Designation: C 1617 – 05

Standard Practice for

Quantitative Accelerated Laboratory Evaluation of
Extraction Solutions Containing Ions Leached from Thermal
Insulation on Aqueous Corrosion of Metals1
This standard is issued under the fixed designation C 1617; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.

1. Scope 1.6 The measurement values stated in inch-pound units are

1.1 This practice covers procedures for a quantitative accel- to be regarded as standard.
erated laboratory evaluation of the influence of extraction 1.7 This standard does not purport to address all of the
solutions containing ions leached from thermal insulation on safety concerns, if any, associated with its use. It is the
the aqueous corrosion of metals. The primary intent of the responsibility of the user of this standard to establish appro-
practice is for use with thermal insulation and associated priate safety and health practices and determine the applica-
materials that contribute to, or alternatively inhibit, the aqueous bility of regulatory limitations prior to use.
corrosion of different types and grades of metals due to soluble 2. Referenced Documents
ions that are leached by water from within the insulation. The
quantitative evaluation criteria are Mass Loss Corrosion Rate 2.1 ASTM Standards: 2
(MLCR) determined from the weight loss due to corrosion of A 53/A 53M Specification for Pipe, Steel, Black and Hot-
exposed metal coupons after they are cleaned. Dipped, Zinc-Coated, Welded and Seamless
1.2 The insulation extraction solutions prepared for use in A 105 Specification for Carbon Steel Forgings for Piping
the test can be altered by the addition of corrosive ions to the Applications
solutions to simulate contamination from an external source. C 518 Test Method for Steady-State Thermal Transmission
Ions expected to provide corrosion inhibition can be added to Properties by Means of the Heat Flow Meter Apparatus
investigate their inhibitory effect. C 665 Specification for Mineral-Fiber Blanket Thermal In-
1.3 Prepared laboratory standard solutions are used as sulation for Light Frame Construction and Manufactured
reference solutions and controls, to provide a means of Housing
calibration and comparison. See Fig. 1. C 692 Test Method for Evaluating the Influence of Thermal
1.4 Other liquids can be tested for their potential corrosive- Insulations on External Stress Corrosion Cracking Ten-
ness including cooling tower water, boiler feed, and chemical dency of Austenitic Stainless Steel
stocks. Added chemical inhibitors or protective coatings ap- C 739 Specification for Cellulosic Fiber Loose-Fill Thermal
plied to the metal can also be evaluated using the general Insulation
guidelines of the practice. C 795 Specification for Thermal Insulation for Use in Con-
1.5 This practice cannot cover all possible field conditions tact with Austenitic Stainless Steel
that contribute to aqueous corrosion. The intent is to provide an C 871 Test Methods for Chemical Analysis of Thermal
accelerated means to obtain a non-subjective numeric value for Insulation Materials for Leachable Chloride, Fluoride,
judging the potential contribution to the corrosion of metals Silicate, and Sodium Ions
that can come from ions contained in thermal insulation G 1 Practice for Preparing, Cleaning and Evaluating Corro-
materials or other experimental solutions. The calculated sion Test Specimens
numeric value is the mass loss corrosion rate. This calculation G 16 Guide for Applying Statistics to Analysis of Corrosion
is based on general corrosion spread equally over the test Data
duration and the exposed area of the experimental cells created G 31 Practice for Laboratory Immersion Corrosion Testing
for the test. Corrosion found in field situations and this of Metals
accelerated test also involves pitting and edge effects and the G 46 Guide for Examination and Evaluation of Pitting
rate changes over time. Corrosion

1 2
This practice is under the jurisdiction of ASTM Committee C16 on Thermal For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Insulation and is the direct responsibility of Subcommittee C16.31 on Chemical and contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Physical Properties. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 1, 2005. Published June 2005. the ASTM website.

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.

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 C 1617 – 05

NOTE 1—The Fig. 1 bar graph was created using the MLCR data shown in Table 1. Standard reference tests using de-ionized water, 1 ppm, 5 ppm,
and 10 ppm chloride solutions were performed on mild carbon steel coupons. The calculated MLCR test results for mild carbon steel coupons were
separated into four ranges. The rating criteria ranges were developed to accommodate the results obtained using this practice on the reference standards
and experimental insulation samples. The ranges used are: MLCR = 0 to 15 mils = range A; MLCR = 15.1 to 35 mils = range B; MLCR = 35.1 to 60
mils = range C, MLCR = 60.1 and higher = range D. The bars on the graph represent the total number of occurrences within the range for each of the
reference solutions.
NOTE 2—It is necessary for each laboratory to develop their own data, with their own individual plate or plates, metal, operators, cleaning procedures,
and environmental conditions to establish the ranges of MLCR calculated for the reference standards. The insulation or other test solutions are then
evaluated against the reference solution results.
FIG. 1 Standard Reference Tests

