AU612638B2 - High temperature refractory fiber - Google Patents

Description

AUSTRALIA

Patents Act 612638 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: *r 9 APPLICANT'S REF.: 5908CIP-B Name(s) of Applicant(s): MANVILLE SERVICE CORPORATION Address(es) of Applicant(s): Ken-Caryl Ranch, Jefferson County, Colorado 80217, United States of America Wendell Graydon Ekdahl Asit Ranjan Chaudhuri William Clyde Miiller Actual Inventor(s): q Address for Service is: Complete Specification for the invention entitled: PHILLIPS, ORMONDE AND FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne, Australia, 3000 HIGH TEMPERATURE e--eEa REFRACTORY FIBER -staetsa Afulld rpfthd fo.wn ing statement is a full description of this invention, including the best method of performing it known to P19/3/84 NE]UN DOLARS FORTY DOLLARS FORTY DOLLARS FORTY DOLLARS

RJW:LS

-ii~i IL-_ ;~YYPIIM i ii HIGH TEMPERATURE REFRACTORY Jf-I(L This application is for a Patent of Addition to Application 28228/84.

Background of the Invention Zirconia (ZrO 2 has been extensively used as an additive in glass formulations as a means of imparting alkali resistance. See for example U.S. Patents 3,859,106; 3,966,481; 4,036,654; 4,330,628. In addition, zirconia by itself or as a predominant component has been used to formulate refractory compositions with relatively high service temperatures. See for example U.S. Patents 2,919,944; 3,035,929; 3,754,950; 3,793,041; 4,053,321; and 4,119,472. One prior Patent U.S. 2,873,197 issued to J.C.

McMullen on February 10, 1959, discloses an alumina-silica-zirconia refractory fiber. However, that Patent does not disclose any specific compositions within Applicants' claimed range. In addition the thermal resistance property discovered and claimed by Applicants 20 is not disclosed in that Patent.

Summary of the Invention 0*e* 00*0 0 0* 00r *00 Applicants discovered that the addition of zirconia to an alumina silica refractory fiber formulation produces a fiber which is significantly more temperature resistant than the alumina-silica fiber alone.

According to the present invention, there is provided a high temperature refractory glass fibre exhibiting shrinkage of 5% of less when subjected to temperatures of about 2600 F for about 4 hours, said fibre, subject to and having a composition, in percent by weight, of: from 41 to less than 56% Si0 2 from 27 to 42% Al203; and from more than 10% up to and including 23% ZrO 2 sair' wmposition excluding: those compositions having from 46 to 52% SiO2, from 32 to 38% Al203 and from 13 to 18% ZrO 2 and having a silica to zirconia ratio in the range of from -2i. i 2.6 to 3.8; and (ii) those compositions having from 45 to 76% SiO 2 from 12 to 32% Al 03 and from 5 to 30% ZrO 2 and having a silica to alumina ratio of from 1.8 to The present invention also provides a method for insulating a structure from exposure to high temperatures comprising the steps of: forming a high temperature refractory glass fibre exhibiting shrinkage of 5% or less when subjected to temperatures of about 2600 °F for about four hours, said fibre, subject to provisos and having a composition, in percent by weight, of: from 41 to less than 56% SiO 2 from 27 to 42% Al 203; and 3 ofrom more than 10% up to and including 23% ZrO 2 oooo said composition excluding: those compositions having from 46 to 52% SiO 2 from 32 to 38% Al 203 and from 13 to 18% ZrO 2 and having a silica to zirconia ratio in the range of from 2.6 to 3.8; and (ii) those compositions having from 45 to 76% SiO 2 from 12 to 32% Al 203 and from 5 to 30% ZrO 2 Sand laving a silica to alumina ratio of from 1.8 to A number of prior art fibres are rated at 2600 F (1425 F) by their manufactures. Comparative tests of shrinkage run against these competitive fibres show the fibres of the present invention to be more thermally-resistant. In addition, this formulation produces a higher melt rate for the same energy input and 30 a greater percentage of recovered fibre per pound of melted batch than conventional alumina/silica refractory melts.

