Evaluation of A Proposed ASTM

Standard Guide to Assess the

Compatibility of Metal-Heat Transfer

Liquid Pairs in Solar Heating and

Cooling Systems

Paul Wencil Brown and

John W. Grimes, II

Structures and Materials Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

October, 1979

Issued November 1979

U S. DEPARTMENT OF COMMERCE

^QC

! 100

.056

79-1919

1979

NATIONAL BUREAU OF STANDARDS

MATIOKAL SUBEAtl or BTAM1>«RD8

XJBBAXT

NBSIR 79-1 91 9 NOV 2 4 i960

EVALUATION OF A PROPOSED ASTM . . STANDARD GUIDE TO ASSESS THE

COMPATIBILITY OF METAL-HEAT TRANSFER

LIQUID PAIRS IN SOLAR HEATING AND ? - >/ w

COOLING SYSTEMS -

Paul Wencil Brown and

John W. Grimes, II

I

Structures and Materials Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D C. 20234

October, 1979

Issued November 1979

U.S. DEPARTMENT OF COMMERCE

Luther H. Hodges, Jr., Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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ABSTRACT

This study was undertaken as part of a round-robin evaluation of a proposed American Society for Testing and Materials (ASTM) testing methodology entitled, "Standard Guide for Laboratory Screening of Metallic

Containment Materials for Use with Liquids in Solar Heating and Cooling

Systems." This study was undertaken solely to evaluate the procedural

aspects of each test method and the results of this study are not intended

to provide an assessment of the suitability of any of the metals evaluated

for use in solar heating and cooling systems. It was determined that

the tests described in this Standard Practice can be carried out as a basis for evaluating metal-heat transfer liquid pair interactions under

conditions simulative of various modes of solar containment system operation.

Key Words: Solar-Heat Transfer Liquid Containment; corrosion; elevated

temperature; heat transfer; liquid flow rate; stagnation.
TABLE OF CONTENTS

Page

ABSTRACT iii

LIST OF TABLES vi

LIST OF FIGURES vii

1.0 INTRODUCTION 1

2.0 SELECTION OF MATERIALS AND SPECIMEN PREPARATION 2

3.0 TEST PROCEDURES AND RESULTS 2

3.1 Test A, Basic Itninersion Test of Atmospheric

Pressure 2 3.1.1 Procedure 2 3.1.2 Results 3

3.2 Test B, Heat Rejecting Surface Test of Atmospheric

Pressure 4

3.2.1 Procedure 4

3.2.2 Results 6

3.3 Test C, High Pressure Test 7

3.4 Test D, Repeated Dip-Dry Test of Atmospheric

Pressure 7 3.4.1 Procedure 7 3.4.2 Results 12

3.5 Test E, Imposed Crevice Test of Atmospheric

Pressure 12

3.5.1 Procedure 12

3.5.2 Results 13

3.6 Test F, Tube Loop Test of Atmospheric Pressure 14

3.6.1 Procedure 14

3.6.2 Results 16

4.0 SUMMARY 17

5.0 REFERENCES 18

6.0 ACKNOWLEDGEMENTS 19

IV
TABLE OF CONTENTS (continued) Page

APPENDIX I - Draft Standard Guide for Laboratory Screening of

Metallic Containment Materials for Use with

Liquids in Solar Heating and Cooling Systems 20

APPENDIX II - Specimen Cleaning Procedures 37

APPENDIX III - Typical Blank Correction Factors for 1 inch by

2 inch (25mm by 51mm) Specimens, Grams 37

V
LIST OF TABLES

TABLE NO PAGE

1 Corrosion Rates Observed for Test A 3

2 Maximum Pit Depths Observed for Test A 4

3 Corrosion Rates Observed for Test B 6

4 Maximum Pit Depths Observed for Test B 7

5 Corrosion Rates Observed for Test D 12

6 Corrosion Rates Observed for Test E 13

7 Maximum Pit Depths Observed for Test E 14

VI
LIST OF FIGURES

Figure No. Page

1 Schematic of the Apparatus Used in Test B 5

2 Apparatus Used in Test D 8

3 Isometric Drawing of Apparatus Used in Test D 9

4 Electro-mechanical schematic of the apparatus

used in Test D showing the gang timer which

controls the cyclic operation of the apparatus

the microswitches which control the travel of

the sample rack, and the power relays which interface between the infrared lamps and the variable

transformers 10

3 Apparatus Used in Test F 15

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1.0 INTRODUCTION

This study was undertaken as part of a round-robin evaluation of a proposed American Society for Testing and Materials (ASTM) testing methodology entitled, "Standard Guide for Laboratory Screening of Metallic

Containment Materials for use with Liquids in Solar Heating and Cooling

Systems." This study was undertaken solely to evaluate the procedural

aspects of each test method and the results of this study are not

intended to provide an assessment of the suitability of any of the metals

evaluated for use in solar heating and cooling systems.

The draft standard guide (Appendix I) includes six test methodologies:

Test A - Basic Immersion Test at Atmospheric Pressure

Test B - Heat Rejecting Surface Test at Atmospheric Pressure

Test C - High Pressure Test

Test D - Repeated Drip-Dry Test at Atmospheric Pressure

Test E - Imposed Crevice Test at Atmospheric Pressure

Test F - Tube-Loop Test at Atmospheric Pressure

These test procedures were designed to allow the simulation of the

following conditions to which a solar collector containment system may

be subjected:

i) operating when filled with flowing heat transfer

liquid (operating full, flow)

ii) filled with heat transfer liquid under no-

(stagnant, full)

flow conditions

iii) partially filled with heat transfer liquid

conditions (stagnant, partially full)'

under no-flow

iv) empty

addition, these test procedures were designed to

the following factors which are likely to affect

allow assessment

corrosion:

i) flow rate

ii) heat transfer mode

iii) alternating wetting and drying

iv) aeration or deaeration

v) the presence of crevices

1
The rationale for selecting one or more of these tests to evaluate a specific aspect of metal-heat transfer liquid interaction is presented

in the commentary for each test in Appendix I.

2.0 SELECTION OF MATERIALS AND SPECIMEN PREPARATION

Alloys of the principal metallic materials most likely to be used as liquid containment materials in solar heating and cooling systems were

selected for use in evaluating these tests. In addition, the selection

of Al, Cu, S/S and mild steel allowed comparison of the various types of

corrosion failure, e.g. pitting, crevice corrosion, and general corrosion,

as functions of each test. Two stainless steel (S/S) alloys, AISI 439,

and 444, two copper (Cu) alloys, CDA 122 and 706, two aluminum (Al)

alloys, ANSI 1100 and 3003, were used in evaluating tests A, B, D and

E. In addition SAE 1015 mild steel and AISI 409 stainless steel were

used in test A only. It was anticipated that the the higher corrosion rates

of these alloys would provide measure of the intersample variability in

this test. ANSI 3003 Al tubing was used in Test F.

Specimens were prepared by shearing rolled stock to approximate coupon size.

For the test requiring 2 inch by 2 inch (51 mm by, 51 mm) coupons, specimens were sheared to 2.25 inches by 2.25 inches (57 mm by 57 mm). Similarly, for the tests requiring 1 inch by 2 inch (25 mm by 51 mm) coupons,

specimens were sheared to 1.25 inches by 2.25 inches (32 mm by 57mm).

