It is a well-known fact that the success in the water treatment and desalination projects mostly depends on timely delivery of equipment pieces and subsystems. Hence, Project Schedule (PS) shall be pivoted around the purchase orders (PO) and the equipment inspections.
This obvious requirement has been never met in practice by the following reasons.
- Despite the dominance of P&ID items in the PS activities no commercial software for PS development and analysis knows how to read P&ID, PFD, Plant Wiring, or One-Line Diagram.
- Inability of the schedulers to assess the impact of P&ID–rooted activities on critical path turns PS into “todo” list hiding the true project picture. Activities like ‘Update of...’ and ‘Correction of...’ become normal practice in the environment with broken logic of the project execution.
- In most cases Purchase Order is a package of items which is formed by the procurement personnel not involved in the PS management.
The first problem is a bottleneck accounting for other PS problems.
- Lack of bi-directional navigation between PS subjects (like valve or pump) and PS activities on subjects (like the pump inspection or the pump test approval) is the main reason of PS analysis inefficiency.
- PS synchronization with engineering data updates is manual, error-prone and time-consuming.
- Due to a lack of the project exact scope and resources definition as a result of skipping the FEED phase, most activities are of duration type, and not of workload one.
- Resources optimization (quality and quantity) and synchronization with other projects is not possible.
- Engineering data approvals are left out of PS.
- Project risk analysis is not part of PS. There is no possibility to implement “what if” scenarios when, for example, testing and/or inspections are poorly done.
- The impact of the OEM market match to the project on PS is beyond the scope. (Example is 6MV/60Hz pump for the Carlsbad SWRO desalination project which did not exist on the market by the time of the project award.)
- There is no way to assess the project change on PS.
The gravity of these problems is seen in every second project ending up with costs overruns of up to 30% and/or schedule slippage of up to 6 months.
To resolve these problems, CP comes with entirely different approach and framework.
For PS visualization and management CP uses activity-type network depicting the activities as arrows and events as nodes. This network is referred to as Arrow Diagram Method (ADM) or Critical Path Method (CPM). Activity is considered an atomic and indivisible piece of work that may be done in isolation from the other activities. Gantt chart is used only for data reporting, for example, in the project commercial offer.
|Fig.1 Graphical presentation of ADM-driven project schedule|
To hold PS internally, CP uses powerful Graph Math Library: network diagram is mathematically described by a unidirectional graph theory offering rich set of analysis techniques.
CP validates PS activities interdependencies based on the following axiom.
PS shall always have a single starting and single ending points and neither activity nor milestone is dangling.
This limitation enforces true concurrent engineering and prohibits merging the project with R&D projects started earlier. Such a merger has more than one starting point.
The PS activity may be a multi-task represented as an ordered list of unstructured activities or another PS network diagram (Fig.1). This allows easy integration of the subcontractor schedules and “what if” scenarios.
The core of CP framework is powerful Activity Scope & Content Editor (ASCE).
ASCE takes advantage of the fact that most project activities are rooted into or may be traced to the P&ID data or Plant Wiring Diagram. The content of such activities is represented by two parts - the description of deliverables nature or type and their scope - project, group, project area, P&ID or its area. For example, “assembly drawings of pretreatment area” may be split into “assembly drawings” and the project sub-area called “pretreatment area”.
ASCE auto-generates a generic database of standard deliverables (PINs, orders, P&ID items and approvals, interlocks and control loops, auditing results, engineering reports and certified drawings) valid for any project and a project-tailored database of the scope entities like the project area, equipment class, supply packages, P&ID diagram and others. Both databases are auto-updated with every project update and used for the PS auto-update. Any activity may be easily compiled from these two databases. Such an approach makes ASCE language understandable, and the PS activities suitable for searching and navigation from P&IDs.
To make PS more manageable, CP moves the body of “light” activities with the load of less than 24 man-hours under the domain of the Outstanding Issues Tracking. If some issue is not resolved, the activity approval is blocked. This approach drastically reduces (by 30 - 50%) the total number of PS activities.
CP offers the generic algorithms library for the activity weight calculation (expressed as its duration of workload in person-hours). It assumes that the activity weight is proportional to the activity scope, the activity type (assembly drawings quantity, instrument I/O quantity, etc.) defining the proportionality law. The latter depends upon the project phase. For example, if the "Instrument Index compilation" activity is done, the workload of activity called "I/O list" is a product of the number of instrument index list entries and the entry weight of 0.1 hour. At an early phase of the project engineering when the instrument index list is not ready another correlation based on the project size may be selected from the generic algorithms library.
