The Protection Of Steel Surfaces From Corrosion. Part 3

Description

This section is from the book "Notes On Construction In Mild Steel", by Henry Fidler. Also available from Amazon: Notes On Construction In Mild Steel.

The Protection Of Steel Surfaces From Corrosion. Part 3

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	Dried to a hard tough film in 24 hours.
2.	At 100° Fahr. ...	" " 16 "

(3)	Specific gravity at 60° Fahr. ...	0.942
	Mineral acid	Nil
	Unsaponifiable matter ...	1.18 per cent.
	Ash ... ••• ••• ••• • ••	0.22

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	Dried to a hard tough film in 24 hours.
2.	At 100° Fahr. ...	" " 16 "

(4)	Specific gravity at 60° Fahr. ...	0.946
	Mineral acid	Nil
	Unsaponifiable matter ...	1.90 per cent.
	Ash	2.22

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	Dried to a fairly hard tough film in 24 hours.
2.	At 100° Fahr. ...	Dried to a hard tough film in 16 hours.

This analysis shows the sample to contain a good deal of "foots," but it is otherwise of satisfactory quality.

(5)	Specific gravity at 60° Fahr. ...	0.943
	Mineral acid	Nil
	Unsaponifiable matter ...	0.42 per cent.
	Ash ... ••• ••• ••• • • •	0.02

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	Dried to a hard tough film in 24 hours.
2.	At 100° Fahr. ...	" " 10 "

The above figures show this sample to be of satisfactory quality.

(6)	Specific gravity at 60° Fahr. ...	0.962
	Mineral acid	Nil
	Unsaponifiable matter ...	1.19 per cent.
	Ash	2.70

When Exposed On Glass In A Thin Film

1.	At 60°Fahr. .....	Dried to a somewhat sticky but fairly tough hard film in 24 hours.
	"
2.	At 100° Fahr. ...	Dried to a hard tough film in 16 hours.

In this sample the specific gravity and the percentage of ash are unduly high, and the drying of the oil not wholly satisfactory.

(7)	Specific gravity at 60° Fahr. ...	0.946
	Mineral acid	Nil
	Unsaponifiable matter ...	4.28 per cent.
	Ash • • • ••• • • • ••• • • •	0.20

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.......	Sticky after 24 hours.
2.	At 100° Fahr.......	Somewhat sticky after 16 hours.

The analysis shows this sample to be adulterated and to contain a large amount of "foots."

(8)	Specific gravity at 60° Fahr. ...	... 0.949
	Mineral acid	... Nil
	Unsaponifiable matter ...	... 4.88 per cent.
	Ash	... 0-08

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	Failed to dry in 24 hours, very sticky film.
2.	At 100° Fahr. ...	Dried to a fairly tough but slightly sticky
		film in 16 hours.

This Analysis Shows The Sample To Be Also Adulterated

(9)	Specific gravity at 60° Fahr. ...	0.946
	Mineral acid	Nil
	Unsaponifiable matter ...	0.96 per cent.
	Ash	0.24

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	Dried to a hard tough film in 24 hours.
2.	At 100° Fahr. ...	" 16 "

The Above Analysis Shows The Sample To Be Of Satisfactory Quality

(10) Specific gravity at 60° Fahr.......	0.945
Mineral acid	Nil
Unsaponifiable matter ...	1.09 per cent.
Ash	0.27

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	• • •	Dried to a hard tough film in 24 hours.
2.	At 100° Fahr.	• • •	" " 16 hours

(11)	Specific gravity at 60° Fahr. ...	0.946
	Mineral acid	Nil
	Unsaponifiable matter ...	1.05 per cent.
	Ash ... ... ...	0.01

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	Dried to a hard tough film in 24 hours.
2.	At 100° Fahr. ...	" " 16 "

(12)	Specific gravity at 60° Fahr. ...	0.947
	Mineral acid	Nil
	Unsaponifiable matter ...	1.17 per cent.
	Ash ... .... ... ... ...	0.25

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	... Dried to a hard tough film in 24 hours.
2.	At 100° Fahr.	... " 16 "

This Sample Of Satisfactory Quality

(13)	Specific gravity at 60° Fahr. ...	0.943
	Mineral acid	Nil
	Unsaponifiable matter ...	1.09 per cent.
	Ash ... ... ... ... ...	0.07 ' „

