How to easily estimate the duration of an Oil & Gas EPC Project

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In order to better understand the challenges faced by Engineering to match the construction schedule, it is worth knowing that the critical path of an oil & gas facilities project is that of its pipework.

Piping is indeed by far the most time consuming activity at the job Site.

Let’s look at all the activities coming into pipe works:

Piping comes in small individual items: straight lengths, are 6 or 12 meter long, elbows, flanges etc. They have to be welded together at the job Site.

Some pre-fabrication at a Site workshop will be done to save time. Pre-fabricated partsare called “spools”. Thanks to pre-fabrication, 2/3 of the welds will be done in the workshop and 1/3 in-situ.

This will save much time as in-situ (field) welds take twice a much time to do as shop welds.

Anyway, the time required to do a weld, even when done at the workshop, is already long enough: a full day for one welder for a 24” weld.

Once fabricated, the spools will be blasted, primed, brought to the erection location, erected and fitted-up.Field welds will be carried out, followed by Non-destructive examinations and post weld heat treatment, if any. Supports also have to be installed and the line pressure tested, flushed, re-instatement done, field joints painted, tracing installed, if any, as well as insulation, if any.

All these completion works take a lot of time.

In fact, contrary to mechanical equipment which are brought already fabricated and tested to Site, piping has to be fabricated, inspected and tested from scratch.

This is why pipe-work is the most likely critical path of any facilities project.

This path is made of the following activities:
- Pre-fabrication
- Erection
- Completion.

The start date and duration of these activities determine the overall duration of the Project. Statistical information is available in contractors’ data bases which allows prediction according to historical data for similar size and type (refining/gas etc.) project.

The overall duration of a Project is indeed determined as follows:

First, the start date of piping pre-fabrication is determined.

Piping pre-fabrication activities can only start once both the construction drawings have been issued and materials have been delivered to Site. In contractors’ experience, for pre-fabrication to effectively start:

• 50% of the piping construction drawings (isometric drawings) must have bee issued

• 75% of the materials of all types (straight lengths, fittings, all grades) must have been delivered at Site.

Statistics show that the 50% of piping isometrics issued mark matches an overall engineering progress of about 80%.

Engineering progress has proved to be linear from 20 to 80%, with a slope which depends on the number of manhours and ranges from 6 to 9%/month.

20% engineering progress is known to be achieved 2 months after 50% equipment have been ordered, which itself usually happens 6 months after the EPC Contract start date (provided the FEED is of good quality).

Having this in mind, you can determine the 50% isometric issue date. For a large job, for instance, with a 6% engineering monthly progress at cruising speed, it will be 6+2+(80-20)/6 = 18 months.

Experience shows that 6 months will elapse between the start of pre-fabrication and the time when erection will reach its cruising speed, corresponding to 20% progress (in other words, 20% weight of pipe-work erected).

Erection speed will reach an upper limit on every job, that will depend on the available space on the ground, restricting the number of personnel and cranes. This cruising speed will typically be 6% by month on a large job. This means that progressing from 20 to 85% will take (85-20)/6 = 11 months.

Finally, once erection has reached the 85% progress mark, its progress will stop being linear and will become asymptotic.

Piping completion works, from 85% erection progress to mechanical completion, i.e. all pipe-work installed, supported, tested, insulated, is best modelled as a constant, typically 6 months on a large job.

The project overall duration therefore comes to:

Piping 50% Isos (18 months) + 6 months from start pre-fab to erection cruising + 11 months erection up to 85% + 6 months completion = 41 months.

This is indeed the typical duration of a large size EPC.

Note that the above modelling is made at the ouset of the project, to determine its overall duration and can also be made any time during the project to determine its remaining duration.

In the later case, accurate estimate of quantities (the 100%) is essential.

Note:

The above explanation overlooks some underlying requirements, that, if not met, will affect the piping path:

- in order to have 75% of piping materials delivered at site on month 18, orders for all types of piping materials will have to be placed in due time, taking into account the lead time of each type of materials (exotics etc.). his will translate into requirements for engineering to issue the corresponding Piping Material Take-Off.