3. Summary of Practice 3.3 Quantitative measurements of corrosion are determined

3.1 The practice uses controlled amounts of test solutions from the weight change (loss) due to the corrosion of the tested
delivered drip wise onto a defined area of small flat coupons of coupons. Reference tests prepared with known concentrations
selected test metals for the purpose of producing, comparing, of solutions that are conducive to the corrosion of the tested
and measuring the corrosion that occurs on the metals due to metal are compared with water solutions containing ions
the exposure. Preparation of the coupons includes sanding to extracted from insulation samples. Calculations of MLCR in
remove oxidation and contamination and making the surface mils-per-year (MPY) made using the methods of Practice G 1
uniform and reproducible. are reported as the quantitative measurement.
3.2 The test is conducted at elevated temperatures, greatly
accelerating the corrosion in comparison with corrosion at 4. Significance and Use
room temperature. The heat makes the solution evaporate 4.1 Corrosion associated with insulation is an important
quickly, allowing an air (oxygen) interface and making thou- concern for insulation manufacturers, specification writers,
sands of wet-dry-wet cycles possible in a short time. designers, contractors, and operators of the equipment. Some

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 C 1617 – 05
material specifications contain test methods (or reference test 4.12 Protective surface treatments and coatings of different
methods contained in other material specifications), for use in types and thickness can be applied to the metal coupons and
evaluating the insulation with regard to the corrosion of steel, compared using various corrosive liquids.
copper, and aluminum. In some cases these tests are not 4.13 Several sets of tests are recommended because of the
applicable or effective and have not been evaluated for preci- number of factors that affect corrosion. An average of the tests
sion and bias. and the standard deviation between the test results are used on
4.2 A properly selected, installed, and maintained insulation the data. Much of the corrosion literature recommends a
system will reduce the corrosion that often occurs on an minimum of three specimens for every test. Consult Guide
un-insulated structure. However, when the protective weather- G 16 for additional statistical methods to apply to the corrosion
resistant covering of an insulation system fails, the conditions data.
for the aqueous environment necessary for corrosion under 4.14 Results from this accelerated corrosion test shall not be
insulation (CUI) often develop. It is possible the insulation considered as an indicator of the useful life of the metal
contains, collects, or concentrates corrosive agents, or a com- equipment. Many factors need consideration for applicability
bination thereof, often found in industrial and coastal environ- to specific circumstances. Refer to Practice G 31 for additional
ments. If water is not present, these electrolytes cannot migrate information.
to the metal surface. The electrochemical reaction resulting in 5. Apparatus
the aqueous corrosion of metal surfaces cannot take place in
the absence of water and electrolytes. Additional environmen- 5.1 The test apparatus must be housed in a reasonably clean
tal factors contributing to increased corrosion rates are oxygen, and non-dusty environment to avoid any effects of contami-
and elevated-temperature (near boiling point). nants.
5.2 Electrically Heated Thermostatically Controlled Flat
4.3 Chlorides and other corrosive ions are common to many
Hot Plate (see Appendix X1)—A 1-ft (30.5-cm) square or
environments. The primary corrosion preventative is to protect
circular plate that has uniform temperature across the surface
insulation and metal from contamination and moisture. Insu-
provides the heated environment. See Appendix X1 for con-
lation covers, jackets, and metal coating of various kinds are
struct design and sources of assembled systems.
often used to prevent water infiltration and contact with the
5.3 Peristaltic Pump (see Appendix X1)—A multi-channel
metal.
peristaltic pump with individual cassettes and silicone tubes is
4.4 This procedure can be used to evaluate all types of recommended to supply 250 (625) mL/day to each specimen.
thermal insulation and fireproofing materials (industrial, com- 5.4 Silicone Rubber Tubing (see Appendix X1), to deliver
mercial, residential, cryogenic, fire-resistive, insulating ce- fluid to the test coupons.
ment) manufactured using inorganic or organic materials. 5.5 Miniature Barbed Fitting (see Appendix X1), for con-
4.5 This procedure can be used with all metal types for nections of tubing (1⁄16 by 1⁄16 in.).
which a coupon can be prepared such as mild steel, stainless 5.6 Band Saw.
steel, copper, or aluminum. 5.7 Balance, capable of 0.0001 (60.0002) g mass determi-
4.6 This procedure can also be applicable to insulation nation.
accessories including jacketing, covers, adhesives, cements, 5.8 Wet-Grinding Belt Grinder/Sander, with used 80-grit (a
and binders associated with insulation and insulation products. belt previously used to make Test Method C 692 stainless steel
4.7 Heat treatment of the insulation (as recommended by the coupons is acceptable) or new 120-grit wet belt.
manufacturer up to the maximum potential exposure tempera- 5.9 Drying Oven.
ture) can be used to simulate possible conditions of use. 5.10 Bottles, plastic 1 L or equivalent, to individually supply
4.8 Adhesives can be tested by first drying followed by each test specimen with test liquid.
water extraction or by applying a known quantity of the test 5.11 Nominal 1-in. Thin-wall PVC Pipe, 15⁄16-in. OD; 13⁄16-
adhesive to a test piece of insulation and then extracting. in. ID by 2-in. lengths.
5.12 High Temperature Grease, Never-Seez or equivalent
4.9 Insulating cements can be tested by casting a slab,
for use as heat transfer grease.
drying, and extracting or by using the uncured insulating
5.13 Rubber O-Ring, 11⁄4-in. ID, 11⁄2-in. OD, 1⁄8-in. thick.
cement powder for extraction.
5.14 Silicone Sealant, GE Silicone II or equivalent.
4.10 Reference tests prepared with various concentrations 5.15 Plastic Straw, 1⁄8-in. drink stirring straw (“swizzle
of solutions that are conducive to the corrosion of the tested stick”) cut to 1-in. length.
metal serve as comparative standards. Solutions containing 5.16 Cleaning Apparatus and Solutions, for the coupons,
chloride, sodium hydroxide, various acids (sulfuric, hydrochlo- stainless steel metal scourer pad, 3-M sanding pad (medium
ric, nitric, and citric acid), as well as “blank” tests using only and fine) or equivalent sand paper, acetone, xylene, water,
de-ionized water and tap water are used. paper towels.
4.11 Research can be done on insulation that has been 5.17 Hand-Held Magnifier, or 10 to 303 binocular micro-
specially formulated to inhibit corrosion in the presence of scope, or both.
corrosive ions through modifications in basic composition or
incorporation of certain chemical additives. Corrosive ions can 6. Reagents and Materials
also be added to the insulation extraction solutions to deter- 6.1 Distilled or De-Ionized Water, containing less than 0.1
mine the effectiveness of any inhibitors present. ppm chloride ions.

