5
AsepticDiaphragmValves
BodyRanges
SurfaceFinish
CRANE ChemPharma, Saunders valve bodies are available in
all mechanically polished and electropolished surface finish
options tomatchpiping system specification. Saunders valve
bodies are also available in a complete range of ASME BPE
compliant internal surface finishes.
Objectives in specifying theappropriate surface finish:
· Result inadefect-freeand consistent surface freeof
anodic contamination
· Minimizeproduct adhesion to the interior surfaceof the
valveandpipeworks
· Achievea surfacewhich is readily cleanablebySIP/CIP
(Steam inPlace/Clean inPlace) consistently,and ina
minimumamount of time
· Enhance corrosion resistance
Surface finish is best described using roughness average
(Ra) value and is now the current industry standard of
measurement. Previous measures, such as grit are less
objective andmoredifficult toquantify. All Saunders product
contact surface finishesaremeasured inRaandasamaximum
value–not anaverage.
Conversion–micrometres tomicro inches
1micrometer
=
39.3701micro inches
1micro inch
=
0.0254micrometers
Ra
y
X
Im =Measuring length
I
0
I
0
I
0
I
0
I
0
Ra=
l
m
x=
l
m
y dx
x=0
Arithmeticmean roughness value:
Electropolishing
Electropolishing of mechanically polished product contact
surfaces improves surface finish smoothness and corrosion
resistance. Mechanical polishing or machining may leave
numerousmicroscopicsurface imperfectionswhichcancause
areasofdifferingelectrical potential due to surface stresses.
Electropolishing can result in up to 50% improvement in
surface finishofmachinedormechanicallypolished surfaces.
The inherent benefits of electropolishing subsequent to
mechanical polishing canbe summarizedas follows:
· Superior surfaces for cleaningand sterilization
· Superior passivated surfaces for corrosion resistanceby
virtueof enhanced chromeoxide surface layer
· Superior high lustreaesthetic appearance
· Superior eliminationof smearedor torn surfaces caused
byabrasive finishing
· Superior removal of inclusions andentrapped
contaminants suchas lubricants andgrit particles
Certification
Typical surface parameters available through Certificate
of Conformity on customer request. Actual surface finish
readingsareavailableuponcostumer request.
