corrosion handbook vf7101protectedv2

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INDEX 1 Introduction ...................................................................................................................................................................4

1.1 About Corrosion Testing...................................................................................................................................4 1.2 About the Author.................................................................................................................................................4 1.3 About TQC ..............................................................................................................................................................4

2 Corrosion .........................................................................................................................................................................5 2.1 The costs..................................................................................................................................................................5 2.2 Types of corrosion ...............................................................................................................................................6

2.2.1 Uniform corrosion .......................................................................................................................................6 2.2.2 Acid corrosion...............................................................................................................................................6 2.2.3 Stress corrosion............................................................................................................................................6

2.3 Corrosion due to stray currents......................................................................................................................7 2.3.1 Pitting corrosion ..........................................................................................................................................7 2.3.2 Fissure corrosion..........................................................................................................................................7 2.3.3 Intercrystalline corrosion..........................................................................................................................7 2.3.4 Bimetal corrosion.........................................................................................................................................8

2.4 The rust principle .................................................................................................................................................9 2.5 The chemistry........................................................................................................................................................9 2.6 Pourbaix diagram ............................................................................................................................................. 10

3 The standards ............................................................................................................................................................. 11 3.1 Types of standards............................................................................................................................................ 11

3.1.1 Condensation moisture loading tests .............................................................................................. 11 3.1.2 Water spray and moisture loading tests: ......................................................................................... 11 3.1.3 Salt water spray tests: ............................................................................................................................. 11 3.1.4 Cyclic Corrosion Tests (CCT): ................................................................................................................ 13

3.2 Spotlight on a some standards.................................................................................................................... 14 3.2.1 ASTM B117 .................................................................................................................................................. 14 3.2.2 ISO 7253 ....................................................................................................................................................... 15 3.2.3 ISO 9227 NSS .............................................................................................................................................. 15 3.2.4 DIN 50021 SS .............................................................................................................................................. 16

3.3 How to select a standard................................................................................................................................ 17 4 The salt .......................................................................................................................................................................... 17 5 The Chamber............................................................................................................................................................... 17

5.1 The operation..................................................................................................................................................... 18 5.2 The compressed air flow ................................................................................................................................ 18

5.2.1 The oil filter ................................................................................................................................................. 18 5.2.2 The pressure regulator ........................................................................................................................... 18 5.2.3 The air saturator ........................................................................................................................................ 19

5.3 The salt water flow ........................................................................................................................................... 19 5.3.1 The stock tank............................................................................................................................................ 19 5.3.2 The pump .................................................................................................................................................... 19 5.3.3 The spray nozzle ....................................................................................................................................... 20


5.4 The operation..................................................................................................................................................... 20 5.5 Maintenance....................................................................................................................................................... 20

6 Evaluation, interpretation, reporting................................................................................................................. 22 6.1 Evaluation ............................................................................................................................................................ 22 6.2 The preparation................................................................................................................................................. 22

6.2.1 Scratching.................................................................................................................................................... 22 6.2.2 Positioning the objects .......................................................................................................................... 23 6.2.3 The final inspection ................................................................................................................................. 23 6.2.4 Detachment................................................................................................................................................ 23 6.2.5 Blister formation ....................................................................................................................................... 23 6.2.6 Corrosion points ....................................................................................................................................... 24 6.2.7 Corrosion percentage............................................................................................................................. 24 6.2.8 Filiform pattern corrosion ..................................................................................................................... 24

6.3 Interpretation ..................................................................................................................................................... 25 6.3.1 Abnormalities............................................................................................................................................. 25 6.3.2 Mutual difference ..................................................................................................................................... 25 6.3.3 Conclusions................................................................................................................................................. 25

6.4 Reporting ............................................................................................................................................................. 25 7 Safety ............................................................................................................................................................................. 26

7.1 Hazardous materials ........................................................................................................................................ 26 7.2 Micro-organisms ............................................................................................................................................... 26

7.2.1 Legionella .................................................................................................................................................... 26 7.2.2 Algae ............................................................................................................................................................. 27


1 INTRODUCTION

1.1 About Corrosion Testing

Corrosion testing gives rise to many interpretation problems, both for the analysts carrying out the work and the client. This booklet has been written to give users of corrosion testing equipment information on carrying out corrosion tests and interpreting the results, using practical examples where possible. The references to equipment are mainly orientated towards Ascott corrosion test chambers, but the operation of other manufacturer’s chambers is likely to be similar. The principle differences will arise from the many different types of corrosion test that exist.

The information provided in this booklet is for guidance only. Though believed to be accurate at the time of writing, this may change over time. So this information should not be used as a substitute for referring to a complete corrosion test standard, at an appropriate revision level.

Although the author and publisher of this booklet are both Dutch, and much of the reference material is therefore drawn from experiences in The Netherlands – everything described herein has a relevance and application globally. 1.2 About the Author

Nico Frankhuizen studied Analytical Laboratory Technology & Analytical Chemistry at MTSL division of MLO in Leiden, Holland. He followed this with 9 years working as a Chemical Analyst at Mavom, a leading Dutch manufacturer of surface treatment chemicals. It was here that he developed an interest in corrosion testing, while applying a variety of corrosion test methods and standards to samples tested within Ascott corrosion test chambers.

Nico went on to work for TQC (see below) where he was able to put his knowledge and experience into the publication of this handbook. His passion is to promote a better understanding of corrosion, its causes and appropriate test methods, amongst corrosion testing practitioners. He also participates in the development of corrosion test standards at European level and beyond. 1.3 About TQC

Founded in 1977 Thermimport Quality Control (now known simply as TQC) started with the supply of test instruments for thermal applications in a wide range of industries. Over the years TQC developed a specialisation in quality control equipment for the surface finishing and protective coating industries. The product range has now developed into a broad and complete line of test-equipment and measuring instruments with the accent on coating and finishing related applications.

Salt spray corrosion

test cabinet Machu test bath CurveX-2 USB

Oven temperature logger Ideal Finish Analysis

software

Drop test / Impact tester Pendulum hardness tester Automatic film applicator Cross cut adhesion tester


2 Column with concrete rot

2 CORROSION

2.1 The costs The loss caused as a result of corrosion on an annual basis amounts to something like €17.5 billion. In the Netherlands, slightly less than 10% of gross national product is lost through corrosion annually. Worldwide, 5 tonnes of steel are lost every second. In 2005 the steel lost to corrosion amounted to 16 times the annual steel production of Corus Steel in IJmuiden.

1 Corus Steel in IJmuiden, Holland It is estimated that around 30% of this loss could be prevented through application of present-day knowledge of steel conservation. This could save could save around €5 billion annually. This figure does not include the savings on health and safety costs. These costs are the result of industrial accidents due to corrosion. Injuries sustained range from minor lacerations to grave trauma that requires long-term hospital admission. Not all accidents involving acute injuries give rise to direct losses, but loss also arises over the long-term as a result of growth in sensitivity to the proliferation of biofilm and the spread of micro-organisms. Research into improving corrosion resistance can result in significant annual savings. Corrosion is not a simple problem. There are at least 12 different forms of corrosion. Research into the various forms corrosion can take varies depending on the industry and on the application. One example is the automobile industry. Previously corrosion was not a significant problem. Nowadays, with the issue of the 10 year chassis guarantee, corrosion testing has become an important part of product development and it figures prominently in sales arguments. Damage caused by corrosion Corrosion leads to loss of strength because corrosion products (oxides and salts) are much weaker than the metal. An additional problem is that corrosion products take up greater volume than the metal. Major constructions can be dislocated by metal swelling. It occurs for example in the form of concrete rot, where the steel rods used for reinforcing the concrete start to rust.