These were then wet ground to their final dimensions with no more than

0.005 inch being removed on each of the last 3 passes of the grinding

wheel. The edges of the coupons were then lightly wet-polished on 600

grit silicon carbide paper to remove burrs. The flat, commercial surfaces

of the coupons were not abraded in any way. After measuring and recording

the dimensions of the coupons, they were rinsed in water to remove any

residual abrasive material. They were then scrubbed with a soft bristled

brush using soapy water, rinsed with tap water followed by rinsing 3

times in distilled water, immersing twice in anhydrous ethanol and blotting

dry. It was noted by visual examination that the copper base alloys were slightly tarnished. These were subsequently cleaned by immersion in

the cleaning solution specified in ASTM Gl-72 [1] (see Appendix II) for

10 seconds followed by rinsing and drying as discussed above. This

procedure was adequate to completely remove the tarnish.

After cleaning and drying, the metal coupons were weighed to the nearest

O.OOOOl gram and placed in a dessicator.

3.0 TEST PROCEDURES AND RESULTS

3.1 TEST A , Basic Immersion Test at Atmospheric Pressure

3.1.1 Procedure

Test A, is a prescreening test which allows evaluation of the interaction

between metal-liquid pairs at elevated temperature. This test was carried

out j'n glass reaction vessels immersed in an oil bath. Triplicate 1 inch

by 2 inch (25mm by 51mm) coupons of each alloy were placed in glass cradles

v'hich, in turn, were placed in reaction vessels. The reaction vessels

2
I

were then filled with a selected volume of heat transfer liquid and the

reaction vessel covers and condensers attached. These were placed in the

oil bath. The bath temperature was increased to 90“ C where it was maintained

for the duration of the 30 day test.

The heat transfer liquid selected for use in this and the other tests was ASTM D 1384 tap water [2]. This was prepared by dissolving 148mg of

sodium sulfate, 165mg, of sodium chloride and 138mg of sodium bicarbonate

per liter in distilled water.

The liquid volume to metal surface area ratio used in this test was

5 ml/cm^. The changes in liquid volume due to evaporation during the test were negligible.

At the conclusion of the test, the samples were removed, cleaned in

accordance with ASTM Gl-72 [1] (Appendix II), and weighed. To compensate

for the removal of uncorroded metal as a result of the cleaning process,

the coupons were recleaned and reweighed with the weight difference

between the first and second cleaning being used as the correction factor

(Appendix III).

3.1.2 Results

O Table I lists the corrosion rates in mdd (mg/dm^/day) which resulted from

30 days of immersion in unstirred ASTM D1384 tap water [2] at 90“C.

Table I

Corrosion Rates Observed for Test A

Corrosion rate, mdd

Coupon

Alloy 1 2 3 Avg.

1100 A1 0.04 0.11 0.26 0.14

3003 A1 0.23 0.16 0.29 0.23

122 Cu 1.69 1.38 1.49 1.52

706 Cu/Ni 1.04 1.11 1.29 1.15

409 S/S Negligible Negligible Negligible Negligible

439 S/S Negligible Negligible Negligible Negligible

444 S/S Negligible Negligible Negligible Negligible

1015 steel 42.2 50.6 45.7 46.2

The depths of the pits which occurred as a result of carrying out Test A

were measured by optical microscopy at lOOX magnification. Maximum pit

depths are listed in Table II.

3
Table II

Maximum Pit Depths Observed for Test A

Maximum Pit Depths, mm

Alloy

1

Coupon Number

2 3

Side

1 2

Side

1 2

Side

1 2

1100 A1 0.15 0.11 0.05 0.04 0.08 0.18

3003 A1 0.12 0.04 0.06 0.08 0.08 0.11

122 Cu 0.03 0.05 0.03 0.07 0.09 0.02

706 Cu/Ni 0.03 0.02 0.04 0.01 * 0.02

409 S/S * * * * * *

439 S/S * * * * * *

444 S/S * * * * * *

1015 Steel Perforation Perforation Perforation

*Pits present were too shallow to measure.

3.2 TEST B , Heat ^Rejecting Surface Test at Atmospheric Pressure

3.2.1 Procedure

Test B allows evaluation of the interaction between metal-liquid pairs

under the conditions of heat transfer at elevated temperature. This test was carried out in modified 2-necked, round bottom flasks. Modification

involved attachment to the bottom of each flask of a one inch (25mm)

i.d. neck terminating in a pipe flange. Figure 1. The 2 inch by 2 inch

(51mm by 51inm) coupon was attached to the flask in a manner also shown

in Figure 1. A viton* rubber gasket was used as a seal between the

* Certain trade names and company products are Identified in order to adequately specify the experimental procedure. In no case does such identification imply recommendation or endorsement by the National Bureau of

Standards, nor does it imply that the products are necessarily the best

available for the purpose.

4
HOT PLATE

Figure 1. Schematic of the apparatus used in test B.

5
bottom surface of the pipe flange and the coupon. A teflon gasket was placed between the top surface of the pipe flange and the retainer to

avoid breaking the flange. Heat was supplied to the specimen using a hot plate. The temperature of the liquid was maintained at 100"C

(nucleate boiling) by using an immersion probe which regulated the hot

plate.

Each flask was filled with 350 ml of ASTM D1384 water [2], the temperature was Increased until nucleate boiling occurred, and this condition

was maintained throughout the duration of this 30 day test. Changes in

liquid volume due to evaporation were negligible. At the conclusion of

the test the samples were removed, cleaned according to ASTM Gl-72 [1],

and weighed. A second cleaning and weighing was carried out to provide

the blank correction factor.

3.2.2 Results

Table III lists corrosion rates in mdd which resulted when test B was carried out for 30 days at 100°C

Table III

Corrosion Rates Observed in Test B

Alloy Corrosion rate, mdd

1100 A1 1.42

3003 A1 2.02

122 Cu 8.32

706 Cu/Ni 4.03

439 S/S Negligible

444 S/S Negligible

Visual observations revealed evidence of both pitting and crevice corrosion in the A1 and Cu based alloys while the stainless steel alloys

remained virtually uncorroded. Table IV lists the maximum pit depths

observed.

6
Table IV

Maximum Pit Depths Observed in Test B

Alloy Pit Depth, mm

1100 A1 0.04

3003 A1 0.04

122 Cu 0.05

706 Cu/Ni Pits present were

439 S/S No pits observed

444 S/S No pits observed

The pit distributions observed were not uniform. Maximum pit densities

occurred within about 1-2 mm from the interfaces with the viton gaskets

while the areas near the centers of the coupons were relatively free of

pits. Shallow crevices ranging in width from approximately 0.1 mm for

the A1 alloys to several mm for the Cu alloys were observed. These initiated at the edges of the viton gaskets and propaged outwards under the

gaskets.

3.3 TEST C , High Pressure Test

Test C was not part of the round-robin and was not evaluated in this study.