- in order to proceed with full swing piping erection around equipment:

• at least 60% of equipment will have to have been erected so that their nozzles are there to connect pipes

• the platforms on equipment have to be erected to allow access to personnel for pipe installation

• the underground networks (pressurised pipes, sewage, cables) must have been installed, backfilling – if not paving – done so that cranes can access,

- in order to proceed with full swing piping erection on pipe-racks and structures, the same have to have been released, i.e. erected, bolting and alignment done,

- Piping pre-fabrication does not proceed directly with the isometric drawings issued by Engineering but after some processing of these drawings, by the construction contractor, called “spooling” and resulting in the issue of a “shop isometric”.

- Effective installation of piping will require availability of pipe supports. The latter are very numerous. Their standardization and timely mass production must be properly planned in order to allow concurrent installation with that of the pipe-work.

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Oil and Gas Refinery Piping Tie-In Weighted Steps

Weighted step in Primavera is an ideal function to eliminate subjective progress . What is the difference between 40% and 75% complete? It is hard to justify when you don’t have a good detail breakdown.

Here we can use the Step feature in Primavera to break down the activities for piping tie-in, each with weighted completion, Step % complete and Step weight %. It is hard to justify Tie-in progress without weighted Step as in my experience site people will estimate the progress based on their judgement.

In my previous experience, I will track piping tie-in progress in 2 ways which are through excel sheet and Primavera software. Excel sheet tracking become so useful when comes to piping supervisor level or when the site team do not have Primavera software.

It helps to keep both planner and field people at the same page when we refer to the progress as the weightage assigned tally with what we have in Primavera P6.

Each of the activity’s steps is a breakdown of all tasks required to complete the Tie-in activity. Steps can be assigned a numerical weight that shows the portion of an activity’s total work that each step represents. Weighted steps enable you to track the progress of an activity based on the number of steps completed.

Below are simple illustration on how Activity Steps in being calculation and how does it contribute to Completed Percentage.

Tie-in Tracking Sheet In Excel Sheet

Download link : http://mbx.cm/t/St10i

Steps Function in Primavera P6

Step 1: Access the project window from the activity bar

Step 2: Click on the calculations tab in the project’s details window.

Step 3: Check the activity percent complete box and answer yes to the prompt.

Step 4: Navigate back to the activities window and click on the GENERAL tab.

Step 5: Look for the use " % Complete Type” option and choose PHYSICAL.

 Step 6 : Look for "Enterprise" tab and click on "Activity Step Template".

Step 7: Add steps to the tie-in activity. In this case I will create an activity template for Tie-in which later will trigger a list of pre-defined list of step templates.

Note: When each step is completed, the activity’s percentage complete changes to reflect the completion each individual weighted step.

Step 7: Enter the relative weights for each step in the activity.

Step 8: When a step is complete, update the weighted step’s status by checking the box marked COMPLETED.

Physical % complete = weight of completed step(s)/sum of all weight.

Workfront Monitoring and Control : Part 2

Sometime back I wrote on WorkFront Monitoring and Control and the necessity of this particular approach in Engineering control. Project management is getting complex that we need more metrics apart from S-Curve that tells where we are and how we stand in term of progress. You only get what you measures.

Here is a little bit of my add on how we can go about WorkFront Monitoring and Control. This is just an idea but you might have some other idea which area better than this.

Steps in Work Front Monitoring.

Quantity Plan at Initial Stage

At initial point the WorkFront quantity are defined and plot in a graph which serve as a baseline. This will be measured against the actual quantity of ISO IFC, piping purchased and the prefabrication.

The graph can be adjusted, for an On-Shore project, the cumulative quantity of steel (tons) of issued IFC Structural drawings. The cumulative dia inch of IFC issued Piping isometrics will show the available piping work front.

In this case I picked up piping as an example. Such progress curves, showing the actual versus planned available workfronts are instrumental to monitor engineering progress, identify shortage and take corrective actions (increase mobilisation).

As a planner it will give us a "feel" how we are doing in term of readiness to meet the milestone date. Let say we should have purchased 70% of the piping dia-inch by end of Sept but in actual fact what we have now in place is only 50%. This will paint a picture immediately that the 20% of lacking can create a huge issue on material availability on the pre-fab or construction stage.. Planner should be able to finalize overall work schedule and resource mobilization plan for Piping work based on work front (drawing and material release) plan in association with project control. The ultimate goal is to achieve the optimized piping work front according to construction priorities, available isometric drawings and available materials.

