DE2932560A1 - METHOD FOR REDUCING THE CORROSIVE EFFECT OF AQUEOUS SALT SOLUTIONS - Google Patents

Description

description

The invention relates to a method for reducing the corrosive effect of aqueous salt solutions on with the Ferrous metal surfaces in contact with saline solution, i.e. a method for inhibiting corrosion of ferrous metals by aqueous salt solutions. According to a specific embodiment of the invention for the petroleum industry, the invention relates to reducing the corrosion of piping, pipelines and other ferrous underground borehole tools made of iron and steel, the aqueous saline solutions exposed as completion fluids, reworking fluids (work over fluids) or packing fluids (packer fluids) can be used.

In the treatment of wells, saline solutions are used for a variety of purposes, in particular when an aqueous liquid of relatively high density is to be used. One can use alkali metal salt solutions use / however, salt solutions are usually used which contain calcium chloride, calcium bromide or mixtures contain of it, since in this way one can form solutions with greater specific gravity. These Salt solutions are corrosive to metal equipment in the wellbore, even if substantially no oxygen is present. This corrosion is relatively insignificant at temperatures of around 93 ° C (2oo ° F), but becomes more important at temperatures of at least 121 ° C (25o ° F) and especially at temperatures above 149 ° C (300 ° F).

Though some corrosion inhibitors that are well suited to the corrosion of hydrochloric acid too

030007/0927

can be used to some extent to inhibit the corrosion of saline solutions cannot readily be said to be an agent inhibiting the corrosive action of hydrochloric acid is necessarily also suitable for inhibiting the corrosion of salt solutions, at least not in a practical level.

From CA-PS 983 041 a water-soluble corrosion inhibitor for salt solutions is known, which is the reaction product contains certain aliphatic saturated carboxylic acids with substituted imidazolines.

U.S. Patent 3,215,637 teaches that a mixture of sodium silicate and zinc chloride inhibits the corrosion of sodium chloride and salt solutions containing calcium chloride. This patent also discusses the disadvantages of other known ones Inhibitors of the corrosive effect of saline solutions, such as sodium nitrate, hydrazine, or pyrogallol Sulfite.

In US-PS 4 olo 111 is the corrosion of aqueous Salt solution-inhibiting preparation disclosed which, as an inhibitor, is a reaction product of a carboxylic acid and a polyamine, an alcohol and an alkylbenzenesulfonic acid.

It is believed that at the time of the present application, the one used in the largest technical range Heavy salt solution inhibitor - at least as is the United States' petroleum industry arrives - the inhibitors Baroid ** ■ 'Coat B-14oo and Corexit ^ 772o are. Analysis of a sample of the Baroid ^ product indicated that it contained about 14% by weight of a volatile amine, about 19% by weight isopropyl alcohol "., about

030007/0927

45% by weight water and the remainder predominantly ethoxylated Amide and a small amount of a carboxylic acid salt.

The present invention is based on the knowledge that ferrous metals at least partially against the Corrosion from aqueous salt solutions can be protected by adding an effective amount to the salt solution introduces a sulfur compound which has the sulfur in the oxide axion state zero or less or below which can be uniformly dispersed in the salt solution and is preferably soluble therein and which is suitable to provide sulfur that is necessary for the reaction with the ferrous metal to be protected is available so that an iron sulfide protective film forms on the surface of the metal that is in contact with the saline solution containing the inhibitor. Preferably used to increase the Effect of the inhibitor at least one quaternary pyridinium salt, quinolinium salt or isoquinolinium salt, the is soluble in the salt solution, in combination with said sulfur compound.

The subject of the invention is therefore the method according to the main claim.

The subclaims 2 to 17 relate to particularly preferred embodiments of the method according to the invention.