3.4 TEST D , Repeated Dip-Dry Test at Atmospheric Pressure

3.4.1 Procedure

Test D, allows evaluation of the effects of cyclic immersion of metallic

specimens in heat transfer liquid coupled with intermediate drying. The

The apparatus constructed to carry out this test is shown in Figure 2 and

is represented schematically in Figures 3 and 4.

This apparatus consists of a frame, an electric motor and pulley arrangement to raise and lower the specimens, two banks of infrared lamps whose

wattages are controlled by two 20A variable transformers, a timer-cycler

coupled with microswitches to control the dip-dry cycle, and a series of

glass and teflon specimen holders attached to an arm which is raised and

lowered on a predetermined cycle. Figure 4 shows the electrical-mechanical

system used. The cyclic immersion and drying of the samples is controlled

by a timer-cycler consisting of 4 microswitches, labelled 1, 2, 3 and 4,

and four cams driven by a timer motor. Microswitches 1 and 2 control the

7
8

Figure

2.

Apparatus

Used

in

Test
9

Figure

3.

Isometric

Drawing

of

Apparatus

Used

in

Test
I A)

To Vorlabla Trontformers

Input 120 V

Output 140 V Figure 4. Electro-mechanical schematic of the apparatus used in Test D showing

the gang timer which controls the cyclic operation of the apparatus the

microswitches which control the travel of the sample rack, and the power

relays which interface between the infrared lamps and the variable

transformers

10
vertical movement of the sample rack and operate in conjunction with the

microswitches labelled 5, 6, 7 and 8 which are mounted on the frame of

the apparatus. Microswitches 5 and 7 control the distance that the sample

rack is allowed to travel while microswitches 6 and 8 reverse the polarity

of the drive motor. A system deactivation microswitch. No. 9, is also

located on the frame of the apparatus. Should the top range limiting

microswitch. No. 7, fail to function, microswitch No. 9 will deactivate

the system.

Microswitch No. 3 in the timer-cycler controls the duration over which

the infrared lamps are activated. This is done by activating two power

relays which interface between the two variable transformers and the

front and rear banks of lamps. Microswitch No. 4 in the timer-cycler

controls the counter. The drip dry cycle used consisted of the following

sequence

1) The specimens were initially immersed in the heat transfer liquid,

2) over a period of 15 seconds the specimens were raised 20 Inches

(0.5m) to a position in the center of the 2 banks of infrared

lamps

,

3) the lamps were activated for 31/2 minutes,

4) the lamps were switched off and the specimens were allowed to

cool for a period of 51/2 minutes,

5) the specimens were lowered into the heat transfer liquid over a period of 15 seconds,

6) the specimens rested in the heat transfer liquid for 30 seconds,

7) the cycle repeated.

The total cycle time was 10 minutes.

Triplicate specimens of the alloys tested were prepared by drilling a 21/ 64-inch (8.3 mm) hole approximately 1/4 inch (6.3 mm) from the end of

each coupon. These were then cleaned and weighed as described in test A,

Section 2.0 above. The specimens were then secured to the apparatus using

glass rods and teflon spacers. The specimens were oriented at an angle

of 45° to the banks of lamps to facilitate uniform heating.

The heat transfer liquid used was ASTM D1384 tap [2] and 1000 ml, high

form beakers were used as containers. Each beaker was filled with

750 ml of heat transfer liquid and evaporative losses were made up daily

using distilled water. The liquid volume to metal surface ratio in this

test was 10 ml/cm.

This test was carried out for 30 days or 4320 dip-dry cycles.

il
3.4.2 Results

Table V lists the corrosion rates in mdd which resulted from carrying

out Test D for 30 days.

Table V

Corrosion Rates Observed for Test D

Corrosion rate, mdd

Coupon

Alloy 1 2 3 Avg

1100 A1 0.44 0.45 0.48 0.46

3003 A1 0.20 0.27 0.47 0.31

122 Cu 0.81 1.06 1.04 0.97

706 Cu/Ni 0.52 0.41 0.61 0.51

439 S/S negligible negligible negligible negligible

444 S/S negligible negligible negligible negligible

3.5 TEST E , Imposed Crevice Test at Atmospheric Pressure

3.5.1 Procedure

Test C allows evaluation of the interaction between metal-liquid pairs

at elevated temperature when an imposed crevice is present. This test

was carried out in the same apparatus with Test Af Triplicate 1 inch

by 2 inch (25mm by 51mm) coupons of the aluminum, copper, and 439 and

444 stainless steel alloys were tested. Specimens were initially

prepared by attaching teflon blocks to the coupons with rubber bands

in accordance with ASTM G48-76 [3]

however, the rapid deterioration of

the rubber bands which occured, effectively eliminated the imposed

crevice. As an alternative, a 0.250 inch (6.4mm) hole was drilled

through the center of each specimen and a threaded 1/4-20 teflon rod

1 inch (25.4mm) in length inserted. Drilled and tapped teflon plugs

1/2 inch (12.7mm) in length and 5/8 inch (15.9mm) in diameter were threaded onto this rod and torqued to 3 inch-pounds (0.34Nm).

This was adequate to form an imposed crevice.

Test E was carried out for 30 days at 90°C in ASTM D1384 tap water [2].

The liquid volume to metal surface ratio was 5 ml/cm^. Changes in

liquid volume due to evaporation during the test were negligible.

12
3.5.2 Results

Table VI lists the corrosion rate data in mdd which resulted from carrying

out the imposed crevice test.

Table VI

Corrosion Rates Observed in Test E

Alloy

Corrosion Rate, mdd

Coupon

1 2 3 Avg

1100 A1 0.34 0.08 0.24 0.22

3003 A1 0.47 0.21 0.42 0.37

122 Cu 1.38 1.35 1.67 1.47

706 Cu/Ni 1.22 1.09 1.28 1.20

439 S/S negligible negligible negligible negligible

444 S/S negligible negligible negligible negligible

13
Table VII lists the maximum pit depths observed in the region of the

imposed crevice.

Table VII

Maximum Pit Depths Observed in Test E

Maximum Pit Depths, mm

Coupon Number

1 2 3

Side Side Side

Alloy 1 2 1 2 1 2

1100 A1 0.04 0.04 0.05 0.05 0.29 0.03

3003 A1 0.04 0.07 0.31 0.67 0.03 0.03

122 Cu 0.06 0.06 0.05 * 0.03 it

706 Cu/Ni * * 0.05 0.02 * it

439 S/S * * * * * *

444 S/S * * * * * *

*Pits present were too shallow to measure.

Comparison of the maximum pit depths and pit densities observed in

Test E with those observed in Test A revealed that, while some coupons

showed significantly greater pit depths and pit densities, this behavior was not consistent. As a consequence Test E has been modified by

striating the teflon surfaces which contact the coupons and by increasing

the torque used to 7 inch-pounds (0.79Nm)

3.6 TEST F , Tube Loop Test at Atmospheric Pressure

3.6.1 Procedure

Test F is a qualitative test to allow examination of the effects of elevated temperature, heat transfer, and flow on the Interaction of metal-fluid

pairs. This test was carried out using the apparatus shown in Figure 5.

