25 May 2005
test reagents. If the test results are correct, the water quality and water treatment
program must be re-evaluated and modified, if necessary. Paragraph 6-6 describes
interpretation of water test results.
Water Sample Testing Methods. Water tests are usually performed with
test kits obtained from commercial sources. Test kits can be used to test for: alkalinity-
phenolphthalein (P); alkalinity-methyl orange (M or total); alkalinity-hydroxyl (OH) or
difference); phosphate (ortho and total); sulfite; nitrite; chloride; molybdate;
phosphonate; chlorine or bromine (total and free); total iron; and total copper.
Corrosion Testing. Corrosion test specimens or corrosion testing
instruments can be used to monitor the rate of corrosion. Corrosion test information can
also be used to evaluate how well equipment is being protected from corrosion by the
water treatment program. The degree of corrosion (if any) that is occurring in large or
critical heating and cooling systems should be determined at all military installations.
Consider the following information when developing a program of corrosion testing:
Corrosion Test Coupons. Corrosion test coupons are usually used as
corrosion test specimens for open and closed cooling systems, closed hot water
systems, and domestic water systems (see Appendix C).
Corrosion Pipe Inserts. Corrosion pipe inserts are often used as
corrosion test specimens in steam condensate return systems (see Appendix D).
Commercial Resources for Testing. Corrosion test coupons and testing
analysis services can be obtained from commercial sources. Corrosion pipe insert
assemblies for steam condensate systems and analytical evaluation of the test inserts
should be obtained from a QA laboratory or contractor under contract with the military.
Guidance for corrosion testing is provided in Appendices C and D.
Corrosion Test Results. Corrosion test results are usually determined as
a rate of corrosion penetration into the metal and reported in mils metal loss per year
(mpy). A mil is 2.5-thousandths of a centimeter (one-thousandth [0.001] of an inch);
thus, the corrosion rate of 10 mpy means that the thickness of a piece of metal is
reduced by 10 x 0.0025 = 0.025 centimeter per year (0.01 inch per year). If the metal
coupon being studied is 0.1588 centimeter (0.0625 inch) thick, this means that it will be
completely dissolved or corroded in just over 6 years. Corrosion rates may also be
expressed in millimeters per year (mmpy) corrosion. The relationship between mpy and
mmpy is: 1 mpy = 0.0254 mmpy; 1 mmpy = 39.4 mpy. Corrosion also may be given as a
weight loss in milligrams per square decimeter per day (mdd). For mild steel, the
relationship is: 1 mdd = 0.2 mpy or 1 mpy = 5 mdd.
Testing Instruments. A variety of electronic instruments are available to
monitor and record corrosion rates. These instruments are installed and maintained by
individuals who have been adequately trained for these activities. The most commonly