With some types of corrosion an impermeable layer of metal oxides is formed, resulting in the halting of the corrosion process. That is the why a metal such as aluminium hardly ever rusts, despite the fact that the metal in itself is extremely sensitive to corrosion reactions.


5 Stress corrosion

2.2 Types of corrosion 2.2.1 Uniform corrosion This relates to the uniform corroding of surfaces without a protective oxide layer. The rate of this type corrosion depends on air humidity in the first instance. In the sea or under industrial circumstances (presence of Cl ions or SO2) hygroscopic corrosion products are created that strongly enhance corrosion formation. The anodic roof layer is an example of uniform corrosion. In this case we have a corrosion layer that limits further corrosion. 2.2.2 Acid corrosion In acid corrosion, metals react with an acid to form a metallic salt and hydrogen gas. Acid corrosion occurs if there is a combination of metals that together form a galvanic element (Zinc and Copper for instance in electrolyte containing an acid (pH < 7). Acid corrosion finds practical use in the galvanising industry. Batteries are an everyday example of acid corrosion. 2.2.3 Stress corrosion Stress corrosion is a reinforced form of corrosion caused by stress points in components. Stress corrosion receives a great deal of attention in the aviation industry. Most people are familiar with the phenomenon of metal fatigue. Stress corrosion can be an equally serious problem, in many industries. Not all metals are vulnerable to stress corrosion. The precipitating conditions for it are: - A stress vulnerable metal - A corrosive medium - Tensions in the metal Without the tensile stress, an identical corrosive medium will often cause no corrosion to the metal worth mentioning. The most familiar example of stress corrosion cracking is chloride tension corrosion in stainless steel. This occurs where three conditions are met: - Presence of chloride in the water. - An elevated temperature. - Presence of tensile stress in the component. The presence of chloride is a necessity to this type of corrosion. There need only be very little chloride present in the water. Tap water, which typically contains 50 mg per litre, already has enough chloride. Temperature on the other hand is variable. A whole ceiling collapsed in Steenwijk in 2001 and in Uster (Switzerland) a concrete swimming bath roof collapsed in 1985 due to stress corrosion cracking in stainless steel reinforcement rods. Ten people were killed in that incident. Tensile tension need not always be caused by user loadings. These tensions can also be tensions produced as a consequence of 'cold deformation’.

4 Acid corrosion

3 Uniform corrosion


6 corrosion caused by stray currents in a water pipe

8 Items susceptible to fissure corrosion

9 Intercrystalline corrosion

7 Pit corrosion on a stainless steel surface

2.3 Corrosion due to stray currents Alternating currents are relatively harmless. Direct currents can cause corrosion in metal objects in the ground such as pipelines and oil and petrol tanks. Stray currents pass only partially through these metal objects, so that and cathode poles are created. These are mostly in fixed locations, meaning that rapid corrosion takes place at the cathode poles. It is not only stray ground that is the culprits when it comes to corrosion. Electrical leakage from technical installations contributes to the problem as well. A possible cause in the domestic situation is poorly functioning electrical equipment.

2.3.1 Pitting corrosion Pitting corrosion occurs in materials that are protected against corrosion by an oxide layer. With pitting corrosion, particles (often chloride ions), penetrate this protective layer. The vulnerability of an alloy to pitting corrosion is indicated by the pitting resistance equivalent (PRE) Stainless steel in particular is sensitive to pitting corrosion. The cheaper alloys are particularly susceptible here. Acknowledged sites for pitting corrosion are urinals fitted with corrosion vulnerable stainless steel fittings. 2.3.2 Fissure corrosion As the name indicates, fissure corrosion occurs in fissures and chinks that get filled up with water. The water in these fissures and chinks cannot replenish itself adequately and so it takes on a different, more ominous composition. Common fissure corrosion sites are: - Screw threads - Assembly points - Sharp corners - Extrusion profiles 2.3.3 Intercrystalline corrosion Intercrystalline corrosion is occurrence of rust along the grain boundaries of an alloy. The crystals themselves stay nearly unaffected but the metal loses its cohesion. While only a small quantity of the alloy corrodes, damage can be very extensive. This type of corrosion often occurs when the material is kept at a relatively high temperature for a long period of time. It results in segregation of the chrome by the formation of chromium carbide Cr23C6 (this compound is very rich in chromium, which itself inhibits corrosion). The process can be opposed by reducing concentrations of the chemical


10. Ships propeller with zinc anode

substances responsible for carbide formation: use of steel with a much lower carbon content (type L steel), or through stabilising the steel with the addition of titanium, niobium or tantalum (indicated by the extensions Ti, Nb or Ta). 2.3.4 Bimetal corrosion Bimetal corrosion, also referred to as galvanic corrosion, is a form of corrosion that occurs if several metal types are in contact with each other. Bimetal corrosion is a predictable process. Each metal has a distinctive vulnerability to corrosion. With bimetal corrosion, the metal most susceptible to corrosion effectively sacrifices itself for the other metals. A necessary condition for the process is that there must be electrical conductivity between the different metals. Today’s shipping industry makes eager use of bimetal corrosion. The propeller on a ship for instance is rarely seen to be corroded. The zinc anode used to protect it is responsible for that phenomenon. The zinc anode is always the first to corrode. The effects of bimetal corrosion vary depending on the corrosive medium in which the ship finds itself. A freshwater ship consequently has need of a different kind of anode to that of a seagoing ship.


2.4 The rust principle Rust is the material that comes to exist on the surface of metals, more particularly steel, due to oxidation, the reaction of the metal with oxygen, a reaction which can be accelerated by the presence of water. Rust is a mixture of iron oxide and hydroxyl groups. Rust is a much used term for a particular form of corrosion, generally the corrosion of steel. Iron in the natural state is found in haematite ore as iron oxide, and Iron in its metallic form has a tendency to return to that former state when it is exposed to air and water. This corrosion is due to the oxidisation reaction that takes place when metallic iron returns to an energetic preferred state. Energy is released as a result. The rusting process can be represented in three basic steps: - the formation of iron(II) ions from the metal itself - the formation of hydroxyl group ions - their mutual reaction in the presence of additional oxygen 2.5 The chemistry An electrochemical process starts up when steel comes into contact with water. The iron at the surface is oxidised into iron (II): Fe → Fe2+ + 2e- The electrons released remove themselves to the tips of the water droplets where more dissolved oxygen is available. They reduce the oxygen and the water to hydroxyl group ions: 4e- + O2 + 2H2O → 4OH- The hydroxide ions react with the iron (II) ions and even more dissolved oxygen to form iron oxide. This hydration is variable, but the most general forms are: Fe2+ + 2OH- → Fe(OH)2 4Fe(OH)2 + O2 → 2(Fe2O3.xH2O) + 2H2O Rust is consequently hydrated iron(III) oxide. Corrosion goes on more rapidly in sea water because of the higher concentration of sodium chloride ions, which boost the conductivity of the solution. The rusting process can likewise be speeded up by acids or slowed down by bases. Hydrated iron oxide is permeable to air and water, which means the metal continues to rust further once a rust layer has been formed. The entire mass of the iron is ultimately transformed into rust. The full formula is as follows:

