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Australia’s $40 billion of concrete sewage infrastructure, if left untreated, could corrode away in 8 years from sulphide attack. 


Concrete sewer manholes are highly prone to corrosion due to acid attack. The corrosion mechanism is fairly simple:

  1. Generation of H2S in sewer lines fills up the Manhole;
  2. Oxidisation of H2to H2SO4 by auto oxidation reduces pH;
  3. Sulphide Oxidising Bacteria (SOB) form colonies as pH drops;
  4. Convert H2to H2SO4 (sulphuric acid) = corrosion of manhole.

One of the solutions to stop corrosion is by spraying PROTECTA-Mag™ (Magnesium Hydroxide coating) on the surface of concrete sewers.


Treat the cause, not just the symptom


PROTECTA-Mag™ prevents corrosion by raising surface pH, thus neutralising acids and inhibiting the formation of acid-producing bacteria. Monitoring results indicate that PROTECTA-Mag™ coating continues to protect the integrity of the concrete walls of the manhole, in spite of continuous sewer flow, for up to 7 years*.


 Compared to existing corrosion protection technologies like plastic lining,

PROTECTA-Mag™ spray coating is 7 times cheaper

over the life cycle of the asset and does not require flow diversion or man entry for application.


A very simple process


Calix's trailer-mounted, purpose-built PROTECTA-Mag™ rig is used to carry out Vertical Spray Operations. A crew of two, trained for the spray application, traffic control and confined space entry (if required) carry out the application.


PROTECTA-Mag™ is sprayed on the concrete surfaces of the man hole using a high pressure air less applicator. For manholes up to 3 metres in depth, spray is carried out using a lance.


For deeper manholes a spray nozzle on a special winch is lowered into the manhole to carry out the cleaning and spraying operation. 

  1. Spraying is carried out without stopping the flow of the sewer or man entry;
  2. An extensive risk assessment is carried out at the site prior to starting work;
  3. The overspray of PROTECTA-Mag™ entering the sewer flows is complementary and beneficial for any downstream Sewage Treatment Plant (STP) and odour control;
  4. The high wall pH and high activity MHL inhibits the re-growth of specific acid forming bacteria (e.g. thiobacillus concretus.

   Hassle free delivery, local service and support you can count on


Our AS/NZS ISO 9001 certified quality system and safety, health and environmental management system are vital elements of our engineering and quality services.


Calix has established a network of local distributors and partners who can deliver PROTECTA-MagTM across Australasia, to ensure you receive excellent customer service and support, wherever you are located. 


Would you like a quote or more information about any of our products, solutions or services?

If you'd like to locate a Calix partner near you, contact us now.

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