Pipeline lowering with 2 crane 3

[ceasar20]

Hello Mates,

we will start the activities of Pipeline lowering (L 300m D 12 inches thx 8 mm X 52 trench depth 1.70 m ) with two cranes every crane have 2 lift points.
I want to ask about:

Two cranes are sufficient?

Recommended distance between lift points ?

The distance between Pipeline and trench centre.

Thank you in advance for your recommendation.

 

[1503-44]

Are you going to lift 300 m all at one time? Usually pipe is welded up set on blocks next to the trench and lowered down into little by little in a continuous progressive manner. You need to clarify exactly what you intend to do. You will certainly not be lifting 300m at one time with 2 cranes, so make it good.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.

 

[ceasar20]

Of course No, total length is 300 m , I will lower every 30 m. I need recommendations.

 

[DekDee]

Please do not take offence but what are you doing being involved in a pipeline when it seems you do not have a clue what you are doing ?
There are probably hundreds of experienced pipeline supervisors out of work at the moment and you think you can do it yourself via an internet forum ?

 

[HTURKAK]

The welded pipe string is lowered into the excavated trench using side-boom cranes. The no. of cranes shall be decided with a calculation,the stresses developing shall be elastic for the deformed shape. That is, the lowered section in the trench, lifted portion and remaining section laying on the supports ,the stresses shall be kept elastic. The following picture depicts the concept.

A novel document for Onshore Pipelines is IPLOCA Road to Success Onshore Pipelines . Membership is required to reach to this document, however one can read online the old version ( 1st Edition ) from the link=

https://issuu.com/pms72/docs/iploca_road_to_success

 

[1503-44]

One has to ask what you intend to do. You didn't say much. Remember, this is Internet and a lot of crazy ideas are floated. Just 3 days ago, that's exactly what someone had in mind. Plus your question is so basic, it gave me the impression that you also don't have much of a clue as how to do this.

In addition to maintaining stresses within the elastic range during lowering, as stated above, it is essential that no, or very, very little elastic stress remains once the pipe is positioned in the trench.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.

 

[LittleInch]

Any reasonable length of 12" thin wall pipe suddenly becomes remarkably flexible when lifted and the potential for buckling the pipe is high unless you know what you're doing. Hopefully someone on your site does as this is nothing like a static lift, but is a constantly moving set of parabolas. AN awful lot of this is just judgement and fine control of the lift devices. That's why you employ good people to do it.

Two lifting points is absolute minimum. I've never seen a pipeline installation using two lift points from a single hook. You really need at least three and preferably 4 machines

12" thin wall you probably want about 25m between lift points.

Distance between pipeline and centre of trench - about 5m max, especially with only two lifting points.

why cranes? A 12" line like this should be within the range of some decent 360 excavators, but side booms or pipe layers are made for this job.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[KevinNZ]

Without comment