OH 6 OFe 2 OH 12 Fe 4

OH 12 e 12 O 3 OH 6 e 12 Fe 4 Fe 4

232-3

--22

-3

+→+

→+++→

+

+

11 Representation of the chemical reaction of rust


12 Iron diagram

13 Aluminium diagram

2.6 Pourbaix diagram By the use of a Pourbaix diagram (named after its originator; Marcel Pourbaix) it can be seen whether a metal is vulnerable to corrosion under known circumstances. The diagram accomplishes this by the use of the balance phases of an electrochemical system. Pourbaix diagrams for a particular material may either appear to be highly complicated or on the contrary very simple. This depends on the composition of the metal and the constituents of the environment in which the metal finds itself. A simple sketch of a Pourbaix diagram is given in this chapter. It shows iron that is immersed in water. The pH value of the water is shown on the horizontal axis. On the vertical axis is the value of the introduced potential in volts. For any given pH value and potential, the domain in which the metal finds itself can be read off from the Pourbaix diagram. These domains are indicated by the drawn lines: Corrosion domain; the metal surface corrodes and metal ions are created Passive domain; the metal surface reacts with oxygen and forms for itself a layer of metal oxide on top of the metal, which results in the rest of the metal remaining protected against corrosion. Immune domain; the metal does not react at all and continues to exist in an unaltered form (M) For any given pH value and potential, the domain in which the metal's environment falls can also be read off from the diagram. These domains are indicated by the dotted lines. It is precisely on the dotted lines that the reaction designated by the dotted lines is in balance. Above the dotted lines the reaction will have more of a tendency to move to the left; under the dotted lines the reaction will have a tendency to move more to the right.

12 Iron diagram


3 THE STANDARDS

The variation in the types of corrosion and applications results in a wide variety of corrosion test standards. It is therefore important to make the right selection and to note your requirements for the tests to be carried out carefully before committing to a particular type of test. Here it is vital that you should take the following points into consideration: - Substrate - Pre-treatment - Intended corrosion type - Finishing - Client requirements - Standard of choice - Market conformity 3.1 Types of standards Huge numbers of standards have been issued since the introduction of corrosion testing at the start of the 20th century. Standards institutes such as DIN, ASTM and ISO are among the most well-known. Individual manufacturers, particularly thoise in the automotive industry, also regularly set up their own standards for suppliers. These standards can be sub-divided into certain categories. On the following pages you will find a summary of different standards broken down according to test type. 3.1.1 Condensation moisture loading tests Condensation moisture tests are used to test the moisture permeability of coatings and the corrosion resistance of water soluble coatings. The duration of these tests varies from 24 hours to several weeks. Standards that apply to these types of test are as follows: - ASTM D2247 - BS 3900 Part F2 - DIN 50 017-KK - DIN 50 017-KFW - DIN 50 017-KTW - RES.30.CT.900 - VDA 621-421 3.1.2 Water spray and moisture loading tests: Water spray tests are used relatively little. Application of these tests is therefore fairly limited. Standards that apply to this type of test are as follows: - ASTM D1735 - GM4465P 3.1.3 Salt water spray tests: Salt water spray testing can be carried out in either a neutral or an acid environment. This type of test is also one of the original corrosion tests. The long list of available tests always makes choice of the right test difficult. One or two of these tests will be singled out for attention further on in this chapter. Salt spray tests can principally be divided into neutral and acetic acid tests. The neutral tests are generally used on ferrous metals, acetic acid tests on aluminium. The following standards relate to salt spray testing:


50180 method A1 50180 method A2 50180 method A3 AS 2331 method 3.1 AS 2331 method 3.2 AS 2331 method 3.3 ASTM B117 ASTM B287 ASTM B368 ASTM G43 ASTM G85 annex A1 ASTM G85 annex A2 ASTM G85 annex A3 ASTM G85 annex A4 ASTM G85 annex A5 ASTM G5894 BS2011 Part2.1 Ka BS2011 Part2.1 Kb BS 3900 Part F4 BS 3900 Part F12 BS 5466 Part 1 BS 5466 Part 2 BS 5466 Part 3 BS 7479 BS EN ISO 7253 BS EN 60068-2-11 BS EN 60068-2-52 D17 1058 DEF STAN 00-35 Pt 3 CN2 DEF STAN 133 method 14 DEF STAN 1053 method 24 DEF STAN 1053 method 36

DIN 50 021-SS DIN 50 021-ESS DIN 50 021-CASS FLTM BI 103-01 GM4298P IEC 68-2-11 IEC 68-2-52 IEC 60068-2-11 IEC 60068-2-52 ISO 3768 ISO 3769 ISO 3770 ISO 7253 ISO 9227 JIS H 8502 Method 1 JIS H 8502 Method 2 JIS H 8502 Method 3 JIS H 8502 Method 4 JIS H 8502 Method 5 JIS Z 2371 JNS 30.16.03 MIL-STD-202 MIL-STD-750 MIL-STD-810 NFX 41-002 RES.30.CT.117 RTCA/DO-160 VG 95 210


Set Temperature - deg. CSet Humidity - % RH

0

& = Air purge (5 mins)= Wall wash (5 mins)

Temperature & humidity controlled air conditioning (1hr 35mins)

30 60 90 120 150 180 210

100

90

80

70

Salt spray (30mins)

Temperature & humidity controlled air conditioning (1hr 40mins)

20

10

240

60

50

40

30

3.1.4 Cyclic Corrosion Tests (CCT): Cyclic corrosion tests are amongst the most demanding tests carried out. These tests require much from test samples and equipment. A cyclic test is a combination test incorporating previous standards and references. The conditions in the chamber vary over well defined periods. These climate changes are responsible for the accelerated corrosion of the samples tested. Special test accreditations are often necessary to be allowed to carry out these tests. Illustrated in the example below is the temperature and humidity profile for the Renault ECC-1 test. Examples of cyclic tests are:

Set Temperature - deg. CSet Humidity - % RH

0

660 720 780 840300 360 420 480 540 600

50

40

30

20

10

240 900 960 1020 1080

Tem

pera

ture

&

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(2hr

40m

ins)

100

90

80

70

60

Tem

pera

ture

&

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(2hr

40m

ins)

T

empe

ratu

re &

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(1hr

20m

ins)

1120 1180 1240 1300 1420

Rep

eat (

part

1)

1360

T

empe

ratu

re &

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(1hr

20m

ins)

Tem

pera

ture

&

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(2hr

40m

ins)

T

empe

ratu

re &

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(1hr

20m

ins)

Tem

pera

ture

&

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(2hr

40m

ins)

T

empe

ratu

re &

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(1hr

20m

ins)

Tem

pera

ture

&

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(2hr

40m

ins)

T

empe

ratu

re &

hum

idity

con

trolle

d

air c

ondi

tioni

ng

(1hr

20m

ins)


