Rust Protection Marine Metal Australia
It’s not surprising that one of the most prominent concerns of marine vessel owners is rust protection. From all around the coastline of Australia, corrosion of metal parts on vessels is of the utmost importance to treat.
While the removal of rust , coating preparation and paint application is a considerable job. A more alarming issue is when the oxidation process causes stress corrosion cracking to occur in the metal. Similar in some ways to fatigue cracking, this form of damage occurs to metal that is rusting and is undergoing stress due to external forces. Such cracks depending on their location may go undetected for a long time. But when put under additional pressure may create a large hole at the worst of times.
How Stress Corrosion Cracking Forms.
Essentially, this is the combination of two elements, stress on the metal parts and the corrosion that is weakening them which causes the cracking to occur. Such cracking would not occur if one of the two elements were not present.
The stress may be caused by external forces, such as components that are under tension, bolts that have been tightened to a considerable degree, or rigging that is also tight. Or, such stress may be internal in nature, such as those caused by cold stamping which is used to fit high-tensile bolts or shackles.
A common source of stress corrosion cracking on marine vessels is roll swagging. This is when a terminal fitting is connecting a wire of a stay or shroud. The metal has been pressed to increase its strength in holding a cable or joint which in turn causes internal stress to occur. The harder the metal becomes, the more stress that is applied internally. When the stress reaches a certain threshold, cracking may occur.
The Effects of Corrosion
The effects of corrosion can sometimes be more complex compared to simple stress. Being exposed to seawater causes metal parts to rust. Surfaces that become wet then dry out may increase the factors that cause corrosion to take hold on the metal which in turn weakens its integrity. This is particularly true for connection points that are undergoing stress.
Another factor is the temperature in which the metal is exposed when in seawater. While temperatures of 50 degrees C are quite high, they can be achieved on exposed metal surfaces under sunlight in warm climates. When temperatures reach that height, they can cause additional stress and subsequently fracturing to occur.
It should be noted that stress corrosion causes numerous small fractures as opposed to a single one as common with fatigue corrosion. Identifying areas of the boat where rust protection is needed is crucial to preventing this type of damage from occurring. Exposed metal on marine boats, yachts, and ships in the warm waters of Australia means that effective rust protection products must be used and combined with replacement of corroded or worn parts.