Brief Description of the Drawing Figure 1 is a portion of a triaxial diagram showing Applicants' example formulations plotted with the shaded area indicating the claimed range.

-2ac Detailed Description of the Preferred Embodiments Initially, four compositions were tried experimentally (see Table 1) seeking a fiber with chemically resistant properties.

Compositional formulations were targeted, the components added in the desired proportions to a three foot diameter, 19 inch deep research melter. The compositions were melted electrically with the melt stream exiting through an orifice and impinging on a pair of eight inch diameter spinners rotating at 12,000 r.p.m. This produces fibers which are generally 2-7 microns in diameter, 1/2 to 10 inches in length (2-3 inch average), and having a varying shot content (35-45., usually).

Thermal tests were run on 'these fibers to identify those candidates with the best refractory performance. Bulk fiber was vacuum formed into a felt for each formulation to be tested. Lengths of these fibrous felt samples were precisely measured, placed in a refractory kiln for a specified time and temperature, allowed to cool, and then remeasured. The results are shown in TABLE I. These shrinkages will be S* lower than for production blanket since the felting has eliminated some of the interstitial shrinkage that will occur in production materials these test samples have higher than normal densities).

20 TABLE I Composition wt) Fiber I.D. SiO Al 0 ZrO 2 3 2 1(Z1) 50.0 43.0 6.7 2(Z2) 47.3 40.1 12.2 25 3(Z3) 50.1 34.6 15.0 4(Z4) 59.1 25.9 14.6 2400F Std 2600F Std* 21 Z2 Z3 Z4 Linear Shrinkage a. 2400F-112 Hrs 3.7 3.2 2.7 2.2 2600F-24 Hrs 3.15 4.15 3.5 2.3 4.15 c. 2600F-125 Hrs 3.70 4.2 3.5 2.3 4.25 d. 2700F-24 Hrs 6.1 7.3 6.8 3.2 9.2 e. 2700F-125 Hrs 10.1 8.0 7.6 3.7 *This fiber composition is disclosed and claimed in U.S.

Patent 3,449,137 and has a formulation of 40-60% silica, 35-551.

alumina, and 1-81 chromia. The specific fibers used in these tests were 43.51 silica, 55% alumina and 1.51 chromia.

-3-

II

The results of these tests indicated that Z3 had the best thermal performance. It was believed that increasing alumina and/or zirconia in the #3 formulation would improve refractoriness.

Accordingly, a family of fibers (5-11 Table II) bascd on the #3 formulation was produced using the three foot research melter in accordance with the procedures outlined above. These formulations are depicted on the triaxial diagram in FIG. 1. These fibers were then subjected to a plurality of temperatures for various periods of time in the refractory kiln to determine refractoriness. The results of these tests and the formulations of the 5-11 fibers appear in TABLE II.

TABLE II Z3 5 6 7 8 9 10 11 Components (wt 1) SiO 50.1 31.3 38.9 38.3 35.3 27.6 34.1 27.6 i5 Al 0 34.6 53.2 45.5 41.3 48.2 53.1 55.0 58.4 2 3 ZrO 15.0 15.3 15.2 20.2 16.2 19.1 10.6 13.7 2 Temp/Time Linear Shrinkage (1) 2200F/24 Hr 1.94 2.72 2.92 3.01 3.52 2.83 2400F/24 Hr 2.47 2.83 2.63 2.80 4.50 2.20 *20 2600F/48 Hr 2.94 2.94 2.90 3.64 4.69 3.23 2700F/24 Hr 3.42 4.07 5.94 6.34 4.79 4.22 3.68 3.06 Even though these tests succeeded in producing a fiber with approximately 10% shrinkage at 2800°F (1538 0 C) as opposed to for these tests did not result in the definition of a commercially "viable fiber. These high alumina formulations (5-11) were significantly more difficult to fiberize than Fibers 6, 7, 8 and 10 had linear shrinkages from 8 to 151 after 260 hours of exposure to 2700*F (1482*C). Note, also, each of these fibers (6, 7, 8 and 10) failed to produce samples of less than 5.01 linear shrinkage for 100 hours of exposure to 2700°F. In order to be rated at a particular temperature, a fiber sample of this type felted) should exhibit no more than 51 linear shrinkage after 100 hours of heat soaking. This insures that a particular fiber will not undergo unacceptable levels of shrinkage exceeding 121) when cycled up to its service temperature repeatedly throughout its service life. When the fiber samples are collected in a normal -4-

LA

i production run and needled into a blanket, rather than being pressed into a felt, the shrinkages seen in this type of test will be more akin to the maximum shrinkages desired during use.

