pipe expansion and contraction during installation

[cvg]

A large waterline project involves 1200m of 1676mm diameter (3940 ft of 66 inch) steel pipe. The pipe is to have welded joints and be encased in concrete for long-term corrosion protection. Our concern is the force that will be transferred to the pipe due to expansion and contraction during installation. The pipe will be heated from the sun when it is lying exposed and from the heat of hydration after it is backfilled in concrete. It will then cool down significantly when the soil backfill is placed on the pipe and after the cool water is placed in the pipe. Because the joints are welded the forces that are transferred to the pipe could be significant.

I am looking for guidance in installation controls to mitigate expansion/contraction concerns during construction.

 

[stanweld]

Contractive forces will only be applied at pinning locations. I doubt that they will be high noting the short length of the pipeline. How will you connect the two ends? Are there changes in direction along the length of the pipeline.

 

[CESSNA1]

CVG:
There are two methods that I know of that are used. One is expansion joints. The other is a bend or two in the pipe to absorb the expansion. The concrete coating presents a problem in that it may crack and drop off from the repeated cycling. Rough estimate is that the pipe will expand 15.4 inches for a 50 deg F temp difference and the concrete will expand 18.7 inches. I am assuming the pipe is above ground?

Regards
Dave

 

[cvg]

the pipe will be installed underground in a trench. the trench will be backfilled with concrete and a large portion of the trench will have a layer of insulation above the pipe.

 

[CESSNA1]

CVG: For an underground pipe, presumably filled with water, and hopefully moving water, I do not beleive that you have a problem. Being undergound will slow the warming of the pipe and the water in it will absorb much of the sun's heat. An empty pipe close to the surface is a different issue. If the top of the pipe is about 3-4 feet beneath the soil surface i think it is a minor problem.

Regards
Dave