Project Planning Control 4 E Part 8 pps

Print packing a1 a2 a3 Finalise pamphlet for b Waiting period Waiting period Pack & disp b1 Invoice b1 Waiting period Finalise pack for b Process replies 2 Printing a1 a2 a3 Order packin

2

2

2 2

2

2

2

2 2

2 2 2

3

3

3 3

3

2 3

3

3 3

3

3

3

3 3

3 3

4

4

4

4 4

7

5

3 3

3 4

4 4

4

4

4

4 4

5

5

5

5 4

4 4 4 5

3 2

F G

K K

L M

M

L

L

G J H

Network applications outside the construction industry

In practice, the test shot will consist of three or more types of advertisingleaflet and record packaging, and the result of each type will have to beassessed before the final main campaign leaflets are printed

Depending on the rate of return of orders, two or more record ordering anddispatch stages will have to be allowed for These are shown on the network

as B1 and B2

Figure 23.4 Pump manufacture – critical path analysis

Print packing a1 a2 a3

Finalise pamphlet for b Waiting period

Waiting period

Pack & disp b1

Invoice b1

Waiting period

Finalise pack for b

Process replies 2

Printing a1 a2 a3

Order packing a1 a2 a3

Deliver

"free ride"

Pack &

dispatch a1 a2 a3

Mail pamphlets a1 a2 a3

Deliver packing

Assess return records

Process replies 1

Pack & disp b2

Invoice b2

Prepare envelopes

Approval Deliver records a

Delivery Order records b1

Order records b2

Delivery Recruit labour

Project Planning and Control

5 Manufacture of a package boiler

The programme in this example covers the fabrication and assembly of a largepackage boiler of about 75 000 kg of superheated steam per hour at 30 bar gand a temperature of 300°C The separate economizer is not included.The drum shells, drum ends, tubes, headers, doors and nozzles are boughtout, leaving the following manufacturing operations:

1 Weld drums (longitudinal and circumferential seams);

2 Weld on drum ends;

3 Weld on nozzles and internal supports;

4 Drill drums for tube;

190

Figure 23.5 Mail order campaign

Network applications outside the construction industry

5 Stress relieve top and bottom drums;

6 Bend convection bank tubes;

7 Fit and expand tubes in drums – set up erection frame;

8 Weld fins to furnace tubes; pressure test;

9 Produce waterwall panels;

10 Gang bend panels;

11 Erect wall panels;

12 Weld and drill headers; stress relieve;

13 Weld panels to headers;

14 Weld on casing plates;

15 Attach peepholes, access doors, etc.;

16 Pressure test;

17 Seal-weld furnace walls;

18 Fit burners and seals;

19 Air test – inspection;

D Insulation and preparation for dispatch

The programme assumes that all materials have been ordered and will beavailable at the right time Furthermore, in practice, subprogrammes would benecessary for panel fabrication, which includes blast cleaning the tubes and finbar, automatic welding, interstage inspection, radiography, and stressrelieving Figure 23.6 shows the main production stages covering a period ofapproximately seven months

6 Manufacture of a cast machined part

The casting, machining and finishing of a steel product can be represented innetwork form as shown in Figure 23.7 It can be seen that the total duration

of the originally planned operation is 38 hours By incorporating the principlethat if the component has to be moved between workstations (efficiency can

be increased if some of the operations are performed while the part is on themove) it is obviously possible to reduce the overall manufacturing time The

Form burner opening

Stress

Weld header

Fit D-wall

Fit intervals

Weld pins

Insulation

Prep for transport

Stress

Do

Weld on studs

Press test

Press test Refract seals

Weld drum ends Radiograph

Radiograph

Do

Do

Do Weld up panel

Drill holes

Weld lugs

Fit conv bank

& expand

Erect risers

Fit roof

Air test

Final check

Drill tube holes

Do

Attach headers

Attach headers

Assemble s.h.

Remove frame

Fit super heat Install refract

Cladding

Despatch

Weld drum circumferent

Do

Do

Do Fin weld

Weld ends and radiograph

Bend convect tubes

Bend s.h.

tubes

Set drums

Erect rear panel

Network applications outside the construction industry

obvious activities which can be carried out while the component is actuallybeing transported (usually on a conveyor system) is cooling off, painting andpaint drying As can be seen from Figure 23.8, such a change in themanufacturing procedure saves 3 hours

Any further time savings now require a reduction in duration of some of theindividual activities The first choice must obviously be those with the longestdurations, i.e

1 Make pattern (8 hours);

2 Cool off (6 hours);

3 Dry paint (8 hours)

These operations require new engineering solutions For example, in (1), thepattern may have to be split, with each component being made by a separatepattern maker It may also be possible to subcontract the pattern to a firm withmore resources Activity (2) can be reduced in time by using forced-draughtair to cool the casting before fettling Care must, of course, be taken not tocool it at such a rate that it causes cracking or other metallurgical changes.Conversely to (2), the paint drying in (3) can be speeded up by blowing warmair over the finished component If the geographical layout permits it, it may

be possible to take the heated air from the cooling process, pass it through afilter and use it to dry the paint!