When Exposed On Glass In A Thin Film

1.	At 60° Fahr.	... Dried to a hard tough film in 24 hours.
2.	At 100° Fahr.	... " " 16 ,,

These Results Show The Sample To Be Of A Satisfactory Quality

(14)	Specific gravity at 60° Fahr. ...	0.950
	Mineral acid	Nil.
	Unsaponifiable matter ...	1.28 per cent.
	Ash ••• ... ... ... ...	0.22 „

When Exposed On Glass In A Thin Film

1.	At 60° Fahr. ...	Dried to a hard tough film in 24 hours.
2.	At 100° Fahr. ...	" " 16 "

The preliminary processes of construction having been completed, and the various plates and bars having gone through the operations of shearing, straightening, planing, punching or drilling, and the like, the assemblage of the parts in the contractor's yard and putting together with service bolts commences, and at as early a stage as is possible the temporary coating of boiled oil should be superseded by the first coat of paint. In some specifications it is laid down that the oil coat should be carefully scraped off before the first coat of paint is applied. It is doubtful to what extent such a stipulation is usually complied with, nor does it appear to be of great moment.

The first coat of paint has usually to do duty as a protective medium for a considerable period of frequently indefinite duration. Some time may elapse, for example, before the material temporarily erected in the contractor's yard is finally put together on the site, and in the interim much exposure to weather may take place, transhipment by sea and the accompanying possibilities of damage by salt water may ensue, while a good deal of rough usage in the various operations of loading up and unloading may be expected. Against all these contingencies the first coat is a valuable preservative.

Among the various and numerous paints recommended or used for the protection of steelwork, none is perhaps more generally considered as one of the best, or at all events more frequently employed, than the well-known oxide of iron paint.

Other paints, for more or less decorative purposes, are not here under consideration, the practical question before us being simply protection from corrosion and decay.

This paint gives rise to the familiar reddish-brown or chocolate colour which characterizes the appearance of much structural steel and iron work, although there are frequently cases in which, for the purpose of maintaining as uniform a temperature as possible, and to avoid absorption of the sun's rays, a white, stone colour, or light grey, paint may be used.

The following chemical analyses of oxide of iron paints, made as samples of the paints used in extensive contracts for constructional and other classes of steelwork, will be found instructive as to their composition, while the variations are such as may be expected to arise in practice in the use of paint of good quality.

Analyses Of Red Oxide Of Iron Paint

(1)	Per cent.
Oil ••• ••• ••• • • • ••• •••	41.23
Insoluble siliceous matter ...	4.72
Ferric oxide (Fe2O3 )	45.31
Calcium carbonate (CaC03)	4.39
Magnesia (MgO)	0.08
Sulphuric anhydride (S03 )...	1.67
Combined water, alkalies, and loss	2.60
	100.00
(2)	Per cent.
Oil ... •• ••• ••• ••• •••	16.86
Insoluble siliceous matter...	8.05
Ferric oxide and alumina (Fe203 and Al2O3)	65.41
Calcium carbonate (CaC03)	5.10
Magnesia (MgO)	0.76
Combined water and loss ...	3.82
	100.00
(3)	Per cent.
Oil. ••• ••• ••• ••• • • • • • •	14.66
Insoluble siliceous matter...	7.90
Ferric oxide	68.07
Lime ••• ••• ••• ••• •••	2.94
Magnesia	0.49
Sulphuric anhydride .......	0.78
Combined water and loss ...	5.16
	100.00
(4)	Per cent.
Oil • • • ••• • • • ••• ••* •••	1518
Insoluble siliceous matter ...	6.67
Ferric oxide ............	71.101
Lime ••• • • ••• ••• •••	2.26
Magnesia ...............	0.60
Sulphuric anhydride	0.25
Combined water and loss ...	3.94
	100.00

1 Corresponding with 8382 per cent, of ferric oxide calculated on the dry pigment.

(5)	Per cent.
Oil ••• • • • • • ••• • • • •••	14.98
Insoluble siliceous matter...	6.69
Barium sulphate ...	1.73
Ferric oxide	70.40
Calcium carbonate ... ... ...	3.79
Magnesia	0.34
Sulphuric anhydride	0.09
Combined water and loss ...	1.98
	100.00

The following are analyses of lead colour or grey paints used for constructional steelwork and for machinery:-1. Analysis of a sample of lead colour paint-

	Per cent.
Oil • • • •• ••• • • • • • • •••	23.83
Basic lead carbonate ... ...	72.42
Carbon	0.08
Insoluble residue (BaS04 ) ...	2.74
Calcium carbonate (CaC03 )	0.93
	100.00

This sample accepted.

