Installation Manual - Future Pipe Industries

9.5. Relief plates
Where pipes are installed close to the surface or where weight of the soil exceeds the permitted wall stress level relief
plates can be used. The relief plates may only be used if:
A The ground consists of sand to a considerable depth.
B The trench is to be filled with sand and very well compacted.
These plates should have a rebate equal to the diameter of the pipe 5-10 cm deep. This rebate must be kept free from
soil during installation for example by means of synthetic foam. The dimensions of the relief plate must be chosen so
that the load-bearing capacity of the foundation is not exceeded. Select the correct size of the relief plate so that the
load bearing capacity of the foundation is not exceeded. The distance between the relief plate and crown of the pipe
may be maximum 0.5 x ID.
Fig. 9.5.a.
The plate must not be installed too high because the spread of the load will cause increased pressure on the pipe as in
fig.9.5.b. Positioning the relief plate within the recommended distance, i.e. ≤ 0.5 x ID, provides better side support.
Fig. 9.5.b.
0,5 D
45°
top load
free space
D
top load
free space
Wavistrong Installation Manual
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polystyrene foam
relief plate
relief plate
spread
relieving