14 ASTM Logo

CCT-1 CCT-2 CCT-4 ECC-1 D17 2028 GM9540P

ISO11997-1 ISO14993 JASO M 609 JASO M 610 P-VW 1209 P-VW 1210

RES.30.CT.119 SAE J 2334 STD1027, 14 STD1027,1375 VDA 621-415

In Annex 1 you will find a reference list showing which Ascott chambers are suitable for what tests. 3.2 Spotlight on a some standards Rather than a full analysis of all the available standards, we will only give full focus to a few of the most popular. We also examine small differences that exist between standards in this comparison. The standards selected here all neutral salt spray standards. References to the operation of the chamber are explained in greater detail in the next chapter. 3.2.1 ASTM B117 The American ASTM B117 standard is the oldest and most used ASTM corrosion test standard throughout the world. It is a neutral salt spray test for relative corrosion investigations. The wide limits make the test easy to manage but they also inhibit replication. This means the results are only suitable for comparative purposes within the same test series. The ASTM standards do not work the international system measurement values. Concentrations are indicated as percentages or ppm, which makes it necessary to convert them to metric. This is a conversion that is often overlooked in practice. As stated, the ASTM B117 is suited primarily to mutual comparison of results. Use of this test is particularly appropriate to static objects such as fences, furniture and similar. For these applications, there is good correlation between test results and practice. A link to the automobile industry is not particularly feasible where this test is concerned. Practical tests have shown that the results obtained with the ASTM B117 are not realistic in terms of the automobile industry. You will find the following parameters on the next page: type parameter min max unit

Salt: 41 63.8 g/l. Tank: pH value: 6.5 7.0 Vapour: 1 2 ml/h. Salt: 41 63.8 g/l. pH value: 6.5 7.2 Angle 15 30 °

Fall out:

Temperature 33.9 36.7 °C pH down: Augment: pH up:

Hydrochloric acid Sodium hydroxide

The ASTM B117 imposes no restriction on minimal chamber capacity. This standard is therefore well suited to use in smaller chambers. As a pitfall, however, the ASTM B117 has very high requirements for the Sodium Chloride used.


15 ISO Logo

3.2.2 ISO 7253 The ISO 7253 is a European standard for a relatively neutral salt spray test. The standard has many equivalents. This standard is also sometimes cited as the BSI-BS-EN-ISO 7253. The standard is recognized and used in many countries. The ISO 7253 is also a relative test. This standard made its contribution to the development of the European automobile industry. The results achieved did not turn out to be in accord with practice however. As was the case with the ASTM B117, this test failed to simulate the needs of the automobile industry. The automobile industry subsequently moved much more towards cyclical testing in an attempt to find a solution for the problem. The test we are discussing here does give replicable results however. The parameters are shown below:

type parameter min max unit Salt: 45 55 g/l. Tank: pH value: 6.0 7.0 Vapour: 1 2.5 ml/h. Salt: 40 60 g/l. pH value: 6.5 7.2 Angle: 15 25 °

Fall out:

Temperature: 33.0 37.0 °C pH down: Hydrochloric acid Augment: pH up: Sodium bicarbonate

In contrast to the ASTM B117, the ISO 7253 does specify a minimal capacity for the chamber. The120 litre chamber cannot be used for example because the minimum capacity is 400 litres. In carrying out tests according to ISO 7253 the maximum daily interruption time permitted is 30 minutes in every 24 hours. The standard stipulates that any inspection that extends only to the spray parameters of the chamber is inadequate for carrying out tests according to the standard. The full calibration takes place by positioning CR4 steel panels according to ISO 3574 with dimensions of 150mm x 75 mm. The panels are to be prepared according to ISO 1514. Immediately before positioning a panel in the test it must be weighed and covered with watertight foil on one side. The panels are placed in the test for a period of 96 hours, subject to a total maximum interruption of 30 minutes and at an angle of 20° (+/- 5°). Following completion of the test all rust must be removed without causing further damage to the panels. This is to be achieved firstly by a combination of brushing and pickling. After rinsing with water and acetone, the panels are then weighed again. The average weight loss of the six panels must amount to 130 mg/m2 (+/- 20mg/m2). 3.2.3 ISO 9227 NSS The ISO 9227, like the ISO 7253, is a European standard. Where the 7253 only describes a neutral test, the 9227 describes a universal standard for carrying out both neutral and acetic acid tests, plus a copper accelerated test. Selection of the type is determined by the suffix. The term NSS stands for Neutral Salt Spray. That makes this standard universal for multiple substrates and test options.


16 DIN logo

With the improvement of corrosion test equipment, resulting in more accurate regulation options, the standards themselves have been sharpened up in turn. That has happened with this standard, as can be seen from the table below. type parameter min max unit

Salt: 45 55 g/l. Tank: pH value: 6.0 7.0 Vapour: 1 2 ml/h. Salt: 45 55 g/l. pH value: 6.5 7.2 Angle: 15 30 °

Fall out:

Temperature: 33.0 37.0 °C pH down: Hydrochloric acid Augment: pH up: Sodium hydroxide

As with the 7253, the ISO 9227 also specifies a minimal capacity for the chamber. That capacity is specified in the standard as being from 400 litres upwards. This limit is determined by the uneven spray pattern obtained in the old chambers. Small modern corrosion test chambers can comply with the standard as far as the spray pattern is concerned, even if they can not comply with the minimum size requirement. As with ISO 7253, the standard gives calibration directions. Here however the mass loss panels are now to be prepared in accordance with ISO 3574 to a matt appearance and then tested for 48 hours without interruption. The corrosion test complies with the standard when the loss of mass lies between 70 mg/m2 (+/- 20mg/m2). 3.2.4 DIN 50021 SS The DIN 50021 is a German industrial standard set up as collective standard for both neutral and copper accelerated corrosion testing. Where specifications are concerned, the standard is the European counterpart of the ASTM B117 standard. The major difference is that the experiences gained with small chambers have been incorporated into the standard, meaning that, here too, use of chambers with a capacity of less than 400 litres are not permitted. The ample parameters make the standard easy to set up and simple to use. Just as the ASTM, the standard describes an indication comparison test. That the DIN standard is closely related to the ASTM standard can be seen readily from the table below. Here, of course, the conversions and rounding up and down have been included. type parameter min max unit

Salt: 40 60 g/l. Tank: pH value: Vapour: 1 2 ml/h. Salt: 40 60 g/l. pH value: 6.5 7.2 Angle: 15 30 °

Fall out:

Temperature: 33.0 37.0 °C pH down: Hydrochloric acid Augment: pH up: Sodium hydroxide


17 SIM card

The lack of a pH requirement for preparation does not give carte blanche for the use of poor quality water. The standard does specify a water quality. As a result of the transfer pumping and the mixing of the salt however the pH value of the solution can change temporarily. The DIN 50021 also requires that there must be no rest period for use of the salt water solution. 3.3 How to select a standard The choice of the right standard is often based on the requirements of clients. If the relevant option is not available, tests will have to be carried out based on market conformity. You will therefore need to determine what is likely to be the best choice for you in the circumstances. Your particular market sector and your competitors could be decisive in this context. The fairly general rule applies that unrealistic requirements are often set for tests due to ignorance. A request for 1000 hours of acetic acid salt spray according to ISO 9227 AASS is an example of an unrealistic standard. As well as the choice of the actual test you will also need to choose a method of reporting. To go back to the practical example again, there is little point in applying a standard 1mm scratch to the SIM card contacts. A more realistic test would be to check them for visible corrosion. That might be a reason for poor contact in the practical situation. And then there is the additional fact that the SIM card is mounted inside the protective housing of the telephone. 4 THE SALT

The purity of the salt used for corrosion testing is usually specified within the test standard. Depending on the standard, this should contain no less than 95.5-95.8% Sodium Chloride, no anti-caking agents, <0.1% Halides and be substantially free of copper and nickel.