14
Figure 5. Apparatus used in test F.

. ' - r4-' ^

L

15
This apparatus consists of two, 3 foot (0.9m) lengths of 3/8 inch

(9.5mm) i.d. , 1/2 inch (12.7mm) o.d. , 3003 A1 tubing bent to form the

configuration shown, a variable flow rate pump, a one-liter reaction

vessel with a 4-opening cover, heating tape, and a 10 A variable transformer. Two lengths of tubing were attached to the inlet and outlet

of the pump using polypropylene fittings and wrapped with heating tape.

To minimize evaporation, rubber stoppers were fitted over the end of

each tube to seal two of the openings in the reaction vessel cover. A condenser was placed in the third opening in the reaction vessel cover and a thermometer in the fourth.

Eight hundred millileters of ASTM D1384 tap water [2] was used as the

heat transfer liquid. The liquid volume to metal surface ratio in this

test was 6.1 ml/cm. The temperature of the heat transfer liquid was maintained at 90°C. The liquid flow rate used was 2 ft/sec (0.6 M/sec).

This test was carried out for 30 days. Loss of liquid due to evaporation during the test was neglegible.

3.6.2 Results

After the completion of the test, the tubes were longitudinally sectioned.

Visual inspection revealed the presence of light pitting.

16
4.0 SUMMARY

The methodology described in Test A was found to be an adequate basis

for a prescreening test. Test A allowed separation of the corrosion

rates of the aluminum and copper based alloys. In addition, the variability

in the corrosion rates of the 1015 steel coupons was low.

The results of Test B, D, and E also indicate that the variation in corrosion

rate as a function of alloy composition may be observed. However, the

variability in the pitting observed in the the aluminum samples in Test E

indicated an undersirable variability in crevice imposition. This test has

been modified to reduce this variability.

Test C was not carried out.

Test F, while qualitative in nature, did allow light pitting to be observed

in the sample of 3003 aluminum tubing tested.

It was determined that the tests described in the Standard Guide maybe

carried out in a reasonable time, at moderate expense, and, with the exception

of Test D, with minimal equipment fabrication requirements. While the test

methods were evaluated under a specific predetermined set of conditions in this

study, they were found to contain sufficient flexibility to allow metal-liquid

pair evaluation under a variety of temperature, flow and aeration conditions

simulative of various modes of solar containment system operation.

17
5.0 REFERENCES

[1] ASTM Gl-72, Preparing, Cleaning, and Evaluating Corrosion Test Specimens, Rec. Practice for 1978 Annual Book of ASTM standards Part 10.

[2] ASTM D1384-70, Corrosion Test for Engine Coolants in Glassware, 1978

Annual Book of ASTM Standards Part 30.

[3] ASTM G48-76, Pitting and Crevice Corrosion Resistance of Stainless

Steels and Related Alloys by the Use of Ferric Chloride Solution,

Test for, 1978 Annual Book of ASTM standards Part 10.

18
6.0 ACKNOWLEDGEMENTS

The authors wish to thank members of materials task group of ASTM

Committee E44 who originally developed the Recommended Practice

evaluated in this report. In particular they wish to express their

appreciation to Mr. James Hill for providing the stainless steel

alloys. Dr. Edward Smith for providing the copper based alloys, and

Dr. Coleman Grandstaff for providing the 3003 aluminum alloy samples.

The authors also wish to acknowledge the Department of Energy, Office

of Solar Applications for supporting this study.

19
APPENDIX I

Draft Standard Guide for Laboratory Screening

of Metallic Containment Materials for Use with Liquids

in Solar Heating and Cooling Systems

1. Scope

1.1 This standard guide practice describes several laboratory test procedures for evaluating corrosion performance of metallic containment materials

under conditions similar to those that may occur in solar heating and cooling

systems. All test results relate to the performance of the metallic containment material only as a part of a metal/fluid pair. Performance in these

laboratory test procedures, taken by itself, does not necessarily constitute

an adequate basis for acceptance or rejection of a particular metal/fluid pair

in solar heating and cooling systems, either in general or in a particular

design. This standard guide is not intended to preclude the use of other

screening tests, particularly when those tests are designed to more closely

simulate field service conditions.

1.2 This standard guide describes apparatus and procedures for several

tests, any one or more of which may be used to evaluate the deterioration

of the metallic containment material in a metal/fluid pair. The procedures

are designed to permit simulation, heating and cooling systems including

(1) operating full flow, (2) stagnant full, (3) stagnant partial fill, and

(4) stagnant empty. Particular attention should be directed to properly

reflecting whether the system is open or closed to atmosphere.

1.3 This standard guide covers the following six tests:

1.3.1 Practice A - Basic Immersion Test at Atmopsheric Pressure

1.3.2 Practice B - Heat Rejecting Surface Test at Atmospheric Pressure

1.3.3 Practice C - High Pressure Test

1.3.4 Practice D - Repeated Dip Dry Test at Atmospheric Pressure

1.3.5 Practice E - Crevice Test at Atmospheric Pressure

1.3.6 Practice F - Tube Loop Test at Atmospheric Pressure

1.4 Practice A is concerned with the interaction of metal and fluid

when both are at the same temperature with no heat transfer from one to the

other. It is regarded as useful for plumbing, pumps, tanking, etc., but of

less significance, taken by itself, for collector panels. Practices B and

F are concerned with the deterioration of the metal when there is transfer

of heat from the metal into the heat transfer fluid. These practices are especially applicable to the collector panel. Practice C permits a variety

of tests but is especially useful in relation to systems that experience high

temperatures, or are closed to the atmosphere. Practices D and E evaluate

specific corrosion problems that may be associated with particular metal/fluid

pairs and particular designs of systems and components.

2. Applicable Documents

2.1 ASTM Standards:

20
D 1384 Corrosion Test for Engine Coolants in Glassware

G 1 Preparing, Gleaning, and Evaluating Corrosion Test Specimens

G 48 Standard Test Method for Pitting and Crevice Corrosion

Resistance of Stainless Steels and Related Alloys by Use

of Ferric Chloride Solutions.

3. Significance and Use

3.1 At this time none of these tests has been demonstrated to correlate

with field service.

3.2 Because these procedures do not restrict the selection of either the

containment material or the fluid for testing, it is essential that consideration be given to the appropriate pairing of metal and fluid. Likewise, knowledge of the corrosion protection mechanism and the probable mode of failure

of a particular metal is helpful in the selection of test conditions and the

observation, interpretation, and reporting of test results.

3.3 The design of solar heating and cooling systems strongly affects

the applicability of the results of the laboratory screening tests. Therefore, the results of these laboratory procedures should be confirmed by com- ponent and systems testing under actual or simulated service conditions.

3.4 Table 1 is provided to assist in an orderly consideration of the

important factors in testing. It is expected that the user of the test

procedure will investigate a range of test times and temperatures for the

containment material /fluid pair, and adjust the time and temperature of testing as necessary. (See Note 1)

3.5 It is essential for the meaningful application of these procedures that

the length of test be adequate to detect changes in the nature of the fluid

that might significantly alter the corrosivity of the fluid. For example.

