According to industry estimates, it costs the US about $36 billion a year to fix the damage caused by corrosion to our water and sewer systems. Corrosion is responsible for over 90% of the 240,000 pipe breaks that occur in the US each year, so protection is a key consideration for utilities and municipalities for preserving their infrastructure assets. SIGMAZINC coatings inhibit corrosion and can extend the lifetime of a fitting by a factor of between 10-100x.
- Corrosion is the result of oxygen combining with a metallic element which can be caused by a number of interacting factors.
- A coating of zinc acts as both a physical and galvanic barrier between the bare metal (ductile iron) and the oxidation process that causes a corrosive attack.
- A zinc rich layer between an asphalt topcoat and the DI protects the ductile iron pipe or fitting by oxidizing before the DI, adding a new barrier of zinc oxide under the top coat.
- Zinc is unique because it has the power to actively self-heal in many environments. Other standard coatings including Fusion Bonded Epoxy (FBE) do not possess this unique ability.
- Unlike FBE, zinc will not chip and does not require special installation or repair procedures.
Zinc Coating Options:
- The ISO has a long-standing commitment to zinc coated pipes and fittings and zinc coatings have been widely used in Europe for the last 50 years.
There are two international specifications for zinc coatings on ductile iron pipes, fittings, joint and accessories, these are ISO 8179-1 and ISO 8179-2.
- SIGMA can provide products that comply with both the -1 and -2 specification.
- 8179-1, often known as METALLIZED ZINC, involves spraying a thin layer of metallic zinc on a pipe or fitting. The -1 spec requires the application of not less than 200 g/m2.
- 8179-2 is often known as ZINC RICH PAINT COAT. This coating is thicker than -1 and its spec requires a higher deposition of not less than 235 g/m2.
- Both SIGMAZINC1 (8179-1 compliant) and SIGMAZINC2 (8179-2 compliant) fittings are supplied with a topcoat of Black Asphaltic Paint, which acts as a sealant and allows the slow formation of zinc compound to form a barrier protecting the iron surface from corrosive attack.
Which Zinc Coating is Better, -1 or -2?
- -1 and -2 are equally durable and reliable.
- SIGMA recommends its SIGMAZINC2 coating as its preferred option for waterworks customers due to logistics and repair capabilities. In the field, both -1 and -2 fittings repairs are always conducted using ZINC-2 coating. There is evidence that the additional mil thickness of the SIGMAZINC2 barrier coating adds enhanced protection against corrosion.
For more information about SIGMAZINC and other corrosion protection products, please contact your local sales manager http://www.sigmaco.com/contact/.