Belzona Polymerics Limited
BELZONA® ANTI-CAVITATION SYSTEM PROTECTS SHIPS
Cavitation damage on ships costs the marine industry millions every year. Shipping is a vital part of the world’s economy, and so their contribution to this is dependent on keeping ships at sea. Cavitation damage is proportional to the rate of flow across the substrate. Therefore, with increasing speeds of vessels, solutions are needed to combat this phenomenon.
Through stringent laboratory testing and sea trials, elastomeric polymer coatings have now been developed to resist the effects of cavitation and save costly downtime. Whereas epoxy coatings are made very hard to resist general erosion, they suffer from impacts and cavitation due to brittleness. The best way of protecting a surface from strong impacts is to cushion the force. A corrosion resistant coating that will compress with impact, and then return to its original state, is the future in combatting erosion by cavitation.
Independent tests were carried out on a Belzona epoxy coating and polyurethane coating. Belzona 1341 is an efficiency enhancing, ceramic filled, epoxy product. It has a proven track record of increasing the efficiency in pumps and in fluid flow situations, as well as stopping corrosion and resisting the effects of erosion. Belzona 2141 is a relatively new polyurethane coating. It has been designed to resist the effects of cavitation and impacts, as well as stopping corrosion.
The independent testing comprised of a 500 hour erosion simulation where the products were subjected to cavitation effects. As can be seen in figures 3 and 4, the Belzona 1341 had slight damage showing in one particular area. In the same area on the Belzona 2141 there is a very slight shadow but no damage. This damage is from the effects of cavitation and proves the capabilities of a polyurethane coating.
Cavitation usually occurs in specific areas. Knowing where the cavitation areas are helps to identify the repair areas. Combining a polyurethane coating with an epoxy coating is a good way to get the benefits from both products.
The combination of Belzona 1341 and 2141 has given impact and cavitation resistance in the areas that were previously damaged. It also gives complete corrosion resistance and improved efficiency. Both products are hand or spray applied and will cure in a matter of hours helping to reduce downtime. When spray applied the products tend to give a smoother finish and offer a faster application on large areas.
If any piece of equipment is suffering from erosion, corrosion and specifically cavitation, efficiency of how that equipment works will be declining. Avoid costly replacement or hot work and look into polymer coatings. Coupling protective coatings with a well scheduled maintenance programme can save your company time and money.
Photo: A Naval ship were repaired by using Belzona Anti-cavitation system