Expansion Joints for Corrosive Service
For certain types of service conditions, there is no substitute
for the excellent corrosion properties of titanium. The
corrosion properties of titanium are particularly valuable
for expansion joints because expansion joints are generally
designed without any corrosion allowance.
Senior Flexonics Pathway manufactures expansion
joints from unalloyed titanium in accordance with ASTM
B265, grade 1. The grade 1 material has the elongation
properties that are best suited for manufacture of
expansion joints.
Since titanium is not easily welded to other materials that
are commonly used for piping in the chemical process
industries, most titanium expansion joints are of van
stoned flange construction. In the van stone process, the
bellows tube is flared to form the flange gasket seating
surface similar to the above sketch. The bellows material
is not welded to any adjacent component. The bellows
can be welded directly to fittings if the pipe fittings are
made from titanium.
MECHANICAL PROPERTIES
Tensile strength at room temperature: 35,000 psi min.
0.2% offset yield strength: 25,000 psi min.
ASME code allowance stress values are:
- 100 F. 8800 psi
- 200 F. 7300 psi
- 300 F. 5800 psi
- 400 F. 4800 psi
- 500 F. 4100 psi
- 600 F. 3100 psi
Not recommended for use above 600 F.