Take the case of piping scope of work in an oil and project.Timely completion of piping construction is not only depending on timely receiving of IFC/AFC engineering drawings and materials from Owner/EPC Contractor but also timely availability of the material should also be addressed. This is where we refer it as Workfront availability.

Here one sees the necessity to measure the issued Workfront.

The figures given is to serve as an example and doesn't depict actual scenario.

	IFC ISO	Piping Purchasing plan	Piping availability at site	Piping Flanges availability	Piping Prefab curve
1/1/14	50%	0%	0%	0%	0%
1/2/14	50%	35%	30%	30%	25%
1/3/14	55%	40%	30%	30%	30%
1/4/14	65%	45%	40%	40%	35%
1/5/14	75%	50%	45%	50%	40%
1/6/14	85%	55%	50%	60%	45%
1/7/14	95%	60%	55%	80%	50%
1/8/14	100%	65%	60%	90%	55%
1/9/14	100%	80%	75%	95%	70%
1/10/14	100%	90%	80%	98%	75%
1/11/14	100%	95%	90%	100%	85%
1/12/14	100%	100%	95%	100%	90%
1/1/15	100%	100%	100%	100%	100%

  

 

Actual Quantity

This will be the actual quantity of each item measured. From this point the Project Manager and Planner will be able to see how far we deviated in term of baseline Workfront planned. This is a crucial information to measure the efficiency of how we deal with Workfront availability.

In my experience, apart from efficiency this graph helps me the most in studying the trend. Base on trend it will give me a confidence level on whether we can meet the intended Workfront work volume. In return I will just pass the pressing question to the team member how are we going to meet the baseline requirement in order to secure the availability.

The figures given is to serve as an example and doesn't depict actual scenario.

	IFC ISO	Piping Purchasing plan	Piping availability at site	Piping Flanges availability	Piping Prefab curve
1/1/14	30%	0%	0%	0%	0%
1/2/14	35%	20%	15%	30%	15%
1/3/14	45%	30%	25%	30%	20%
1/4/14	50%	40%	35%	40%	25%
1/5/14	60%	45%	40%	50%	30%
1/6/14	75%	55%	50%	60%	35%
1/7/14	85%	60%	55%	80%	40%
1/8/14	90%	65%	60%	90%	45%
1/9/14	95%	70%	65%	95%	55%
1/10/14	100%	85%	80%	98%	60%
1/11/14	100%	90%	90%	100%	70%
1/12/14	100%	100%	95%	100%	80%
1/1/15	100%	100%	100%	100%	100%

 

 

 

 

 

 



Planner Role in Pre-Commissioning, Commissioning and Start-up

Pre-Commissioning, Commissioning and Start-up

Pre-Commissioning, Commissioning & Start-Up is the last visible and important step in an EPC project execution process. It moves the project from the “end of construction” to the “commercial operation” status. This phase covers initial and primary dynamic tests, including guarantee performance tests.

Some definition always used TnC stage are :

To enable a smooth transition from construction to commissioning it is required to complete construction work in small packages (known as systems). This enables Pre-Commissioning work to progress from an earlier point in the schedule, in return to reduce the final pre-commissioning peak workload substantially.

 

Systems should be defined by colour coding a set of A3 P&IDs. System boundaries should be “flagged” in RED and system numbers should be clearly marked at regular intervals on the respective line-work and equipment. System summary sheets should be prepared which list the system content by line and equipment numbers.

 

Detailed Pre-Commissioning / Commissioning Execution Plan
A plan is developed that identifies all of the major pre-commissioning activities by system. The plan will be developed in reverse and will clearly identify “system ready for pre-commissioning” milestones.
Commencement of system turnover from construction to commissioning should ideally commence at approximately 70% erection completion. From this point handover of systems should be made on a regular basis.