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 C 1617 – 05
6.2 Metal Test Coupons, meeting the composition require- 7.3 Cut the coupon into approximately three equal pieces
ments of applicable ASTM Specification for Mild Steel, using a band saw equipped with a metal cutting blade.
Stainless Steel, Copper, or Aluminum. Mill certificates of 7.4 Prepare the edges of the coupons with a sander to
chemical composition and mechanical properties are required. produce smooth, even, and flat surfaces.
The gage of the metal shall be 16 to 22-gage depending on type 7.5 Permanently mark each coupon for identification. If
of metal and availability. metal stamp impressions are used to mark the coupon, do not
6.2.1 Some researchers will want to maintain traceability to allow the impression to deform the back face of the coupon.
the metals used in other C16 corrosion procedures. Specifica- 7.6 Clean the surface to be tested by lightly wet sanding
tion C 739 uses cold rolled, low carbon (<0.30 %) commercial with a fine sanding pad in distilled or de-ionized water. Wet
quality shim steel. Specification C 665 uses cold rolled, low sand the back surface of the coupon to establish a clean
carbon, quarter hard, temper No. 3, strip steel. It is possible condition that can be reproduced after testing. Rinse in distilled
other metal grades meeting Specification A 53/A 53M, Speci- or de-ionized water, followed by rinsing in acetone. Dry and
fication A 105, and other common ferrous steel specifications polish the test surface using a clean paper towel. Do not touch
are of interest for use in the tests. If stainless steel coupons are the test surface with bare hands thereafter.
to be used, it is recommended that they be 16-gage and 7.7 Heat the coupons to drive off surface moisture and
prepared following the sensitization procedure described in obtain a constant weight. Cool the coupons in a moisture-free
Test Method C 692 Section 9 on Test Coupons (sensitize environment and weigh using a precision balance to 0.1 mg.
stainless steel coupons by heating at 1200°F (649°C) in an Record the weight and coupon identification.
argon (inert) or air (oxidizing) atmosphere for three hours). 7.8 Cut the polyvinylchloride (PVC) pipe into 1-in. lengths.
Galvanized steel is not suitable for test because the elevated Remove the ragged edges to make smooth flat-sanded ends.
temperatures recommended by the practice are above the Drill a 1⁄8-in. hole in the side of the pipe, 1⁄8 in. from the top end
recommended use temperature of galvanized metal. However, and then clean the pipe in de-ionized water and dry.
with suitable adjustments to slow the drip rate and lower the 7.9 Position an O-ring approximately 0.5 in. from a smooth
temperature of the hot plate, there are possibilities for the flat-sanded end of the PVC pipe. Put a 0.125-in. bead of
development of test practices. silicone sealant completely around the space formed by the
6.2.2 It is likely that different results will be found when pipe and O-ring. Position the pipe in the center of the coupon
switching between various metal grades. The use of standard with the hole oriented to the corner for easy access. While
solutions of corrosive ions provides a benchmark against which tightly holding the pipe down, push the O-ring into contact
the leachable ions contained in the insulation are evaluated. with the coupon, squeezing out some silicone sealant to form a
The standard solutions are run during every test sequence, after continuous, watertight seal. Avoid silicone sealant on the inside
having previously established the range of results for the of the pipe and metal. Allow the silicone to cure completely
individual laboratory and the type, grade, and lot of metal. (overnight) before testing.
6.3 Chemically Pure Salts and Reagent Grade Acids shall 7.10 Cut 1-in. pieces of the plastic straw with one end at a
be used for preparation of corrosion solutions used as reference 45° angle. Insert the straw into the hole in the PVC pipe so that
standards for plate calibration and comparison with extraction the angle is down and the drip falls in the approximate center
solutions. of the coupon. The barbed fitting is used to attach the straw to
6.4 Chloride Reference Standards are prepared from a 1000 the peristaltic pump tube. Fig. 2 shows a completed test coupon
ppm (mg/L) chloride solution using 1.64 g of sodium chloride with the components labeled. Figs. 3 and 4 show a hot plate
to one liter of de-ionized water. For a liter of a 1-mg/L chloride with the coupons installed.
solution, mix 1 mL of 1000 ppm chloride solution to one liter.
Quantity and concentration of the reference standards are made 8. Solution Preparation
as needed for the desired test. 8.1 Procedure A:
8.1.1 Many industrial insulation materials are required to
7. Metal Coupon Preparation meet the requirements of Specification C 795 using Test
7.1 Shear 2 by 7-in. (51 by 178-mm) coupons from the test Methods C 692 and C 871. If the material has been extracted
metal, with the long dimension parallel to the long dimension for Test Method C 871 testing, a suitable procedure is the
of the sheet. dilution of the concentrated extraction solution with de-ionized
7.2 Grip coupon with suction cup holder (see Fig. 1 of Test water for use in this test. Refer to Test Method C 871 for the
Method C 692) or other means to facilitate wet grinding on belt details of the extraction. Briefly described, the procedure
grinder. Grind parallel to the long dimension of the coupon involves extracting duplicate ground-up samples of 20 g each
using a well-used 80-grit (a belt previously used to make Test in 450 g of boiling water for 30 min, adjusting the final solution
Method C 692 stainless steel coupons is acceptable) or new weight to 500 g, and then filtering to remove the solids.
120-grit wet belt with just enough pressure to remove the dull 8.1.2 Combine 375 mL from each of the two extraction
finish and leave the metal bright. The degree of surface solutions described in 8.1.1 to provide a uniform 750-mL
roughness is expected to affect the test, do not over-grind. A solution. Dilute 375 mL of the solution with 2625 mL of
reference coupon or comparative roughness standard is useful. de-ionized water to total 3000 mL. One thousand millilitres of
The belt-ground face is the test surface. Immediately rinse in the resulting solution is used in a 4-day test for one metal
de-ionized water and dry with a clean paper towel to prevent coupon. The two extractions provide enough diluted solution
flash corrosion. for six coupon tests of four-day duration. The minimum

