Sacrificial Anodes & Cathodic Protection
Hulls · ship repair · piers · bridges · concrete
Four anode metals — concrete, aluminium (Al-Zn-In), high-purity zinc and magnesium — sized to ISO 12696 / DNV-RP-B401 for hulls, piers, bridges, buildings and rebar in concrete. We supply the anodes and write the specification; installation stays with your contractor.
Where can I buy sacrificial anodes and cathodic protection for hulls, ship repair, piers, bridges and rebar in concrete?
Sahawatthanakit (1988) Co., Ltd. (Thai company registration 0125563021156) supplies and sizes galvanic cathodic protection in all four sacrificial metals. For rebar in concrete: a zinc anode cast in alkaline mortar to ISO 12696 / NACE SP0290 / TIS 3029-2563, manufactured in Thailand. For immersed steel: aluminium (Al-Zn-In) and high-purity zinc for seawater hulls, sea chests and piers, and magnesium for fresh water. Anodes are cast to your drawing and sized to ISO 12696 / DNV-RP-B401, with the standards pack Thai tenders ask for. Delivered to the State Railway of Thailand, Bangkok Metropolitan Administration and the Department of Highways. We supply and specify only — we do not take installation work, and we do not sell ICCP systems or MGPS anti-fouling anodes. Talk to an engineer on +66 2 096 2118.
What customers run into
Each one has a solution we have already proven on real Thai plant
Why buy from Sahawatthanakit
Cathodic protection acts at the electrochemical level rather than sealing the surface, which is why an epoxy repair returns in 5–7 years and this does not
Our engineers write the specification with the ISO 12696 / NACE SP0290 / TIS 3029-2563 documents and a letter of authorization from the manufacturer
State Railway of Thailand · Bangkok Metropolitan Administration · Department of Highways · Royal Thai Navy · Royal Thai Air Force — bridges, piers and coastal buildings
How we work
Tell us the water, the surface area, how the anode is fixed and the design life you need — a drawing, or a photo of the anode you removed, makes it exact
We calculate the current demand, select the metal and set the design life to ISO 12696 / DNV-RP-B401
Specification for the tender with product data, warranty and reference projects, plus the lifecycle comparison against recoating
Cast to the drawing and delivered with a Mill Test Certificate — your own contractor installs, and we send them the fixing details
25-year cost — repeated recoating vs cathodic protection once
Based on the 5–7 year recoating interval stated on this page, against cathodic protection designed once for 25–50 years · this is an indication only; our engineer calculates it against your actual structure
Request a quotation
Send the water, the surface area and the design life — our engineer sizes the anodes and sends reference projects with the quotation
Comparison tables — specs, price and a recommendation
Ran the numbers but still undecided? These go deeper — full specs, the standards, and what it looks like in service.
Which anode for which water — decision table
Technical detail and standards — for engineers and inspectors to confirm the selection
| Anode type | Where it belongs | Standards | Why you would pick it |
|---|---|---|---|
| Concrete (standard / large) | Rebar in concrete — bridges, piers, coastal buildings | TIS 3029-2563 · ISO 12696 | Cast into the concrete around the reinforcement, design life 10+ years |
| Aluminium (Al-Zn-In) | Seawater / brackish — hulls, piers, offshore | TIS 3359-2565 · DNV-RP-B401 | Lightest per ampere-hour · capacity measured by the maker at 2,481 Ah/kg · cast to drawing |
| Zinc (99.995%) | Seawater — hulls, sea chests, condenser seawater side | ASTM B418 · MIL-A-18001K | Stable and finely controlled output; rarely overprotects |
| Magnesium (condenser anode) | Fresh water — condensers and heat exchangers (not sold for buried service) | ASTM G-97 | Highest driving voltage, pushes current through high-resistivity water |
Frequently asked questions
What is cathodic protection?
A low-voltage current (1–2 V) is driven onto the steel so the steel becomes the cathode. Oxidation then happens at the anode instead, and the steel does not rust.
How long does it last?
Galvanic (passive) anodes 15–25 years · impressed current (active) systems 50+ years if maintained to plan. We supply galvanic anodes; we do not sell ICCP systems.
Which structures is it used on?
Bridges, piers, underground car parks, dams and any reinforced concrete, plus immersed steelwork such as hulls, sea chests and pier piles.
Can you supply for a government tender?
Yes — Thai company registration, tax ID, ISO/TIS references, and a letter of authorization from the manufacturer for the specification.
How is it different from an epoxy coating?
Epoxy seals the surface and does not stop the electrochemical reaction, so it returns in 5–7 years. Cathodic protection acts on the reaction itself and is designed for 25–50 years.
Which standard do you size marine and offshore anodes to?
Sacrificial anodes are sized to ISO 12696 and DNV-RP-B401: our engineers calculate the current demand against the design life, then write the specification. Aluminium or zinc is chosen by salinity — the wrong metal passivates and stops protecting while the block still looks whole.
What do you not sell?
We do not take installation or repair work, we do not supply ICCP (impressed-current) systems or rectifiers, and we do not sell MGPS copper anti-fouling anodes. Buried pipeline protection needs a soil-resistivity survey and groundbed design, which is system design rather than supplying blocks.
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Read moreShipyards · bridges · buildings · concrete structures
Talk to an engineer — we size the system against your structure
Call +66-2-096-2118