Can you give us more details about your job?

Is it,

1. a pipeline from an offshore platform to land?
2. a pipeline at an offshore platform?
3. a pipeline run on land?
4. a pipeline within a refinery?
5. a single line or a few in parallel? 
6. a combination of the above?
7. other?

No 1 and no 3 are essentially linear jobs while 2 and 4 are not so linear, each segment might be very different, production rates will be different as well as logic. You are talking about a replacement so it might require getting out existing instead of abandoning, and then placing new one.

Materials deliveries can be critical, especially on remote locations. Material delivery and consumption are better modeled using consumable resources, this cannot be done using regular resources in an effective way so that if for some reason deliveries become late no changes in schedule logic are needed. Those changes in schedule logic might not be easy on some job types. Material deliveries is something some schedulers do not include because modeling for it is absent in their software, the work-around using delivery activities is frequently not a good one. 

http://www.pmknowledgecenter.com/node/104

If the work is to be continued on different shifts you might need software capable of modeling different crews and productivity on different shifts on the same activity. If the work requires shutting down some production facilities this is usually very costly and sometimes will require updating the schedule on daily or even per shift basis.

Linear jobs cannot be modeled without considering that usually the work is done working on several activities at the same time with some physical distance/offset, while excavating a crew at some distance is placing bedding, another at some other distance is placing the pipe, another is back filling and so on for this SS and FF lag is used. Do not pretend any model to be perfect, usually neither the extremely granular using hundreds of short duration activities and no SS/FF(lag), or a single parallel set of long duration activities activities will make it a best choice. 

I would only consider Asta PP or Spider Project to model such jobs, my personal choice is Spider Project. 

Hi Nithin

For linear projects such as pipelines the choice of software is particularly important and I will say right now that P6 is wholly inadequate for such projects.

Also the practice of using long duration task bars and SS lead lags is the wrong approach (although Vladimir will give you good reasons opposite)

The normal sequence of tasks in a pipeline project are:

Site clearance > excavate and bed > string pipes > weld pipes either Fully Automatic : Semi Automatic : Manual welding : this is usually the critical task > Weld Test > Joint cover > Lift and Lay welded pipe > backfill stage 1 > Marker tape and/or FOC > Backfill stage 2 > Final Top and/or Fencing.

The choice of welding will determine the duration of each task - the welding element should not exceed 5 days.

Along the line there will be Flow control valves and Air release valves within concrete chambers.

You also have to allow for civil crossings such as ditches - culverts - roads - wadis etc.

The best form of software is a dedicated time chain form such as Vicos or Tilos.

Second best is Asta PowerProject in Task per Line mode or Spider.

The biggest problem you will face is spacial clash where more than one task is planned in the same location at the same time.

I hope this helps.

Best regards

Mike Testro