It is often said that the desalination project is all about delivery or lead times (LT).
They may be categorized on LT for the final product and LT for the product engineering documentation. The latter usually includes the general assembly drawings (GA), cross section ones (CS), loads and forces distribution, the manufacturing plan, the inspections and tests plan and others. The documentation LT is a starting point for any detailed mechanical design while the product LT is used for the plant construction scheduling.
CP includes unique algorithms library for predicting lead times for typical equipment classes based on the equipment type, size, and the design and construction attributes. The prediction algorithms use default Inspection and Test Plan (ITP) applied by CP to all P&ID items and added to the project scope. ITP impact on PS is usually not analyzed at the bidding phase. This omission is listed first in the project delivery delay causes.
CP auto-generates PS together with the workloads and allocated resources according to the project preferences, P&ID, PFD, CFD and Plant Wiring. The project preferences include the following points.
- Project contract type – LSTK, EPC, EPCM, etc.
- Main contractor and subcontractors
- Project partitioning onto construction work areas and their sequencing
- Purchase Orders sequence and quantity in each lead time category,
- Available resources: technicians, engineers, supervisors,
- Plant commissioning sequence;
- Extended scope (like intake and/or product delivery piping).
CP creates and optimizes the PO packages before PS auto-generation. Each PO package handles the P&ID items of the same class and similar lead time category. It includes general requirements specifications, auto-generated datasheets in Excel, purchasing terms and conditions, and a payment scheme rooted into Inspection and Test Plan.
The PO package may include special groups of items - Item Supply Group and Functional Supply Group. The former contains P&ID items that are already sized. These functionally related but dissimilar items are supplied by the same vendor, pre-assembled on skid. Examples are the dosing system and the pump set containing the pump, the motor, and instruments.
Functional Supply Group (FSG) is a cornerstone concept of CP. It focuses the designer attention on functionality, implementation details being considered trivial or too multiple to specify. Classic example is the agitator which mixing quality is characterized by G-factor. Available on the market products with the same G-factor differ by the impeller shape and quantity, rotation speed and construction materials. An agitator, a motor and a VFD forms FSG.
Mentioned above the PS preferences list includes PO sequencing. CP sorts the PO packages by the lead time in descending order: the heavy equipment with the longest lead time is handled first. The following order of the PO packages is typical for the megaprojects.
- Large pump sets of 500 kW and above
- Vessels and tanks
- Valves of ANSI class #300 and #600
- Filters and membrane arrays
- All piping and balance of valves
- Electrical equipment – variable speed drives, MCC panels and switchgears
- Auxiliary turnkey packages
- Balance of the plant
This pattern is also applied to the piping procurement: metal piping and fittings shall be ordered first, then the FRP piping and fittings followed by the plastic ones.
The auto-generated PS may be modified - unnecessary work packages can be easily removed from the project or outsourced to a subcontractor.
CP contains powerful tools to analyze and optimize PS (critical path analysis, slack time minimization, probability analysis, prediction correction, etc.) or print it according to the user preferences (as Gantt chart, or Excel datasheet covertable to MS Project Manager).
CP solves the problem of generic resources leveling and allocation. Despite its criticality to success of the project, this problem has not been addressed by commercial software in the volume necessary to define the following points.
- The optimal ratio between different resource categories like process, electrical, instrumentation and control, mechanical and others
- The resource quantity necessary to meet the project deadline
- The best strategy in case of insufficient resources - to hire or to outsource
- The resource availability for other projects
- The resource costs against the time distribution curve
- The resources usage in the long-term activity planning.
Fig. 2 Project duration as function of the resource ratio
The chart of Fig.2 is auto-generated by CP and shows the effect of the resource availability on the project time frame. As follows after point A extra resources contribute little to the PS shrinking. To replace generic resource with named one in the programs like MS project office requires at least 4 steps and some brainwork. This replacement is time-consuming and never fully done in practice.
Without named resources, the project progress forecasting - the basis for the project success - is hardly possible. To automate naming resources, CP tracks the activities of designers and reviewers across the projects and defines the level of their involvement in the specific project disciplines and creates the designer digital signature. This information is stored in the User Resume, which is a solid basis for selection of the future project team.
PS of five sample projects (S300, S750, S1000, S1001, and S1800) show that the resource usage in a single project is inherently low, and the work outsourcing or concurrent work in a number of projects should be a common practice. The electrical, instrumentation and control, mechanical and civil engineering are best candidates for outsourcing.
The heaviest part of the project is mechanical design, which may be executed by any engineering company even having no previous experience in the water treatment or desalination.