حاضرة عامة بعنوان: “Corrosion Protection (CP) & Duplex Stainless S teels (DSS)”

دائرة الهندسة المدنية
ومعهد الدراسات البيئية والمائية

يتشرف
ان بدعوتكم لحضور محاضرة عامة بعنوان:

“Corrosion Protection (CP) & DuplexStainless Steels (DSS)”

يقدمها المهندس
مصعب حسين الاحمد
Corrosion Eng
ineer
Petroleum Development Oman

وذلك يوم الخميس الموافق 20 تشرين الثان
ي 2014، من الساعة 0:02-00:3
قاعة ENG242 –الدور الأول - كلية الهندسة والتك
نولوجيا

Lecture abstract:
Corrosion can be defined in different ways
for instance, “An attack on metallic materials by reaction with its enviro
nment”. Specifically corrosion refers to the metal deteriorate. Corrosion p
henomena are usually electrochemically occurred in the nature, essentiallylike a battery. If the metals are exposed to an environment containing wat
er, they can give up electrons and become positively charged ions, given
that an electrical circuit which can be completed. This phenomenon can be l
ocally concentrated to form pits or a crack or an extension across a wide-r
anging area to form general wastage. Atoms, ions, reactions and anything
else seek to be in the most stable state. Therefore, materials composition
al elements have natural tendency to return back to their most thermodynami
cally stable state. It means basically, formation of the oxides, sulfides
, or other metallic compounds mainly deliberated to be ores. If water and
oxygen exist, under the normal conditions iron and steel will corrode. Abs
ence one of these materials usually leads to no corrosion taking place. Rap
id corrosion may take place in water, the corrosion rate increased by an i
ncrease in temperature or aeration, by the acidity or the velocity of the
water and by the presence of organics such as bacteria or by the less preva
lent factors.
The basic principle of cathodic protection (CP) is a simple
one. Through the application of a cathodic current onto a protected structu
res, anodic dissolution is minimized (Oxidation rate is lowered). Cathodicprotection is often applied to coated structures, with the coating provid
ing the primary form of corrosion protection. The CP current requirements t
end to be excessive for uncoated systems. Moreover, two types of CP which
are mainly used in applications which are Sacrificial anode and impressed c
urrent and both of them are used to reduce the corrosion rate of the protec
ted structure. Duplex stainless steels have two-phased microstructure of au
stenite and ferrite. In order to obtain the mixture of approximately equal
proportions of austenite and ferrite, the duplex stainless steel has to co
ntain 28 wt% chromium and 6 wt% nickel equivalent. Austenite stabilizers induplex stainless steels are nickel, nitrogen, carbon and copper whereas
ferrite stabilizers are chromium and molybdenum. The austenitic-ferritic al
loys have good corrosion resistance, good weldability, and excellent form
ability coupled with superior strength.