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 C 1617 – 05

FIG. 2 Test Coupon with Components Identified

FIG. 3 Test Coupons on Hot Plate

FIG. 4 Test Cells on Hot Plate

recommended number of specimens per test set is three. 8.2 Procedure B:

Additional test sets are used to provide greater confidence in 8.2.1 There are insulation materials that do not readily wick
the results. The unused 125 mL from each of the extraction water, and cannot be made to wick by heat treatment. Some
solutions are available for Test Method C 871 or other chemi- manufacturers consider it inappropriate to subject them to a
cal analysis. severe leaching of soluble ions by Procedure A because it

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 C 1617 – 05
exposes a maximum surface area to water for extraction, which quickly fill all the test coupon cells with 1 mL of de-ionized
would not happen under ordinary conditions of use. An water using an automatic pipette. Determine the time it takes
alternative extraction procedure is as follows: for the first cell to evaporate the water (expect 2 to 3 min) and
8.2.2 Slice the material cross-sectionally on a band saw into verify that the other cells dry within 45 s of the first. When
0.25-in. wide pieces. Cut enough slices so that the exposed necessary, reposition or otherwise adjust the coupons.
surface area totals 2 ft2. A 2-in. thick block sample would 9.1.3 New plates are evaluated by performing a number of
require 12 slices that are 5.11-in. long. A 11⁄2-in. thick block tests using only standard solutions to determine the range of the
sample would require 16 slices that are 4.93-in. long. results for each standard solution. A Frequency Histogram
8.2.3 Record the weight of the slices. similar to Fig. 1 is developed for the individual lab, test
8.2.4 Stack the slices using plastic spacers (flattened plastic equipment, and metal used in the test. Guide G 16 is helpful in
stir-straws) between the slices, and secure the stack with rubber analyzing the data.
bands or monofilament fishing line. 9.1.4 A small fan used to circulate the air above the test
8.2.5 Place the stack or stacks in the bottom of a suitable apparatus is helpful to the evaporation process by moving the
container. If the material floats, an appropriate means is air saturated with water.
necessary to weight the material so it remains submerged. 9.2 General Procedure:
8.2.6 Pour in enough heated de-ionized water to cover the
9.2.1 Place each coupon with the attached PVC tube on the
stack completely. If boiling water exceeds the desired extrac-
flat plate using sufficient high temperature grease between the
tion temperature, the manufacturer needs to specify the water
coupon and the plate to maintain good contact (no air space).
temperature.
8.2.7 Agitate the contents 3 times over a 15-min period. 9.2.2 Fill the liquid reservoirs for the peristaltic pump with
After 15 min, filter the water though a Whatman number 41 the test and standard reference solutions and attach the indi-
filter or equivalent. Rinse the container and slices with de- vidual feed tubes to the barbs in the plastic stir-straws. Record
ionized water. Record the total volume of water obtained from the coupon identification and solution information.
the extraction. 9.2.3 Start the peristaltic pump previously calibrated to
8.2.8 Adjust the final volume to 3000 mL to test three deliver 250 mL/day to each sample.
coupons for four days. 9.2.4 Monitor the reservoir bottles daily to ascertain that the
8.3 Reference Standards: delivery to each sample is 250 6 25 mL/day. Refill if needed
8.3.1 The use of reference tests to compare the measured for longer duration tests.
corrosion resulting from the insulation solutions to that of 9.2.5 At the conclusion of the test period (normally 96 h),