Additional samples of various blanket formulations were melted, analyzed for chemistry, and tested for shrinkage. The amount of linear shrinkage is a time/temperature phenomenon.

Accordingly, although this fiber is rated for use in the 2550 to 2650*F (1400 to 1455*C) range, the samples were inserted in a kiln at 2700*F (1482'C) for four hours to 1) accelerate the tests thereby reducing the time required and 2) to insure that the blanket could withstand limited exposure to peak temperatures above those recommended for usage without catastrophic failure. The results of S these tests appear in TABLE III.

TABLE III 1 By Weight 4 ,q Samole No.

12 13 14 16 17' 18 19 21 22 23 24 26 27 28 29 31 SiO 53.1 51.9 50.0 51.7 49.0 48.0 49.2 54.7 49.4 50.2 51.9 49.7 49.7 47.6 49.3 46.0 46.4 46.2 46.2 50.1 Al 0 L-3 45.8 42.5 44.3 42.1 38.9 38.2 36.4 30.3 35.0 34.1 32.9 34.7 34.8 37.3 34.6 37.3 37.2 37.0 37.3 32.0 ZrO 0.4 4.682 5.3 5.4 11.2 13.2 13.8 14.1 14.5 14.7 14.7 15.0 15,0 15.2 15.3 15.3 15.4 15.5 15.6 17.4 1 Linear Shrinkage (2700°F for 4 Hrs.) 15.6 14.6 14.9 13.3 12.1 9.2 8.2 12.9 11.3 9.7 9.1 6.8 8.2 10.9 9.7 8.1 6.8 7.2 7.6 TABLE III (Con't) 1 By Weight 1 Linear Shrinkage Sample No. SiO Al 0 ZrO (2700'F for 4 Hrs.) -2-3 2 32 49.3 32.4 17.4 7.4 33 47.2 34.4 17.5 8.6 34 47.4 33.9 17.6 47.4 34.2 17.7 7.2 36 48.0 33.2 17.8 7.3 37 47.7 33.4 17.8 7.2 For these tests, an acceptable level of shrinkage is defined as 121 at 2700*F. While this level of shrinkage might be considered high for normal use, it should be remembered that the amount of shrinkage has been intentionally aggravated by exposing 15 these samples to a temperature (2700°F) exceeding its recommended service temperature (2550-2650*F).

S* Much of the blanket made using this formulation will find its way into insulation modules of the type described in U.S. Patent 4,001,996. In such a modular configuration, the blanket will undergo less shrinkage since only a small portion of its surface is exposed to the internal furnace temperatures. Further, a major portion of any gap which might form as a result of such shrinkage will be filled as the compressed modules expand.

Additional fibers of varying compositional percentages of 25 silica, aluminum, and zirconia were produced and tested in order to further define the invention. The composition of these fibers 38-139, as well as the shrinkage results are shown in Table IV below. The compositional percents were normalized to 1001 for ease of plotting in Figure 1. That is, impurities and/or ignition losses may result in the silica, alumina and zirconia levels totalling slightly more or less than 1001. To normalize, the percentages are added and then each component percent is divided by the total. The normalized percents than add to 1001 .11. In addition to 2700*F shrinkage tests, both 2400°F and 2600*F shrinkage tests were run on most of these blanket samples. All of these shrinkage tests were done on blanket samples for 4 hours at the stated temperature.

OWNS-

For each sample run (0 and A-G) the starting and target compositions are given. These runs were made standard production equipment. The target formula was added to the starting formula until the target fiber composition was achieved. Sampling of the fiber during the transition period was done on a regular point (38-139) during the transitions.