5 THE CHAMBER

The construction of the corrosion test chamber has evolved as the test standards have evolved. Although the basic salt spray test has not changed greatly since its first introduction there have been significant changes to the chamber design. These changes have arisen due to the use of modern materials and control technology which are better suited to modern testing requirements and the ever tighter specifications of the test standards. The old chambers were big and cumbersome containers that often worked without heating and that frequently caused more corrosion to their surroundings than they did to the panels being tested.

19 TQC test chamber

18 Corro Salt


20 Diagrammatic overview of an old model chamber

22 Pressure regulator and meter

21 schematic representation of a modern corrosion test chamber

5.1 The operation The construction of a corrosion test chamber is specified in the standards elaborated earlier. The diagrammatic overview shown in ill.19 is that of an original chamber. Here you see all the essential constituent parts of the chamber. The primary components are: - Bubble tower, pre-saturator - Salt water stock - Spray nozzle.

Modern chambers incorporate a number of essential changes with regard to the old models. Mechanical level regulators have been replaced by digital regulators and the suction velocity of the salt water is regulated by a hose pump. The appearance of the old open boxes has consequently changed drastically, as can be seen in illustration 20. It is relevant to have an idea of how the chambers work so you can make proper use of them. The components will be explained starting from the external supply and up to the spray nozzle. The compressed air flow is dealt with first, and then the salt water flow. 5.2 The compressed air flow 5.2.1 The oil filter The purpose of the oil filter is to remove oil from the compressed air delivered to the chamber. Any form of oil contamination has serious consequences for the ongoing operation of the chamber. Any traces of oil that get through will frequently manifest themselves in the air humidifier that positioned further on in the diagram. Proper maintenance of your compressed air installation is essential so as to avoid defects caused by oil. If there is any doubt regarding the quality of the compressed air the oil filter can be inspected visually for the presence of oil remnants. 5.2.2 The pressure regulator Compressed air systems have a higher pressure than the pressure needed in the pre-saturator. The pressure regulator consists of a regulating valve and a gauge. Presetting the correct pressure is important in order to obtain good atomisation in the venturi spray nozzle. Faulty adjustment of the pressure is frequently responsible for drying up the vapour in the chamber to a large extent. The pressure regulator is


24 Salt water stock tank

23 Air saturator

decisive for the force at which the dry air flows through the pre-saturator. The ideal working pressure is the pressure that causes the least drying out of the vapour, but still ensures atomisation is adequately fine and satisfactory. The regulation of the pressure is therefore a fine balance between vapour formation and air humidification. This entails that no standard pressure at which a chamber works best can be specified. Small differences in the surroundings and in the assembly of the equipment are more than enough to account for variations. 5.2.3 The air saturator The air saturator (also known as a humidifier or bubble tower) has a key function in the compressed air flow. In essence, the air saturator is nothing more than a hot water boiler through which the air bubbles. For as long as these air bubbles remain in the water, they take up moisture and the dry air is moistened. The moistened air serves to prevent drying out of the salt spray aerosol. Drying out of the aerosol results in an increase in the salt content of the vapour. Frequently this increase in the concentration forms an impediment to achieving compliance with standards that have narrow salt content tolerances. Operation of the air saturator is affected not only by the pressure of the compressed air but also by the set temperature. The temperature also compensates for the cooling down of the compressed air that takes place as soon as it reaches the spray nozzle. These are settings that are accessible to the user and allow the temperature of the air saturator to be adjusted as needed, typically 10-15 degrees Celcius above the chamber temperature. Downstream of the air-saturator is the spray nozzle. The operation of the spray nozzle is explained in more detail below as part of the salt water flow. 5.3 The salt water flow 5.3.1 The stock tank The salt water stock is an essential part of the corrosion test. In principle it forms the chamber’s main source. The standard used already gives specifications for the salt concentration and ph value of the solution. Some standards go even further by specifying a minimum age for the salt water stock. In some standards for instance the prepared solution must only be used after remaining undisturbed for 24 hours. This is in order to limit the presence of carbonates. A problem that frequently arises is algae growth in the tank and the pipes. Algae need daylight to be able to grow. Further information on algae is to be found in the Safety section. 5.3.2 The pump Old chambers were equipped with gravity fed systems with a float chamber. This had the purpose of maintaining an even pressure in the spray nozzle suction line at all times. This system has now generally been replaced with direct injection systems which maintain a slight positive pressure at the atomiser by using something like a peristaltic pump. The old chambers were also fitted with a valve that regulated the suction force of the venturi spray nozzle. The present-day pumped systems simply allow the speed of the pump to be varied which in turn determines the rate at which salt spray atomisation takes place in the chamber. The quantity of vapour created and the fall-out inside the chamber is directly proportional to the pump speed.


25 Venturi spray nozzle

26 Typical Ascott chamber touch-screen control interface

A flow meter is usually placed downstream of the pump to indicate the flow. Possible blockages in the pipe can cause a total standstill in this flow. A daily inspection to make sure the flow meter shows a good reading is recommended. 5.3.3 The spray nozzle All corrosion test chambers are equipped with a venturi spray nozzle. As a result, the compressed air pressure that is set is directly responsible for the suction of the spray nozzle. Old spray nozzles were made of stainless steel. The preference nowadays is for use of plastic spray nozzles, since these are less vulnerable to scaling and contamination. A filter is positioned ahead of the spray nozzle to prevent it from clogging up. This filter is a gathering site for crystals and algae. Regular replacement of the filter prevents damage to the spray nozzle. The vapour produced is a fine mist of salt water droplets. Defective spray nozzles generally cause a poor spray pattern because of the formation of large drops. Alignment of the spray nozzle also plays a role here. The distribution of the vapour must be the same throughout the chamber as a whole. The chamber is required to have a uniform spray pattern which in turn will create a uniform fall-out on to the samples under test. 5.4 The operation The chamber is operated by means of different types of controls. Precisely how these control elements work is described in your chamber's manual. It is recommended that not all users should be given the right to make adjustments to all data. Full instructions for use of your corrosion test chamber are set out in the user manual. It is important to read this through carefully before use. In the worst case, significant settings are overlooked due to not being fully aware of how the chamber operates. 5.5 Maintenance Your corrosion test chamber is also subject to wear and tear. Just like a car, a test chamber needs regular maintenance. Not only an annual service by a trained technician, but also periodic maintenance by yourself as the user. As user, you should check the following parameters on a daily basis: - Temperature in the chamber - Temperature in the pre-saturator - Air pressure - Fall-out rate - pH value of the precipitate - Sodium chloride concentration in the fall-out


Daily Checks for Month: February

Day

Chamber Tem

p (°C)

Air Saturator

Temp (°C)

Air

Pressure (Bar)

Fallout (m

l/80cm2/hour)

pH

of Fallout

Water

Conductivity (μs)

