ANTICORROSIVE COMPOSITION

Abstract

A mineral wool or other fibrous product which comprises in at least a surface layer thereof an anticorrosive composition comprising one or more alkali metal silicate components of the formula Me.sub.2O.Math.xSiO.sub.2, wherein x has a value of from 0.5 to 4.0, one or more alkali metal phosphate components of the formula Me.sub.2O:nP.sub.2O.sub.5, wherein n has a value of from 0.33 to 1 and/or hydrates thereof, and one or more carboxylic acids having 6-22 carbon atoms and/or salts thereof.

Claims

1. A mineral wool or other fibrous product, wherein the product comprises in at least a surface layer thereof an anticorrosive composition comprising: (a) one or more alkali metal silicate components of the formula Me.sub.2O.Math.xSiO.sub.2, wherein x has a value of from 0.5 to 4.0, (b) one or more alkali metal phosphate components of the formula Me.sub.2O:nP.sub.2O.sub.5, wherein n has a value of from 0.33 to 1 and/or hydrates thereof, (c) one or more carboxylic acids having 6-22 carbon atoms and/or salts thereof.

2. The product of claim 1, wherein the product is a stone wool product or a glass wool product.

3. The product of claim 1, wherein the product is an insulation product.

4. The product of claim 3, wherein the product is an aerogel insulation product.

5. The product of claim 1, wherein the product is a pipe section, a roof product, a facade product, a mat, or a wired mat.

6. The product of claim 1, wherein the surface layer of the product has a thickness of from 0.5 cm to 10 cm.

7. The product of claim 1, wherein the anticorrosive composition is dispersed substantially throughout the entire product.

8. The product of claim 1, wherein in at least one of the one or more alkali metal silicate components x is from 0.5 to 3.0.

9. The product of claim 1, wherein at least one of the one or more carboxylic acids has 7-14 carbon atoms.

10. The product of claim 1, wherein at least one of the one or more alkali metal silicate components is Na.sub.2SiO.sub.3.

11. The product of claim 1, wherein at least one of the one or more alkali metal phosphate components is a sodium phosphate.

12. The product of claim 1, wherein at least one of the one or more alkali metal phosphate components is Na.sub.3PO.sub.4.

13. The product of claim 1, wherein at least one of the one or more carboxylic acids is of formula HO.sub.2C(CH.sub.2).sub.nCO.sub.2H wherein n in the formula is 2-20.

14. The product of claim 13, wherein n in the formula is 8.

15. The product of claim 1, wherein the composition comprises 60-96 weight parts (a), 1-25 weight parts (b), and 1-20 weight parts (c), based on 100 parts by weight of (a), (b) and (c).

16. The product of claim 1, wherein the composition further comprises at least one surface-active compound selected from soaps and surfactants.

17. The product of claim 1, wherein the composition further comprises at least one surface-active compound selected from alkali-stable water-dispersible surfactants, alkali-stable water-soluble surfactants, and emulsifying surfactants.

18. The product of claim 1, wherein the composition comprises 100-500 g/L Na.sub.2SiO.sub.3, 2-50 g/L sebacic acid, 20-80 g/L Na.sub.3PO.sub.4, 0.1-100 g/L surface-active compound.

19. The product of claim 1, wherein the composition further comprises a hydrophobic agent comprising at least one silicone compound.

20. The product of claim 1, wherein the composition further comprises one or more water-miscible organic solvents.

21. A method of imparting anticorrosive properties to a mineral wool or other fibrous product, wherein the method comprises contacting at least a surface of the product with an anticorrosive composition comprising: (a) one or more alkali metal silicate components of the formula Me.sub.2O.Math.xSiO.sub.2, wherein x has a value of from 0.5 to 4.0, (b) one or more alkali metal phosphate components of the formula Me.sub.2O:nP.sub.2O.sub.5, wherein n has a value of from 0.33 to 1 and/or hydrates thereof, (c) one or more carboxylic acids having 6-22 carbon atoms and/or salts thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The invention will be described in more detail and merely by way of example on the basis of the drawings in which

[0075] FIG. 1 is a schematic illustration of the setup of the tests described below;

[0076] FIG. 2 shows a real setup of the testing equipment;

[0077] FIG. 3 is a graphical representation of the cycling test set forth below;

[0078] FIG. 4 shows the top side of steel coupons previously covered by ProRox PS (see below) treated with corrosion inhibitor after 21 cycles (no removal of deposits);

