Question:
Can some of you review attached work flow chart for the replacement of condemned pressure vessels. Please advise if some thing is missing.
Answer:
Here is a rough outline of what I see for this project.
• Understand the reason for and the conditions for the Project
• Verify what exists now
• Identify what is to be removed
• Identify all Hazards and Risks
• Identify what can be reused and what needs to be replaced
• Establish the parameters for the new design
• Create the new Design
• Verify the new vessel can be built, transported and installed
• Perform all HAZOP, Safety and Risk reviews
• Obtain all Approvals
Some might suggest that this list is too detailed and the project is not that complicated. Well, I do not see any details of exactly what the existing equipment is like, what kind of plant it is, what country it is in and so on.
This is what I recommend:
Understand the reason for and the conditions for the Project
Why are we doing this? It is not possible to do a good job on this project or any other if everyone does not understand the objective. Have the Client explain fully what the objective is relative to this project.
What are the conditions for the Project? Will the Plant be Shut-Down? Will the Unit be Shut-Down? How long will the Plant/Unit be Shut-down? Will the Existing piping (affected by this project) be drained, steamed out and made safe for hot work?
Verify what exists now
For this project we are not talking about the whole plant or Unit. Based on the information in the original question we are only talking about a single vessel.
Meet with the responsible members of the Clients staff related to this project. Collect copies of all relevant P&IDs (Do not assume the P&IDs are up to date). Do a detailed walk down of the Vessel and ALL connected piping including Utilities. Mark-up the P&IDs for any additions or deletions. Locate the closest isolation valve for every line. If a line currently connected to the vessel does not have a remote isolation valve then mark up for possible addition of a temporary valve.
On a copy of the existing Plot Plan identify the equipment and any structures (pipe Supports) that need to be removed.
On a copy of the Underground Sewer, Piping and Electrical drawings mark up where the work area is located.
Have a formal review of all effected P&IDs. Include Client and Engineer Company personnel responsible for the work. This should include: Process, Piping, Electrical, Instrumentation, Construction (Removal), Safety, etc.
Identify what is to be removed
Once you are sure the P&IDs agree with what is in the field then meet with the Client and Process and prepare a set of Demolition P&IDs. Mark the P&IDs with a Cloud (with cross hatch) for the Vessel, the Piping and all instruments to be removed. Review it and get agreement of all parties. Using these marked-up P&IDs start a written Scope of Work (SOW). The SOW is the basis for all down-stream activity including the man-hour estimate and Schedule.
Identify all Demolition Hazards and Risks
Using the Demolition P&IDs do a full HAZOP and Risk assessment for the Demolition phase of the work.
Identify what can be reused and what needs to be replaced
It is likely that piping will be reused with the new vessel project and it is prudent to go through this exercise to insure that all the options have been considered. To accomplish this activity all items under consideration need to be inspected by qualified Inspectors. If an object is required but cannot be reused “As-Is” or repaired then it must be replaced. This affects the Budget.
A major item on the possible “Reuse” list is the Foundation. What is the condition of the existing Foundation?
Is the new vessel the same size? Is the new vessel the same weight? Will the new operating weight be the same as the original vessel?
All of these questions need to be answered and if the existing foundation needs to be removed and redesigned then there is a big impact to the budget and schedule.
What about the existing Underground items, (Storm Sewers, Oily Water Sewers, Chemical Sewers, Electrical Power and Control Conduits or Duct Banks)? What’s down there? What does the project do about it?
Establish the parameters for the new design
Update the existing Plot Plan for the New Vessel. Add any new pipe supports or other equipment.
Create the new Design (Manual or CAD)
Once you have the updated P&IDs and the appropriate Vessel information then the detailed Design work can move forward. It is likely there will be both an office design effort and some field design work.
This phase of the work includes the detailed Orientation of all the internals of the vessel, all the Nozzles, all the Ladders, all the Platforms, all the Piping up and down the vessel, all the Pipe Supports and Guides for these pipes along with all the Instrumentation, the conduits and Lights.
The Field effort could include the design of piping with long runs and Tie-Ins out of the immediate area where the vessel is.
Verify the new vessel can be built, transported and installed
This is a critical activity. Yes any vessel can be built but time has passed since the plant was built originally. Where will the Vessel be built? Where is this job site? Based on the size of this Vessel how will, it be shipped? Will it come by ship or barge? Is there Off-Loading facilities available at the plant? Or near by? How far will the vessel be required to travel over land to reach the Plant? Is there a clear path inside the plant to the site of the lift? Are there Cranes available with-in the time frame that have the capacity to make the lift?
Perform all HAZOP, Safety and Risk reviews
Once the new design is completed then another Safety review needs for the new design.
Obtain all Approvals
Once the Design is finished, all Safety and Risk evaluations are completed, including recommended corrections.
The Client should be able to give the Approval to Proceed.
Proceed with final detail documentation, procurement, Fabrication and Construction.
prognosis: Lead or Lag