According to the invention, aqueous solutions of alkali metal halides can be used inhibit in their corrosion effect, although the best results are achieved when the salt solution contains at least one halide salt of a polyvalent metal, such as calcium chloride, calcium bromide, Calcium iodide, zinc chloride, zinc bromide, zinc iodide

030007/0927

2T32560

or a mixture of such salts. These saline solutions are commonly used for petroleum drilling purposes as well as in used in other areas of technology. For example, salt solutions of this type can be used for separation processes where solids of different densities are separated by flotation. Furthermore, these Salt solutions in addition to the corrosion inhibitor, if desired contain various functional additives, such as additives that impair the flowability

Prevent Io (fluid loss additives), gelling agents, rubbing

exercise reducers or surfactants. Saline solutions, which, according to the invention, can be inhibited in their corrosive action, include aqueous solutions of organic compounds Acids that have been weighted with a suitable metal halide salt to their specific To increase weight, although in most cases the solutions treated according to the invention normally do one Have a slightly basic pH and essentially aqueous solutions of calcium halides, zinc halides

Represent 2o or mixtures thereof.

The corrosion inhibitor system used according to the invention shows a good corrosion inhibition effect, especially at higher temperatures, at which the by the Corrosion caused by saline solutions is relatively severe. The system continues with a great variety of functional additives compatible. The corrosion inhibitor systems used according to the invention also have an effect especially in the most preferred embodiments as a defoamer, thereby mixing in the active ingredients is simplified on the spot.

The sulfur compound used in the present invention is preferably a water-soluble thio compound. for example a thiocyanate, such as an alkali metal thio

030007/0927

- Io -

cyanate or, more preferably, ammonium thiocyanate. You can also use an organic thioamide, im essentially all compounds of this type are suitable. This class of compounds includes thiourea, Polythioureas and hydrocarbon-substituted ones Derivatives thereof and thioamides of the general formula

SD "

A-C-N

an Indian

A is a hydrocarbon group having 1 to 12 carbon atoms or a pyridyl group and the groups
R ″ in each case hydrogen atoms or alkyl groups with 1

up to 8 carbon atoms
mean. Examples of thioamides of this type are thiourea, 1,2-diethylthiourea, propylthiourea, 1,1-diphenylthiourea, thiocarbanilide, 1,2-dibutylthiourea, dithiobiurea, dithiobiuret, thioacetamide, thionicotinamide and thiobenzamide. Water-soluble sulfides, such as ammonium sulfide and alkali metal sulfides or the corresponding hydrosulfides, including hydrogen sulfide, are further sulfur compounds which are suitable according to the invention. Elemental sulfur, which can be dispersed in the salt solutions, can also be used, although the above-mentioned soluble thio compounds are preferred.

The sulfur compounds mentioned above are preferably used in combination with a quaternary pyridinium salt or quinolinium salt suitable as an inhibitor aid or isoquinolinium salt, which is in the aqueous

030007/0927

Saline solution is stable. This salt preferably corresponds to one of the general formulas below

or

R ¹ R ¹

-R

R ¹ R

in which

R is an alkyl group with 1 to 2o carbon atoms, a benzyl group or an alkylated benzyl group, the aromatic ring of which has one or more alkyl substituents with a total of 1 to 2o carbon atoms having,

R ^{1 are} each hydrogen atoms or alkyl or alkoxy groups having 1 to 6 carbon atoms and

X is any suitable anionic radical, such as a halide radical, a sulfate radical, an acetate radical or a nitrate residue

mean. It is evident that the person skilled in the art will not select any compounds from the compounds mentioned, which have such a high carbon content that the compound is no longer or at least not in the effective concentration is soluble in the saline solution. In the general formulas given above, X preferably stands for a bromine atom or a chlorine atom une most

030007/0927

most preferred for a bromine atom. The group R preferably stands for a relatively high molecular weight alkyl group having about 6 to 16 carbon atoms. Furthermore, the groups R ¹ preferably represent hydrogen atoms. In general, the pyridinium salts are preferred. In terms of both solubility and effectiveness, the most preferred compound of this type is n-octylpyridinium bromide. If desired, mixtures of such salts can also be used.

Although any appreciable amount of the sulfur compound does some degree of inhibition of corrosion caused, at least about 0.3 g of the sulfur compound per liter of the salt solution are usually required,

15 in order to achieve protection that is suitable for practical use. Concentrations of up to 20 g of the inhibitor per liter the saline solution are not harmful, at least in most cases. More than 3 g of the inhibitor compound per liter of the saline solution, however, results in only a small

gen or no further protection, whereby in certain cases actually less protection than with the application smaller amounts can be achieved. The preferred upper limit of 3 g / l applies when the Sulfur compound is used alone or in combination with the heterocyclic quaternary compound,

d. H. when the quaternary compound is used, the total concentration of the quaternary compound exceeds and the sulfur compound is preferably not 3 g / l. Most preferably the total concentration is Sulfur compound and quaternary salt about 0.5 to 2 g / l of the salt solution.

