SANS 664 Gate Valves Made of Ductile Iron (Spheroidal Graphite Iron)

In the demanding landscape of municipal water infrastructure, reliability is not just an option—it is a necessity. At Metalsin, we understand that the South African water sector requires robust solutions capable of withstanding high pressures and challenging environmental conditions.

SANS 664 NRS resilient seal gate valves: cap top (left) & handwheel operated, made of ductile iron (spheroidal graphite iron) body.

This is why our flagship product line focuses on SANS 664 gate valves made of ductile iron (spheroidal graphite iron). Combining the strict dimensional and performance standards of SANS 664 with the superior metallurgical properties of ductile iron, we supply valves that ensure longevity and operational safety.

Versatile Design for Municipal Applications

Our SANS 664 gate valves are engineered to meet the diverse needs of municipal waterworks and irrigation systems. While the material provides the strength, the design provides the functionality. Key configuration features include:

• Stem Types: Available in both Rising Stem (where the stem moves upward as the valve opens, providing a visual indication of position) and Non-Rising Stem (ideal for underground installations or tight spaces).
• Operation: We offer flexible operation methods, including the standard Cap Top & T-key for underground utility access, or a Handwheel for above-ground pump station usage.
• Corrosion Protection: Every valve body and bonnet undergoes rigorous surface preparation followed by Fusion Bonded Epoxy (FBE) coating on both internal and external surfaces. This ensures potable water safety and prevents rust and corrosion.

Why We Use Ductile Iron (Spheroidal Graphite Iron)

The core strength of our valves lies in the material of the body and bonnet. While older valve designs relied on Grey Cast Iron, modern waterworks demand the superior properties of Ductile Iron, also technically known as Spheroidal Graphite Iron (SG Iron).

The Manufacturing Secret: The Nodularization Process

The superior quality of Metalsin’s valves starts in the foundry. The transformation from standard iron to high-grade ductile iron requires a precise metallurgical procedure known as the Nodularization (or Spheroidization) Process.

Casting and pouring process for ductile iron gate valve bodies.

• Base Metal Preparation: We start with a low-sulfur base molten iron. High sulfur content can interfere with the process, so strict control of the raw material is essential.
• Magnesium Treatment: The critical step involves treating the molten iron with a nodularizing agent, typically a Magnesium-Ferrosilicon alloy. Magnesium is the key element that changes the graphite structure.
• Inoculation: Shortly after adding magnesium, an inoculant is added to promote the formation of graphite centers.
• The Result: This chemical reaction forces the carbon (graphite) to precipitate into microscopic spheres (nodules) rather than the flakes found in ordinary grey iron.

The Advantages of Spheroidal Graphite Iron in Valves

Because of this controlled production process, the “spheroidal” structure fundamentally changes the metal’s behavior, offering distinct advantages for SANS 664 gate valves:

Ductile iron gate valve body in stock.

• High Tensile Strength: Unlike grey iron where graphite flakes create stress points (cracks waiting to happen), the spherical nodules allow the metal to hold together under immense force. It can withstand much higher internal pressures without bursting.
• Ductility and Elongation: As the name suggests, this iron is “ductile.” It has the ability to bend or deform slightly under stress without fracturing. This is crucial for surviving ground shifting, pipe misalignment, or water hammer effects.
• Impact Resistance: Spheroidal graphite iron is far more resistant to impact damage during transport, installation, and operation.
• Weight Reduction: Because ductile iron is stronger, the valve walls can be cast thinner than those of grey iron while maintaining the same pressure rating. This results in a lighter valve that is easier to handle and install.

International Equivalent Material Grades

At Metalsin, we ensure our castings meet the highest global standards. While we manufacture specifically for the SANS 664 standard, the ductile iron used in our foundries adheres to equivalent international material grades to ensure consistent quality and mechanical properties. We utilize the following International Equivalent Material Grades for our valve bodies and bonnets:

When selecting valves for municipal supply, the material is just as important as the design. Metalsin’s SANS 664 gate valves, made from premium ductile iron (spheroidal graphite iron), offer an ideal balance of structural integrity, corrosion resistance, and operational flexibility, whether you require flanged ends for bolting connection or socketed ends for fast gasket sealing; in all cases, our use of SG Iron produced via precise nodularization ensures a leak-free, durable service life.