TABLE IV Composition basis to define each sample Shrinkage 2400°F 2600°F Sample No. SiO 2 A12 3 -2 -23 Starting: Target(O): 0-38 0-39 o t 5 0-40 0-41 S" 0-42 0-43 0-44.

20 0-45 0-46 %to 0-47 0-48 25 Starting: Target(A): A-49 A-51 A-52 A-53 A-54 A-56 A-57 A-58 54.0 50.0 51.9 53.9 53.2 52.2 51.4 51.2 50.6 50.6 50.4 50.2 50.2 50.0 60.0 50.7 51.2 50.7 51.8 59.1 60.0 59.4 60.2 59.1 59.7 46.0 35.0 46.3 43.5 41.4 38.8 38.0 36.8 36.6 36.2 36.1 35.8 35.6 35.0 25.0 34.2 34.2 34.6 33.6 25.7 25.5 25.6 25.3 26.2 25.5 ZrO 2 RUN 0 15.0 1.8 2.5 5.4 9.0 10.6 12.0 12.7 13.3 .3.5 13.9 14. 1 RUN A 15.0 15.0 15.1 14.6 14.7 14.6 15.2 14.5 15.0 14.5 14. 6 14.8 2700*F 10.5 14.0 7.8 6.1 5.1 4.8 5.6 4.7 3.8 3.2 2.2 7.4 9.8 9.1 20.6 18.7 -7- TABLE IV (Con't) Composition Shrinkage Sample No. SiO 2 Al 20 3 ZrO 2 2400*F 2600*F 2700 0

'F

RUN B Starting: 60.0 25.0 15.0 Target(B): 40.0 38.0 22.0 B-59 58.9 26.0 15.1 2.2 5.0 11.3 52.1 -33.0 14.9 2.0 3.7 7.8 B-61 52.0 32.1 15.9 2.4 3.2 B-62 50.4 32.6 17.0 2.0 2.6 7.8 B-63 49.1 33.4 17.5 2.1 3.0 7.4 B-64 47.5 34.8 18.5 2.2 2.6 6.3 46.2 34.8 19.0 2.2 3.2 Does B-66 45.5 34.9 19.6 2.3 2.9 15 B-67 44.7 35.1 20.1 2.3 2.7 .s.B-68 42.9 36.1 20.9 2.1 2.3 3.6 0: B-69 41.9 36.7 21.4 2.4 2.9 5.7 RUN C Starting: 40.0 38.0 22.0 0;~0 Iarget(C): 57.0 38.0 be* C-70 41.7 36.9 21.4 2.6 2.8 5.7 0:40. C-71 41.5 37.4 21.1 2.1 3.1 3.3 .00C-72 50.9 37.6 11.5 2.6 4.9 8.9 C-73 54.8 37.0 8.2 3.0 7.5 11.4 :925 C-74 56.3 37.2 6.5 2.7 4.1 8.6 P e C-75 57 .4 36.8 5.8 2.7 5.9 11.2 C-76 57.1 37.0 5.9 3.1 6.5 14.2 C-77 57.0 37.0 6.0 3.3 6.0 11.6 C-78 56.7 37.6 5.7 3.6 6.7 14.4 C-79 57-.8 36.3 5.9 3.2 7.4 15.2 RUN D Starting: 50.0 35.0 15.0 Target(D): 59.0 33.0 50.2 35.1 14.7 2.5 3.1 5.9 D-81 50.2 34.9 14.9 2.3 3.4 6.2 D-82 49.7 35.1 15.2 2.5 3.2 6.7 TABLE IV (Can't) Composition Shrinkage .Sample No. SiO2 A-120 ZrO2 2400*F 2600*F 2700*F RUN D (Can't) D-83 54.7 36.5 8.8 2.7 7.4 12.7 D-84 57.6 35.1 7.3 3.2 8.1 15.6 58.5 34.0 7.5 2.8 6.9 11.6 D-86 58.6 .33.8 7.6 2.6 6.2 10.7 D-87 59.7 32.3 8.0 2.9 8.4 12.5 D-88 59.4 33.2 7.3 2.6 6.7 13.9 D-89 60.2 32.2 7.6 2.7 7.1 14.9 D-90 59.6 32.7 7 0 ARUN E Starting: 58.0 32.0 TargetCE): 53.0 32.0 15.0 E-91 59.3 32.4 8.2 2.1 5.6 12.4 E-92 57.0 32.0 11.0 2.3 3.3 5.9 E-93 56.4 31.6 12.0 1.7 3.2 6.6 E-94 55.3 31.9 12.8 1.8 3.1 6.6 E-95 54.3 32.1 13.6 1.7 5.9 13.8 *E-96 54.2 31.8 14.0 1.7 5.9 13.8 E-97 54.6 32.2 13.2 1.5 5.6 14.1 .8:E-98 53.5 32.7 13.8 1.0 2.1 4.2 E-99 53.8 32.4 13.8 :925 E100 52.8 33.6 13.6 1.4 2.6 RUN F Starting: 53.0 32.0 15.0 Target(F): 54.0 26.0 20.0 F-101 53.0 32.4 14.4 1.9 2.9 7.1 F-102 53.0 30.9 16.1 2.0 3.0 5.9 F-103 52.2 31.0 16.8 2.0 3.2 4.6 F-104 52.0 30.5 17.5 1.6 3.9 6.7 F-105 53.1 29.7 17.2 1.9 3.7 7.8 F-106 52.2 29.1 18.7 2.4 4.0 8.3 F-107 52.6 28.6 18.8 3.0 5.0 10.7 F-108 53.0 28.3 18.7 3.8 7.2 14.4 F-109 53.5 28.1 18.4 4.1 7.6 16.3 F-110 53.2 27.8 18.9 4.1 8.9 18.2 TABLE IV (Con't) b Composition Sample No.

