S32707 duplex Stainless Steel Seamless Pipe
UNS S32707 SAF 2707 HD Seamless Pipe
With a nominal PRE (%Cr + 3.3%Mo+16%N) of 49, the new grade 2707 HD
has significantly improved corrosion resistance in chloride
solutions compared with currently super duplex stainless steels
(e.g. F53, UNS S32750) and the 6Mo austenitic stainless steels
(e.g. 254SMO, UNS S31254). This makes SAF 2707 HD particularly
interesting for use in applications involving hot seawater.
Compared with the current super-duplex grades, SAF 2707 HD also
extends safe operating conditions in a number of other chloride
containing acidic environments, e.g. in critical heat exchangers in
oil refineries. Some references for SAF 2707 HD in industrial heat
exchanger applications are highlighted.
Since their introduction more than 15 years ago, super-duplex
stainless steels, such as UNS S32750, S32760 and S32520, have found
widespread use in industries such as oil and gas, petrochemical and
chemical processing. Their popularity is attributed to an
attractive combination of high corrosion resistance, excellent
mechanical properties and also a relatively low cost compared to
other higher performance materials, such as super austenitic
stainless steels and Ni-based alloys.
Despite a very broad range of applications for superduplex
stainless steels, there are areas where the corrosion resistance of
these grades is insufficient for a long service life, and where
more expensive materials, with even higher corrosion resistance,
As an example, the corrosion resistance for different duplex
stainless steels in seawater applications has been much discussed
during the last decade, and even though the existing super-duplex
stainless steels do not corrode in seawater at lower temperatures,
they have some limits in higher temperature service. There was a
clear desire, therefore, for new grades with a higher corrosion
resistance than was available from existing super-duplex stainless
To that end, SAF 2707 HD was developed. In addition to a high
chloride corrosion resistance, it also offers increased mechanical
properties over e.g. SAF 2507 (UNS S32750). The improved corrosion
resistance extends the use of duplex stainless steels in aggressive
chloride environments, such as in hot tropical seawater.
With the high costs often associated with maintenance, and the
desire to prolong the periods between planned inspections,
increased reliability is a key factor in lowering overall life
cycle costs. The selected materials of construction need to
withstand the often variable service conditions experienced, and to
perform also in cases of shorter periods of non-stable operating
conditions. With this background, a further development of the
super-duplex stainless steels has been a natural step in order to
meet the current and future industry demands for economical, high
• SAF 2707 HD has excellent resistance to pitting and crevice
corrosion in chloride containing environments, as well as to
chloride induced stress corrosion cracking. SAF 2707 HD also shows
very good results against general corrosion in organic acids.
• The mechanical properties of SAF 2707 HD are high. The high yield
strength may give design and cost advantages compared to other high
• The weldability of SAF 2707 HD is good.
• The excellent corrosion performance of SAF 2707 HD has been
verified in a number of process plant heat exchanger installations.