When a quaternary salt is used, it is used in an amount effective to do all of it 35 to improve the corrosion inhibition of the system.

030007/0927

2,32560

The ratio of quaternary salt to sulfur compound varies from system to system, and in general Can achieve advantageous results when the two components in a weight ratio of 0.1: 1 to Io: 1 can be used, although a ratio of 0.125: 1 to 4: 1 is even more preferred. Most preferred however, a ratio of 0.2: 1 to 1: 1, especially when the concentration of the ingredients reaches the upper or lower limits indicated in the preceding paragraph. The expert however, is capable of doing so for any given saline system and combination of inhibitor ingredients select the optimal concentrations and ratios.

The addition of a small but effective amount

of a water-soluble cobalt salt to the system, both

+2, for example, an amount of 0.05 to 0.5 g Co / 1 der

Saline solution, improves the effectiveness of the corrosion inhibitor system, although the addition is not required to be applicable or even commercial to achieve suitable effect. Thus, although the addition of the cobalt salt has a better effect This addition is normally not a preferred embodiment for routine applications because of the somewhat increased toxicity and environmental protection problems. If you use a cobalt salt, you can do any Use cobalt (II) compound, which is soluble in the aqueous salt solution to the extent that is sufficient for the to give the desired concentration of cobalt (II) ions.

Cobalt salts, such as CoCl ₂ , CoBr ₃ , CoSO ₄ , Co (NO ₃ J ₂ , cobalt (II) acetate or cobalt (II) benzoate) are all suitable sources of cobalt (II) ions. Cobalt benzoate and cobalt bromide are particularly preferred.

030007/0927

_ 14 -

2 <? 3256Q

The present invention is further illustrated by the following examples and comparative approaches.

Test method:

In preparation for the corrosion tests described below, pipe sections (N8o) with an outer diameter of 6o, 3 mm (2 3/8 inch) were cut. The pipe sections are cleaned by tumbling them in aluminum oxide grit, whereupon they are subjected to ultrasound treatment in a trichlorethylene bath, rinsed with acetone, dried and stored in a desiccator. To carry out the tests, the pipe section is placed in the test solution in an autoclave, whereupon the test temperature and the test pressure are set as quickly as practically possible. The stated test times are the times during which the pipe section was exposed to the solution at the stated temperature and pressure. All tests were carried out under static conditions, ie without agitation, at a pressure of 69 bar (looo psi). After the test bath has cooled to about 66 ⁰ C (150 ° F), the tube section is removed from the bath, rinsed in acetone, and washed in inhibited aqueous hydrochloric acid for about 3 to 4 minutes with agitation to remove the during the Tests to dissolve formed iron sulfide film. The pipe section is then washed with water, scrubbed with a brass brush and pumice stone soap, heated in hot water to accelerate evaporation of the acetone, rinsed with acetone, dried, cooled and weighed.

In all of the corrosion tests, the various additives were used in the specified amounts to make 100 ml of the saline solution admitted. In all tables is the. Corrosive

030007/0927

2332560

2
The "Percent Inhibition" is the following amount:

Corrosion rate without inhibitor - corrosion

sion speed of the test solution

Corrosion rate without inhibitor

The following different quaternary salt solutions were-io the manufactured and used:

Solution a: decylquinolinium bromide (DQBr)

Solution B: Dodecylquinolinium bromide (DodQBr)

Solution C: tetradecylpyridinium bromide (TdPBr)

Solution D: hexadecylpyridinium bromide (HdPBr)

Solution E: Decylpyridinium bromide (DPBr)

Solution f: dodecylpyridinium bromide (DodPBr)

Solution G: alkyl-substituted tetradecylpyridinium bromide (AIkTdPB)

Solution H: hexylpyridinium bromide (HPBr)

Solution I: Octylpyridinium bromide (OPBr)

Solution J: o, 4: 1 OPBr: ammonium thiocyanate

Solution K: 0.26: 1 OPBr: ammonium thiocyanate.

