Steel Construction Vol 40 No 1 - Architecturally Exposed Steel | Page 22

SAISC TECHNICAL

What DESIGNERS and FABRICATORS
need to do to achieve a

QUALITY CORROSION CONTROL SYSTEM
By Spencer Erling, Education Director, SAISC

Background
The starting point for all coating systems is
to clearly define what duty the system
must perform (paint or for that matter hot
dip galvanizing or any other system) which
by and large include:
• Corrosion protection
• Architectural finish (decorative), or
• A combination of architectural/
corrosion protection.

Terry Smith, a well-known face at the
Institute and in the steel industry, has
joined the Corrosion Institute of
Southern Africa as editor of its newly
found magazine, Corrosion Exclusively.
Terry has an extraordinary wealth of
knowledge regarding anything
corrosion-related and is often called
in when steelwork contractors have
an issue with the right type of
corrosion protection prescription
for their projects. We thank him and
the Corrosion Institute for allowing us
to publish this article by Spencer
which appeared in their first issue –

Vol. 1 Issue 1 2015.

When it comes to architectural/ decorative
finishes, it is, I would like to believe,
commonly accepted that hot dip
galvanizing is a very cost effective
corrosion protection system for the right
applications and in more recent years has
become, along with paint, the coatings of
choice for architectural decorative finish to
steel structures.
The importance of this definition becomes
obvious once one considers (at the risk of
upsetting paint manufacturers and
suppliers) that in an enclosed project in
Gauteng, one could get away with no paint
or maybe a one coat paint or coating
system. I know of several 50 year old
partially open to the weather factories
where 99% of original zinc chromate
primer on a poorly wire brushed system is
still in remarkably good condition.
Specifications
Having made up our mind what the
purpose of our coating system is, it
becomes necessary to specify the system
using technically correct language, which
should reference SABS (or other
international) specifications, codes of
practise and/or paint manufacturer’s data
sheets.
Sadly, many specifiers do not compile a
performance specification us ing national
reference standards such as
SANS 1200HC, which is still based on

20

Steel Construction Vol. 40 No. 1 2016

sound reasoning. However, SABS have
adopted ISO 12944, now as SANS 12944,
which is a far more comprehensive
standard on which to base their specific
project performance specification.
I therefore suggest that one has three
choices on which to compile a
performance specification:
1. Follow the guidelines of SANS 1200 HC
and/or SANS/ISO 12944.
2. Approach a ‘friendly’ paint
manufacturer and
3. Make use of a reputable corrosion
consultant.
To this end we usually approach either our
friendly paint manufacturer or a corrosion
consultant for their advice as to what
system to use for what environments. The
paint manufacturer recovers the cost of
this consultation in the selling price of his
paint. This could lead to the temptation to
over specify systems with a view to profit
for the company. On the other hand a
corrosion consultant will charge for his
advice.
When it comes to seeking advice about
what steps to take when applying the
paint system to ensure a good quality
end product, both SANS 1200 HC and
SANS 12944 are useful standards. These
documents are full of useful “do’s and
don’ts” such as not painting in humid
conditions, very cold weather or for that
matter on very hot steel and so on.
After that we need to rely on the paint
manufacturer’s instructions to get a good
quality coating. If asked to do so the
manufacturers will do a quality overview of
the application and will also provide
guarantees for the life of the system.
Make sure any offered guarantee is specific
to the needs of what the project team