[0079] FIG. 5 shows the bottom side of steel coupons previously covered by ProRox PS 960 (mandrel wopund pipe section) treated with corrosion inhibitor after 21 cycles (no removal of deposits);

[0080] FIG. 6 shows a close-up of the coupons shown in FIG. 5

[0081] FIG. 7 shows a close-up of a test coupon (A-21-6 as identified below) shown in FIGS. 5 and 6 after cleaning;

[0082] FIG. 8 shows the top side of steel coupons previously covered by Prorox PS960 not treated with corrosion inhibitor after 21 cycles (no removal of deposits);

[0083] FIG. 9 shows the bottom side of steel coupons previously covered by ProRox PS 960 not treated with corrosion inhibitor after 21 cycles (no removal of deposits);

[0084] FIG. 10 shows the side of steel coupons previously covered by ProRox PS 960 not treated with corrosion inhibitor after 21 cycles (no removal of deposits);

[0085] FIG. 11 shows a close-up of FIG. 10;

[0086] FIG. 12 shows a close-up of a test coupon (B-21-6 as identified below) shown in FIGS. 8 to 11 after cleaning;

[0087] FIG. 13 shows the top side of steel coupons previously covered by ProRox PS 960 WR-Tech treated with corrosion inhibitor after 21 cycles (no removal of deposits; see Test A below);

[0088] FIG. 14 shows the bottom side of steel coupons previously covered by ProRox PS 960 WR-Tech treated with corrosion inhibitor after 21 cycles (no removal of deposits; see Test A below);

[0089] FIG. 15 shows a close-up of a test coupon (A-22-4 as identified below) as shown in FIGS. 13 and 14 after cleaning;

[0090] FIG. 16 shows a close-up of a test coupon (A-22-6 as identified below) as shown in FIGS. 13 and 14 after cleaning;

[0091] FIG. 17 shows the top side of steel coupons previously covered by ProRox PS 960 WR-Tech treated with corrosion inhibitor after 21 cycles (no removal of deposits; see Test B below);

[0092] FIG. 18 shows the bottom side of steel coupons previously covered by ProRox PS 960 WR-Tech treated with corrosion inhibitor after 21 cycles (no removal of deposits; see Test B below);

[0093] FIG. 19 shows a close-up of a test coupon (B-22-2 as identified below) as shown in FIGS. 17 and 18 after cleaning; and

[0094] FIG. 20 shows a close-up of a test coupon (B-22-3 as identified below) as shown in FIGS. 17 and 18 after cleaning.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0095] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description in combination with the drawings making apparent to those of skill in the art how the several forms of the present invention may be embodied in practice.

[0096] In order to test the performance of the anticorrosive composition according to the present invention, the CUI performance of stone wool pipe sections of the commercially available product ProRox PS 960 with an anticorrosive composition according to the present invention has been compared with the anticorrosive performance of a standard stone wool pipe section of ProRox PS 960 without the anticorrosive composition according to the present invention.

Test Setup and Test Conditions

[0097] The test setup in general follows ASTM G189-07, but with the following modifications: [0098] PTFE spacers between samples have been replaced by special silicone O-rings [0099] Clamping of the test equipment and coupons is achieved using a spring compression system to counter for thermal expansion of the system. [0100] Ring formed test coupons are 14.3 mm wide compared to the width in ASTM G189-07 of 6.35 mm

[0101] None of the modifications can be considered a relaxation compared to the test method and apparatus described in ASTM G189-07.

Equipment

[0102] The following simulation equipment is used: [0103] a) Ring shaped test coupons made from carbon steel pipe, ASTM A106 Grade B, with a width of 14.3 mm and diameter of 60 mm, polished to a 600 grit finish. [0104] b) O-rings for sealing and separation. [0105] c) Pipe insulation, 160 ex., 60 inside with and without corrosion inhibitor. [0106] d) Aluminium pipe jackets. [0107] e) Specially designed test rig consisting of two end pieces, between which test rings are mounted. [0108] f) Threaded rods mounted with coil springs to tighten the arrangement. The coil springs ensure that thermal extensions can be absorbed. [0109] g) Julabo Corio heating/cooling bath with circulation as well as pipe and hose connections. The bath is programmable according to the time/temperature control. [0110] h) Liquid circulating non-corrosive heating medium that can run at 60 and 150 C. Thermocouples measuring the temperature on the pipe surface under the insulation. [0111] i) Control computer. [0112] j) Data logger for logging temperature during test. [0113] k) Test liquid delivery system/metering pumps with controllers. [0114] l) Silicone sealant. [0115] m) Insulation for heating pipes between heaters and installation.

