Navigating the Divide Between Cast Iron and Malleable Iron Fittings

Apr 11, 2024 | News

In the realm of plumbing and industry, the choice between cast iron fittings and malleable iron fittings is like picking between tradition and adaptability. While both boast iron’s strength, they diverge in manufacturing, properties, and applications. This introduction sets the stage for unraveling the contrasting worlds of these fittings, illuminating their distinct advantages and ideal contexts. Let’s explore the differences between cast iron vs malleable iron fittings, along with their real-life applications:

Cast Iron Fittings

Composition and Production:

Cast iron comprises iron alloys usually containing 2% to 4% carbon (occasionally up to 5%). It’s crafted by smelting iron ore or pig iron, blending it with diverse scrap metals and alloys. Cast iron fittings are fashioned via casting, pouring molten material into molds where it solidifies into the desired form.


  • Grey Cast Iron: Grey cast iron is pretty common. It’s good at resisting corrosion but tends to be brittle. It’s as strong as low or medium carbon steel but not great with tensile strength or handling shocks.
  • White Cast Iron: White cast iron is using in different fittings. It’s strong when you press down on it and holds up well against wear.
  • Ductile Cast Iron: Ductile cast iron is tough. It’s made stronger and more flexible by adding magnesium, which forms nodules in the iron.


  • Well caps and well seals are common items made from grey cast iron.
  • White cast iron is using in applications like teeth of a backhoe’s digging bucket and lifter bars in ball mills.
  • Ductile cast iron is using for items like pitless spools, well seals, and well caps due to its improved properties.
Cast Iron Fittings
Cast Iron Fittings

Malleable Iron Fittings

Transformation Process:

Malleable cast iron pipe fittings begin as cast iron fittings but undergo an annealing heat treatment process. Initially, white cast iron with a high carbon content is cast, and then it’s heated to just below its melting point for an extended period. This transforms carbon into graphite, resulting in malleable cast iron.


Malleable iron has properties similar to mild steel. It is less brittle than grey cast iron, allowing for bending and shaping without cracking.


  • Malleable iron is more ductile and easier to work with.
  • It has good hardness and abrasion resistance.


  • Malleable iron is more expensive than grey cast iron.
  • Its tensile strength is lower compared to steel.
Malleable Iron 130 Equal Tee BSPT Thread

Real-Life Applications

Cast Iron:

  • Used in drainage systems, sewer pipes, and manhole covers due to its corrosion resistance.
  • Structural components like columns and beams in historical buildings.

Malleable Iron:

  • Commonly used for pipe fittings, flanges, and valves in plumbing systems.
  • Railings, furniture, and decorative hardware due to its workability.
  • Automotive parts and machinery components.

Remember, the pressure rating of a fitting depends on the temperature of the materials used with it. The proper term for malleable fittings is now “class” rather than “pound”. Fuild Tech is a malleable iron fittings supplier can always manufacturing and providing high quality products worldwide.