Ovoid Pipes

Ovoid concrete pipes are produced and tested in accordance with the relevant provisions of BS EN1916:2002/BS5911-1:2002 Class 150 including dimensional tolerances, crushing, hydrostatic, water absorption and joint tests.

The ovoid pipe has better velocity characteristics at low flows than equivalent circular pipes, which provides:

Lower operating costs, where some sewers may be laid without the need for pumping.

Better self cleansing and therefore less risk of siltation and blockage.

Are there any precautions to take for concrete pipes laid to steep gradients?

It is recommended that anchor blocks be cast into the ground every 3 or 4 pipe joints behind the socket (also consider installing packers on the face of sockets to prevent concrete to concrete contact).

How frequent should I be testing the pipeline during installation?

It is highly recommended to test the pipeline every 3 or 4 pipes laid as an absolute minimum (do not wait until whole line is installed before carrying out such test).

What are the appropriate ‘roughness values’ for concrete pipes?

Roughness values are:

Foul sewers: 1.5mm.

Surface water sewers: 0.6mm.

What are the recommended minimum depths of cover for concrete pipes?

Minimum depth of cover to top of pipes is 0.6m with bedding class S (360o granular bedding). For cover depths less than 0.6m, then the pipeline should be protected with either a full concrete surround, or a reinforced concrete slab should be placed over it (spanning sufficient distance onto trench walls).

What concrete pipes are generally reinforced?

Marshalls CPM concrete pipes are generally reinforced in sizes DN675 and above (it is possible to reinforce some of the smaller sizes and also to provide un-reinforced pipes in some of the larger sizes – usually made to order).

What is the maximum permissible velocity in concrete pipes?

Limits are not normally placed on maximum velocities but certain criteria such as the potential for erosion should be considered for steep gradients.

What is the maximum working pressure that concrete pipes can withstand?

Concrete pipes are designed to operate at low heads of water. The BS performance requirement is set at a minimum of 0.5 bar.

What is the most likely cause of air test failure for a concrete pipeline on site?

Common causes of air tests failures include:

Displaced seals (usually due to use of wrong pipe lubrication during installation).