25 A number of corrosion tests were carried out, the results of which are summarized in the tables below are.

030007/0927

line

Aqueous saline solution: 52% by weight CaBr ₂ solution Temperature: 177 ° C (35o ° F)

Time: 68 hours

Approach inhibitor oxygen

Quaternary compound Thio compound Another compound scavenger

4 5 6

7 8 9

Io 11 12

13 14 15

16 17 18

Corrosion rate

ο, 5 ml solution ο, 5 ml solution

ο, 5 ml solution ο, 5 ml solution ο, 5 g solution.

ο, 5 g sol. ο, 5 g sol. ο, 5 g sol.

ο.5 ml solution ο.5 ml solution Footnote 1)

Footnote 2) ο, 5 ml sol

E (DPBr) E (DPBr)

F (DodPBr) F (DodPBr) C (TdPBr)

C (TdPBr) D (HdPBr) D (HdPBr)

ο, 3 g thiourea

ο, 3 g thiourea

ο, 3 g thiourea

ο, 3 g thiourea -

A (DQBr) ο, 3 g thiourea B (DodQBr) ο, 3 g thiourea

ο, 3 g thiourea footnote 1)

0.3 g thiourea footnote 2). G (AIkTdPB) o, 3 g thiourea

0.3 g NH ₄ SCN 0.5 ml Corexit 772o

0.3 g NH ₄ SCN l, o ml Corexit 772o

o.25 ml solution E (DPBr) o.5 ml solution E (DPBr)

0.3 g NH ₄ SCN 0.3 g NH ₄ SCN

/ 9.8;
(o, ol63;
91.5 (0. (0, 67, O ₃₎
o, ol37)
ool87) Ni
-Q 19.6 <o, oo4o) CO 88.6 (c, O? Rl) cn
CD
0 25.4 (O. oo52) 74.4 (0, ol52) 3o, 3 ok oo62) 81.7 (0, ol67) 48, '4 (0, , oo99) 47.9 (O ₅ , oo98) 4o, l (0, ; OO82) 32.8 (0 , oo67) 49.4 (0. , olol) 25.0 (0
(0 , oo53) 27 ·, 4
22, o (0 , oo56)
, oo45) 19.1 (0 _; oo39) 19.1 , oo39)

Continuation of row 1

Approach inhibitor oxygen

Quaternary compound Thio compound Another compound scavenger

Corrosion rate

19th ο, 25 ml sol ml sol. ml sol. . H (HPBr) o, 3 G NH ₄ SCN 2o o, 5 o, 25 ml sol ml sol. H (HPBr) o, 3 G NH ₄ SCN 21st o, 5 ml sol. . I. (OPBr) o, 3 G NH ₄ SCN 22nd o, 5 - I. (OPBr) o, 3 G NH ₄ SCN 23 o, 5 - G (AIkTdPB) o, 3 G NH ₄ SCN 24 E. (DPBr) o, 3 G NH ₄ SCN O 25th o, 3 G NH ₄ SCN 10 0 0 7 / 26th
27 ο
Φ footnote: -

0.3 g Na ₃ S ₃ O ₄

0.3 g Na ₂ S ₂ O ₄
0.6 g Na ₂ S ₃ O ₄

(o, oo61) 29.8

(o, oo62) 3o, 3

(o, oo4 ¹ )) 24, o

(o, oo45) 22, o

(o, oo48) 23.5

(o, oo98) 47.9

(o, oo69) 33.8

(o, oo91) 44.5

(o, ol61) 78.8

1) 0.5 ml of a mixture of one part isopropanol and 4 parts of the reaction product
1-dodecyl bromide and triethylamine

2) 0.5 ml of a mixture of 1 part isopropanol and 4 parts of the reaction product from I-D0-decyl bromide and triethanolamine

3) The corrosion rates of Runs 2-14 compare best to that
Corrosion rate 79.8 (o, ol63) of batch 1, while the corrosion rates
of approaches 15 to 27 with the corrosion rate 67, o (o, ol37) of the repeated approach> f
are to be compared, since these groups of approaches were each carried out on the same days.

