6.10. PIPELINES


PIPELINES - A simplified step by step pipeline construction exercise, incl. manhours & costs. (Note: This page continues use of Excel downloads, to be replaced by stand-alone calculators in due course. However, in the meantime a multi-purpose EMMA will serve admirably to track excavation, or stringing, or welding, or laying, or backfilling, or all manpower requirements)



This step by step assessment of the work scope, manhours and equipment needed to construct a buried steel pipeline, using MS Excel calculation files* that can be downloaded for each step, will culminate in a ball-park estimate of the total project cost. In addition, based on a single operating crew/equipment unit, an activity duration for each will be calculated**. If the user does not have Excel, the illustrations can be used as a guide to calculating hours and costs 'manually'. As a minimum, the following information will be required.

  • Diameter and length of pipeline
  • Planned hours per working day and working days per week.
  • Actual or 'guesstimated' labour and equipment cost rates.

*Note: Where 0 appears in red font a quantity will be required, minimum 1.

**Note: If the activity duration which results is not likely to be acceptable, an increase to working hours/days and/or an increase to the number of crews can be changed, in order to achieve a reduced duration. Example 1 (right) assumes 8 hrs per day, 5 days/week, with one crew(2 teams) which will take 99 work days or 19.8 weeks to complete. Example 2 increases the working hours/days and adds a second crew, reducing the schedule to 44 working days or 7.3 weeks. 

See Enbridge video (Above) for an overall introduction to stages of pipeline construction.

EXAMPLE 1
EXAMPLE 1
EXAMPLE 2
EXAMPLE 2


EXERCISE

If interested in pipelining, the reader is invited to put the following series of calculation files to the test, by producing a basic ball-park construction estimate for a 20" sch. 40 seamless steel pipeline over a distance of 100 miles in Arizona, USA. At the end of the exercise, comparison with recent data will be possible, allowing the reader to decide whether his/her estimate was in the right 'ball-park' (ie +/- 25%).



6.10.1. SURVEY THE ROUTE

Time for a pipeline route survey and the cost thereof is often under-estimated, particularly if undertaken across country in extreme weather conditions, through dense vegetation, or where security is a factor. Learn more from Mustang.

Illustration only. Click Download below. Copyright Peter Farrell 2014
Illustration only. Click Download below. Copyright Peter Farrell 2014
Download
PL1. Survey manhours/costs.
Pipeline survey manhours.xls
Microsoft Excel Table 25.5 KB

Add hire of equipment, vehicle(s), accommodation, messing etc



6.10.2. CLEAR THE ROUTE

Clearance of a pipeline route can involve the width of a highway (say 15 -30 metres), because space is required throughout its length to excavate the trench, stockpile soil, set down pipe lengths alongside the trench for aligning, welding, wrapping etc., and set up the side booms for lowering. In addition a roadway is required to one side for traffic moving up and down the route, plus laydown and maintenance areas at strategic locations. Special equipment can be needed through difficult terrain, river crossings etc

Illustration only. Click download right
Illustration only. Click download right
Illustration only. click download right. Copyright Peter Farrell 2014
Illustration only. click download right. Copyright Peter Farrell 2014
Download
Clearance labour hours & costs.
Pipeline route clear manhours US.xls
Microsoft Excel Table 54.5 KB
Download
Clearance equipment operating hours & costs
Pipeline route clear equip hrs US.xls
Microsoft Excel Table 64.5 KB


6.10.3. EXCAVATE THE TRENCH

Soil conditions might vary along the length of a pipeline's route, ranging from sand to rock, influencing the hours that will be taken to excavate these particular sections. For maximum accuracy, therefore, an estimate should be divided up as appropriate. Where sandy conditions exist, sloping sides of the trench will be necessary, for safety reasons, but excavation will proceed smoothly. In firm soil, vertical sides might be permissable, whereas in rock progress could be very difficult and slow. Good quality excavated material should be suitable for backfill, with surplus having to be disposed of by some means, possibly by spreading local to the route. Otherwise some backfill material might have to be sourced and brought in. See VIDEO below of trenching M/C in action.

Copyright Peter Farrell 2014
Illustration only. Click Download below
Illustration only. Click Download below.
Illustration only. Click Download below.
Illustration only. Click Download below. Copyright Peter Farrell 2014
Illustration only. Click Download below. Copyright Peter Farrell 2014
Download
Trench excavation quantities + surplus after backfill, in firm or sandy soil conditions
Pipeline excav. & backfill qtys US.xls
Microsoft Excel Table 25.0 KB
Download
Excavation equipment operating hours and costs. (Rock free)
Pipeline excav equip hrs US.xls
Microsoft Excel Table 154.0 KB
Download
Excavation labour hours and costs. Supervision, operators and manual workers.
Pipeline excavn m-hrs US.xls
Microsoft Excel Table 20.5 KB


6.10.4. STRING PIPING

The first stage involving the handling of piping is to uplift pipe lengths from storage areas, transport them along the pipeline route and place them roughly where they will be aligned, welded and wrapped, using sleepers or other means to support above the ground. This operation is known as 'stringing' the pipes and would normally be done after trenching, but not always. The number of storage areas will depend upon the length of pipeline and the rate of pipe stringing upon the number of crews operating along the route. This VIDEO by Jason LaValley demonstrates a stringing operation admirably.