[0116] A schematic of the test setup can be seen in FIG. 1 and a picture of the test setup can be seen in FIG. 2.

Test Conditions

[0117] Two separate tests were conducted. The Conditions during the test were as follows:

TABLE-US-00001 Test 1: a) Cyclic testing with the following temperature conditions, see also FIG. 3 for graphical representation of the test cycle. Total water injection per test cycle is 85 mL and total injection of 1785 mL for the entire test is 21 days. Step Wet Ramp up Dry Ramp down Temperature [ C.] 60 60 to 150 150 150 to 60 Duration [hr] 18 1 4 1 Water injection 40 mL/10 min. + no no no 2.5 mL/hr [0118] b) Test duration 21 cycles (21 days) [0119] c) Test solution is deionized water [0120] d) Test solution enters through the top of the insulation via two feed tubes placed 42.9 mm apart, see FIG. 1 and FIG. 2 [0121] e) The insulation is drained via a centred hole in the bottom of the insulation, see FIG. 1 [0122] f) 6 identical ring formed test coupons made from carbon steel pipe, ASTM A106 Grade B, with a width of 14.3 mm and diameter of 60 mm, polished to a 600 grit finish [0123] g) The insulation material is sealed to the test pipe using silicone, creating a 25 cm long annulus. The insulation is secured tightly to the pipe surface using stainless steel wire. The outer aluminium jacket is secured around the insulation using hose clamps and sealed longitudinally and to the flange ends using silicone.

TABLE-US-00002 Test 2: Test conditions identical to Test 1, but with a higher volume of water injected per test cycle. Total water injection per test cycle is 119 mL and total injection of 2499 mL for the entire test is 21 days. Step Wet Ramp up Dry Ramp down Temperature 60 60 to 150 150 150 to 60 [ C.] Duration [hr] 18 1 4 1 Water injection 42.5 mL (injected over a no no no period of 10 min.) + 4.25 mL/hr

Anticorrosive Composition Tested

[0124] Two different concentrations of the anticorrosive composition were used in the two tests and were applied to the stone wool insulation with different techniques, resulting in the same concentration of anticorrosive composition per cubic centimeter of treated pipe insulation.

Test 1:

[0125] To apply the anticorrosive composition to a 500 mm long pipe insulation, with inner diameter of 60 mm, a total of 0.85 L of the anticorrosive composition mixture is needed, in order to treat the inner layer of the pipe insulation with a depth of 10 mm. The anticorrosive composition according to the present invention tested was as follows:

[0126] 33.75 g/L Na.sub.2SiO.sub.3+2.25 g/L sebacic acid+6.75 g/L Na.sub.3PO.sub.4+250 mL/L isopropyl alcohol and 750 mL/L demineralized water

[0127] The corrosion inhibitor was applied to the test specimen by mixing in a plastic container of 1 L size 0.75 L of demineralized water and then mix in the following chemicals in the order listed below: [0128] 1. 33.75 g of sodium silicate Na2SiO.sub.3 and let dissolve under stirring/shaking [0129] 2. 2.25 g of sebacic acid, and let dissolve under stirring or shaking [0130] 3. 6.75 g trisodium phosphate Na.sub.3PO.sub.4 and let dissolve

[0131] In the end 0.25 L IPA (isopropyl alcohol) is to be used with each 0.75 L mixture.

[0132] The solution is then sprayed on the inner side of the pipe insulation, first the IPA and then the anticorrosive mixture to ensure that at the inner layer of the insulation product is fully impregnated with a depth of around 10 mm, and then dried.

[0133] The insulation sample, now treated with the anticorrosive composition is then tested for CUI performance as per above-described Test 1.

Test 2:

[0134] To apply the anticorrosive composition to a 500 mm long pipe insulation, with inner diameter of 60 mm, a total of 0.13 L of the anticorrosive composition mixture is needed, in order to treat the inner layer of the pipe insulation with a depth of 10 mm. The anticorrosive composition according to the present invention tested was as follows:

[0135] 220 g/L Na.sub.2SiO.sub.3+14.67 g/L sebacic acid+44 g/L Na.sub.3PO.sub.4+10 g/L emulsifying co-surfactant+4 g/l alkali stable surfactant

[0136] All chemicals dissolved in demineralized water in the above order balanced to 1 L.

