High Silicon Cast Iron Tubular Anode

This tubular anode, made of high silicon cast iron alloy containing 14% to 18% silicon, is highly resistant to both acidic and alkaline environments. It develops a porous, semi-conductive silicon dioxide (SiO₂) film on its surface, which helps reduce its consumption rate over time.

Keeper Anodes employs a specialized centrifugal chill casting process using static metal molds to create these high-quality alloys with consistent weight and superior microstructure. The anode’s surface features a unique granular texture that enhances current distribution, improving its utilization efficiency by 85% to 90%. Accelerated corrosion tests confirm that our chill casting anodes provide more ampere-years per pound compared to competing products.

This type of tubular high silicon cast iron anode is well-regarded for its centralized cable connection and enhanced sealing properties, which benefit from additional sealing materials inside the anode. After making the connection, it can be sealed using polyurethane alone or a combination of polyurethane and Novoid A electrical sealant.

Our tubular high silicon cast iron anode finds widespread use in various applications for impressed current cathodic protection, including deep well systems, shallow installations, and offshore structures.


Centrifugal Casting Process

Our tubular high silicon cast iron (HSCI) anodes are created using a centrifugal chill casting method. In this process, the mold spins at speeds exceeding 1000 rpm, generating a force that eliminates trapped gas and directs impurities to the inside of the anode, where they won’t affect performance. This results in a dense, tightly packed metal structure that enhances the anode’s lifespan.

Low Connection Resistance

The center connection of our anodes, featuring zinc wedge-lock or bolt connectors, ensures minimal resistance (less than 0.001 ohms). This design allows for a balanced distribution of current along the entire length of the anode, extending its lifespan and providing consistent current discharge. Additionally, the connection component is protected with high-quality epoxy resin to prevent moisture ingress.

Low Consumption Rate

The coarse stippled surface texture of our anodes increases the surface area relative to weight, reducing current density and resulting in 30% more amp-years compared to traditional stick anodes.

Easy Installation

We offer a unique cable connection device for rapid installation. Typically, two workers can connect over 200 anodes in less than eight hours, making the installation process efficient and straightforward.

ISO 9001 Quality Control

Our anodes undergo rigorous manufacturing, inspection, and testing procedures to ensure consistent high-quality products. Anode samples are taken before and after each casting process according to ASTM sampling standards to maintain quality standards.

Chemical Composition

Element ASTM A518 / A518M Grade 1 (Si – Fe) ASTM A518 / A518M Grade 3 (Si – Fe – Cr) BS 1591 1975
Silicon (Si) 14.2% ~ 14.75% 14.2% ~ 14.75% 14.25 ~ 15.25%
Chromium (Cr) 0.5% max. 3.25% ~ 5.0% 0.5% max.
Manganese (Mn) 1.5% max. 1.5% max. 0.5% max.
Copper (Cu) 0.5% max. 0.5% max.
Molybdenum (Mo) 0.5% max. 0.2% max.
Carbon (C) 0.65% ~ 1.1% 0.7% ~ 1.1% 1.4% max.
Phosphorus (P) 0.25% max.
Sulphur (S) 0.1% max.
Iron (Fe) Remainder Remainder Remainder

Note: ASTM A518 Grade 3 chemistry is well-suited for environments with electrolytes containing high levels of chloride ions. This grade includes a higher amount of chromium, which helps improve the performance of the anode under these conditions.

Electrochemical Properties

For anodes made of the same material and structure, differences in how quickly they wear away are mainly influenced by the chemical and physical conditions of the environment they’re in. Interestingly, the rate at which they wear down doesn’t seem to be greatly affected by how much electrical current is flowing through them per unit of surface area. Using coke breeze around the anode in soil ground beds tends to slow down their rate of wear.

Environment Nominal Current Density Consumption Rate
Soil / Fresh Water 0.2 – 0.5 A/ft² (2 – 5 A/m²) 0.2 – 1.2 lbs/A.y (0.1 – 0.5 kg/A.y)
Coke Breeze 0.5 – 1 A/ft² (5 – 10 A/m²) 0.1 – 0.7 lbs/A.y (0.05 – 0.3 kg/A.y)
Seawater 1 – 5 A/ft² (10 – 50 A/m²) 0.7 – 1 lbs/A.y (0.3 – 0.5 kg/A.y)



High Silicon Cast Iron Tubular Anode Linedrawing

Item No. Diameter Length Surface Area Weight
KA-42-TA2 XS 2.3″ (58 mm) 42″ (1067 mm) 2.1 ft² (0.19 m²) 23 lbs (10.5 kg)
KA-42-TA3 XS 2.8″ (71 mm) 2.4 ft² (0.25 m²) 31 lbs (14.1 kg)
KA-42-TA4 XS 3.8″ (96 mm) 3.5 ft² (0.3 m²) 43.2 lbs (19.6 kg)
KA-60-TA2S Ф2.3″ (58mm) 60″ (1524 mm) 3 ft² (0.28 m²) 32.8 lbs (14.9 kg)
KA-60-TA3S Ф2.8″ (71mm) 3.6 ft² (0.34 m²) 45.0 lbs (20.4 kg)
KA-60-TA4S Ф3.8″ (97mm) 5 ft² (0.46 m²) 61.7 lbs (28 kg)
KA-60-TA5AS Ф4.8″ (122mm) 6.3 ft² (0.59 m²) 125 lbs (56.7 kg)
KA-84-TA2 Ф2.28″ (58mm) 84″ (2134 mm) 4.2 ft² (0.39 m²) 46.1 lbs (20.9 kg)
KA-84-TA3 Ф2.8″ (71mm) 5.1 ft² (0.48 m²) 63.1 lbs (28.6 kg)
KA-84-TA4 Ф3.8″ (96mm) 6.9 ft² (0.64 m²) 86.4 lbs (39.2 kg)
KA-84-TA5 Ф4.8″ (122mm) 8.9 ft² (0.83 m²) 110 lbs (49.9 kg)
KA-84-TA5A Ф4.8″ (122mm) 8.9 ft² (0.83 m²) 175.3 lbs (79.5 kg)

Remarks: The dimensions and weights listed are standard. Custom sizes and weights for the anodes can be provided upon request.

Additional information


High Silicon Cast Iron




Pipelines, Deep Well


Brackish Water, Deep Ground Bed, Seawater, Soil