.  Utilities required for the process - Air compressors, Nitrogen Plant, Fire Fighting systems, Hot Oil Heating Systems requirement, Air Dryers etc
3.  Major Instrumentation Systems - PLC / SCADA / DCS system (which one or combination of the above etc)
4.  Approximate Instrument List - Kind of Networks used, kind of Instruments used, system architecture (rough sketch / drawing showing the different networks connectivity between them)


Management Wise:

a.  The total cost of the project - around X +20% approximation (within the accuracy of +/- 20% accuracy)
b.  The total manpower requirement for the plant 
c.  Total List of Raw Materials requirement & their quantities 
d.  Approximate time required for completion of the project 

Philosophies wise: 

1.  Plant Operating Philosophies / Plant Design Philosophy & design Basis
2.  Instrumentation Engineering philosophy - Design & selection basis documentation
3.  Control Systems Philosophies - Heirarchies being implemented, design basis for selection of PLC / SCADA / DCS Systems, Third Party Interfaces, OPC Interfaces, Serial Interfaces between systems, Interfaces between DCS, ESD, F&G systems
4.  Safety Shutdown Systems philosophy - LOPA Studies / HAZOP studies / CHAZOP studies etc including SIL calculations.  

Now apart from the above, the following are the deliverables at the end of the FEED.

1.  Mass & Heat Balance Calculations
2.  Process Flow Diagrams
3.  Process & Instrumentation Diagrams (only 70 - 75% accurate)
4.  Load list for electrical
5.  Major Equipments & their Sizing (Major Equipments 100% accurate, however, there might be an addition of a one or two pumps / motors / blowers that might get added during the detail engineering stages but not vessels / heat exchangers or tanks).
6.  Instrument list - which is 80% to 90% accurate.  

However, please do remember the following:

1.  Instrumentation Datasheets / Process Datasheets / Mechanical Datasheets are not the deliverables of FEED.  They are preapred during the Detail Engineering Phase
2.  Instruments Selection, Sizing Calculations are finalized / done during the detail engineering phase only.  


Hope i am correct.  However, request senior professionals to comment on the same.  

Sastry Musti
Instrumentation & Control Systems Engineer

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## Bever

thank you for the usefull info

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## daffodils

I like how Sastry has broken the answer into different philosophies. I will try to answer in a more basic way
FEED - Done by Engineering Contractor (FEL-1 is business planning focused, FEL-2 - PFD focused, FEL-3 is P&ID focused). FEL-2/3 also involves significant work by all engineering disciplines (Mech, Inst, piping, electrical, CSA etc)

Fabrication - usually done by a vendor or fabrication company who is contracted by the engineering (FEED) contractor. Fabrication of vessels, columns, reactors based on specifications provided by the engineering contractor or maybe a technology licensor.

Construction: is done by a construction contractor. Can be same as engineering contractor (in cases like Bechtel etc) or a purely contruction company. The construction company works on the design of the engineering company to install / erect equipment made by fabricators.

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## mrkssastry

Daffodils,

Thanks for the reply & for a very short & sweet yet complete information regarding the FEL / FEED.  Well done sir.  

Sastry

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## 101043728

Dear Sastry & Daffodils

Very informative. May I detail information for Mechanical Engineering discipline in FEL 2/3 please?

Many Regards,
Deven

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