Corrosion looks like a cosmetic problem right up until it isn't. On an EWP, rust does two things that matter: it eats away the load-bearing metal, thinning members and reducing their strength, and it creates the pits and notches where fatigue cracks like to start. What makes it insidious is that the corrosion that matters most is often the corrosion you cannot see — inside box sections, under fittings and beneath a skin of sound-looking paint. This guide covers how corrosion attacks a machine, why some environments are far harder on steel than others, where the hidden damage hides and how it is properly treated.
The forms corrosion takes
Corrosion on an access machine ranges from trivial to structural:
- Surface rust on paintwork — unsightly and a warning sign, but not yet structural in itself.
- Pitting, where localised corrosion eats small deep cavities that act as stress raisers and crack starters.
- Section loss, where sustained corrosion thins a structural member and directly reduces its load capacity.
- Internal corrosion inside box sections and tubes, where water sits unseen and eats the member from the inside out.
- Corrosion under fittings, brackets and around fasteners, where crevices trap moisture and hold it against the metal.
Why some environments are brutal
Corrosion needs moisture, oxygen and time, and some working environments supply all three in abundance. A machine's history matters as much as its age when it comes to rust.
- Coastal and marine work, where salt-laden air dramatically accelerates rusting on any unprotected steel.
- Regular washdown environments, such as food, agricultural or industrial sites, where water is repeatedly driven into every crevice.
- Machines stored outside without protection, cycling through dew, rain and heat that keeps the metal wet.
- Areas where paint and coatings have been damaged, chipped or worn through, giving moisture direct access to bare steel.
Where inspectors go looking
A competent inspector treats visible surface rust as a prompt to look deeper, because the corrosion that threatens the structure is usually out of sight. Attention goes to the low points where water collects, the insides of box sections, the crevices under brackets and fasteners, and any area where the coating has failed.
Where section loss is suspected, thickness can be measured — including by ultrasonic techniques that gauge remaining wall thickness without cutting — and heavily corroded areas may be cleaned back to reveal the true extent. Because corrosion pits also seed fatigue cracks, corroded critical welds and members receive particular scrutiny during the major inspection — an AS 2550.10 requirement timed at 5 years for some equipment and 10 years for the rest, according to its class.
How corrosion is treated
Treating corrosion properly means dealing with the metal, not just the appearance. Painting over rust simply hides it while it keeps working underneath.
- Remove the corrosion back to sound metal so the true extent of any section loss is known.
- Assess whether the remaining material still meets the structural requirement, which is an engineering judgement for load-bearing members.
- Where section loss has gone too far, repair or replace the affected structure as engineered work rather than filling or plating over it.
- Treat and recoat the cleaned metal with a suitable protective system to keep moisture out.
- Address why the corrosion started — a drain that was blocked, a coating that failed — so it does not simply return.
Keeping rust at bay
Prevention is overwhelmingly cheaper than repair. Keeping the coating system intact — touching up chips before they spread — denies corrosion its foothold, and washing salt and contaminants off machines that work in coastal or corrosive environments removes the accelerant.
Letting water drain rather than pool, keeping drain holes in box sections clear, and storing machines under cover where possible all extend structural life. A machine with a known coastal or washdown history deserves closer inspection of its hidden areas than its outward appearance might suggest.
This guide is general information prepared by EWP Australia and is grounded in publicly available Australian Standards and Safe Work Australia material. It is not a substitute for the current published edition of the relevant standard or for site-specific engineering advice. Always work from the current standard and consult a competent person for your specific equipment and application.