Note 1 - Gorrosion, whether general or localized, is a time dependent phenomenon. This time dependence can show substantial nonlinearity. For

example, formation of a protective oxide will diminish corrosion

with time, while certain forms of localized attack accelerate with

time. The minimum time required for a test to provide a corrosion

rate that can be extrapolated for the prediction of long-term performance varies widely, depending on the selection of metal and fluid,

and on the form of corrosion attack. Therefore, it is not possible

to establish a single minimum length of test applicable to all

materials and conditions. However, it is recommended that for the

tests described in this recommended practice, a test period of no

less than 30 days be used. Furthermore, it is recommended that the

effect of time of testing be evaluated to detect any significant time

dependence of corrosion attack.

21
exhaustion of chemical inhibitor or chemical breakdown of the fluid, may occur after periods of months in selected cycles of operation. (See Note 2)

4. Materials and Reagants

4.1

Any metallic material may be selected for evaluation. The material

shall be capable of being described with sufficient accuracy to perit reproduction of the test.

4.2 Any heat transfer fluid may be selected for evaluation. However, it

is expected that the fluid will be selected with consideration given to possible

interactions of material and fluid under the conditions of testing. The fluid

should be capable of being described chemically, as to its basic components and

the presence or absence of minor components that affect the interaction with

the metal. It is permitted to precondition the fluid before testing. Any such

preconditioning treatment shall be described in the Report.

4.3 Particular attention shall be directed to avoidance of materials,

fluids, or metal/fluid pairs that can be hazardous to the operator. The flammability, vapor pressure, and toxicity of the heat transfer fluid shall be known

prior to initiation of testing and appropriate precautionary measures shall be

taken to insure the safety of all test personnel.

5. Sampling and Test Specimens

5.1 The test specimens shall be selected from material that may reasonably represent that material as it would be applied in a solar heating and

cooling system.

5.2 For laboratory corrosion tests that simulate exposure to service

environments, a commercial surface, such as a mill finish, closely resembling

the one that would be used in service, will yield the most significant results.

For more searching tests of either the metal or the environment, standard surfaces finishes may be preferred. Ideally, the surface finish should be

recorded in surface roughness terms, such as rms in.

5.3 General Cleaning:

5.3.1 General cleaning may be accomplished with a wide variety of

cleaning media. Water-based cleaners should be followed by an alcohol

Note 2 - Many fluids that may be considered for solar applications contain

additives to minimize the corrosivity of the fluid. Many such additives are useful only within a specific concentration range, and some additive may actually accelerate corrosion if the concentration falls

bellow a critical level. Depletion kinetics can be a strong function of the exposed metal surface area. Therefore, for tests involving fluids with such additives, consideration must be given to the

ratio of metal surface area to fluid volume as it may relate to an operating system.

22
dip after thorough rinising. Solvent cleaners such as petroleum fractions, aromatic hydrocarbons, and chlorinated hydrocarbons are generally

acceptable. Chlorinated solvents, however, should not be used on titanium, stainless steel, or aluminum. Mechnical cleaning of very

smooth surfaces may be accomplished by the use of a paste of magnesium

oxide or alumina.

5.3.2 Any of the methods suitable for cleaning a given corroded

specimen may be used to compelte the cleaning of specimens prior to

test, provided that they do not cause localized attack. The cleaned

specimens should be measured and weighed. Dimensions determined to the

third significant figure and weight determined in the fifth significant

figure are usually satisfactory.

5.4

Metallurgical condition - Specimen preparation may change the

metallurgical condition of the metal. For example, shearing a specimen to

size will cold work and may possible fracture the edges. The specimen may be

tested in this condition if it is believed that such condition may be encountered in service. In such case, the condition shall be described in the report

of results. However, it is recommended that changes in metallurgical condition be corrected for customary testing. For example, sheared edges should

be machined or the specimen annealed.

5.5

Alternative specimen designs, particulaly those incorporating crevices or metal coupling as may be encountered in application, are recommended.

5.6

For many metals, electrolytic cleaning is a satisfactory method for

cleaning after testing.

5.6.1 The following method is typical; after scrubbing to remove loosely attached corrosion products, treat the specimen as a cathode in

hot, dilute sulfuric acid under the following conditions.

5. 6. 1.1

5. 6. 1.2

5. 6. 1.3

5.6. 1.4

5. 6. 1.5

Electrolyte - Sulfuric acid (5 weight percent).

Inhibitor - 0.2 volume percent organic inhibitor,

(see Note 3)

Anode - Carbon or lead, (see Note 4)

Cathode - Test specimen.

Cathode Current Density - 2000 A/m^

Note 3 - Instead of using 0.2 volume percent of any proprietary inhibitor,

and 0.5 kg/m^ of such inhibitors as diorthotolyl thiourea,

quinoline ethiodide, or betanaphtol quinoline may be used.

Note 4 - If lead anodes are used, lead may deposit on the specimen and cause

an error in the weight loss. If the specimen is resistant to nitric

acid, the lead may be removed by a flash dip in 1+1 nitric acid.

Except for the possible source of error, lead is preferred as an

anode as it gives more efficient corrosion product removal.

23
5. 6. 1.6 Temperature - 75°C (165°F), and

5. 6. 1.7 Exposure Period - 3 min.

5.6.2 After the electrolytic treatment, scrub the specimens with a brush, rinse thoroughly, and dry.

5.6.3 It should be noted that this electrolytic treatment may result

in the redeposition of metal, such as copper, from reducible corrosion products, and thus, lower the apparent weight loss.

5.7

Chemical cleaning of specimens after testing is satisfactory provided

the following methods are used.

5.7.1 Copper and Nickel Alloys - Dip for 1 to 3 min. in HCl (1+1) or H2S0^ (1+10) at room temperature. Scrub lightly with bristle brush under

running water, using fine scouring powder if needed.

5.7.2 Aluminum Alloys - Dip for 5 to 10 min in a water solution containing 2 weight percent of chromic acid (chromium trioxide, CrC02) and 5 volume

percent of orthophosphoric acid (H^PO^, 85 percent) maintained at 80®C (175°F).

Ultrasonic agitation will facilitiate this procedure. Rinse in water to remove

the acid, brush very lightly with a soft bristle brush to remove any loose

film, and rinse again. If film remains, immerse 1 min in concentrated nitric

acid and repeat previous steps. Nitric acid alone may be used if there are

no deposits.

5.7.3 Tin Alloys - Dip for 10 min in boiling trisodium phosphate solution

(15 percent). Scrub lightly with bristle brush under running water, and dry.

5.7.4 Iron and Streel - Suitable methods are:

5. 7. 4.1 Preferably, use electrolytic cleaning (Section 5.6)

5. 7. 4. 2 Immerse in Clark's solution (hydrochloric acid - 100 parts,

antimonious oxide - 2 parts, stannous chloride - 5 parts ) for up to 25 min.

Solution may be cold, but it should be vigorously stirred.

5. 7. 4. 3 Remove scales formed on steel under oxidizing conditions in

15 volume percent concentrated phosphoric acid containing 0.15 volume percent of organic inhibitor at room temperature.

5. 7. 4. 4 Clean stainless steel in 20 percent nitric acid at 60°C

(140 F) for 20 min.

24
5. 7. 4. 5 In place of chemical cleaning use a brass scraper or brass

bristle brush or both, followed by scrubbing with a wet bristle brush and

fine scouring powder. (See Note 5)

5. 7. 4. 6 Other methods of cleaning iron and steel include immersion

in hot sodium hydride, and cathodic pickling in molten caustic soda.

