Inhibition of Copper Pitting Corrosion in Aggressive Potable Waters

Table 4

Estimated pit initiation times and computed pit propagation rates based on 𝐸_pit=325mV and 𝐸^𝑒_pit=260mV(versusAg-AgCl). If 𝐸_pit or 𝐸^𝑒_pit was not observed during test, pit initiation time could not be estimated. Tests are grouped by respective adjustments to control water quality and large-scale results are bolded.

Test number			Propagation rate (𝜇m/day)
	Initiation time (days)		Maximum		Average
	𝐸pit	𝐸^𝑒pit	𝐸pit	𝐸^𝑒pit	𝐸pit	𝐸^𝑒pit
Control
S1	10	10	11.7	11.7	3.9	3.9
L1	𝟒𝟐	35	4.8	4.6	2.7	2.6
Chlorine
S2	—	—	—	—	—	—
S3	—	—	—	—	—	—
S4	141	97	8.0	3.8	3.3	1.7
S5	49	45	9.9	8.8	4.2	3.8
S6	14	14	16.4	16.4	3.1	3.1
L2	407	4.7	3.2	3.2	1.9	1.9
Phosphate
S7	28	25	16.4	14.2	3.7	3.5
S8	32	32	14.9	14.9	3.9	3.9
S9	—	—	—	—	—	—
S10	—	—	—	—	—	—
S11	—	—	—	—	—	—
S12	—	—	—	—	—	—
L3	77	77	2.8	2.8	1.7	1.7
L4	—	—	—	—	—	—
Silica
S13	14	14	11.3	11.3	3.8	3.8
S14	16	16	18.2	18.2	2.6	2.6
S15	—	—	—	—	—	—
S16	—	—	—	—	—	—
L5	77	35	2.8	2.5	1.1	1.0
L6	—	—	—	—	—	—
Organic matter
S17	21	21	16.7	16.7	3.0	3.0
S18	14	14	10.8	10.8	3.1	3.1
S19	48	44	3.1	2.8	1.9	1.7
S20	28	26	3.2	3.1	1.9	1.8
S21	20	20	8.7	8.7	4.5	4.5
L7	70	29	6.5	4.9	2.8	2.2
L8	217	71	3.3	2.1	1.9	1.2
Alkalinity
L9	35	15	5.8	5.1	3.1	2.8
L10	35	15	0.7	0.7	0.5	0.5