The document describes the various steel treatment and painting processes used on Atlas Copco generators and light towers to protect them from corrosion when exposed to outdoor environments. Different components receive different treatments based on their exposure and importance. All steel components receive a galvanization treatment before further treatments and painting. The canopy receives powder coating, while critical components and the base frame undergo nitrogen laser cutting and cataphoresis before final painting. These treatments help provide long-term corrosion protection and extend the life of components.

1. STEEL TREATMENTS
AND PAINTING
PROCESS
In this document, we will explain detailed the process and treatments that all
Atlas Copco product ranges, manufactured in our Product Company located
in Zaragoza (Spain) suffer in order to achieve the best performance avoiding
corrosion over the years.
Written by: Bárbara Gregorio
Technical sales support for generators and light towers
PN - 2960 0400 00

2. INTRODUCTION
Generators and light towers spend much
of their working lives outside exposed to
the elements.
The environments can be tough: rain,
seawater, wind, ultraviolet radiation,
natural and industrial dust, sand and mud.
For obvious reasons, these vital machines
must be kept in constant working order
and therefore need protection from the
elements and be secure from damage.
This is why a well- designed, well
produced and long-lasting canopy is of
the utmost importance.
Steel tends to be the standard material on
all middle and large machines. It is
resistant, it is strong and it can withstand
the heat and vibration the machines
produce, and it is able to protect the inner
workings of the machine also.
MAIN GOAL:
AVOID CORROSION
One of the only disadvantages to be
overcome with canopies made of steel is
corrosion. Steel oxidizes on contact with
the oxygen dissolved in water, and the
presence of salt or heat can accelerate this
process.
The corrosion of steel is an
electrochemical process requiring oxygen
in its dissolved (aqueous) form, and the
chemical formula looks like this:
4Fe + 3O2  2Fe O2 (iron oxide or
rust)
It is the loss of electrons from the steel
and the gain of electrons by OH-
(hydroxide ions) created in the process
that drives the reaction.
To inhibit corrosion, the steel plates used
in canopy construction are protected by
Galva-steel process.

3. STEEL PRE-TREATMENT: GALVA-STEEL
In the continuous hot-dipped galvanization process that produces Galva-steel, the steel
sheets are submersed in molten zinc and a chemical reaction takes place in which the zinc
is permanently bonded to the steel.
The external layer is pure zinc, but successive layers are a mixture of zinc and iron, until
the interior, which is pure steel. This layer can reach up to 25µm thickness.
External aspect sample Under microscope
Pretreatment for normal steel plate (> 3mm):
Cleaning: removing of dust, rust, chips. If there is rust, sandblasting is needed
Warm alcalic degreasing
Zn phosphation
Cr-3 passivation
Drying in order to remove all water between welded plates.
The result of this process means there is a considerable barrier between the steel plate and
air ensuring that if the painted surface is compromised, there will still be, during a
substantial time-period, no corrosion of the steel and only the presence of white zinc
oxide. The corrosion of the steel and production of red iron oxide will be greatly
inhibited.

4. The high levels of zinc present in Galva-steel make it more resistant to standard welding
processes (zinc splatters and tends to burn producing toxic zinc oxide vapour).
Advantages of Galva-Steel canopies:
• Galvanized steel (Galva-Steel) offers very high resistance to corrosion and is the first
choice when using any sheet metal that must be almost continually exposed to the
elements.
• Besides being affordable, durable and effective, this metal is also popular because it can
be recycled and reused multiple times.
All the canopies of our generators and light towers are galvanized and also some critical
parts as: mast support, exhaust pipe, base frame supports…
STEEL CUTTING PROCESS: N2 LASER
This is a high-pressure laser cutting system, used in all our steel pieces in order to achieve
excellent quality.
Oxygen laser burns the material accelerating the oxidation or corrosion status, but
nitrogen gas, acts as a coolant to the material (stops burning it) while using the maximum
power available, and allowing the laser to vaporize it.
Nitrogen protects the metal from corrosion:
• No oxidation of the steel occurs
• No additional heat is generated
• A high quality (clean-cut) edge is achieved
• The clean cut makes it easy to weld and paint or powder-coat the metal
• Paint will not fall off the edges

5. PAINTING PROCESS: CATAPHORESIS
The lifting beam is one of the most important components in our generators. This
structure is meant to stand 4 times the weight of the machine without plastic deformation.
For its painting, we apply a special process called, cataphoresis. It is based on electrical
deposition of anticorrosion material using anodes. It grants minimal risk against corrosion
compared with the traditional painting/coating processes.
This painting method is also applied in sensitive pieces of our Hilight range as the base
frame. Normally these pieces are not galvanized.
Main benefits are:
• Being equal thickness of the paint on all surfaces
• Being coat able of interior, exterior and corner part of the materials
• Decreasing environmental pollution to minimum through water-based system
• Maximum corrosion resistance