(See Note 6)

5.7.5 After cleaning and thorough rinsing, dry and weigh the samples.

6. Calculations and Interpretation of Results

6.1

The deterioration of the containment material shall be determined

by measurement of weight loss and by examination at lOX magnification for

incidence of localized attack.

6.1.1

Whichever cleaning method is used, the possibility of removal of

solid metal is present. Such removal would result in error in the determination of the corrosion rate. One or more cleaned and weighed specimens should

be recleaned by the same method and reweighed. Loss due to this second weighing

may be used as a correction of the first one. (See Note 7)

6.1.2

The total surface is calculated (making allowance for the change

in surface area due to mounting holes). The weight loss is divided by the area to get a weight loss per unit area. This again may be divided by the

duration of the test to get a corrosion rate in weight loss per unit area

per unit time (such as mg/dm^*day = mdd). This figure may be divided by

the density of the metal and modified by appropriate conversion factors to

obtain a figure in terms of rate of loss in thickness of the specimen (such

as mils per year = mpy).

6. 1.2.1 For instance:

= 100,000 - '^t AT

where:

Rjj^dd ” corrosion rate, mdd,

Wq = original weight, g.

Note 5 - Such vigorous mechanical cleaning is applicable when wieght loss is

large and hence errors in weight loss will produce only smalle errors

in corrosion rates. Blank connections will be difficult to apply.

Note 6 - These methods may be hazardous to personnel. They should not be

carried out by untrained personnel or without supervision.

Note 7 - The use of suitable inhibitors will diminish the attack and will

permit reasonable degree of reproducibility with specimens varying

in degree of rusting.

25
t A

T

Or:

L ° = area, cm , and

= duration, days.

6 . 1 . 2 . 2 R

mpy

393.7

ATD

where

:

t A

T

D

corrosion rate, mpy,

original weight, g, final weight, g,

O ^ r-n 2

3 density, g/cm •

area, cm , 6.1.3 duration, years, and

Any incidence of localized corrosion, whether pitting, crevice

attack, integranular attack, cracking, or any other form of localized attack,

shall be identified and rated under at least lOX magnification, and shall be

reported. The location, distribution, and maximum depth of attack shall be

reported for any localized attack.

6.2 Any changes of the heat transfer fluid, e.g., appearance or odor,

should be reported with the results. Any changes in the appearance or condition of the test apparatus indicative of interaction with the metal specimen

or fluid shall be described.

6.3 In the event of film formation and buildup, the nature of the film

and its degree of buildup shall be reported.

6.4 For the evaluation of containment material couple, an effort should

be made to utilize the same procedures as for a single material test. However,

because of the variability permitted in the design of the specimen for the

couple, it may be appropriate to report weight loss or penetration. For all

tests of metal couple/fluid performance, special attention should be given to

observation and reporting of localized corrosion and evidence of galvanic

attack.

7. Report

7.1 The containment material shall be identified by standard specification where applicable, or by chemical analysis. In case of identification by

standard specification, supplemental identification by typical analysis for

such specification, or by chemical analysis of the specimen is desirable.

7.2 The dimensions and configuration of the specimen shall be reported.

In the case of metal couple, the description shall include at least the following elements: (1) a description of the individual components of the couple;

(2) a description of the method of attachment or association of the couple

26
!

including any third material introduced as a binder or for other function and

the procedures of connection, e.g., surface preparation, conditions of attachment, and cleaning; (3) any change of the containment materials resulting from

the coupling procedure; and (4) a description of the relative areas of exposure

of the components of the couple to the heat transfer medium.

7.3 The heat transfer fluid shall be identified by standard specification

I where applicable, by initial chemical analysis, or by proprietary designation.

Use of trademarks, or names of patented or proprietary products, without accomji panying chemical description is discouraged but not prohibited. For aqueous

j transfer fluid, the analysis of the water used shall be reported.

! 7.4 The test used shall be identified. The test conditions used shall be

I specified, including specimen preparation, time and temperature schedule, degree

I of atmospheric exposure of the heat transfer fluid, stirring, and flow rate,

; where applicable. The method of temperature measurement and control, with com- ment on its accuracy and precision, shall be described. The nature of boiling

I of the fluid shall be described if boiling was observed during the test. Any

deviation from the standard procedure shall be reported and so identified as a deviation.

I 7.5 The report shall provide both weight loss and average penetration

! rate when applicable. The time dependence of the corrosion rate shall be comI mented upon (see Note 1, Section 3.4) with a plot of corrosion rate as a function of time being provided when this time dependence is significant. All

I instances of localized deterioration of the test specimen shall be reported.

: In the event of pitting or other non-uniform attack, the frequency of attack

j and maximum penetration shall be reported.

I

’I 7.6 A commentary on the results and their interpretation, particularly

their applicability to various designs or solar heating and cooling systems, is

optional but desirable.

Practice A - Basic Immersion Test at Atmospheric Pressure

8. Scope

8.1 This test procedure is intended to provide a simple, rapid exposure

test for evaluation of metal and fluid interaction. The apparatus, as typically

constructed, is open to the atmosphere. Therefore, the results of this test

procedure may not be applicable to closed systems.

27
9. Apparatus

9.1 The vessel i.s typically a 1000 ml beaker or reaction flask or heat

resistant glass (see Note 8). Provision is made for closing the top of the

reaction vessel while providing openings for temperature measuring devices,

reflux condenser, and stirring device, as necessary. The specimen may be

suspended in a cradle of non-metallic material or supported by a rack either

constructed of a non-roetallic material or insulated so as to prevent galvanic

interaction of specimen and rack.

9.2 The vessel may be heated by mantle, hot plate, or bath. Selection

of heating method can affect accuracy of temperature control. For certain

fluids the more localized heating typical of a hot plate in comparison with

the constant temperature bath, may produce changes in the heat transfer fluids.

9.3 The fluid may be stirred to simulate flow conditions. For those

fluids in which aeration or deaeration can be simulated by gas sparging, the use of such sparging devices is optional. For low boiling fluids the use of

a cold trap is recommended.

10. Procedure

10.1 The specimen shall be cleaned in accordance with Section 5 and then

weighed to an accuracy of 0.1 mg immediately prior to testing. The specimen

shall be suspended in a cradle or attached to a specimen rack and placed in the

test vessel. The vessel shall be filled with the heat transfer fluid to cover

specimen. A volume of about 500 ml is recommended. Condenser, temperature

measuring device, stirring device, and heating device shall be mounted as necessary

.

10.2 Typically the vessel is then heated to the desired test temperature

and held at that temperature for the duration of the test. However, it is

permitted to select any schedule of times and temperatures (see Note 1, Section 3.4).

Note 8 -- For certain containment materials there exists the possibility that

silicate from the glass of the apparatus contaminating an aqueous

heat transfer fluid, would significantly affect the corrosion

observed in this test. The effect of silicate from this source would

be minimal in those cases in which silicates are a part of the cor- rosion inhibitor system, or in which silicates are otherwise present

in the heat transfer fluid. However, for those cases in which the

affect of silicate from glassware could have a significant effect

on the results, it is recommended that other materials be used for

the apparatus, such that no significant extraneous effects will be

introduced in the results of the test. (See Reference 1.)