Further time reductions are possible by increasing the machining time ofthe milling and drilling operations This may mean investing in cutters ordrills which can withstand higher cutting speeds It may also be possible to

Figure 23.8 (Revised)

Project Planning and Control

194

Figure 23.9 (Original)

Figure 23.10 (Revised)

Network applications outside the construction industry

increase the speed of the different conveyors which, even on the revizednetwork, make up one hour of the cycle time

For those planners who are familiar with manufacturing flow charts it may

be an advantage to draw the network in precedence format (see Chapter 12).Such a representation of the initial and revised networks is shown in Figures23.9 and 23.10, respectively

It is important to remember that the network itself does not reduce theoverall durations Its first function is to show in a graphic way the logicalinterrelationship of the production processes and the conveying requirementbetween the manufacturing stages It is then up to the production engineer orcontroller to examine the network to see where savings can be made This is,

in fact, the second function of the network – to act as a catalyst for the thoughtprocesses of the user to give him the inspiration to test a whole series ofalternatives until the most economical production sequence has beenachieved

The use of a PC at this stage will, of course, enable the various trial runs

to be carried out quite rapidly, but, as can be seen, even a manual series oftests takes no longer than a few minutes As explained in Chapter 14, the firstoperation is to calculate the shortest forward pass – a relatively simpleoperation – leaving the more complex calculations of float to the computerwhen the final selection has been made

Networks and claims

From the contractor’s point of view, one of themost useful (and lucrative) applications of net-work presentation arises when it is necessary toformulate claims for extension of time, disruption

to anticipated sequences or delays of equipmentdeliveries There is no more convincing systemthan a network to show a professional consultanthow his late supply of design information hasadversely affected progress on-site, or how a latedelivery has disrupted the previously statedmethod of construction

It is, of course, self-evident that to make thefullest use of the network for claim purposes, the

method of construction must have been

pre-viously stated, preferably also in network form.The wise contractor will include a networkshowing the anticipated sequences with histender, and indicate clearly the deadlines bywhich drawings, details and equipment arerequired

In most cases the network will be accepted as

a fair representation of the construction gramme, but it is possible that the client orconsultant will try to indemnify himself by suchstatements that he (the consultant) does notnecessarily accept the network as the only logical

pro-Networks and claims

sequence of operations, etc Therefore it is up to the contractor to use his skillsand experience to construct the works in the light of circumstances prevailing

at the time

Such vague attempts to forestall genuine claims for disruption carry littleweight in a serious discussion among reasonable people, and count even lessshould the claim be taken to arbitration The contractor is entitled to receivehis access, drawings and free issue equipment in accordance with his statedmethod of construction, as set out in his tender, and all the excuses ordisclaimers by the client or consultant cannot alter this right Thosecontractors who have appreciated this facility have undoubtedly profitedhandsomely by making full use of network techniques, but these must, ofcourse, be prepared accurately

To obtain the maximum benefit from the network, the contractor must showthat:

1 The programme was reasonable and technically feasible;

2 It represented the most economical construction method;

3 Any delays in client’s drawings or materials will either lengthen the overallprogramme or increase costs, or both;

4 Any acceleration carried out by him to reduce the delay caused by othersresulted in increased costs;

5 Any absorption of float caused by the delay increased the risk ofcompletion on time and had to be countered by acceleration in other areas

or by additional costs

The last point is an important one, since ‘float’ belongs to the contractor It isthe contractor who builds it into his programme It is the contractor whoassesses the risks and decides which activities require priority action Themere fact that a delayed component only reduced the float of an activity,without affecting the overall programme, is not a reason for withholdingcompensation if the contractor can show increased costs were incurred

Examples of claims for delays

The following examples show how a contractor could incur (and probably claim) costs by late delivery of drawings or materials by the employer

re-Example 1

To excavate a foundation the network in Figure 24.1 was prepared by thecontractor The critical path obviously runs through the excavation, giving the

Set cages

Make up cages Clear

area

Concrete

Assimilate

Steel drgs Prelim

drgs

Blind Shutr.

5

15Project Planning and Control

path through the reinforcing steel supply and fabrication a float of 4 days Ifthe drawings are delayed by 4 days, both paths become critical and, in theory,

no delays occur However, in practice, the contractor may now find that thedelay in the order for reinforcing steel has lost him his place in the queue ofthe steel supplier, since he had previously advised the supplier thatinformation would be available by day 10 Now that the information was onlygiven to the supplier on day 14, labour for the cages was diverted to anothercontract and, to meet the new delivery of day 29, overtime will have to beworked These overtime costs are claimable

In any case, the 4-day float which the contractor built in as an insuranceperiod has now disappeared, so that even if the steel had arrived by day 29 andthe cage fabrication took longer than 3 days, a claim would have beenjustified

198

Figure 24.1

Figure 24.2

Test run Handover

Elect conn.

Conn.

pumps Erect

pumps Deliv.

Deliv.

Elect conn.