known corrosive solutions allows for a degree of calibration of carefully remove the coupons. In the event of a power outage,
the practice. Ideally the number of test coupons for each or a plugged tube during the test, add additional test time to the
solution is three. Conduct the tests on the same plate at the end of the test to allow the delivery of the full amount of liquid.
same time as the insulation solutions. Include this information in the final report.
8.3.2 The reference solutions for mild steel and copper
coupons include de-ionized water and various solutions of 10. Cleaning Coupons
chloride ranging from 1 to 10 mg/L and ideally bracket the
10.1 Remove the coupons and clean the heat transfer grease
corrosion found for the insulation coupons. The reference
from the back of the coupon.
solutions for aluminum coupons include de-ionized water and
various solutions of sodium hydroxide. Solutions that are more 10.2 Remove the PVC pipe and O-ring, and carefully cut
concentrated than 10 mg/L produce high corrosion and are away any silicone sealant still remaining on the coupon.
better tested using reduced exposure times. Xylene is helpful to remove the silicone.
10.3 The cleaning procedure is important to the accurate
9. Test Procedure determination of the weight lost due to corrosion. For this test
9.1 Test Plate Conditions: method it has usually been found sufficient to clean the steel
9.1.1 Start the heated plate previously tested and regulated coupons using very coarse stainless steel pot scrubbing pads to
to operate at 230°F with water dripping onto the plate. The hot remove traces of the silicone sealant and large deposits. Follow
plate shall be maintained at this temperature throughout the that by wet sanding with “medium” sanding pads to remove
test. It is important to establish this control prior to beginning deposits in the test area. A sharp-pointed tool is helpful to
tests for data collection. The individual heated plate, digital gently loosen corrosion products in deep pockets. A final
controller (when used), thermocouple position, and the insula- cleaning is done by lightly wet sanding for 60 s with a solution
tion covering the thermocouple (when used) are important to of 1 part hydrochloric acid to 3 parts water using “fine” sanding
the determination of the temperature control. When any pads to remove corrosion products in the test area and return
changes are made it is necessary to re-establish the temperature untested areas, both front and back, to their condition at the
control of the test set-up. start of the test.
9.1.2 It is useful to test the evaporation rate of each coupon, 10.4 Detailed methods for chemically cleaning coupons
especially on newly constructed plates, to verify that the after testing are given in Practice G 1 Section 7 on Methods for
coupons are being heated evenly. Start the peristaltic pump Cleaning After Testing. If necessary (or desirable) suggested
with the feed tubes in de-ionized water and allow the tempera- chemical cleaning procedures in Practice G 1 are C.1.2 for
ture controller to stabilize. Turn off the peristaltic pump and aluminum, C.2.3 for copper, and C.3.1 for iron and steel.

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 C 1617 – 05
10.5 Rinse in distilled or de-ionized water, followed by TABLE 1 Mass Loss Corrosion Rate (MLCR) Calculated Using
rinsing in acetone. Dry and polish the test surface using a clean Practice G 1 (see Section 11)
paper towel. Do not touch the test surface with bare hands NOTE—MLCR expressed in mils per year.
thereafter. 0-ppm 1-ppm 5-ppm 10-ppm
10.6 Heat the coupons to drive off surface moisture and De-ionized Chloride Chloride Chloride
obtain a constant weight. Cool the coupons in a moisture-free Water Solution Solution Solution