2

^
11.

Precision and Accuracy

11.1

This test procedure describes a general procedure for detecting interaction of metal and fluid. Because of its simplicity and because it is based

on standard practices of corrosion testing, it is believed that this test procedure will prove reproducible and repeatable with good accuracy. However, at this

time their is not adequate data on the metals and fluids of solar applications

to permit a statement of precision and accuracy. The procedure is set forth in

this standard guide for the purpose of standardizing testing in order to develop

meaningful precision and accuracy data..

Practice B - Heat Rejecting Surface Test at Atmospheric Pressure

12.

Scope

12.1 This test procedure is intended to simulate deterioration of the

containment material resulting from heat transfer through the containment

material into the heat transfer fluid. If curvature of the heat transfer surface is anticipated to be significant. Practice F should be considered. The

apparatus, as typically constructed, is open to atmosphere. Therefore, results

of this test procedure may not be applicable to closed systems.

13.

Apparatus

13.1 A schematic of the apparatus is shown in Figure 1. It is typically

a 500 ml round bottomed reaction flask with a 1 in. (25 min) inside diameter

pipe flange opening for the attachment of the specimen (see Note 7, Section 9.1).

Provision is made for closing the top of the reaction flask while providing

openings for temperature measuring devices, reflux condenser, and stirring

device, as necessary. The gasket shall be of a material appropriate to the

temperature and chemical environment so that there is no significant interaction, other than the mechanically imposed crevice, with the containment material

or the heat transfer fluid.

13.2 The temperature shall be controlled so as to produce the desired

test temperature on the surface of the specimen in contact with the test fluid.

The accuracy and precision of such control can be significantly affected by the

method of temperature measurement. A simple method would be the imbedding of

a thermocouple in the specimen when specimen thickness is adequate, or bonding

of the thermocouple to the specimen by welding or other such attachment. In

many cases such methods would provide sufficient accuracy. When greater accuracy

of temperature measurement is required, it is possible to use systems of two or more thermocouples through the thickness of the specimen, and to thereby calculate a surface temperature. For those tests dealing in effects of metal/

fluid interaction in a very narrow temperature range, such more accurate methods

of temperature control are strongly recommended. The method used shall be

described, with comment on its accuracy and precision, in the report of the

results.

29
14.

Procedure

14.1 The specimen shall be cleaned, and weighed to an accuracy of 0.1

mg immediately prior to testing. The specimen shall be mounted between the

gasket and heater, and secured to the reaction flask. The flask shall be

filled with 250 ml of the test fluid. Condenser, temperature measuring device,

and stirring device shall be mounted as necessar)'.

14.2 It is permitted to select any schedule of tiroes and temperatures

(see Note 1, Section 3.4). It is recommended that consideration be given to

anticipated field operation in the selection of a schedule of heating, holding,

and cooling cycles. It is recommended that stirring be used for simulation of

operating full flow conditions.

15. Precision and Accuracy

15.1 This test procedure has been used by one laboratory for the screening of stainless steels and various aequeous heat transfer fluids for application in solar collectors. The results are reported to have satisfactory

repeatability and reproducibility, but no supporting data are provided. Therefore, the precision and accuracy of this test procedure are unknown. The

procedure is set forth in this standard guide for the purpose of standardizing testing in order to develop meaningful precision and accuracy data.

Practice C - High Pressure Test

16. Scope

16.1 This test procedure is intended to simulate the conditions of high

temperature and pressure in a pressurized system under stagnant full, stagnant

partial fill, and stagnant empty conditions. This test procedure can provide

for test conditions simulating operation of systems closed to atmosphere.

17. Apparatus

17.1 This test is performed using an autoclave, or comparable device,

capable of producing the required conditions of temperature and pressure.

Specimens shall be independently supported from one another by a rack, and

may be suspended in cradles or directly mounted on the rack. Supporting

materials shall be selected so as to avoid interaction with the specimens or

test fluid (see Note, 8 Section 9.1), and mounting shall be accomplished so

as to avoid any galvanic interaction.

18. Procedure

18.1 The specimen shall be cleaned, and weighed to an accuracy of 1 mg

immediately prior to testing. The specimen shall be mounted in a cradle or

on the rack. The rack shall be placed in the test chamber and the chamber

shall be filled with the test fluid so that the specimen is totally immersed,

partially immersed, or suspended in the vapor phase as desired. The chamber

shall be sealed.

30
18.2 The test may be run for any selected schedule of time, temperature,

and pressure. (See Note 1, Section 3.4).

19. Precision and Accuracy

19.1 This test procedure has been used by one laboratory for the

screening of copper and various heat transfer fluids for closed solar systems.

The results are reported to have satisfactory repeatability and reproducibility, but no supporting data are provided. Therefore, the precision and

accuracy of this test procedure are unknown. The procedure is set forth in

this standard guide for the purpose of standardizing testing in order to

develop meaningful precision and accuracy data.

Practice D - Repeated Dip Dry Test at Atmospheric Pressure

20. Scope

20.1 This test procedure is intended to simulate alternating wetting

and drying conditions. This procedure, as customarily performed, is open to

the atmosphere. Therefore, the results of this procedure may not be applicable to closed systems.

21. Apparatus

21.1 The apparatus shall consist of a hydraulically or mechanically

operated arm from which the specimen is suspended in a glass cradle (see Note 8,

Section 9.1). The arm lowers the specimen into a beaker containing the test

fluid and then raises the specimen into a device that will provide for drying

of the specimen. Selection of the drying device shall take into consideration

the possible degradation effects related to the method of drying, e.g.,

degradation of fluid by infra-red radiation from heat lamps, or effects

atmosphere exposure. A system of automatic control shall provide repeated

cycles of selected periods of immersion and selected periods of drying.

22. Procedure

22.1 The specimen shall be cleaned, and then weighed to an accuracy of

Ool mg immediately prior to testing. The specimen shall be suspended from the

movable arm in the cradle. A beaker of the test fluid be aligned under the

specimen and the drying device and cycling device are activated.

22.2 Any cycle of dip and dry times may be selected. (See Note 1,

Section 3.4).

23. Precision and Accuracy

23.1

This test procedure has been used by several laboratories in the

past for evaluating the resistance of metals to corrosion resulting from

drying of a corrosive environment splashed on the metal, particularly as ornamental automotive trim. The results are reported to have satisfactory

repeatability and reproducibility, but no supporting data is provided.

31
Therefore, the precision and accuracy of this test procedure are unknown.

The procedure is set forth in this standard guide for the purpose of

standardizing testing in order to develop meaningful precision and accuracy

data.

Practice E - Crevice Test at Atmospheric Pressure

24. Scope

24.1 This test may be used to evaluate the general corrosion resistance

and to detect susceptibility to crevice corrosion attack for metallic containment materials. This test procedure is generally similar to ASTM G48, a standard test method for stainless steels.

25. Apparatus

25.1 The apparatus for this test is described in ASTM G48. (See Note 8,

Section 9.1).