Concentration of Salt Solution /Specific G

ravity

1 35 .2 45 .2 1 .5 1 .60 6 .7 5 .7 54 .1

2 35 .3 45 .1 1 .5 1 .61 6 .8 5 .8 54 .6

3 34 .8 45 .0 1 .5 1 .56 7 .1 6 .0 55 .2

4

5

6

These daily checks must be recorded. The table above shows an example of how this can be done. In addition to this daily maintenance work, there are also some periodic maintenance tasks: Peristaltic pump hose: The hose is subject to wear. The kinetic friction of the pump mechanism, undissolved crystals and the corrosive salt mixture all play a role in this. It is recommended that the pump hose should be replaced monthly. Filter: The filter placed in the spray nozzle serves to protect it. The filter is also sensitive to growth of micro-organisms however. These micro-organisms and any dirt and oil residues are visible as a brown discoloration of the filter. The filter should be replaced monthly. Cleaning the walls and the base: Due to the corrosion of the panels that takes place in the chamber there is serious contamination of the base. Periodic flushing away of the oxide deposit and salt remnants avoids clogging and discoloration of the base while at the same time it improves resistance to growth of micro-organisms. Cleaning the stock tank: Like the chamber, the salt water stock tank needs to be cleaned regularly. Through exposure to light and contamination, a slimy deposit can appear on the walls of the tank. This deposit, which is called biofilm, can cause major problems. This is often a source of malfunctions in the pipes. The deposit can best be removed using hot water and a clean cloth. Additional maintenance work will be carried out during major servicing of the chamber by your supplier. This annual service maintenance is therefore highly important. The maintenance work will include but is not limited to: - Replacement of hoses. - Air saturator drainage. - Check on operation of bubble devices. - Check on correct working of heating elements - Checking of temperature measurements. - Inspection of the technical status of the chamber. Preventive maintenance avoids damage to your equipment and reduces the likelihood of breakdowns.


27 Screws for the corrosion test

6 EVALUATION, INTERPRETATION, REPORTING

6.1 Evaluation The various tests standards generally give some guidance on the reporting of test results. The question of how these results are to be assessed often depends on the samples being tested. Here again factors such as the client's requirements, the type of substrate and the application play a major role. Before the components placed into the test, the option can be taken of marking the components with a standard scratch. How this should be done and how the procedure must be evaluated is clarified further in this chapter. 6.2 The preparation Corrosion tests generally require a certain period of time in the chamber. The test objects will change in appearance due to corrosion. This can make recognition of the objects difficult after the test. A good way of marking the objects is therefore very handy. Lacquered panels can often be marked on the lacquer. Smaller components such as screws, plugs and unlacquered materials cannot be marked with a marking pen. The marking pen, suitable for use on lacquered panels, is not suitable for unlacquered objects. Corrosion of the object can not only render the ink invisible, but corrosion can actually be caused by use of the marking pen. The effect of a marking on an unlacquered panel is unpredictable. If a possibility exists for marking the object in a different way, that is to be preferred. Any effective way of marking the objects must comply with the following requirements: Unambiguous. All objects belonging to a test must be given a label that conforms to an identical structure. Unique. No two objects with the same coding must be placed in the chamber. Each object must be uniquely traceable. External registration. It is recommended that either analogue or digital records should be used for registering the test. Here also the full particulars of the objects must be noted in all cases. 6.2.1 Scratching The method of placing a standard scratch is often underestimated. The primary problems with the placement of a scratch are often caused by setting the scratch knife incorrectly or by using a Stanley knife instead of a special purpose scratching tool. The scratch similarly also cannot be placed just anywhere on a panel. Extremities such as the edges, holes and sharp angles all affect the results. Any minimum distances that apply are stated in the relevant report standard. A minimum distance of 1 cm is commonly maintained. In addition to use of a Stanley knife, incorrect positioning of a standard knife is one of the major causes of deviations in final results. These deviations can lead to huge differences in the ultimate results. The effect of these cannot be labelled as either positive or negative.


28 Deviating objects

29 Panel with some detachment

30 Panel with serious detachment

31 Magnified blister

6.2.2 Positioning the objects When positioning objects in the test, care must be taken to ensure that no interaction can be caused between them. From space-saving considerations, objects are often placed too close together or too close above or below each other in the chamber. A number of defects can occur because of this: Frequently occurring problems are: • Contamination. By placing objects in multiple layers, droplets

from the upper layer will fall on panels in one or more of the underlying layers. Any undissolved salts and salts carried in the falling liquid will influence the results of the objects onto which the droplets fall.

• Electrical conductivity. Where electrical conductivity takes place

between objects of different composition this causes bimetal corrosion. This erroneous result is often not traceable or visible as an anomalous corrosion pattern.

• Incorrect angle. Where not only standard panels are being

tested, but also larger objects with a divergent shape at the same time, the test angle is not uniform in all cases. If the correct test angle for the divergent form of objects cannot be achieved, the angle actually used must be indicated in the report. Once the objects have all been placed in the test, the positions allocated must be maintained throughout the whole of the test.

6.2.3 The final inspection When the objects emerge from the test they must be assessed according to a set of possible parameters. The final inspection can take place according to a number of different techniques. Below are some examples of the different methods used for inspection. 6.2.4 Detachment Scratched components are assessed based on detachment that commences from the scratch. After leaving the test, the panels are either blown clean with compressed air or scraped with a blunt spatula, depending on the substrate and the selected standard. No excessive force is used in this operation. The detachment in millimetres is measured commencing from the scratch. Where the detachment is serious and parts of the panels are completely bare after completion of the test, this is usually reported as total detachment. The panel in illustration 30 is an example of serious detachment. 6.2.5 Blister formation Lacquered objects can also be assessed on blister formation in the lacquer. On completion of the test the panels are carefully rinsed with water and then dried. In this type of evaluation an assessment is not only made of the intensity of the blisters, but also the size. The diversity of the standards available has also had its effect on this form of evaluation. The gradation scales and the sequence order used for the assessment vary according to the standard used. An accurate assessment needs to take place immediately after removal from the test. The different norms also use their own individual assessment times for this process.


34 Filigree pattern corrosion

33 Various galvanised panels showing corrosion

6.2.6 Corrosion points Unlacquered panels that have had a corrosion resistant pretreatment or that have a corrosion resistant substrate are often assessed on the number of corrosion points. This assessment varies according to the standard used in the same way as in the blister formation assessment. The notation method ranges from reporting the number of corrosion points per panel to an assessment based on intensity and size. In this method of evaluation the objects are also rinsed with water and then dried with compressed air. Care must be taken when using the method to ensure that dried salt remnants are not mistaken for corrosion points. 6.2.7 Corrosion percentage If the standard or the needs of the market so require, unlacquered objects can also be assessed on the corrosion percentage. One example of this is the Qualicor standardisation for salt spray. Under this standard, galvanised steel panels are assessed according to the corrosion percentage. The percentages are reported as white rust (zinc oxide) or brown rust (iron oxide). Values for these can be indicated within the requirements set by the market. The test is primarily an approve or reject test. The corrosion percentage is given in all cases but it is subordinated to the standard used. An example of a comparative investigation of a number of galvanised panels is shown in illustration 33.