-O CO ΓΟ

Rub

Aqueous saline solution: 52% by weight CaBr ,, solution Temperature: 177 ° C (35o ° F)
Time: 16 hours

approach

2a 29 3ο 31 α 32 3000 33
34 35 0927 36
37

η
Quaternary connection

h i b i t ο r oxygen f-

Thio connection Another connection interceptor

o, l ml diluted solution E.
0.25 ml diluted solution E.
0.5 ml diluted solution E.

l, o ml diluted solution E.
0.25 ml solution E (DPBr)
0.25 ml solution E (DPBr)

0.25 ml solution E (DPBr)
0.25 ml solution E (DPBr)
0.5 ml solution H (HPBr)

37 ο, 5 ml Sol. I. (CODr) 38 ο, 5 ml Sol. F. (DodPBr) 39 O, 5 ml Sol. C. (TdPBr) 4ο S. footnote D. row 1 41 Footnote·: -

o, 3 g thiourea o, 3 g thiourea o, 3 g thiourea

0.3 g thiourea 0.3 g thiourea 0.05 g thiourea

0.1 g thiourea 0.2 g thiourea 0.3 g thiourea

0.3 g thiourea 0.3 g thiourea 0.3 g thiourea

o, 3 g thiourea see footnote 1), series

1) 1 ml of solution E (DPBr) diluted with 9 ml of water.

Corrosion Ge
speed oo4o) 19.6 (O, oo37) 18.1 (O, oo25) 12.2 (O, oo25) 12.2 (O, oo26) 12.7 (O ₁ , oo34) 16.6 (O ₁ , oo25) 12.2 (O, , oo28) 13.7 (O, , oo33) 16.1 (O, , oo28) 13.7 (O, , oo26) 12.7 (O , oo28) 13.7 (O , OO33) 16.1 (O , oo54) 26.4 (O

OO
I.

Row 3

Aqueous salt solution: solution of 852 g CaCl ₀ in 25oo ml of a 52 wt .- ^ _o aqueous solution of CaBr

'177 ° C (35o ° F) ^{λ z}

16 hours

Temperature: time:

Approach inhibitor oxygen corrosion

Quaternary compound Thio compound Further compound scavenger speed

42 * - (DPBr) o, 3 G - 43 - (DPBr) o, 6 G - 44 - o, 3
o, 6 G
G - O 45 ο, 5 ml solution E. row 1
row 1 o, 3
o, 6 G
G NH ₄ SCN 46 ο, 5 ml solution E. (HdPBr) o, 3 G NH ₄ SCN Ά00 ( 47
48 Footnote 1)
Footnote 1) (HdPBr) o, 6 G NH ₄ SCN
NH ₄ SCN Ό927 49
5o see footnote 2),
see footnote 2), o, 6 G NH ₄ SCN
NH ₄ SCN 51 0.5 ml of solution F. NH ₄ SCN 52 0.5 ml of solution F. NH ₄ SCN 53 - NH ₄ SCN

2 ml Baroid 14oo
1 ml Corexit 772o

Footnote 1)

Footnote 1)
see footnote 2), row 1

see footnote 2) row 1

(o, oo79) 38.7

(o, oo72) 35.2

(0.0066) 32.3

(o, oo3o) 14.7

(o, oo31) 15.2

(o, oo4o) 19.6

(o, oo43) 21, o

(o, oo26) 12.7

(o, oo26) 12.7

(o, oo28) 13.7

(o, oo29) 14.2

(o, oo38) 18.6

Footnote:

1) 0.5 g of a mixture of 1 part isopropanol and 4 parts of the reaction product
1-dod (cylbromide and triethylamine

CO CTJ

Row 4

Aqueous saline solution: solution of 852 g CaCl

177 ° C (35o ° F) in 25o ml of a 52% CaBr ₉ ~ solution

Temperature:
Time:

