Ductile Iron
Ductile iron is an engineered material that is lighter and stronger than cast, or grey, iron, the traditional choice for manhole covers and gratings. Ductile iron, which conforms to the ASTM A536 standard, offers the combination of a significantly higher strength-to-weight ratio, impact resistance and predictable mechanical performance. These characteristics make it possible to design covers and gratings that are stronger and more durable, while also delivering ergonomic and functional advantages not readily available with traditional alternatives.

To understand the differences between ductile iron and cast iron is to understand why PAM products are superior in design and performance.

Why Ductile Iron is Better

Ductile Iron		Cast Iron
• Engineered material — Strength    derived from structural design    and material performance		• Traditional material — Strength    derived from sheer weight and    bulk
• Predictable mechanical    performance — Materials allow    designs that achieve strength    and ergonomic and functional    efficiency		• Unpredictable performance — Only    way to achieve strength is to add    more material; little design flexibility,    vulnerable to catastrophic failure
• High strength-to-weight ratio —    Makes lightweight, user-friendly    designs achievable		• Relatively low strength-to-weight    ratio — Results in heavy, hard to    handle covers and gratings
• Ergonomically positive — Features    like hinged covers and automatic    locks can be incorporated;    one-man operation, enhanced    safety		• Ergonomically negative —        Two-man operation, chance of    back, hand and foot injuries
• Highly impact resistant		• Impact sensitive due to brittle    nature of material