Choosing the right Composite Manhole Cover
Why choose a Composite Cover over a steel or cast cover?
Composite technology and manufacturing has progressed significantly over recent years with
almost all areas of Civil Engineering seeing the use of composites as a viable alternative to the more traditional steel or cast covers and grates.
For years the traditional materials were considered the only option due to the weight loading capacity requirements. This resulted in most installations having capable but heavy
to lift steel covers and grates.
More and more civil engineering sectors have seen the benefits of a composite cover. Composites will not rust, cannot be traded for scrap therefore eliminating the theft issue. Composites can withstand extremes of temperatures and have an excellent strength to weight ratio making them significantly more user friendly. You will see composites in use within industries such as Railways, Telecoms, Highways, Street Lighting and Utilities to name a few.
How do I know what size and load rating?
Cover size
This is often an area of confusion, but manhole covers are determined by their ‘clear opening size’, which is essentially the size of the hole within the frame and not the overall size of the cover.
For example, an Amlite AC6060D400 Cover and Frame is listed as a 600mm Square Cover and Frame with a D400 load rating.
The first part of this description 600mm is the clear opening distance if you took a tape and measured from one inside point of the frame across to the other corresponding point of the frame as shown in these images.
The actual cover size in this case is 644mm. Same applies to Circular Covers where you would measure the inside diameter of the frame.
Load ratings
Composite covers are manufactured to varying thicknesses and strengths according to where they will be installed. For example the Amlite cover range can accommodate an installation for just pedestrian traffic up to fully laden 40ft trucks depending on the application.
Guide to load ratings
Common load classifications according to standard BS EN124
A15 – For areas only accessible to pedestrians and pedal cyclists.
B125 – Suitable for Pedestrian, driveways and areas accessible by lighter vehicles.
C250 – Suitable for areas with slow moving heavy traffic.
D400 – Suitable for all types of road vehicles.
Regarding load ratings always check the local standard applicable to acceptable load classification.
We hope this guide is of help but most importantly if you are unsure please ask, we are here to help.