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Tutorial: Progress Calculation/Tracking System for Oil and Fuel Storage Tank Fabrication

If Progress Calculation/Tracking System for Oil and Fuel Storage Tank Fabrication Works is not in placed for a specific project or you are drafting a progress tracking system, this tutorial could help you to complete your work. Scope of work is the same as described in the earlier post “Oil and Fuel Storage Tank Construction Project – Sample WBS”. We will focus specifically on the fabrication of an external floating type tank with single deck and internal pontoon. The three main components of progress calculation system are

(1) WBS (work breakdown structure) elements

(2) Work Step

(3) Work Step Weight Factor

Tank WBS element is broken down into fabrication components which are the deliverable of fabrication work.

See sample WBS as below.



Work Steps and Weight Factor for Tank Bottom & Roof Plate Fabrication

Fabrication works steps for Bottom & Roof Plate may include as minimum before sent for erection on site.

1) Blasting/Primer coating of plates
2) Marking and cutting operation
3) Weld edge finishing/grinding to remove burrs and slag
4) Inspection as per API 650 or specific client requirements.

As for progress calculation, “Material Received at Shop” and “Delivery at Site” is added so as to claim the progress as part of shop fabrication. 5% progress is earned when material is received at shop as well as once fabricated materials arrived at site. Sample Work Step and Weight Factor for each fabrication step is defined as below to illustrate progress calculation. It should be discussed and agreed with Owner/Client before official progress report is issued.

Work Steps
Weight Factor
Material Received at Shop
5%
Blasting/Primer Coating of Plates
25%
Marking and Cutting Operation/ Weld edge Finishing/Grinding to remove burrs and slag
50%
Inspection as per API 650 or Specific Client Requirements.
15%
Delivery at Site
5%

Work Steps and Weight Factor for Shell Side Fabrication

Fabrication work steps and weight factor for Shell Plates are slightly different from Bottom and Roof plate fabrication as it involves rolling and circular shaping of shell plates, reinforcement pads welding for nozzles and man ways installation.

Work Steps
Weight Factor
Material Received at Shop
5%
Blasting/Primer Coating of Plates
15%
Marking, Cutting/Shaping & Weld Edge Finishing
60%
Inspection as per API 650 or Specific Client Requirements.
15%
Material Delivery at Site
5%

Work Steps and Weight Factor for Tank Accessories and Fittings Fabrication

Work steps and Weight factor of Tank Accessories and Fittings may include as minimum before sent for field erection at site.

Work Steps
Weight Factor
Material Received at Shop
5%
Marking/Cutting/Welding Preparation Complete
35%
Full Weld Done/NDT
35%
Blasting Painting/ Galvanised
15%
Final Inspection
5%
Material Delivery at Site
5%

3 Points to Understand How WBS and Work Step Weight Factor Works to Evaluate Overall Physical Progress

1. Prepare Progress Status by Quantity Sheet

1.1 Populate each component per GA drawing which is in line with WBS, for instance, each fabrication member of annular plate, sketch plate and rectangular plates are listed to track the overall progress of Tank Bottom fabrication.


1.2 Record the actual status of fabrication progress. E.g Blasting/Primer Coating Completion Date, Final Shop Inspection Completion Date, etc. This is to monitor and claim the progress of each fabrication step.


1.3 Fabrication status is calculated based on the quantity of each member, for instance, 450 kg of progress is earned out of 5320 kg once a bottom plate member delivered at site.



2. Prepare Progress Summary by Quantity

Prepare progress summary sheet that includes the total quantity of all members, overall progress of each work step. e.g 100% progress for a work step “Marking/Cutting/Weld Edge Finishing” is earned when all the members completed on that particular step. 100% progress for delivery at site for Tank Bottom fabrication is earned when all the tank bottom plates are delivered on site. Remember that progress status is measured in terms of quantity at this stage.



3. Prepare Physical Progress Status Sheet

Work steps weight factors and man hour weighting are used when physical progress is measured, for instance, 250 man hours is estimated to be spent in order to complete Tank Bottom plate fabrication prior to field construction on site. Therefore, man hour weighting (W) “0.179” is calculated against overall tank fabrication works as shown in below figure.
Complete the spreadsheet with Work Steps and Weight Factor for Tank Bottom & Roof Plate Fabrication as stated above.

To find out Individual progress (e.g Tank Bottom Plate),

Tank Bottom Plate Fabrication = A1B+A2C+A3D+A4E+A5F, “A” is equal to Quantity Progress where linked to “Fab Status by Qty” sheet.

To find out “Overall Percent Complete” when tank bottom fabrication is completed,

Overall Progress = Weighting of Tank Bottom (0.179) x Individual progress of Tank Bottom (100%) = 17.9%



Download the Sample Progress Calculation/Tracking System for Oil and Storage Tank Fabrication for your quick reference. I hope you enjoy it.

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