Which class of manhole cover should be used on a main city road or highway?

HD-20 (Heavy Duty, 20-tonne test load) or EHD-35 (Extra Heavy Duty, 35-tonne test load) should be used, depending on the traffic density and axle loads (Table 1).

What does the permanent set test check?

It measures the permanent deformation of the cover after the specified test load is applied and removed. This ensures the cover can withstand its design load without permanently bending (Clause 10.2).

What is the key material requirement for these covers?

The material must be ductile iron (also known as spheroidal or nodular graphite iron) conforming to the grades specified in IS 1865 (Clause 4).

Are these manhole covers watertight?

The standard design is not inherently watertight, but it specifies that double-sealed covers can be provided if required by the purchaser for special applications (Clause 7.1.3).

IS 15701

: 2006

Ductile Iron Manhole Covers and Frames

CurrentFrequently UsedSpecificationBIMTransportation · Drainage, Sewerage and Sanitary Fittings

Download PDF BIS Portal Google

This standard specifies the requirements for circular, square, and rectangular ductile iron manhole covers and frames. It classifies them into different load-bearing classes (from Light Duty to Extra Heavy Duty) suitable for various locations like footpaths, residential roads, and highways. The code details material properties, design features, dimensions, testing procedures (load test, permanent set), and marking requirements.

Specifies requirements for ductile iron manhole covers and frames, focusing on materials, design, and load bearing capacity.

Quick Reference Values

Test Load for LD-2.5 Class (Footpaths)25 kN

Test Load for MD-10 Class (Light Traffic)100 kN

Test Load for HD-20 Class (Main Roads)200 kN

Test Load for EHD-35 Class (Heavy Traffic/Commercial)350 kN

Material Specification ReferenceDuctile Iron as per IS 1865

Maximum Permissible Permanent Set1/300th of the clear opening

Practical Notes

Always select the load class based on the actual traffic conditions, not just the road type. For example, a residential street used by heavy garbage trucks may require a higher class than MD-10.

Ensure the frame is properly bedded in concrete to prevent rocking or rattling, which is a common cause of premature failure and noise complaints.

Ductile iron is significantly less brittle than grey cast iron (used in older covers), offering a major safety advantage as it bends under overload rather than shattering suddenly.