6.2.8 Filiform pattern corrosion Aluminium panels are frequently tested for filiform pattern corrosion. As was the case with detachment, measurement is made commencing from the standardised damage. Here the minimum and maximum filiform pattern corrosion formation is also measured. A term such as total detachment cannot apply directly in this case. With filiform pattern corrosion the corrosion percentage must be reported however.

32 Corrosion points on stainless steel


6.3 Interpretation 6.3.1 Abnormalities Test objects can exhibit local abnormalities as a result of small deviations in both the production process and the test conditions. Where there is inaccurate interpretation, these abnormalities can result in significant deviations in the results and so affect the final conclusions. Abnormalities do need to be taken into account in the reporting, but always with an accompanying note. The standards that are used will always indicate the extent to which abnormalities are required to contribute to the result. A frequently occurring cause of abnormalities is grease and acid residue originating from being touched by the fingers. In order to ensure an accurate report, always indicate the results actually found in the abnormality and the size of the abnormality. 6.3.2 Mutual difference Mutual difference between panels always occurs. This difference is not only caused by small deviations in the panels, pretreatment and coating but also by deviations in the chamber itself. These small variations cannot be prevented and are taken up into the interpretation without further comment. Where the mutual differences become so large that we are justified in regarding them as significant differences, these will need to be processed according to the requirements of the standard. This lead to the results achieved by seriously deviating panels needing to be rejected. It is therefore always important to set up at least duplicate tests in all cases. 6.3.3 Conclusions Since there is no linear connection between the different tests and reality, it is therefore not advisable to form any conclusions regarding quality. The final judgement regarding quality is left to the client. All possible conclusions are always subject to interpretation and to the personal preferences of the assessor. For the purpose of presenting an accurate picture, results must be as objective and impartial as possible. Many clients will be keen to see conclusive statements relating to the tests requested. Precisely what overall conclusion can be derived from the results is a matter for the supplier. If the supplier has drawn up uniform requirements however, you will be able to provide an assessment in that case. 6.4 Reporting The results obtained must be processed into a report on conclusion of the test. Apart from results, a good report contains information on the test used and on the prevailing circumstances. Not only the results themselves, but also how they were obtained are important for the client. Many standards set out specific requirements for the actual report. It is usual for the following parameters to be stated alongside the results: - Standard used - Make, type and serial number of the chamber - Date and time the components went into the test. - Date and time the components came out of the test. - Statement to the effect that no deviations were made from the standard during the test. - Method of applying standardised damage where relevant. - Analyst(s) responsible for conducting the test - Layer thickness of any coating applied to the objects. - Identification of the test objects both internal and external. In many cases it is advisable to have the results accompanied by photographs. The use of photographs in evaluation of results makes it possible to trace any extremes even after a long period of time. Use of photographs is very positively regarded as a rule. You will find an example of these in appendix 1


35 Legionella

7 SAFETY

7.1 Hazardous materials In the implementation of a neutral corrosion test, the use of hazardous materials for the test is limited to a minimum. Hazardous materials are used however in tests such as acetic acid corrosion tests and industrial tests. In using these materials it must be ensured that the standards that apply to their use are complied with at all times. Not only your ability to show the safety sheets, but also the use of personal protective equipment must be taken into account. If materials are being used for which special requirements are set as regards safety measures, these requirements must be incorporated into the Risk Inventory and Evaluation dossier that is periodically drawn up by the laboratory. Ergonomics Many problems in the use of corrosion test chambers are due to physical overexertion. Unwise lifting often constitutes the basis of such physical exertion. Heavy weights are frequently lifted. The sacks of salt in the form in which they are delivered weigh 25 kg. If lifting with the strain on the back, serious problems can arise over the long-term. A proper lifting position is essential for good health. When scratching and scraping the panels it is not a sharp object that is used, yet the object is sharp enough to cause injury. If the hand should slip through careless use, it can cause lacerations. The tools used are not generally sterile and may introduce dirt into any wound that is made. Dirt that gets into the wound can cause tetanus. A preventive vaccination can avoid serious problems. 7.2 Micro-organisms 7.2.1 Legionella Legionella pneumophila is a bacterium of the genus Legionella that causes legionnaires disease or legionella flu. The illness (also called legionellosis) can arise when people breathe in the bacteria (for example in a shower or by means of a spray installation). The influenza variant (also called Pontiac Fever) is generally temporary and of a passing nature. Legionnaire’s disease on the other hand amounts to a chronic lung disorder that can have fatal consequences. The condition for infection is that the bacterium enters the body via the nose or the mouth and it is able to establish itself in the lungs. Spreading of the pathogen also takes place by means of so-called aerosols; small water droplets that can contain the bacteria and that are caused by turbulent water movements. The natural environment for Legionella pneumophila is the soil and freshwater, but generally in large quantities. Nearly all strains of the Legionella genus are polyglot, which means that they are not limited to particular geographical sites but have spread throughout the world and can occur anywhere. Legionella pneumophila appears to increase in numbers rapidly under favourable circumstances. Optimal growth conditions are provided by stagnant water with a temperature between 25 and 55°C (the optimal temperature is 37°C) and the presence of biofilm or other organic material. Such circumstances appear to be abundantly present in hot water systems designed by human beings, such as hot and cold water pipes, swimming baths, drinking fountains, air coolers, etc. If the water is unable to flow through the whole of the water system it is possible that water will remain standing in 'dead' corners. This gives the bacteria the opportunity to multiply in the slime layers (biofilm) on the inside of pipes, or in the sunken detritus at the bottom of pipes and in reservoirs. Legionellosis is therefore primarily seen as “a disease of civilisation". A much used prevention measure is heat treatment of water systems prior to disinfecting them, followed by flushing of the distribution system. In this process the water is heated to 60°C or higher so that the Legionella is in principle killed off. The dead organic material is washed away by the flushing. In practice however, it proves very difficult to obtain


36 algae

uniform heating throughout the entire system in complex industrial water systems due to so-called 'dead' corners, zones where little if any water movement takes place. It appears also from recent scientific studies that Legionella pneumophila is able to use dead organic material for its growth, so that even killing off the live bacteria can mean a potential stimulus for the surviving Legionella. All of this makes combating Legionella pneumophila extremely difficult. Epidemiology The first reported outbreak dates from 1976 when a massive epidemic of pneumonia occurred among ex-servicemen of the American Legion in the USA (Philadelphia). Following investigation, it was possible to relate this outbreak to particular bacteria. These bacteria were named Legionella pneumophila and the genus to which they belonged was called Legionella, as an analogy to the first known outbreak. Temperatures at which Legionella can manifest 70° to 80°C: total killing of Legionella 66°C: Legionella dies within 2 minutes. 60°C: Legionella dies within 32 minutes 55°C: Legionella dies within 5 to 6 hours 55°C: Legionella can survive but does not reproduce itself 35 to 46°C ideal temperature for Legionella to reproduce itself 20 to 50°C Legionella has the ability to grow 20°C: Legionella can survive but the bacteria are not active.