[0137] The solution is then sprayed on the inner side of the pipe insulation and the inner layer of the insulation product is fully impregnated with a depth of around 10 mm and then dried.

[0138] The insulation sample now treated with the anticorrosive composition is then tested for CUI performance as per above-described Test 2.

Results

[0139] Upon conclusion of the 21 test cycles, specimens were washed with deionized water and a nylon brush, rinsed with ethanol and dried to remove loose corrosion products and insulation from the surface, before the first weighing. Following this, corrosion products were removed from the test specimens by immersion in inhibited 16 wt % hydrochloric acid as per DS/EN ISO 8407. Following rinsing the test specimens were weighed again.

[0140] After removal of corrosion products, the extent of localized corrosion was estimated (if relevant), as well as measurement of pitting depth (if relevant).

[0141] The results are summarized in Table 1 (Test 1 with ProRox PS 960 treated with corrosion inhibitor), Table 2 (Test 1 with ProRox PS 960) and table 3 (Test 2 with ProRox PS 960 treated with corrosion inhibitor, and higher water injection during test)

[0142] Photographs from Test 1 of test coupons tested with Prorox PS960 treated with corrosion inhibitor prior to and after removal of deposits and corrosion products can be seen in FIGS. 4 to 7.

[0143] Photographs from Test 1 of test coupons tested with ProRox PS 960 prior to and after removal of deposits and corrosion products can be seen in FIGS. 8 to 12.

[0144] Photographs from Test 2 of test coupons tested with ProRox PS 960 WR-Tech treated with corrosion inhibitor prior to and after removal of deposits and corrosion products can be seen in FIGS. 13 to 20.

Test 1 ProRox PS 960 Treated with Corrosion Inhibitor

[0145] Regarding the results from testing with Prorox PS960 treated with corrosion inhibitor, there is an error in the weight result from test coupon A-21-1, as some of the original mill scale from the unexposed side of the coupon was removed during cleaning, thus resulting in an erroneous weight loss result. The coupon was upon inspection free from corrosion, and only one very shallow small pit-like attack was observed using 10 magnification.

[0146] On test coupon A21-6 one small diameter pit was detected.

[0147] Due to the very few, small and shallow localised attacks observed on the tested coupons and the inherent uncertainties and measurement error associated with determining the area of affected surface, calculation of localised corrosion rate has not been performed as this would give misleading results.

[0148] During the 21 cycles of testing water draining from the test were measured to be slightly alkaline (app. pH 8-10).

ProRox PS 960

[0149] The corrosion attacks observed on the test coupons as result of the test although localised in nature due to the wetting properties of the insulation material and the metal surface do not give rise to pronounced pitting corrosion, instead the corrosion is observed to be general in appearance upon removal of the corrosion products, see FIG. 12.

[0150] During the 21 cycles of testing water draining from the test was measured to go from slightly alkaline (app. pH 8) to slightly acidic (app. pH 6).

Test 2 ProRox PS 960 Treated with Corrosion Inhibitor

[0151] The tests were conducted in duplicate with a 40% higher water injection volume than in Test 1.

[0152] The coupons were upon inspection free from corrosion and only small areas with shallow localised corrosion was observed upon inspection under 10-50 magnification. The total area of these the localised corrosion attacks was less than 0.5% of total exposed sample area.

[0153] Due to the very few, small and shallow localised attacks observed on the tested coupons and the inherent uncertainties and measurement error associated with determining the area of affected surface, calculation of localised corrosion rate in table 3 has not been performed as this would give misleading results. The calculated average annual uniform corrosion rate, based on all twelve test coupons and on the 21 test cycles, is 2.22 m/year.

[0154] During the 21 cycles of testing water draining from the test A&B was measured to be slightly alkaline (app. pH 8-10).

Conclusion

[0155] The modified ASTM G189-7 test schedule was carried out successfully testing stone wool insulation material with and without treatment with corrosion inhibiting compounds using no spacers to the pipe substrate. The stone wool insulation material impregnated with corrosion inhibiting compounds results in a markedly lower corrosion rate on the pipe specimens compared to tests performed with the standard stone wool pipe insulation material. The calculated annual uniform corrosion rate, based on the 21 test cycles, is in average approximately fourteen times lower on the test substrates using the anticorrosive insulation material.