environment. 19.02 35.17 57.31 62.61

11.68 29.87 40.91 56.48
14.04 33.00 66.76 110.54
11. Inspection of Coupons 12.13 37.91 52.46 131.35
12.45 29.80 16.53 52.27
11.1 Weigh using a precision balance to 0.1 mg. Record the 14.42 22.72 42.51 35.42
weight and coupon identification. Calculate the average MLCR 6.13 35.42 76.33 67.01
using Practice G 1 Section 8 on Assessment of Corrosion 13.27 31.78 111.82 57.48
21.25 17.04 42.19 98.92
Damage, as shown below. 7.59 37.78 44.42 132.35
~K 3 W! 12.83 32.55 53.61 61.52
MLCR 5 mils per year (1) 6.70 36.12 54.25 36.42
~A 3 T 3 D! 16.08 25.66 41.87 90.44
19.02 14.93 54.50 95.48
where: 11.42 31.08 65.67 63.44
K = 3.45 3 106 (a constant to convert cm/h to mils/year), 14.81 34.21 70.46 99.63
T = time of exposure in h, 9.38 34.46 42.57 69.63
18.38 36.06 63.44 107.28
A = area of exposure (cm2); based on the inner radius (cm) 8.62 27.38 50.10 58.84
of the plastic pipe: A = p 3 r2 (3.142 times radius of 8.49 24.19 48.63 65.10
circle (squared)), 12.13 15.25 55.40 64.27
5.36 33.70 69.12 71.29
W = mass loss from the coupon (g) = (initial recorded 4.66 32.10 39.06 78.37
weight of coupon) − (weight of coupon after exposure 5.55 35.04 43.21 88.52
and cleaning), and 6.57 22.98 41.93 30.57
D = bulk density of the test metal (g/cm3); carefully 5.87 39.44 36.76 39.25
7.21 35.04 25.66 50.93
measure with a micrometer and weigh several stacks 6.45 34.66 30.06 128.41
of coupons, average the results to obtain: D = weighed 3.45 41.48 41.68 97.52
mass (g) / length 3 width 3 height (all cm). 2.30 41.55 29.61 98.03
11.93 42.70 38.74 82.84
11.1.1 Example Calculations (for De-Ionized Water): 9.19 33.32 38.10 105.31
K = 3.45 3 106 13.15 28.98 33.00 96.50
T (h) = 96 14.10 21.38 58.27 84.50
A = 3.142 3 (0.594 in.)2 = 1.108 in.2 3 6.452 cm2/in.2 = 7.149 cm2 12.25 16.08 39.31 59.55
W (de-ionized (DI) water) = 16.5971 − 16.5875 = 0.0096 12.25 17.17 40.78 45.57
D (mild steel) = 7.88 g/cm3; D (aluminum) = 2.72 g/cm3; 9.96 32.42 48.25 56.80
D (copper) = 8.81 g/cm3 4.60 34.72 23.10 63.63
3.70 34.02 27.19 67.01
11.1.1.1 Mathematical Simplifications: 2.43 33.38 35.61 48.82
3.32 25.66 77.16 75.76
A 3 T 3 D: mild steel = 5408.08, Al = 1866.75, Cu = 6046.34
1.21 33.12 30.76 48.95
Factor = (K = 3.45 3 106) / (A 3 T 3 D): mild carbon
1.28 44.04 42.57
steel = 637.93, Al = 1848.13, Cu = 570.59
5.87 37.46 42.63
11.1.1.2 Measured Data: 7.15 23.36 41.61
3.96 28.15 61.27
W (DI water) = 16.5971 − 16.5875 = 0.0096 3 637.93 (factor mild 11.23 25.02 27.76
steel) = 6.124 mils per year 10.02 36.83 49.27
MLCR = 6.124 (mils per year) 10.28 21.64 67.65
9.38 27.63 68.54
11.2 Rate and categorize the MLCR of the insulation or 12.25 18.51 42.44
other test solutions against the MLCR of standard reference 9.38 40.14
tests to determine an estimate of the corrosiveness of the 36.76
54.12
soluble ions contained in the solution. Utilize data collected 67.40
from a number of test sets to develop a chart similar to Fig. 1. Average and (Standard Deviation)
The data shown in Table 1 are standard reference tests used to
9.5 (4.8) 30.5 (7.4) 48.0 (16.4) 74.6 (26.0)
create the Fig. 1 bar graph. It is necessary for each laboratory
to develop their own data, with their own individual plate or
plates, metal, operators, cleaning procedures, and environmen-
tal conditions to establish the ranges of MLCR calculated for the results obtained using this practice on reference standards
the reference standards. The insulation or other test solutions and experimental insulation samples tested on mild carbon
are then evaluated against the reference solution results. An steel coupons.
example rating criteria for estimating corrosiveness is: MLCR 11.3 Individual laboratories working in conjunction with
= 0 to 15 mils = range A; MLCR = 15.1 to 35 mils = range B; material manufacturers, specification writers, designers, con-
MLCR = 35.1 to 60 mils = range C, MLCR = 60.1 and higher tractors, and operators of the equipment are encouraged to
= range D. The rating criteria were developed to accommodate develop and share their own rating criteria through testing,

