The SFF Group is a complete supplier of piping products in all material grades, with a special focus on sophisticated material grades. Our stock is considered to be one of the most complete in the industry, with a wide range of products and material grades. Click to see our Scope of Supply and Stock Program.
Duplex stainless steels (DSS) consist of approximately equal amounts of ferrite and austenite phase. They possess both good mechanical properties and corrosion resistance. To achieve the desired microstructure, high amounts of chromium and nickel are added, as well as a proper heat treatment. However, DSS are susceptible to embrittlement and loss of corrosion resistance when used above 300 °C or receiving an undesired heat treatment. Formation of intermetallic phases is the main reason causing these effects. Although welding potentially could lead to embrittlement, the DSS are designed to avoid this from occurring when welded in a proper way.
Typical application:
Compared to normal duplex stainless steels, super duplex stainless steels (SDSS) contain increased additions of alloying elements. The additions lead to increased resistance to pitting corrosion. Therefore, SDSS is suitable to use in aggressive chloride-ontaining environments.
Typical applications:
Stainless steel 316 (SS316) is an austenitic stainless steel, where chromium, nickel and molybdenum are the most important alloying elements. SS316 has a high resistance to acidic corrosion, and the steel is easy to form. Compared to duplex steels, SS316 has a lower yield and tensile strength but can be used at higher temperatures. When being welded, SS316L is used instead of 316. SS316L contains less carbon, which prevents the steel from being vulnerable to grain boundary corrosion after welding.
Typical applications:
Super austenitic 6Mo steel is an alloy with increased Mo additions
compared to SS316. Therefore, 6Mo is more resistant to
acidic corrosion while also having increased strength. 6Mo also
exhibits high resistance against pitting and crevice corrosion,
as well as stress corrosion cracking. The alloy can be used in
seawater and environments containing hydrochloric or sulphuric
acids.
Typical application:
Titanium grade 2, unalloyed titanium, consists of minimum
99.6 % titanium. The small amount of alloying elements remaining
have a solution strengthening effect. Pure titanium has a
density of almost half the value of iron and has an advantage if
weight reduction is important. Furthermore, titanium has excellent
corrosion resistance. Titanium also has good formability
and welding properties.
Typical applications:
Inconel 625 is a nickel superalloy containing high amounts of chromium and molybdenum. The alloy has high strength and corrosion resistance at a wide temperature range, from cryogenic to about 1000 °C. This makes it suitable to use at temperatures where stainless steel can not be applied. However, nickel alloys have their drawback in being expensive due to the high cost of nickel.
Typical application:
Carbon steels are steels where carbon is the main alloying element.
This material grade has a relatively low cost while still having
good mechanical properties. By changing the carbon content and
heat treatment procedure, various combination for strength and
ductility may be achieved. As carbon steels are going from being
ductile to brittle when cooled below a certain transition temperature,
special low-temperature carbon steels (LTCS) have been designed
to remain ductile at lower temperatures.
Carbon steels have low corrosion resistance and often need additional
corrosion protection when used in a corroding environment.
Galvanizing of bolts, external coating of tubes and internal cladding
of tubes are examples of corrosion protection used for carbon steel
in piping.
Typical application:
