Brochure

QUALIFYING CASTINGS
Casting quality is frequently cited as a safety issue. Global
sourcing of castings has heightened customer awareness
and concern about the integrity of these castings.
Emerson enforces a comprehensive quality specification for
its Fisher control valves that must be met by all suppliers of
pressure-containing and structural metal castings. These
requirements exceed those specified by ASME, ISO, and EN.
Emerson requires casting suppliers to submit all weld
procedures for approval to ensure they meet requirements
of ASME Section IX and Pressure Equipment Directive (PED).
In addition, samples must be submitted to the Emerson
materials lab for metals that are especially problematic to
cast and heat treat, such as duplex stainless steel and
high-nickel alloys.
GOING BEYOND CODES
Minimal stress on all features of a
pressure vessel greatly improves
fatigue life and therefore, safety.
Simply meeting minimum wall
thickness requirements is not
sufficient.
Using advanced finite element
analysis (FEA) models, our engineers
analyze complex geometries in
control valve designs to locate stress
concentrations. A cross sectional
look at the finite element analysis
model of an actuator illustrates
areas of varying stress levels as
shown by the color gradient. Design
modifications to minimize stresses
can be quickly implemented before
prototyping or production tryouts.
In addition to meeting minimum
wall thickness specified in standards,
every Fisher structural design
undergoes a proof hydrostatic test
to verify that the stress does not
exceed the code allowable stress and
to validate the FEA model.
Fisher control
valves are used in
safety-critical areas
of nuclear power
plants and it is
imperative that they
work when called
upon. They undergo
rigorous qualification
testing to satisfy the
requirements of ASME
QME-1, IEEE382,
IEEE344, and IEEE323.
Fisher
®
Technology Development | 3