Pipe Bedding
Trench Bedding
The term "bedding" is used to mean the complete arc material (granular or concrete) that supports the pipe within the trench against the total external load on the pipeline. The type of bedding, depend on pipe size, type of sub-soil, the load on the surface of the trench, the cover depth and trench width.

Bedding Factor
The load required to produce failure of a pipe in the ground is higher than the load required to produce failure in a crushing test machine. The ratio of the failure load for the pipe installed in the ground to the failure load in the crushing test machine is known as the Bedding Factor. The Bedding Factor varies with the support angle of granular material under the pipe. The Bedding Factors for Class D, N, F, B, S and A beddings are 1.1, 1.1, 1.9, 2.5 and 2.6 respectively.

Class N & D bedding
For Class N bedding these materials may be used:-

All-in aggregate
All-in aggregate can be of 20 mm diameter for all pipe sizes. Where available, 10 mm nominal size may be used for 100 & 150 mm pipes.

Sand
Sand may be coarse, medium or fine.

As dug material
As dug material is suitable where it has a compaction fraction of up to 0.3 and does not exceed 20 mm or 40 mm for 600 mm or larger diameter pipes.

Classes F, B and S beddings
Single size granular material
Single size granular material of Nominal single sizes of 10 mm, 14 mm or 20 mm may be used for pipe sizes from 100 mm to 500 mm diameter and 14 mm, 20 mm or 40 mm may be used for pipe sizes larger than 500 mm diameter.
2nd Industrial City, New Saniya,
New Al – Kharj Highway,
P.O. Box 17952,
Ar – Riyadh 11494,
Kingdom Of Saudi Arabia.
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