Effective steel – duplex and super duplex
Duplex grade stainless steel is approximately twice as strong as regular austenitic or ferritic steel. Duplex stainless steels have similar corrosion resistance to that of type 304 and 316 austenitic stainless steel. When it comes to corrosion cracking or SCC resistance, duplex does well. As duplex has less nickel and molybdenum content than austenitic steels with around the same resistance to corrosion it can often be much cheaper.
The micro structure of duplex steel is two-phase austenite and ferrite – basically a 50/50 composition. As duplex has a higher yield strength this can have cost savings with reduced section thickness and reduced weight! Duplex is used mainly in oil and gas industries, along with marine and high chloride environments. Duplex is also used in storage of ethanol; a new type of duplex called ‘lean duplex’ which is low in molybdenum (0.3%) and low in nickel.
Super duplex stainless steels were first developed 70 years ago in Sweden for use in the sulphite paper industry. Due to a very high tensile strength, super duplex has better resistance to erosion, corrosion cracking and corrosion fatigue than conventional steels. Super duplex steel is best suited to marine, shipping, architectural and of course chemical industries, where its austenitic ferritic iron chromium-Nickel Alloys with Molybdenum composition aid its essential corrosion resistance.
Super duplex has a low coefficient of thermal expansion making it ideal for mechanical components like heat exchangers, cooling pipes and high strength wiring solutions. Of course this high thermal conductivity also makes super duplex easily welded.
Pipe fittings – duplex and super duplex
Butt weld Pipe fittings are used in connecting and creating pipe-work systems where they are welded into the system using circumferential butt welds. These pipe fittings are used in conjunction with ANSI pipe and Flanges which can be supplied in the corresponding size ranges. Pipe fittings are manufactured to dimensions and tolerances in accordance with ANSI B16.9 , ANSI B16.28, and MSS SP43.
We supply Butt weld pipe fittings in the following forms, but others are available.
Long radius and Short radius elbows , these enable the piping run to move through either 45,90, and 180 degree angle.
Equal and Reducing tees allows connection of a branch at right angles from the main pipe run size.
Concentric reducers are used to connect two different size pipes together whilst maintaining good flow characteristics.
Eccentric reducers are also used to connect two different pipe sizes together but with one straight side to enable pipe run to be placed against a wall.
End Caps are used to blank off the end of a pipe run.
Stub Ends, Lateral tees, Barred tees, Swage nipples, Pipe nipples, 3D & 5D Induction bends are also available in our butt weld pipe fitting range.
Butt weld pipe fittings are available to ASTM A815 for Duplex . ASTM B366 for Nickel Alloys , ASTM A403 for Stainless Steels other standards are also available.
Our pipe fittings are usually supplied in accordance with one of the following classes.
WP-S : These pipe fittings are manufactured from Seamless pipe starting material which is pulled or pressed to achieve the desired finished fitting.
WP-W : These pipe fittings are manufactured either from Welded pipe starting material or plate material which is pressed in to shape and then welded.
WP-WX : These pipe fittings are manufactured either from Welded pipe starting material or plate material which is pressed in to shape and then welded. But then all welds are subject to a 100% radiograph in accordance with ASME section VIII, or other supplied standards.
Pipe flanges – duplex and super duplex
At Chemipetro we stock a range of flanges made from premium quality materials including duplex, super duplex, nickel alloy, 6 moly stainless steel and titanium. Our pipe flanges are also designed in standard dimensions to ensure enhanced functionality and flexibility.
All pipe flanges can be supplied with grooves, back faces, bevels and bores inlaid, and are available in sizes between ¼” – 72″ (6mm to 1,800mm). Custom pipe flanges can also be manufactured by us to a client’s individual specifications.
For low-pressure piping we offer threaded pipe flanges which don’t require welding, or for higher pressure situations we stock slip-on flanges, weld-neck flanges and socket weld pipe flanges for the best connectivity. We also stock blind pipe flanges for easy pipe inspection, spectacle flanges for limiting the pipe flow, orifice pipe flanges for trouble-free access and lap-joint flanges for quick disassembly.