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experimentation, refinement, and experience, for particular 12.3.2 Provide information on treatment of the metal sur-
insulation types, metal classification, and metal types. face and surface coatings if used.
11.4 Visually examine test coupons under good lighting for 12.4 Results:
evidence of corrosion. Personnel involved in the inspection 12.4.1 Number of specimens tested, and the time period
shall demonstrate natural or corrected near distance vision exposed.
acuity of 20/25 or greater Snellen fraction with at least one eye 12.4.2 Describe the severity of corrosion (density, size, and
and be trained for corrosion detection. Examine all cleaned depth) in the test area of each coupon using procedures in
coupons using 10 to 303 magnification for areas of pitting and Practices G 46 and G 1 for guidance.
corrosion and characterize using Practices G 1 and G 46. 12.4.3 Report the actual mass loss and calculated average
11.5 Guide G 16 is helpful for guidance. MLCR in “mils per year” of each coupon and the reference
11.6 Stainless steel coupons are inspected and evaluated for tests using 11.1.
corrosion cracking using the procedures of Test Method C 692 12.4.4 Rate the insulation results against the reference tests
Section 14 on Inspection of Coupons. for an estimate of the corrosiveness of the leachable ions
following the guidelines of 11.2 or 11.3 or both.
12. Report
12.5 Optional:
12.1 Report the following information: 12.5.1 Chemical analysis data run in accord with Test
12.2 Insulation Solution: Method C 871.
12.2.1 Manufacturer, product name, lot number, type, size, 12.5.2 Report other statistical and graphical representations
density, and other identifying information for insulation used to of the data, such as pictures, maximum pit depth, and precise
prepare the solution. area within the test exposure area where corrosion occurred,
12.2.2 Method used to prepare the solution (A or B). where obtainable and desirable for the particular investigation.
Indicate the quantity and temperature of the water, and the
length of time of the extraction. 13. Precision and Bias
12.2.3 The weight of the insulation extracted and final
volume of the extraction solution. 13.1 Appendix X2 provides a discussion and review of
12.2.3.1 The volume of this extraction solution used and the controlled and uncontrolled variables. Table 1 is a summary of
volume of de-ionized water used to make the final test solution. all individual standard reference coupons tested using the
12.2.4 Information on heat treatment or other special treat- general guidelines of this practice. The tests were conducted
ment of the insulation. over a 2-year period by a single lab using three heating plates
12.2.5 Information on the reference solutions tested for and two operators. A full report on supporting documentation
comparison. will be filed with ASTM.
12.3 Metal:
12.3.1 Type or types of metal used (mild steel, copper, 14. Keywords
aluminum, stainless steel) including ASTM classification and 14.1 chloride; corrosion; corrosion under insulation; inhibi-
any mill certificate of chemical composition. tion; metal; protective coatings; steel; thermal insulation

APPENDIXES

(Nonmandatory Information)

X1. ACCESSORIES

X1.1 Hot Plates

X1.1.1 A commercial hot plate with 1⁄8-in. thick copper
plate on surface to provide uniform surface temperature has
been used by a lab with mixed results.
X1.1.2 Test Method C 518 hot plate with 1⁄8-in. thick copper
plate on surface to provide uniform surface temperatures.
X1.1.3 A 12-in. square flat plate heater from Thermcraft,
Inc., PO Box 12037, 3950 Overdale Road, Winston Salem, NC
27117-2037. Cat# P-VFR-12-12, 1650 Watts, 240 V. This
heater was topped with a 1-in. thick aluminum plate and a
1⁄8-in. thick copper plate to achieve equal heat distribution at FIG. X1.1 A One-Foot Square Flat Plate Heater
the surface. See Fig. X1.1.

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X1.1.4 Temperature control is obtained with a controller
such as a Eurotherm 91e,3 with control thermocouple mounted
on the top surface, covered by a small section of ceramic wool.
3
The sole source of supply of the Eurotherm 91e controller unit known to the
X1.2 Peristaltic Pump and Accessories committee at this time is Eurotherm Controls, Inc., 11485 Sunset Hills Road,
Reston, VA 20190-5286. If you are aware of alternative suppliers, please provide
X1.2.1 A multi-channel peristaltic pump with silicone rub-
this information to ASTM International Headquarters. Your comments will receive
ber tubing and barbed fittings must be used to deliver test liquid careful consideration at a meeting of the responsible technical committee,1 which
at the rate of 250 mL/day (610 %) to each coupon. you may attend.