Illustration only. Click Download right.
Illustration only. Click Download right.
Illustration only. Click Download right. Copyright Peter Farrell 2014
Illustration only. Click Download right. Copyright Peter Farrell 2014
Download
Equipment operating hours for collecting pipe lengths from storage and placing alongside trench.
Pipestring equip hrs US.xls
Microsoft Excel Table 151.0 KB
Download
Manhours for collecting pipelengths from storage and distributing alongside trench at ground level.
Pipe string manhrs - US.xls
Microsoft Excel Table 198.5 KB


6.10.5. ALIGN & WELD PIPE LENGTHS

Common practice is to perform all welding together of pipe lengths at ground level, followed by application of cathodic protection, before lowering long sections (Can be 1km) of the pipeline into the trench. This VIDEO demonstrates the latest equipment used to align large diameter pipes in pipelines.

Illustration only. Click Download right.
Illustration only. Click Download right.
Illustration only. Click Download right. Copyright Peter Farrell 2014
Illustration only. Click Download right. Copyright Peter Farrell 2014
Download
Equipment operation hours associated with aligning pipes for welding.
Pipeline align-weld equip hrs pre-lay US
Microsoft Excel Table 26.0 KB
Download
Supervisory, operators, welding and manual labour hours for aligning and welding pipe lengths
Pipeline align-weld manhrs pre-lay US.xl
Microsoft Excel Table 27.0 KB


6.10.6. PROTECT / WRAP THE PIPING

Wrapping is just one form of protection for buried pipelines and may all be done in the field, usually after welding and before lowering into the trench. Alternatively, pipe lengths can be wrapped before delivery to site, leaving only the area of the weld unwrapped, for completing in the field, before or after lowering. This VIDEO demonstrates a small diameter pipe being wrapped in the field. Other forms of piping protection are described by this DENSO pdf file.

Illustration only. Click Download below
Illustration only. Click Download below
Illustration only. click Download below. Copyright Peter Farrell 2014.
Illustration only. click Download below. Copyright Peter Farrell 2014.
Download
Pipeline wrapping equipment operating hours
Pipeline wrap equip hrs US.xls
Microsoft Excel Table 22.5 KB
Download
Supervisory, operators and labour hours for pipe wrapping.
Pipeline wrap mhrs US.xls
Microsoft Excel Table 22.0 KB


6.10.7. LOWER THE PIPE INTO THE TRENCH

Pipe lowering operations normally  will be carried out by one or more side booms, together with associated equipment items, the numbers depending on the lengths of segments that have been prepared at ground level. This VIDEO by Lance Romberg shows a long section of a pipeline being lowered into its trench using 3 sidebooms. This article published by Pipeline International discusses various aspects of lowering equipment. Depending on circumstances in the field, lowering can be done using excavators, cranes etc.

Illustration only. Click Download below
Illustration only. Click Download below
Illustration only. Click Download below. Copyright Peter Farrell 2014
Illustration only. Click Download below. Copyright Peter Farrell 2014
Download
Equipment hours for operations involving lowering of pipe into trench.
Pipeline equip hrs lowering US.xls
Microsoft Excel Table 22.5 KB
Download
Work crew manhours for pipe lowering operations
Pipeline lowering m-hrs US.xls
Microsoft Excel Table 22.5 KB


6.10.8. BACKFILL THE TRENCH

Following final NDT and hydrotesting of the pipeline, backfilling and compaction takes place in layers, using original excavated material if of good quality, or material screened through a 'padder', otherwise more suitable soil or sand imported from elsewhere. This article in Pipelines International discusses various aspects of backfilling pipelines including equipment used. The following video covers lowering, testing and backfilling to high standards.

Illustration only. Click Download right.
Illustration only. Click Download right.
Illustration only. Click Download right. Copyright Peter Farrell 2014
Illustration only. Click Download right. Copyright Peter Farrell 2014
Download
Equipment hours to backfill and compact over the pipeline.
Pipeline backfill equipment hrs US.xls
Microsoft Excel Table 28.5 KB
Download
Labour hours to work with the backfilling and compaction equipment.
Pipeline backfill mhrs US.xls
Microsoft Excel Table 33.5 KB


6.10.9. EXERCISE CONCLUSIONS

EXERCISE CONCLUSIONS - If the reader has opted to produce the suggested basic construction estimate, the following info. will be of interest:

  • Applying the US 'inch-mile' rule of thumb estimating method to a 20" x 100 mile pipeline, the total capital cost will be +/- $400m.
  • Invariably the cost of equipment and materials for a multi-disciplined heavy engineering project will comprise in the region of 60% - 70% of the total, with pipelines mostly on the high side.
  • The above facts are supported by a recent check on steel pipe prices in the USA, suggesting that 100 miles of 20" pipe would cost just under $300m, or 75% of the project value.
  • If correct, all other activities and purchases for this hypothetical project, including construction, would amount to 25% of the cost, or +/- $100m.

NOTE: If only basic hourly rates were used for labour and heavy equipment in the above calculations, further allowances will have to be made for items such as overtime premiums, incentive bonuses, home leave, construction management and supervision, servicing and repairs, tools and consumables, transport and accommodations, contingencies, insurances, contractors' overheads and profit, all of which could compute to a factor of 3 or 4 times the basic costings.

HYPOTHETICAL PIPELINE COST BREAKDOWN

The cost tabulation below represents just one of a multiplicity of scenarios and degrees of difficulty that could apply to such a pipeline. The scope of front end activities would depend on whether obtaining approvals etc was to be a smooth, or long drawn out process. Values of equipment and materials would depend upon the pipeline's intended service. Weightings of listed construction activities could vary by +/-several percentage points, depending upon terrain, numbers of river crossings etc

Did your estimate come within the range $21m - $35m? If so, the exercise could be considered successful. Comments/clarifications welcomed.