2. Analysis Of A Sample Of Lead Colour Paint

	per cent.
Oil ••• • • ••• ••• ••• •••	29.85
Barium sulphate	2.37
Basic lead carbonate	62.21
Calcium carbonate ...	4.51
Carbon	0.60
	99.54

This sample accepted.

3. Analysis Of A Sample Of Lead Colour Paint

	per cent.
Oil • • • ••• ••• •• •••	9.61
Barium sulphate	4212
Basic lead carbonate	34.65
Calcium carbonate ...	11.40
Ferric oxide and alumina ...	0.27
Magnesia	0.14
Carbon	1.50
Combined water, alkali, and loss ...	0.31
	100.00

This sample was rejected as of inferior quality.

4. Analysis Of A Sample Of Lead Colour Paint Used For Machinery

-	Per cent.
Oil ••• ••■ ••• •••	27.64
Basic lead carbonate	70.03
Insoluble siliceous matter...	0.87
Ferric oxide	1.03
Lime • • • • . • • • • ••• •••	0.26
Magnesia	0.13
	99.96

This sample accepted.

5. Analysis Of A Sample Of Lead Colour Paint

	Per cent.
Oil • • • ••• ••• ••• ••• •••	26.46
Basic lead carbonate	65.97
Carbon ... ... ... ... ...	0.48
Insoluble residue (BaS04 )...	5.15
Calcium carbonate ...	1.71
Magnesia ...............	0.19
	99.96

This sample considered to be of satisfactory quality. Accepted. 6. Analysis of a sample of lead colour paint -

	Per cent.
Oil ••• •• • • . . . ••• • •	10.24
Insoluble matter (barium sulphate)	5.46
Basic lead carbonate	73.89
Carbon ... ... ... ... ...	1.28
Ferric oxide (alumina)	0.32
Calcium carbonate ...	8.04
Magnesia	Trace
Combined water, alkali, and loss ...	0.77
	100.00

This sample considered to be of satisfactory quality. Accepted. 7. Analysis of grey lead paint -

	Per cent.
Oil ••• ••• ••• ••• ••• •••	23.53
Turpentine......	2.54
Pigment	73.93
	100.00

Analysis Of The Pigment

	Per cent.
Basic white lead	86.97
Insoluhie siliceous matter...	8.86
Ferric oxide	0.16
Calcium carbonate ... ...	0.66
Carbon	3.04
	99.69

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The Protection Of Steel Surfaces From Corrosion. Part 3

Description

The Protection Of Steel Surfaces From Corrosion. Part 3

When Exposed On Glass In A Thin Film

When Exposed On Glass In A Thin Film

When Exposed On Glass In A Thin Film

When Exposed On Glass In A Thin Film

When Exposed On Glass In A Thin Film

When Exposed On Glass In A Thin Film

When Exposed On Glass In A Thin Film

This Analysis Shows The Sample To Be Also Adulterated

When Exposed On Glass In A Thin Film

The Above Analysis Shows The Sample To Be Of Satisfactory Quality

When Exposed On Glass In A Thin Film

When Exposed On Glass In A Thin Film

When Exposed On Glass In A Thin Film

This Sample Of Satisfactory Quality

When Exposed On Glass In A Thin Film

These Results Show The Sample To Be Of A Satisfactory Quality

When Exposed On Glass In A Thin Film

Analyses Of Red Oxide Of Iron Paint

2. Analysis Of A Sample Of Lead Colour Paint

3. Analysis Of A Sample Of Lead Colour Paint

4. Analysis Of A Sample Of Lead Colour Paint Used For Machinery

5. Analysis Of A Sample Of Lead Colour Paint

Analysis Of The Pigment

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