PETROCO has developed expertise in the field of modernization of instrumentation from pneumatic to microprocessor based Distributed Control system (DCS) or Fieldbus Control System (FCS).
PETROCO has performed re-instrumentation and FCS/DCS/PLC implementation projects to exploit technological improvements in field and control room instrumentation to the full.
A complete range of services are provided
-Site surveys
-Front-end engineering design
-Detail design
-FCS/DCS/PLC software implementation
-Installation, pre-commissioning ,
commissioning and startup
-Training
-Post-startup audits
-Software maintenance
Project Management
PETROCO has unique experience in identifying the key factor for successful re-instrumentation projects:
-Close coordination between Customers
And PETROCO team
-in-depth site survey and understanding of process operations
-Application of proven with the most suitable proprietary software
-Use of proven digital systems to ensure low costs and high reliability
-Schedule and budget control
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Sample of Hot Cutover Procedures for Critical Continuous Processes
(From a conventional system to a DCS or Foundation Fieldbus , without stopping production)
2 Ways for a Refinery Revamp:
- During Plant Shut-Down
- During Plant in Operation (Hot Cutover)
Revamp during Plant Shut-Down:
Advantages:
- Safe cutovers of all loops
- Less effort per loop cutover
Disadvantages:
- Loss of production and profit
- Parallel revamp works may cause difficulties and errors
Revamp during Plant in Operation:
Advantages:
- No loss of production and profit
- Time schedule can be handled flexible
Disadvantages:
- Needs perfect planning
- High effort per loop cutover
General:
- for each individual refinery revamp project the conditions are different and so an individual plan for the Hot Cutover has to be specified this presentation assumes that a new central control room will be build, where this is not the case some mentioned requirements have to be adapted accordingly the complete application software for the new DCS has been finished and tested 100% close cooperation between end-user and DCS supplier is mandatory
Planning
- Hot Cutover of a unit must be planned from the beginning of the project all points have to be reviewed for adaptability and classified special considerations are needed for certain loops (e.g. shutdown loops) lists of loops to be cutover within one sequence have to be prepared (loops at the same Equipment should be cutover within one day)
Organizing & Manpower
- To maintain the rhythm of a smooth cutover it is necessary to dedicate sufficient manpower to the cutover process. The following is the minimum manpower required:
- 1 SYSTEM engineer in the central control room to manage the cutover (if cutover will be managed from local control room with a remote station these tasks will also be managed by the SYSTEM engineer in the local Control room)
- 1 SYSTEM engineer in the local to support the field cutover efforts
- 1 operator in the field
- 1 operator in the local control room, to operate from the "old" system
- 1 operator in the central control room to operate loops which have been cutover
- pipe fitters, electricians, instrument technicians
Hardware & Training
- new DCS hardware and software as well as the application software have to be installed completely and fully tested in advance all customer operators and engineers should be trained on the new DCS, to avoid any operating problems after a loop cutover if possible a remote station should be installed in the local control room, so that cutover procedure can be managed from local control room (this simplifies the communication between all involved team members):
Prerequisite / Requirements:
- cutover will be controlled from the Main Control Station (either from the Central Control Building or from the Local Control Room)
- all tasks will be directed by the "cutover team"
- verybody involved in the cutover procedure must be informed about takeover of specified loop
Typical Procedure for Transferring a Control Loop to the DCS:
Execution:
- control loop will be switched to manual mode control valve will be placed in bypass position
- during cutover process value will be monitored continuously for adjustments of bypass valve if necessary
- process value (PV) will be recorded from the "old" indicator
- field team will cutover new transmitter
- if indicated value on the new DCS operator stations is acceptable, old I/P of control valve will be exchanged with new I/P
- output direction, controller direction and valve function (3 positions: 0%, 50%, 100%)will be verified
- loop will be switched to AUTO mode in DCS, alarms will be enabled
- cutover team will adjust the tuning constants and than will hand over the loop to operations
Indicating and Loop:
Cutover procedure for indicating loops is identical with the procedure control loop transmitter.
Digital Loop:
Cutover procedure for digital loops is only different in preparation, procedure is the same.
Digital Loops (Motor Control):
- cutover of a motor/pump can only be done during shutdown of the particular motor if a backup exists, cutover can be executed with little notification
- motors/pumps without backup need special consideration
- cutover procedure itself is as for the digital loops
General Comments:
- after finishing the cutover of a loop, this must be indicated clearly at the "old" control system
- if during cutover of a loop a failure occurs, this has to be solved immediately or the loop has to be switched back to the old DCS
- control valves without bypass, have to be fixed during cutover procedure with a clamp
-
Cutover Procedure for Safety Systems:
- shutdown loops dedicated to a particular section of a unit should be cutover in its entirety within one sequence
- each shutdown logic should be scanned and confirmed safe for cutover by the responsible design engineer
- this effort should be completed prior to cutover and monitored throughout the shutdown system cutover
- all shutdown valves will be placed on manual control before any associated shutdown loops are cutover
- all inputs will be cutover before any outputs
- review of the shutdown logic to insure that the outputs are in a safe state for cutover
- all outputs will be cutover at the "new" ESD
- shutdown test will be performed
- return valves from manual control to normal control
Summary:
The success of a "Hot Cutover" depends mainly on:
- a well-defined and understood plan
- cooperation between all involved parties
- communication
- training on the new system
- each person involved with the "Hot Cutover" must be familiar with the used cutover procedures and methods