Page 36 - 2022 - Q3 - Minerva in Focus

MARINE TECHNOLOGY Hydraulic Cylinders: Chrome plating offers high hardness and corrosion resistance at a reasonable cost.
Chrome plating
For years, it has been the preferred method for coating hydraulic cylinder piston
rods and various other critical components (the other being metal spray). For the
above reason, the chrome plating method is found on parts used for multiple ap-
vs. laser cladding
plications, such as hydraulic cylinders for cranes, cargo hatch covers on ships, rods
Moving towards used in various demanding offshore environments such as drill ships and oil plat-
forms, as well as in mining and earth-moving machinery.

chrome plating Chrome plating limitations & disadvantages In addition, the various sizes of plating baths
required and long delivery times, in cases
Chrome plating disadvantages at a glance:
replacement • • • Equipment downtime of re-chroming, are other disadvantages of
Thin coatings
chrome plating, which I am sure superinten-
dents reading this article have experienced
Oxidization
• Long delivery times during drydocks. Superintendents of bulk
• Materials & Workshop unavailability carrier vessels are often told that ten or more
Chrome plating has severe limitations and days are required for the chrome plating of
disadvantages, which have become increas- 20 pcs of their damaged hatch cover rods!
ingly obvious in recent years as equipment
downtime becomes less and less tolerable by
owners, plant operators, and inspecting bodies.
Additionally, in chrome-plated rods, the adhe-
sion of the chrome coating with the parent
material is often poor, resulting in peeling off.
Chrome-plated rods are also vulnerable to im-
pact, creating surface defects that destroy the
coating and the seals.
Another limitation is that with chrome plating,
we can apply only very thin coatings with a
thickness that usually does not exceed a few
tenths of a millimeter which, combined with Picture 2: Damaged-corroded hydraulic
the natural micro-cracking of the chrome-plat- cylinder rod
ed surface, leads to penetration of air and
water, oxidization of the base metal, and even- Similarly, superintendents of container vessels
tual destruction of the chrome-plated coating. with big crane hydraulic cylinder rods may be
Oxidization is a prevalent issue in marine unpleasantly surprised when they learn that no
environments in which salt water and humidity local chrome plating facility can accommodate
demand very high corrosion resistance. Marine their 5-meter-long rod, which means they will
superintendents and offshore engineers often need to spend time and big money to get their
witness corrosion that starts from the upper cylinders back in operation. If a rod is so dam-
part of the rod, which stays out of the liner and aged that it cannot be chrome plated, then a
the protection the oil offers and eventually new one must be manufactured, and sourcing
progresses all over the rod surface. the right material locally is always an issue,
particularly nowadays.
Of course, the most significant disadvantage
of chrome plating is its heavy environmental
impact. Hexavalent chrome is a toxic, carcino-
genic material requiring special treatment.
Environmental sustainability and health and
safety have become extremely important, and
rightfully so. The usage of chrome is strictly
regulated worldwide, with the EU and USA, es-
pecially, imposing stringent regulations, which
will eventually lead to the banning of chrome
plating. Regulations, restrictions, and social
pressure incur additional costs to chrome
plating, rendering the procedure sooner rather
An insight by Antonis Kalampokas than later obsolete.
General Manager, INJEGOV
Picture 1: Chrome Plating station

36 MINERVA IN FOCUS – ISSUE 21 / Q3 2022