7.2.2 Algae Algae are the non-systematic collective name for a number of groups of relatively simple organisms that convert light into energy by means of photosynthesis. Although algae are in general regarded as simple plants, they belong to more than one domain, and include eukaroyts and bacteria, and to more than one species, including plants and protozoa. Algae can be both monocellular and multi-cellular organisms and they take on a relatively complicated form as seaweed. Algae have no leaves, roots, blooms or other organic structures that that are typical of the higher plants> They differ from other protozoa in that they are phototrophic, although this does not apply to all algae, since some groups are mixotrophic. Some unicellular sorts are entirely dependent on external energy sources and have lost their photosynthetic abilities. All algae have derived their photosynthetic structures from the blue algae (also cyano bacteria) and produce oxygen as a by-product of photosynthesis. It is estimated that algae produce 73 to 87% of the oxygen that is available to human beings and other land animals. The different forms of algae play an important role in the aquatic ecology. Microscopic forms that live suspended in the water column — called phytoplankton, provide the food base for most marine food chains. In very high densities (so-called algal blooms) these algae may discolour the water and outcompete or poison other life forms. Seaweed grows mostly in shallow marine waters. It is used as food or harvested for useful substances such as agar and fertiliser. The study of sea algae is called phycolgy or algology.

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Appendix 1:

Ascott selectie tabel

Salt Spray Chambers CCT

Chambers Standard Plus Premium

Test Standard Number Country/

Industry/ Company of

Origin

S 120 S

S 450 S

S1000 S

S 2000 S

S 120 +

S 450 +

S1000 +

S 2000 +

S 120 xp

S 450 xp

S1000 xp

S 2000 xp

CC 450 xp

CC 1000 xp

CC 2000 xp

Condensation Humidity Test Standards ASTM D2247 USA • • • • • • • • • • • BS 3900 Part F2 UK • • • DIN 50 017-KK Germany • • • • • • • • • • • DIN 50 017-KFW Germany • • • • • • • DIN 50 017-KTW Germany • • • • • • • RES.30.CT.900 Rover • • • VDA 621-421 Germany • • • • • • •

Water Fog Humidity Test Standards ASTM D1735 USA • • • • • • • • • • • • • • •

GM4465P General Motors • • • • • • • • • • • • • • •

Salt Spray/Mist/Fog Test Standards 50180 method A1 Fiat • • • • • • • • • • • • • • • 50180 method A2 Fiat • • • • • • • • • • • • • • • 50180 method A3 Fiat • • • • • • • • • • • • • • • AS 2331 method 3.1 Australia • • • • • • • • • • • • AS 2331 method 3.2 Australia • • • • • • • • • • • • AS 2331 method 3.3 Australia • • • • • • • • • • • • ASTM B117 USA • • • • • • • • • • • • • • • ASTM B287 USA • • • • • • • • • • • • • • • ASTM B368 USA • • • • • • • • • • • • • • • ASTM G43 USA • • • • • • • ASTM G85 annex A1 USA • • • • • • • • • • • • • • • ASTM G85 annex A2 USA • • • • • • • ASTM G85 annex A3 USA • • • • • • • ASTM G85 annex A4 USA • • • • • • • ASTM G85 annex A5 USA • • • • • • • ASTM G5894 USA • • • • • • • BS2011 Part2.1 Ka UK • • • • • • • • • • • • • • • BS2011 Part2.1 Kb UK • • • • • • • • • • • • • • • BS 3900 Part F4 UK • • • • • • • • • • • • • • • BS 3900 Part F12 UK • • • • • • • • • • • • BS 5466 Part 1 UK • • • • • • • • • • • • BS 5466 Part 2 UK • • • • • • • • • • • • BS 5466 Part 3 UK • • • • • • • • • • • • BS 7479 UK • • • • • • • • • • • • BS EN ISO 7253 UK • • • • • • • • • • • • BS EN 60068-2-11 UK • • • • • • • • • • • • • • • BS EN 60068-2-52 UK • • • • • • • • • • • • • • • D17 1058 Renault • • • • • • • • • • • • DEF STAN 00-35 Pt 3 CN2 UK - Defence • • • • • • • • • • • • • • •


DEF STAN 133 method 14 UK - Defence • • • • • • • • • • • • • • • DEF STAN 1053 method 24 UK - Defence • • • • • • • • • • • • • • • DEF STAN 1053 method 36 UK - Defence • • • • • • • DIN 50 021-SS Germany • • • • • • • • • • • • DIN 50 021-ESS Germany • • • • • • • • • • • • DIN 50 021-CASS Germany • • • • • • • • • • • • FLTM BI 103-01 Ford • • • • • • • • • • • • • • •

GM4298P General Motors • • • • • • • • • • • • • • •

IEC 68-2-11 Europe • • • • • • • • • • • • • • • IEC 68-2-52 Europe • • • • • • • • • • • • • • • IEC 60068-2-11 Europe • • • • • • • • • • • • • • • IEC 60068-2-52 Europe • • • • • • • • • • • • • • • ISO 3768 Europe • • • • • • • • • • • • ISO 3769 Europe • • • • • • • • • • • • ISO 3770 Europe • • • • • • • • • • • • ISO 7253 Europe • • • • • • • • • • • • ISO 9227 Europe • • • • • • • • • • • • JIS H 8502 Method 1 Japan • • • • • • • • • • • • JIS H 8502 Method 2 Japan • • • • • • • • • • • • JIS H 8502 Method 3 Japan • • • • • • • • • • • • JIS H 8502 Method 4 Japan • • • JIS H 8502 Method 5 Japan • • • JIS Z 2371 Japan • • • • • • • • • • • • JNS 30.16.03 Jaguar • • • • • • • • • • • • • • • MIL-STD-202 USA - Military • • • • • • • • • • • • • • • MIL-STD-750 USA - Military • • • • • • • • • • • • • • • MIL-STD-810 USA - Military • • • • • • • • • • • • • • • NFX 41-002 France • • • • • • • • • • • • • • • RES.30.CT.117 Rover • • • • • • • • • • • • • • • RTCA/DO-160 RTCA Inc. • • • • • • • • • • • • • • • VG 95 210 Germany • • • • • • • • • • • • • • •

Cyclic Corrosion Test (CCT) Standards

CCT-1 Japan - Automotive • • •



ECC-1 Renault • • • D17 2028 Renault • • •

GM9540P General Motors • • •

ISO11997-1 Europe • • • ISO14993 Europe • • •

JASO M 609 Japan - Automotive • • •

JASO M 610 Japan - Automotive • • •

P-VW 1209 VW/Audi • • • P-VW 1210 VW/Audi • • • RES.30.CT.119 Rover • • •

SAE J 2334 USA - Automotive • • •

STD1027, 14 Volvo • • • STD1027,1375 Volvo • • •


VDA 621-415 Germany - Automotive • • •

Miscellaneous Test Standards Horizontal Mistspray Denso • • • DIN 50 014 Germany • • •

• = chamber with any optional accessories indicated, can fully comply with all requirements of this test standard. • = chamber with any optional accessories indicated, can fully comply with the salt spray requirements of this test standard, but a separate controlled humidity test chamber may be required to fully comply with all parts of this test standard.

• = chamber with any optional accessories indicated, can fully comply with the salt spray requirements of this test standard, but a separate combined condensation/UV test chamber will be required to fully comply with all parts of this test standard.

Appendix 2: Report Example

corrosion handbook vf7101protectedv2

Documents

corrosion testing

types of corrosion

uniform corrosion

acid corrosion

stress corrosion

pitting corrosion

fissure corrosion

intercrystalline corrosion