X2. RUGGEDNESS VARIABLES

X2.1 Uncontrolled Variables X2.2.2 Duration of the Test—The test is designed to run for
X2.1.1 Atmosphere Within Laboratory—Humidity and air four days but it is acceptable for different control or insulation
temperature of the room are normal for personnel comfort but solutions to be tested for longer or shorter duration if needed.
vary with location, season, and time of day. A fan is helpful in X2.2.3 Rate and Volume—The amount of solution used
circulating the air above the cells and reducing the localized over a specific time period is controlled and reported. The
humidity from the water evaporating from the cells. Elevation described equipment will deliver approximately 0.17 mL as 5
and atmospheric pressure will also influence the boiling drops per minute. It is possible to change the rate that the
temperature and evaporation rate from the cells. solution is delivered. This will influence the evaporation rate
X2.1.2 Rate of Evaporation from Coupon—While directly and the time that the cell is wet and dry. The use of intermittent
related to the hot plate temperature and delivery rate of delivery to allow larger volumes of solution to collect in the
solution, which are controlled, the time that the coupon cell and then pausing while the solution evaporates is an option
remains wet can be different in each cell because of the way the to be investigated. This option will cover the exposed area
solution spreads out and the atmosphere within the laboratory. completely and is expected to result in less localized corrosion.
X2.1.3 Distribution of Localized and General Corrosion X2.2.4 Solution Concentrations—The standard reference
Pattern—The method calculates all metal loss as general solutions are made from chemically pure reagent grade mate-
corrosion, that is, having occurred evenly over the entire rials and de-ionized water. Standard laboratory practice will
exposed area. However, the actual corrosion is almost entirely allow different laboratories to make identical solution to test
localized, with deeply pitted areas and edge effects accounting and establish a basis for comparison to the insulation solutions.
for most of the metal loss within the exposed area. The effect The insulation solutions are prepared using specifically de-
is more pronounced when strong corrosive agents generate scribed extraction and dilution procedures.
significant metal loss. X2.2.5 Cell Tubes—The material and height of the cell
X2.1.4 Change in Corrosion Rate—The method assumes tubes are specifically described. A test using Lucite tubes rather
the rate to be constant over the test period and then extrapolates than PVC tubes showed no significant difference. This rein-
that rate to calculate one year of corrosion reported as mil per forces the conclusion, based on the low corrosion of the
year. A shorter duration test for strong corrosive agents will “blank” de-ionized water tests, that the chloride content of the
help minimize the changes that occur as the products of PVC did not contribute to the corrosion rate because it does not
corrosion and the concentration of ions from the solutions build leach from the cell tube. The height of the tube and initial tests
up. using capped tubes showed that condensation for the evapo-
X2.1.5 Different Metal Qualities and Variables Between or rating solution will re-enter the cell and change the overall time
Within a Lot—The metal meets the ASTM specification the cell is wet and will affect corrosion.
requirements but there are possible localized variances within X2.2.6 Cleaning—Mechanical methods have been used
the sheet of metal the coupons are cut from. with good success on bare coupons and the cleaning materials
used are described. Chemical methods following the guidance
X2.2 Controlled Variables of Practice G 1 paragraph 7.2 are necessary if the purpose of
X2.2.1 Temperature of Hot Plate During the Test—A spe- the test is to check metal coating, as mechanical methods will
cific set point is provided but it is acceptable to raise or lower unintentionally remove the coating. Chemical means of clean-
it slightly to adjust for local conditions and include the ing bare steel coupons increased the measured weight loss but
information in the report. made cleaning much easier.

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X3. SHORT HISTORY OF THE TASK GROUP

X3.1 The task group was formed to investigate various and tested with the goal of developing an ASTM test method.
approaches to obtaining a non-subjective, numeric value for The document was written as this practice to provide greater
judging the potential contribution to the corrosion of metal that latitude to describe multiple sample preparation and evaluation
may come from thermal insulation materials. It is suspected criteria. This will allow different material standards and speci-
that an important motivation to beginning this work was fications to specify exactly how the tests are to be run within
corrosion resulting from chemical fire retardant treatments that the framework of the practice.
were used during in the late 1970s. Several analytical ap-
proaches were tried, including electrochemical evaluation. The X3.4 A major problem faced over the years in the devel-
results from these tests and a Round Robin interlaboratory opment of a non-subjective measurement is that corrosion is
study were unsatisfactory and the approach was discontinued. not a well-behaved physical phenomenon that acts consistently
and predictably every time. The ASTM G01 Committee on
X3.2 A test procedure referred to as the Stansbury test was
Corrosion of Metals suggests it is usually necessary to run a
investigated and advanced to a Round Robin interlaboratory
large number of tests to develop a meaningful statistical data
study. Metal coupons were sandwiched between insulation
base for comparison and measurement. This requires a large
samples in a water-tight container. De-ionized water was added
amount of work by the primary investigators and others in
to partially immerse the metal. The procedure attempted to
support of the method and to conduct Round Robin interlabo-
measure the pit depth and categorize the general corrosion on
ratory studies.
metal coupons at the metal-air-wet insulation interface. The
results from the Round Robin interlaboratory study were
X3.5 It is important to be aware that accelerated test
inconsistent and the corrosion depressions were too small for
methods usually represent a worst case scenario and are not
accurate measurement. The approach was discontinued.
normally useful for predicting the life expectancy of equipment
X3.3 A test protocol developed by Tutco Scientific Inc. and or actual rate of corrosion that will be found in real life
referred to as the Tutco Accelerated Corrosion Test (TACT) situations. These methods are primarily useful for comparative
was started in 1998 after the unsatisfactory round robin trials of and qualitative evaluations of the tested materials. It is difficult
the Stansbury procedure. TACT was further refined, expanded, to correlate the laboratory result with the in-service situations.

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