For municipal drainage and sewage projects, selecting a manhole cover is not simply a matter of choosing a diameter. The load class, material, clear opening, cover-and-frame design, surface treatment, locking requirements, and quality documentation all affect whether the product matches the project. This guide explains what a D400 ductile iron round manhole cover means in practice and what procurement teams should specify before requesting quotations.

 

 

 

1. What Does D400 Mean for a Manhole Cover?

 

Under EN 124 classification, D400 indicates a 400 kN test load class. It is commonly selected for areas exposed to substantial vehicular loading, such as urban arterial roads, highways, and other heavy-traffic zones. The load class is a starting point for specification; the complete cover and frame design, dimensions, installation conditions, and applicable project requirements should also be confirmed.

 

EN 124 Class Test Load Typical Application
A15 15 kN Pedestrian-only zones, gardens
B125 125 kN Sidewalks, cycle lanes, car parks
C250 250 kN Curbside zones, light vehicle areas
D400 400 kN Urban arterials, highways, heavy vehicle zones
E600 600 kN Dockyards, airports, extreme heavy-load zones
F900 900 kN Aircraft pavements, special industrial zones

Key point for procurement

A D400 marking should be evaluated together with the relevant test requirements, dimensions, frame configuration, and project drawings rather than treated as a substitute for a complete specification.

 

 

 

2. Why Choose Ductile Iron for D400 Applications?

 

Ductile iron QT500-7 is the material specified for this product. Compared with conventional grey cast iron, ductile iron offers a combination of strength and ductility that is well suited to cast components exposed to traffic loading and impact.

 

Property Grey Cast Iron (HT200) Ductile Iron (QT500-7)
Tensile Strength 200 MPa ≥500 MPa
Yield Strength Not well-defined ≥320 MPa
Elongation <1% (brittle) ≥7%
Impact Resistance Lower resistance to shock loading Higher energy absorption
Typical Failure Behavior More brittle fracture behavior More ductile deformation behavior

 

Material properties can vary by grade, specification, and test method. The values above are used here as a practical comparison for the grades identified in this guide.

 

 

 

3. Engineering Features to Check Before Ordering

 

A D400 cover is a system rather than a single round plate. Procurement teams should confirm the following features against the project drawings or technical specification:

  • Cover and frame: confirm that the cover is supplied with the matching frame required by the project.
  • Clear opening: specify the required opening size; do not rely only on the nominal outside diameter.
  • Hinge and locking: confirm whether an integral hinge, retained cover, or security lock is required.
  • Surface pattern: confirm anti-slip requirements and the required top-surface marking.
  • Surface treatment: specify asphalt anti-rust coating or an alternative treatment where required.
  • Marking: identify the required pipeline/service marking, such as “Sewage”, or provide a custom marking.
  • Dimensions and tolerances: confirm the production drawing and applicable dimensional tolerance requirements.

 

 

 

4. D400 Manhole Cover Specifications

 

Parameter Specification
Product Type Round manhole cover with matching frame
Material Ductile Iron QT500-7
Load Class EN 124 D400 (400 kN test load)
Nominal Diameter 750 mm for the referenced product configuration
Casting Process Sand casting
Surface Treatment Asphalt anti-rust coating
Surface Pattern Cross-hatched anti-slip pattern
Pipeline Identification Cast “Sewage” marking
Hinge Mechanism Integral cast hinge lug; cover remains attached to frame
Security Lock Brass lock cylinder insert, optional
Dimensional Tolerance CT8-CT10 (ISO 8062), per stated factory capability
Applicable Standard EN 124
Quality Documentation Material test report, dimensional inspection, performance test, hardness record

 

  WhatsApp： +86-184 3796 0706