118 hours

approach

Inhibitor corrosion rate

Percent inhibition

54 ο, 1 ml Sol. J. (o, 4: 1 ; OPBr: NH ₄ SCN) 55 ο, 2 ml Sol. J. (o, 4: 1 : OPBr: NH ₄ SCN) 56 ο, 4th ml Sol. J. (o, 4: 1 ^: OPBr: NH ₄ SCN) ο 57 ο, 6th ml Sol. J. (o, 4: 1 OPBr: NH ₄ SCN) U) 58 ο, 2 ml
ml Solution K
Solution K (o, 26
(o, 26 1 OPBr
1 OPBr : NH ₄ SCN)
: NH.SCN)
4th 3OO7J 59
6ο ο, 4th ml Solution K (o, 26 1 OPBr : NH ₄ SCN) ο 61 ο,
ο, 6th
2 ml
ml Solution K
Baroid (o, 26
14oo 1 OPBr : NH ₄ SCN) 927 62
63 ο, 4th ml Baroid 14oo 64 ο. 6th ml Baroid 14oo 65 ο, 2 ml Corexit 772o 66 ο. 4th ml Corexit 772o 67

(ο, ο2ο2) 98.8

(ο, ο176) 86.1

(ο, ο15ο) 73.4

(ο, οΐοΐ) 49.8

(ο, οο86) 42.1

(ο, ο18ο) 88.1

(ο, ο128) 62.6

(ο, οο95) 46.5

(ο, οο78) 38.2

(ο, ο167) 81.7

(ο, ο155) 75.8

(ο, ο186) 91, ο

(ο, ο168) 82.2

(ο, οίδο) 88.1

Control 13 26

5ο 57 11

37 53 61

17th

23

17 11

INJ -O

cn σ> ο

Row 5

Aqueous saline solution: solution of 852 g CaCl Temperature: 149 ° C (3oo F) Time: 72 hours

in 250 ml of a 52% strength by weight CaBr ^ solution

approach

Inhibitor

68 ο, Ι ml Lsg, K (ο, 26: 1 OPBr : NH ₄ SCN) 69 ο, 2 ml Solution K (ο, 26: 1 OPBr : NH ₄ SCN) 7ο ο, 4 ml Solution K (ο, 26: 1 OPBr : NH ₄ SCN) O
ω 71 ο, 6 ml Solution K (ο, 26: 1 OPBr : NH ₄ SCN) ο 72 ο, 2 ml
ml Baroid
Baroid 14οο
14οο 107/0 73
74 ο, 4 ml Baroid 14οο 75 ο, Ι ml Corexit 772ο 76 ο, 2 ml Corexit 772ο 77 ο, 4 ml Corexit 772ο 78 ο, Ι ml Dowell Α163 ^Χ) 79 ο, 2 ml Dowell Α163 ¹ ^ 8ο ο, 4 ml Dowell Α163 ^1} 81 Footnote:

Corrosion Ge
speed 49.4 Percentage
Inhibition ι (ο, οΐοΐ) 35.2 control IO
M. (ο, οο72) 24, ο 29 I. (ο, οο49) 13.2 51 (ο, οο27) 12.7 73 (ο, οο26) 48.9 73 (ο, οΐοο) 41.6 1 (ο, οο85) 39.6 16 (ο, οοδί) 44.5 2ο (ο, οο9ΐ) 32.8 Io (ο, οο67) 24.5 34 (ο, οο5ο) 51.9 5ο (ο, οΐοβ) 46.97 - 5th (ο, οο96) 38.2 5 (ο, οο78) 23

1) Dowell Α163 is an imidazoline-type inhibitor.

Row 6

Temperature: 177 ° C (35o ° F)

Time:

72 hours

Approach saline solution

Inhibitor

Corrosion percentage rate inhibition

α »tv -a

82 19 % ZnBr ₂ , 46 % CaBr ₃

83 19 % ZnBr ₂ , 46 % CaBr ₂

84 29 % ZnBr ₂ , 41 X CaBr ₃

85 29 % ZnBr ₃ , 41 % CaBr ₃

86 57% ZnBr ₃ , 2o % CaBr ₃

87 57 % ZnBr ₂ , 2o % CaBr ₃

0.4 ml solution K (0.26: 1 OPBr: NH ₁ SCN)

0.4 ml solution K (0.26 OPBr: NH.SCN)

0.4 ml of solution K (0.26: 1 OPBr: NH ₄ SCN)

(0, O245) 119.9 control 10
to (0, oo35) 17.1 86 (0, o2o7) lol, 3 control (0, oo43) 21, o 79