Conn.

pipes Erect

4 Pump 2

12 11

7

Networks and claims

What the programme does not show, and what it need not show, are the

resource restraints imposed by the contractor to give him economical working

A network submitted as a contractual document need only show the logic

from an operational point of view Resource restraints are not logic restraints

since they can be overcome by merely supplying additional resources.The contractor rightly pointed out that he always intended to utilize thefloat on the first set of pumps to transfer the pipe fitters and electricians to thesecond pump as soon as the first pump was piped up and electrically

connected The implied network, utilizing the float economically was

therefore as shown in Figure 24.3

Now, to meet the programme, the contractor has to employ two teams ofpipe fitters and electricians which may have to be obtained at additional costfrom another site and certainly requiring additional supervision if the twopumps are geographically far apart Needless to say, if the contractor shows

the resource restraints in his contract network, his case for a reimbursement of

costs will be that much easier to prove

Examples of force majeure claims

The causes giving rise to force majeure claims are usually specified in thecontract, and there is generally no difficulty in claiming extension of time forthe period of a strike or (where permitted) the duration of extraordinary bad

weather What is more difficult to prove is the loss of time caused by the effect

of a force majeure situation It is here where a network can help the contractor

to state his case

Example 1

A boiler manufacturer has received two orders from different clients and hasprogrammed the two contracts through his shops in such a way that as one

Figure 24.3

Project Planning and Control

boiler leaves the assembly area, the parts of the second boiler can be placedinto position ready for assembly The simplified network is shown in Figure24.4 Because the factory had only one assembly bay, Boiler No 2 assemblyhad to await completion of Boiler No 1, and the delivery promises of Boiler

No 2 reflected this

Unfortunately the plate for the drum of Boiler No 1, which was orderedfrom abroad, was delayed by a national dock strike which lasted 15 days Theresult was that both boilers were delayed by this period although the plate forBoiler No 2 arrived as programmed

The client of Boiler No 2 could not understand why his boiler should bedelayed because of the late delivery of plate for another boiler, but whenshown the network, he appreciated the position and granted an extension Hadthe assembly of Boiler No 2 started first, Boiler No 1 would have beendelayed 70 days instead of only 15, while Boiler No 2 would have incurredstorage costs for 60 days Clearly, such a situation was seen to be unrealistic

by all parties The revized network is shown in Figure 24.5

200

Figure 24.4

Figure 24.5

Networks and claims

Example 2

The contract for large storage tanks covered supply erection and painting Badweather was a permissible force majeure claim During the erection stage,high winds slowed down the work because the cranes would not handle thelarge plates safely The winds delayed the erection by four weeks, but by thetime the painting stage started, the November mists set in and the inspectorcould not allow painting to start on the damp plate The contractor submitted

a network with the contract to show that the painting would be finished before

November Because of the high winds, the final coat of paint was, in fact,delayed until March, when the weather permitted painting to proceed.Figure 24.6 illustrates the network submitted which, fortunately, clearlyshowed the non-painting month, so that the client was aware of the positionbefore contract award The same point could obviously have been made on abar chart, but the network showed that no acceleration was possible after thewinds delayed the erection of the side plates To assist in relating the weeknumbers to actual dates, a week number/calendar date table should beprovided on the network

The above examples may appear to be rather negative, i.e it looks as ifnetwork analysis is advocated purely as a device with which the contractorcan extract the maximum compensation from the client or his advizers Nodoubt, in a dispute both sides will attempt to field whatever weapons are attheir disposal, but a more positive interpretation is surely that network

techniques put all parties on their mettle Everyone can see graphically the

effects of delays on other members of the construction team and the cost ortime implications that can develop The result is, therefore, that all parties willmake sure that they will not be responsible for the delay, so that in the endeveryone – client, consultant and contractor – will benefit: the client, because

he gets his job on time; the consultant, because his reputation is enhanced; andthe contractor, because he can make a fair profit

Figure 24.6

Project Planning and Control

Fortunately the trend is for claims to be reduced due to the introduction ofpartnering In these types of contract, which are usually a mixture of firmprice and reimbursable costs, an open book policy by the contractor allows theemployer to see how and where his money is being expended, so that there are

no hidden surprizes at the end of the contract ending up as a claim

Frequently any cost savings are shared by a predetermined ratio so that allparties are encouraged to minimize delays and disruptions as much aspossible In such types of contracts network analysis can play an importantpart, in that, provided the network is kept up to date and reflects the true andlatest position of the contract, all parties can jointly see graphically where theproblem lies and can together hammer out the most economical solution

202

Resource loading

Most modern computer programs incorporatefacilities for resource loading or resource alloca-tion Indeed, the Hornet program mentioned inChapter 17 features such a capability, and itsmethod of operation is shown in Chapter 30

In principle, the computer aggregates a ular resource in any time period and comparesthis with a previously entered availability levelfor that resource If the availability is less than therequired level, the program will either

partic-1 Show the excess requirement in tabular form,often in a different colour to highlight theproblem; or

2 Increase the duration of the activity requiringthat resource to spread the available resourcesover a longer period, thus eliminating theunattainable peak loading

The more preferable action by the computer is(1), the simple report showing the overrun It isthen up to management to make the necessaryadjustments by either extending the time period –

if the contractual commitments permit – ormobilizing additional resources In practice, of