FEED & DEtail Engineering
Basic Engineering Design (BED) covering: [/B]
•Conceptual process studies (material balances, process flowsheets,…) and preliminary plot plan.
•Preliminary Piping and Instrument Diagrams.
•Definition and sizing of main equipment resulting in process specifications.
•Specification of effluents.
•Definition of control and safety devices.
•And, generally speaking, all the basic studies required to support a Basic Engineering Design Package (BEDP) containing all data needed by a competent contractor to perform the Detail Engineering.
•These basic engineering studies may consist of consolidating a Process Package initiated by an external process licensor.
Front End Engineering Design (FEED) covering:
•Mechanical data sheets of the main equipment, starting from the process specifications issued during the BED and incorporating the specific requirements of codes and standards to be applied to the project in question.
•Thermal rating of heat exchangers.
•Preparation of tender packages for the main equipment.
•Development of process and utility Piping and Instrument Diagrams released for detail engineering.
•Development of detailed plot plans and hazardous areas.
•Elaboration of the main piping, instrument, electrical and civil works layouts.
•And, generally speaking, all the studies to be performed before ordering the main equipment.
Detail Engineering, covering:
•Purchasing of equipment, main and bulk.
•Thermal rating of heat exchangers.
•Development of Piping and Instrument Diagrams released for construction.
•Development of detailed piping drawings, including isometrics and stress calculations.
•Development of detailed drawings related to instrumentation, electrical facilities and civil works.
•Management of vendor drawings.
•Cost and schedule control.
•Start-up procedures
Feed Verification:
For P&ID review it is better to create a check list of items be checked and proceed to check them. For line sizing Major line sizes the determine the pressure drop of system, heat exchangers and other major pressure drop items along with line sizes the determine Pump head and compressor discharge pressures, should be checked. Remember line sizes of all lines will be rechecked during Detailed Engineering, However pump heads, Compressor Discharge and pressure drop across major equipment should be frozen during FEED. Better to use some approved software for pressure drop as two phase flow calculations can get very time consuming without good software. It is also important to see if Deign basis is followed in line sizing. For example, Design basis may call for 110 % of maximum flow for line sizing and 125% of pressure drop while considering pressure drop. We need to confirm to both the requirements. A Good practice for all design reviews is to prepare a detailed check list of items to be checked and keep ticking off items after they are resolved.
During FEED most of the pressure drops are based on assumed pipe lengths and pressure drops across vessels and heat exchangers. For liquid flow specially control valves and pumps, static head will play important role. At the feed stage what best you can do is fix location of pumps and control valves elevations if offshore, if onshore the effect of length will be more prominent.
Apart from above, another important aspect of FEED verification is finalization of design cases. Ensure HMB include all the possible cases through the production profile (years). Depending on location of the plant, ambient temperature may play significant role in considering design cases.
Actually there many-many things to check/ verify. Preparing check list will certainly help you out.
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