25.2 Because the rubber band typically employed in the G48 test loses

elasticity at temperatures above 50 C, an alternative specimen design may be

employed for higher temperatures. In this design washers of an inert material

e.g., acetal copolymer, are secured to the faces of the coupon. Grooves may

be cut in the face of the washer that bears on the coupon so that each

washer forms several separate crevice contacts. The ratio of the exposed

area to the crevice area is significant, a ratio of 15 to 1 being typical.

The plastic nut and bolt are torqued to 5 in-lb (0.6N.m). (See listed

Re ferences .

26. Procedure

26.1 The specimen shall be cleaned, and weighed to an accuracy of 0.1 mg

immediately prior to testing. The crevice is applied either by rubber band

as described in G48, or by application of washers as described in Section 25.2

The specimen shall be placed in the test flask, fluid shall be added, and the

condenser shall be installed. The flask shall be heated to the desired test

temperature (see Section 9.2).

26.2 Any length of test time may be selected. (See Note 1, Section 3.4)

27. Precision and Accuracy

27.1 This test procedure is derived from ASTM G48 v;hich describes the

method for the evaluation of stainless steels using a solution of ferric

chloride. It is expected, although data is not proA^ided, that precision and

accuracy comparable to that of G48 can be developed for stainless steels

tested with other aqueous media. No data are provided for stainless steels

with non-aqueous media or other metals. The procedure is set forth in this

standard guide for the purpose of standardizing in order to develop meaningful

precision and accuracy data.

32
Practice F - Tube Loop Test at Atmospheric Pressure

28. Scope

28.1 This test procedure is intended to simulate deterioration of containment materials when heat is transferred through the containment material tubing

into heat transfer fluid inside the tube.

29. Apparatus

29.1 The apparatus for this test shall consist of a heating tape with

appropriate power and control systems, and a variable flow pump with a reservior for the heat transfer fluid (see Note 8, Section 9.1). The apparatus shall be assembled as shown in Figure 2. Alternative methods of heating

may be provided.

29.2 The primary sample typically consists of a 36 in. (914 mm) length

of tubing bent around an 8 in. (203 mm) diameter mandril so that each leg

of the U-bend is of approximately equal length. Other specimen designs are permitted if such more closely approximate conditions of application. Care

should be taken in making the U-bend so that fluid flow through the tube is

not significantly restricted. The tubing sample shall be mounted with an inclination of the plane of the U-bend at about 45 degrees to horizontal during

testing. Secondary samples of similar or dissimilar metal tubing may be

introduced in the loop as indicated in Figure 2.

30. Procedure

30.1 The U-bend specimen and any secondary specimens shall be cleaned

and installed as shown in Figure 2. The U-bend shall be wrapped with a heating

tape, or an alternative heating device shall be mounted. The reservoir shall

be filled and the cycling mechanism for control of temperature and fluid flow

is activated.

30.2 Any cycle of fluid flow and heating may be used for this test.

(See Note 1, Section 3.4)

31. Precision and Accuracy

31.1 This test procedure has been used by one laboratory for the screening of aluminum and various heat transfer fluids. The results are reported to

have satisfactory repeatability and repoducibility , but no supporting data are provided. Therefore, the precision and accuracy of this test procedure are unknown. The procedure is set forth in this standard guide for the purpose of

standardizing heating in order to develop meaningful precision and accuracy

data.

33
Re ferences

1. For information on the effort of silicates from glass test apparatus, see Corrosion Inhibitors, C. C. Nathan, ed., NACE, 1973, p. 120-121.

2. For information on the design of Crevice Test Specimens, Particularly

for Practice E, see D. B. Anderson, Galvanic and Pitting Corrosion - Field and Laboratory Studies, R. Baboian, et. al., eds., ASTM STP 576,

1976, 231-242; also R. J. Brighman and E. W. Tozer, Corrosion, 32 (7),

1976, 274-276.

34
CONDENSER

500 ml REACTION FLASK

PIPE FLANGE (FLASK]

GASKET

SPECIMEN

ELECTRIC HEATER

BACKUP PLATE

F igure Schematic of Apparatus for Heat Rejecting

Surface Test.

35
36

Figure

2.

Schematic

for

Apparatus

for

Tube

Loop

Tests
APPENDIX II

Specimen Cleaning Procedures [1]

Aluminum alloys: 20g CrO^, 50 ml 85% H^PO^, H

2 O to 1 liter. Immerse

specimens for 8 minutes at 80°C.

Copper alloys: 500 ml cone HCl , 100 ml cone H2S0^, 400 ml H

2 O.

Immerse specimens for 2 minutes at room temperature.

Steel alloys: 500 ml cone HCl, lOg Sb202> 25g SnCl

2

* Immerse specimens for 15 minutes at room temperature,

stir solution.

Stainless Steel

alloys: 100 ml cone HNO^, 900 ml H

2 O.

Immerse specimens for 20 minutes at 60°C.

APPENDIX III

Typical blank correction factors for 1 inch

by 2 inch (25 mm by 51 mm) specimens, grams

1100 A1 0.00023 409 S/S negligible

3003 A1 0.00038 439 S/S negligible

122 Cu 0.00066 444 S/S negligible

706 Cu 0.00059 1015 Steel 0.00430

37
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NB5-114A (REV. 9-76)

U.S. DEPT. OF COMM. 1. PUBLICATION OR REPORT NO. BIBLIOGRAPHIC DATA NBSIR 79-1919

SHEET

(S.Go\^t. Accession Nni

11 ^ . 4 4. TITLE AND SUBTITLE 5. Publication Date Evaluation of a Proposed ASTM Standard Guide to Assess November 1979

the Compatibility of Metal-Heat Transfer Liquid Pairs in

Solar Heating and Cooling Systems

7. AUTHOR(S) 8. Performing Organ. Report No,

P. W. Brown and J. W. Grimes

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS ("Sfreer, City, State, ZIP)

Department of Energy

20 Massachusetts Avenue, N. W.

Washington, D. C. 20545

13, Type of Report & Period Covered

.... 15. SUPPLEMENTARY NOTES

1

: Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT {A 200-word or less factual summary of most significant infonaation. If document includes a significant bibliography or

literaturo survey, mention it here.) This study was undertaken as part of a round- robin evaluation of a proposed American

Society for Testing and Materials (ASTM) testing methodology entitled/ ''Standard

Guide for Laboratory Screening of Metallic Containment Materials for Use with Liquids

in Solar Heating and Cooling Systems." This study was undertaken solely to evaluate

the procedural aspects of each test method and the results of this study are not

intended to provide an assessment of the suitability of any of the metals evaluated

for use in solar heating and cooling systems. It was determined that the tests

described in this Standard Practice can be carried out as a basis for evaluating

metal-heat transfer liquid pair interactions under conditions simulative of various

modes of solar containment system operation.

17. KEY WORDS rs/x to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name

separated by semicolons)

Soiar-Heat Transfer Liquid Containment; corrosion; elevated temperature; heat

transfer; liquid flow rate; stagnation

18. AVAILABILITY Unlimited

I I For Official Distribution. Do fJot Release to NTIS

I Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

XI Order From National Technical Information .Service (NTIS), Springfield, VA. 2216).

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF

PRINTED PAGES

44

2?.. Price

$4.50

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