(ο, 1494) 731, o control (o, o521) 254.9 65

Claims (1)

Patent attorneys Dipl.-Ing. H. Veickmann, Dipl.-Phys. Dr. K. Fincke Dipl.-Ing. F. A. Weickmann, Dipl.-Chem. B. Huber Dr. Ing.H. Liska 8000 MUNICH 86, DEN Hi. > PO Box 860820 MÖHLSTRASSE 22, CALL NUMBER 98 39 21/22 HtM / cb 27,321-F THE DOW CHEMICAL COMPANY 2o3o Abbott Road, Midland, Michigan / USA Process for reducing the corrosive effect of aqueous salt solutions Claims 1 / Process to reduce the corrosive effect on aqueous salt solutions on iron-containing metal surfaces in contact with the salt solution, thereby characterized in that the saline solution is a corrosion-inhibiting amount of a Sulfur compound is added which contains the sulfur in the oxidation state of zero or less and uniformly can be dispersed in the saline solution. 2, method according to claim 1, characterized that you have the sulfur compound in a 030007/0927 2 * 32560 An amount of at least about 0.3 g / L of the saline solution is used. 3. The method according to claims 1 or 2, characterized characterized in that a water-soluble thiocyanate or thioamide is used as the sulfur compound used. 4. The method according to claims 1, 2 or 3, characterized in that the salt solution at least a representative of calcium chloride, calcium bromide, calcium iodide, zinc chloride, zinc bromide and zinc iodide Group contains. 5. The method according to any one of the preceding claims, characterized in that one for further To reduce the corrosive effects of the saline solution, an effective amount of at least one representative of the quaternary pyridinium salts, quinolinium salts or isoquinolinium salts added, the quaternary salt such is selected to be sufficiently soluble in the saline solution to be the effective amount in the saline solution to be able to solve. 6. The method according to claim 5, characterized in that the total weight of sulfur compound plus any quaternary salt present is no more than about 3 g / l. 7. The method according to claim 6, characterized in that the quaternary salt in one Amount of 0.1 to 10 parts by weight per part by weight of the sulfur compound is used. 8. The method according to claim 7, characterized in that g e k e * n η, that the total concentration of the J 030007/0927 2 * 132560 Sulfur compound and the quaternary salt is 0.5 to 2 g / l of the salt solution and the weight ratio of quaternary salt to sulfur compound is 0.125: 1 to 4: 1. 9. The method according to claim 5, characterized in that a quaternary salt is used, the one of the general formulas below or corresponds in which R is an alkyl group with 1 to 2o carbon atoms, a benzyl group or an alkylated benzyl group, the aromatic ring of which has one or more alkyl substituents with a total of 1 to 2o carbon atoms having, R ^{1 in} each case hydrogen atoms, alkyl groups or alkoxy - groups with 1 to 6 carbon atoms and X is an anionic group
mean.
35 030007/0927 10. The method according to claim 9, characterized in that a compound of the specified general formulas used in which R represents an alkyl group having 6 to 16 carbon atoms. 11. The method according to claim Io, characterized in that a compound of the specified general formulas used in which X stands for a bromine atom. 12. The method according to claim 11, characterized in that a compound of the general formulas given is used in which R ^{1 are} hydrogen atoms. 13. The method according to claim 12, characterized in that there is a quaternary compound Pyridinium salt used. 14. The method according to claim 13, characterized in that there is a total concentration of Sulfur compound and pyridinium salt of 0.5 to 2 g / l of the salt solution and a weight ratio of pyridinium salt to sulfur compound of 0.125: 1 to 4: 1 applies. 15. The method according to claim 14, characterized in that the pyridinium salt is octylpyridinium bromide and a thiocyanate or a thioamide is used as the sulfur compound. 16. The method according to claim 15, characterized in that there is a weight ratio of Pyridinium salt to sulfur compound of o, 125: 1 to 4: 1 applies and ammonium thio- 030007/0927 293256Q cyanate or thiourea is used. 17. The method according to at least one of the preceding Claims, characterized in that the salt solution is an effective amount of a water-soluble Cobalt salt is added to further reduce the corrosive effect of the salt solution. 030007/0927