6. PAINTING PROCESS: POWDER
Our canopies are all finished and protected with a powder
coating paint. This polyester type of material, applied in
two layers, with a final thickness of 80-180 µm
(depending on the piece) gives an extreme resistance to
corrosion in aggressive environments.
MAIN PROCESS STEPS:
1. Pretreatment based in 4 stages:
Phosphatizing degrease,
wash, passivation and
blowing
2. Drying by forced convection heater
3. Natural cooling of the parts
4. Apply powder coating in cabin
TESTS:
The tests that the samples are involved:
1. Corrosion resistance: Salt spray test in accordance
with ISO 9227
 Measurement of coating disbanding on either side
of the cross cut and from edges.
 Measurement of blistering and corrosion degree
except edges and cross cut in percentage in
comparison with total exposed surface.
Sample: 83 µm galvanized and powder coated, after 870 hours in salted fog cabin

7. 2. Control polymerization rate on customer’s part by DSC analysis (Mechanical
properties)
 Adhesion in accordance with ISO2409
 Impact resistance (1kg 50cm) in accordance with ISO6272
PRIME PROCESS
Base frame is always the most punished system of a generator if we talk about portable
equipment. That’s why the design of our generator and light towers is robust enough to
support multidrop applications, but now also the paint is resistant enough to corrosion
and humid/tropical areas. In case of the containers range, the full structure is treated with
this process, achieving a thickness of 210 µm.
Typically and due to high costs, these metal sheets are not pre-treated, so instead of
using previous processes (Galva-Steel) we use a prime process with Epoxy resin (before
painting). Zinc phosphate epoxy primers are the most frequently encountered and give the
best durability within the group.
Priming ensures better adhesion of paint to the surface, increases paint durability, and
provides additional protection for the material being painted against environmental
agents.
Our primer process complies with standards as: ISO2409, ISO1520, ISO7253 (corrosion
and mechanical testings).
*Note: not all ranges have this process, please ask and confirm with Atlas Copco support.

8. CONCLUSION
What’s the impact of a rusty canopy?
Your brand image can be damaged, and your product can be perceived as a low quality
one. Even if the bodywork of the machine doesn’t affect to the performance, nobody
wants to buy/rent a deteriorated product!
Is that important for the performance?
Even if it doesn’t affect directly on the performance result, canopy is in charge also of the
protection of the main elements inside it. Higher maintenance costs could be a feasible
sales argument.
Why each piece of the structure suffers a different process?
In Atlas Copco we understand the needs of every “corner” of our machines, lifting beam
and base frame will not be challenged in the same in a construction site, so the design and
the treatments can not be neither the same. In addition, it is a way of being competitive in
terms of cost, supplying the best process to each piece.
COVER OUR CUSTOMERS NEEDS ARE IN
TERMS OF QUALITY, PERFORMANCE AND
LIFETIME, OUR MAIN GOAL TO ACHIEVE.
THAT’S WHY THE DESIGN OF OUR CANOPIES,
CONTAINERS AND BASE FRAMES ARE
TOGETHER WITH THE RAW MATERIALS USED
AND PAINTING PROCESSES, SO DETAILS
ANALAYSEZ AND TESTED.

9. All the described processes will not be efficient with a weak machine design, that’s why all our units have been improved with round
edges (mainly in canopies but also in QAS base frames) to facilitate the correct drying of the paint, avoiding irregularities of quantity
of paint, color of the paint… Below a summary table per engine range and process or treatment.
For any further doubt contact Atlas Copco technical support team.
STEEL TREATMENTS PAINT PROCESS
Galva Steel
canopy
Galva steel
critical parts*
Stainless Steel
Roof
N2 Cut base
frame
N2 Cut Canopy
Cataphoresis
base frame
Powder coating
canopy
Prime process lifting
beam
Prime process
base frame
Prime process full
container
QAS Kd S3A x x x x x x x
QAS Pd S3A x x x x x x x
QAS Vd S3A x x x x x x x
QAS Vd S2 x x x x x x x
QES Kd S3A x x x x x
QES Jd S3A x x x x x X**
QES Jd FCO x x x x X**
QES Vd S3A x x x x x
QES Vd S2 x x x x
QES Md FCO x x x x
QAC Cd x x x
QEC Cd x x
HILIGHT H5+ x x x x x x
HILIGHT B5+ x x x x x x
HILIGHT E3+ x x x x x x
*Critical parts: Mast, exhaust, base frame supports, hot parts… **Just in skid frame option
Atlas Copco does not assume responsibility for possible errors. Atlas Copco reserves the right to make changes without prior notice.