industry quality review september 2008 nace central area conference
TRANSCRIPT
Industry Quality ReviewSeptember 2008
NACE Central Area Conference
Magnesium AnodeElectrochemical Properties
-1.75V Open Circuit Voltage High Potential
-1.55V Open Circuit Voltage Standard Alloy
1000 Amp-hrs/pound - Theoretical
500 Amp-hrs/pound - Nominal
50% current efficiency - Nominal
Quality & Performance Factors
Alloy Chemistry
Potential (voltage)
Current efficiency
Alloy Chemistry
ASTM B843 defines alloy requirements
>98.5% magnesium
Typically, 100% testing of every heat
Chemistry alone does not identify quality
Open Circuit Potential
Hi-potential magnesium -1.75V to -1.77V
Standard alloy -1.50V to -1.55V
Open circuit potential is controlled by chemistry and casting process
Current Efficiency
% of energy within the alloy that is available as cathodic protection current
Measured in Amp-Hr/pound
Nominal 50% efficiency for both H-1 and high potential alloys
Determines life of anode
ASTM G97 test (Destructive test, 14 days, $1000 cost
Anode Life
Life (yrs) = 0.116 x Wt (lbs) x Efficiency x 0.85 (Utiliz. Factor)
Anode Current (amperes)
Value Analysis*Efficiency Life (Years) Annual Cost
50% 16.76 $14.92
40% 13.41 $18.64
30% 10.05 $24.87
20% 6.70 $37.31
*17# anode at 50 mA, Assumes total installed cost of $250
Alloy and market development by DowForeign sources (China, Russia, Mexico) entered
market in late 90’sInitial quality problems with foreign anodes Foreign quality problems resolved by 1999US suppliers not competitive with foreign sourcesChina/Mexico dominant suppliers to US market by
2002
Mag Anode Industry History
Quality Developmentof Foreign Sources
Early 98
Late 98
1999
60
56
52
48
44
40
36
32
28
1.65 1.70 1.75 1.80 1.85OPEN CIRCUIT POTENTIAL IN (-) VOLTS (vs CuCuSO4)
2002/ 2003Quality Results
60
56
52
48
44
40
36
32
28
%C
UR
RE
NT
EF
FIC
IEN
CY
1.65 1.70 1.75 1.80 1.85OPEN CIRCUIT POTENTIAL IN (-) VOLTS (vs CuCuSO4)
2003 Industry Sampling
5 high potential anodes obtained on open market in mid-2003
Tested according to ASTM G97 standard by third-party laboratory
Results confirmed widespread quality problems in industry
2003 Industry Sample Results
A -1.75v 49.3% 16.53 $15.12
B -1.72v 41.6% 13.95 $13.98
C -1.63v 12.1% 4.06 $61.58
D -1.63V 11.0% 3.69 $67.75
E -1.61v 4.8% 1.61 $155.28
Sample OCP vs Current Life* Annual CuCuSO4 Efficiency (yrs)
Cost**
*17# anode at 50 mA, **Assumes total installed cost of $250
Quality Concern Validation
Anode quality presentation by T. May (MESA) in Oct 2003 w/publication in MP in Jan 2004
Anode quality presentation by B. Gummow (CORRENG) in Feb 2004 at Northern Area Conference
Anode quality presentation by M. Yunovich (CCTechnologies) in Mar 2004 at Corrosion 2004
Quality concerns apparent in late 2002/2003Producers capable, but not providing qualityDiminished user quality control programsImpact of low quality magnesium not well
understood
2003 Industry Assessment
2005 Industry Sample Results
A -1.81 57% 19.11 $13.08
B -1.79 56% 18.77 $13.32
C -1.79 55% 18.44 $13.56
D -1.79 55% 18.44 $13.56
E -1.68 29% 9.72 $25.72
F -1.59 16% 5.36 $46.64
Sample OCP vs Current Life*Annual CuCuSO4 Efficiency (yrs) Cost**
*17# anode at 50 mA, **Assumes total installed cost of $250
2005 Industry Assessment
Quality of cast anodes is generally improvedExtruded magnesium anodes are quality alternativeNo significant changes in end-user QA programsStill some scrap out there
2007 Industry Sample Results
A -1.77 61% 20.45 12.22
B -1.77 55% 18.44 13.56
C -1.77 54% 18.1 13.81
D -1.75 46% 15.42 16.21
E -1.65 29% 9.72 25.72
F -1.60 26% 8.72 28.67
G -1.67 24% 8.05 31.06
H -1.60 10% 3.35 74.63
Sample OCP vs Current Life*Annual CuCuSO4 Efficiency (yrs) Cost**
*17# anode at 50 mA, **Assumes total installed cost of $250
2007 Industry AssessmentIndustry sampling validates continuing quality concernsNo significant changes in end-user QA programsRecent supply instability and price volatility likely to increase quality concerns
End-User Impact
Average of 2007
tests
-1.70V 38% 12.74 $19.62
Industry Standard
-1.75V 50% 16.76 $14.92
OCP vs Current Life* Annual
CuCuSO4 Efficiency (yrs) Cost**
*17# anode at 50 mA, **Assumes total installed cost of $250
+$4.70
ConclusionsAnode quality continues to be major industry concernEconomic impact to industry estimated at >$2MM per yearEnd-users and resellers largely unaware or unconcerned of impact of qualityInstability of magnesium market makes overall quality improvement unlikely
Industry Quality ReviewSeptember 2008
John Cole – MESA Products, Inc.