Oil and Fuel Storage Tank Construction Project – Sample WBS

Oil and Fuel Storage tanks (API 650 design) are typically used in petrochemical plants. They are large field fabricated storage tanks operating at low pressures or atmospheric pressures. There are various types of tanks such as fixed roof tanks and floating roof tanks, etc. Tank bottom is usually constructed of overlapping steel plates welded by manual or automatic welding technique. Tank shells are constructed from courses of steel plates. E.g. First shell course, 2nd shell course and so on.

In this article, we will focus on a specific type of tank, external floating roof type with single deck and internal pontoon. Sample Work Breakdown Structure (WBS) for an external floating roof type designed tank construction project can be decomposed as the following. As tank erection work is only focused, detailed WBS for foundation work is intentionally left at level 1.  It is just to show that foundation is required for the above ground storage tank.

Sample WBS for Separator Pressure Vessel Manufacturing

The following is a sample WBS for a cylindrical or spherical separator pressure vessel manufacturing. It is used to separate oil, gas and water from the total fluid stream (mixed phase) in the process industry. Separators can be either horizontal or vertical. Similar WBS can be applied for both types. 

    1. Engineering
     1.1 Document submission and approval
    2. Procurement
     2.1 Main Body (shell plate, dish head)
     2.2 Accessories (i.e. flanges, pipe, nozzle neck, gaskets, copper tubes, etc.)

Level of Schedule in Planning

Level 3 schedules are the most used in planning. Level of schedule is usually decomposed into 5. The intention of decomposing schedule level is to manage and control the project or task to the manageable level.

Level 1 Schedule is the highest level, called overall project summary level.

It includes major milestones or achievements, highlights major activities and key deliverables. Especially, it is also used in progress reporting.

Established by the client as an initial plan and can be integrated into level 2 and level 3 schedules which involved sub contractor and vendors’ in puts (commitments). Examples of level 1 element are

(a)   Engineering, Procurement and Construction (For Oil refinery plant expansion project )

(b)   Engineering, Procurement and Construction (For Chemical Plant Shutdown Work)

Level 2 Schedule is the area or system summary (roll up summary of level 3 schedule). It is also called major summary schedule. It is used to integrate into level 3 and level 4 schedules which involved detail tasks. It can be used to report the project area or trade progress status.

Examples of level 2 element are

(a)    Utility Plant Modification Project, Hydro Cracker Revamp Work ( For Oil refinery plant expansion project)

(b)   Furnace Area, Compressor Area Shutdown Work (For Chemical Plant Shutdown Work)

Level 3 Schedule is a project coordinating and project reporting schedule. Roll up summary of level 4 schedule. It is a primary tool for the project status tracking and manpower loading analysis. It shows the summary of each discipline. For instance, piping engineering, mechanical engineering, civil/structure engineering, process engineering and electrical and instrumentation engineering are level 3 elements which are the disciplines of design engineering. Normally developed and established by EPC (engineering, procurement and construction) contractor. Used as a proposal schedule during the process of tendering. Also is used as a guide line for subcontractors and vendors for their bid submissions. Applied critical path method and used as monitoring schedule during the project execution phase. Normally, level 3 schedule represents the area of responsible manager such as engineering schedule by engineering manager, procurement by procurement manager and construction by construction manager. Can be integrated into level 4 and level 5 schedule. The 3 month look-ahead schedule is produced from this level and distribute to the responsible engineer or manager to plan ahead.

Level 4 Schedule is a low level schedule. It consists of the task or work categories to be carried out. Level 3 schedule is further broken down into level 4 as an execution schedule (working schedule). The detail task lists and work sequence are shown in this level. Depending on the nature of project, the level 4 schedule may be level 1 schedule of subcontractor (and/or) vendors. For example, we have a new project that required the new pump no- “P28” to be purchased and installed. Purchasing of pump materials and manufacturing steps are apart of pump vendor’s level 4 element. When the pump vendor’s schedule is roll-up into the highest level , the time frame from the purchased order issued date to deliver date at site, is level 1 element of vendor’s schedule. That information becomes main contractor’s level 4 schedule input. 6 week look-ahead schedule, 3 week look-ahead schedule are frequently produced form this schedule by filtering the time frame, and distribute the responsible engineer or manger to plan ahead before getting close to the targeted date.

Level 5 schedule is the lowest level of schedule. The task list and work sequence is usually developed by the task supervisor or engineer and incorporated into level 4 schedule to monitor day to day work.

Creating Project schedule

The following information should be available before schedule is being developed.

1. Scope and specification ( what are we going to build/do?)
2. Work Volume (Quantity of work/Budget quantity)
3. When (When the project must be completed or delivered?)

1. Scope and specification

This is one of the important area of a schedule. Project member who develops the schedule must understand

• The detail activities and method of statements to be delivered or built
• The following documents should be gathered before developing a schedule 

WBS ( Work Breakdown Structure ) for Engineering and Construction

If someone asked what is the typical work breakdown structure for EPC (Engineering Procurement and Construction) for a petrochemical revamping project, I would say, refer to the following WBS. The first picture below shows up to level-2 WBS for an EPC project, including shutdown. The detail design engineering can be broken down into disciplines engineering. Then, construction scope can be separated into pre-turn around and major construction. 

The level 1 WBS elements are as follows;

1. Feasibility study

2. Basic design and engineering

3. Detail design and engineering

4. Procurement

5. Construction