Agenda Item: 650-757
Revision: 4
Title:
Hg & Cu in Hydrostatic Test Water Contacting Aluminum
Submittal Date: May 14, 2012 Revision November, 11 2014
Handled By:
Al Holman (Previously Larry Foster)
Marathon Petroleum
aeholman@marathonpetroleum.com
419-421-2663
Purpose: Mercury and Copper can be very corrosive to aluminum. The standard does not address these
two elements.
Background: Larry Foster proposed making requirements for Annex AL aluminum tanks standalone
similar to Annex S. Annex H needs to reference Annex S as many seal components are stainless.
Through my research I have concluded the following:
API 650 Section:
7.3.6.3 The Purchaser shall be responsible for:
Proposed changes as follows:
1. Furnishing and disposing of the water for hydro-testing the tank from the water source tie-in location
as designated on the Data Sheet, Line 14. If biocide or caustic additions are specified to the
Manufacturer, the Purchaser is responsible for determining or identifying disposal restrictions on the
treated water.
2. Specifying the test water quality. Potable water is preferred for hydro-testing. . The Purchaser shall
consider issues such as:
a.
b.
c.
d.
e.
f.
low temperature brittle fracture,
freeze damage,
amount of suspended solids,
sanitation issues,
animal/plant incubation and/or growth,
acidity,
g.
h.
i.
j.
k.
l.
m.
general corrosion,
pitting,
protecting against cathodic cells,
microbiologically-induced corrosion,
material dependent sensitivity to trace chemical attack,
disposal,
residuals left in the tank after emptying.
3. If consideration of above issues indicates unacceptable risks, Purchaser shall consider mitigating
actions. Mitigation actions may include:
a.
b.
c.
d.
e.
pre-test sampling of the test water to establish a baseline test for water quality.
water treatment
cathodic protection
water quality and/or corrosion monitoring
Post-test rinsing or other treatments
4. If the Purchaser-supplied test water causes corrosion, the Purchaser is responsible for the required
repairs.
5. For the following metallurgies, describe on the Data Sheet, Line 14, (using a Supplemental
Specification) any additional restrictions on the water quality:
a. Carbon Steel—For carbon steel equipment where water contact exceeds 14 days, including filling
and draining (e.g., consider adding an oxygen scavenger and a biocide, and raise the pH by the
addition of caustic).
b. Stainless Steel—See Appendix S
Proposed Change: b. Stainless Steel Material — See Appendix S and X
c. Aluminum Components—See Appendix H
Proposed Change: c. Aluminum Material — See Appendix H and AL
Appendix AL
AL.7.5 Quality of Test Water
AL.7.5.1 The materials used in the construction of aluminum tanks may be subject to severe pitting,
cracking, or rusting if they are exposed to contaminated test water for extended periods of time. The
Purchaser shall specify a minimum quality of test water that conforms to AL.7.5.1.1 through AL.7.5.1.8.
After the hydrostatic test is completed, the tank shall be promptly drained, cleaned, and dried.
AL.7.5.1.1 Water shall be substantially clean and clear
AL.7.5.1.2 Water shall have no objectionable odor (that is, no hydrogen sulfide)
AL.7.5.1.3 Water pH shall be between 6 and 8.3.
AL.7.5.1.4 Water temperature shall be below 50 ̊̊C (120 ̊F)
AL.7.5.1.5 Water mercury content shall be less than 0.005 parts per million.
AL.7.5.1.6 Water copper content shall be less than 0.02 parts per million.
AL.7.5.1.7 Water shall have chloride content not exceeding 200 ppm.
AL.7.5.1.8 The water used to test the tank shall either:
1) Be potable water with a free residual chlorine of at least 0.2 ppm, or
2) Be tested for its bacteria content and found acceptable by owner for such use
Appendix H
As Written:
H6.6.3 Because of possible corrosive effects, consideration shall be given to the quality of water used
and duration of test. Potable water is recommended. For aluminum or stainless steel floating roofs, S.4.10
shall be followed.
Proposed Change:
H6.6.3 Because of possible corrosive effects, consideration shall be given to the quality of water used
and duration of test. Potable water is recommended. For aluminum floating roofs, AL 7.5 shall be
followed. For stainless steel floating roofs c, S.4.10 shall be followed.