 

A method of pre-commissioning progress monitoring will be developed to allow progress to be monitored by:

• Overall pre-commissioning completion for the complex
• Pre-commissioning completion by Process Unit
• Pre-commissioning completion by system
• Discipline completion by system
• Vendor Schedule.

Some client would like to categorise the punch list in order to prioritise. Below is the example.
Category A : Items that must be cleared prior to start of Pre-commissioning
Category B : Items that can be cleared during pre-commissioning
Category C : Commissioning Items

Immediately prior to the hydrotest of each system, a Punch-List will be performed by an integrated Punch- List team consisting of construction, and EPC Commissioning Engineers (from relevant disciplines).

When all “A” type items have been cleared and a small but manageable amount of “B” type items are left, a handover can be progressed from the construction to the commissioning group. Since mechanical completion has been achieved with agreed exception items, it is classed as an interim handover to permit construction completion and Pre-Commissioning activities simultaneously.

Control and responsibility of work on the system rest with the commissioning group. Any construction work will require written permission from the Lead-commissioning Engineer of the particular Process Unit. Permission will be granted on a job by job basis.

This would involve a line-by-line detailed check of the actual physical installation against the latest P&I diagrams issue, job specifications, piping hanger and support drawings, vendor drawing, etc., for erection of the unit in accordance with all drawings and applicable specification. The systems would also be checked from an operating viewpoint for proper location and orientation of valves, vents, drains, steam tracing and traps, sample connections, etc.

Once the unit is precommissioned, the Commissioning Team will conduct the following main activities:

• Purging
• Leak Test / Tightness Test
• Spring Hanger Check
• etc

to start with initial Start-up operations assuring that every activity is accomplished smoothly and safely. The Commissioning Subcontractor Team would take care in troubleshooting any operating or process problems, should they arise, and would investigate any operating deviations as they occur.

 

Pre-Commissioning Complete
When the Pre-Commissioning work on each utility system is complete it can then be commissioned providing it is safe to do so. For non-utility systems the point at which the process Unit is considered to be “ready for Start-up” is when all non-hydrocarbon systems have been pre-commissioned. At this stage the Unit is presented as “Ready for Commissioning” This triggers several safety activities as follows:

• A final Punch-List to determine if the unit is ready to accept hydrocarbons
• A pre-start up safety review
• The introduction of a full permit to work and safety system.

Commissioning Complete
When all commissioning for a process unit is completed the unit is declared “Ready to Start-up”.

Role of a Planner

A planner need to be well aware of the whole Pre-Commissioning, Commissioning and Start-up flow in order to provide a realistic schedule. He or she should be able to advise not only the project manager but also the commissioning manager on the schedule impact in the area of commissioning.

A good knowledge in commissioning will help planners to maintain a full resources loaded schedule complete with commissioning activities.

My Experience.

In my experience I will work out with Process, QC, Commissioning manager and Project manager on each test package. Base on this test package, I will know which piping activities, electrical activities, instrument activities and etc that linked to each test package.

Below is the example of the piping scope where I will plan and link from Piping fabrication, tie-in and commissioning. This requires a good understanding in P&ID , tie-in and TnC knowledge and interpretation.

Hydrostatic pressure testing of the Unit shall be performed to prove strength of the materials and weld integrity after completion of the construction. The tests shall be made on new or repaired equipment and piping.

For this project, I would have to go in detail in order to create "activity code" for test medium, test-package number, tagging number or even job number.

 What was expected from us

Below are what my client expected from me especially during the commissioning and start-up planning. These can be details that can be useful for you as well.

• Prepare, update & maintain the relevant Commissioning schedules through contact with Company & Contractors Commissioning Teams, using logic network planning (Critical Path Method or CPM), and the Project WBS as appropriate
• Develop mini plans/schedules as necessary, including resource loading the commissioning plans/schedule.
• Participate as required in the integration of Commissioning schedule into the Overall Project schedule.
• Define & maintain the Work Breakdown Structure working closely with the Commissioning Site Leaders.
• Project lookahead plans and liaise closely with the CSU (Commissioning & Start Up) team to monitor and confirm that the necessary preparatory works (e.g. vendor mobilization, material availability, etc.) are in place.
• Monitor Contractors scheduling & perform analysis to validate Contractors dates