-io2 -2-3 b .0 .0 9 0 0 59*0 0*55

S

4 *0 S S 4 05 *0

I

*00 Starting: Target(G) G-111 G- 112 G-113 G-114 G-115 G-116 G-117 G-118 is G-119 Starting: H1-120 B1-121 20 H-122 H-i123 H1-124 H1-125 H-126 H-127 11-128 H1-12 9 H-130 H1-131 H1-132 H1-133 H1-13 4 11-13 5 11-136 11-137 H1-138 H1-139 54.0 50.0 53.7 52.9 52.8 52.0 51.6 51.8 51.7 51.2 51.0 50.0 50.1 48 .2 47 .7 47 .0 46.3 45. 9 44 .9 44.4 43.7 43.6 43.3 41.9 39.3 37.9 35.4 35.5 32.5 32.3 31.0 30.6 26.0 35.0 27 4 28.1 28.3 32.0 32.0 32.7 33.8 34.1 34.1 35.0 35.0 37.0 37.6 38.3 39.1 39. 5 40.7 41.1 41. 7 41.8 41.6 41.9 41.9 42.0 42.0 42.0 41.4 41.7 41 .8 41.9 -r2 RUN G ,A0.0 15.0 19.0 19.0 18.9 16.0 16.3 15.6 14.5 14.7 14.9 RUN HI 15.0 14.7 14.8 14.7 14.6 14.5 14.6 14.4 14.5 14.6 14.5 14.5 16.2 18.7 20.0 22. 6 22. 26.0 26.0 27.1 27.5 Shrinkage 2400*F 2600*F 3.8 3.8 10.3 12.1 12 12. 12.2 12.2 10.0 9.3 9.' 9.2 8.9 8.6 2 700'*F 12.3 3.6 The results from TABLE IV are depicted graphically in FIG.

1. FIG. 1 is an enlargement of a portion of a Si, Al, Zr triaxial diagram to enable the plotted formulations to be seen more clearly.

Even in the enlarged view of FIGURE 1, some points were too close to other formulations to be plotted as distinctly separate points. Of the data points tested at 2600°F (38-139) it can be seen that points 41, 74, and 132-139 test at less than SL shrinkage at 2600*F but are outside the claimed range. Points 95-97 and 108-111 exhibit shrinkage above 51 at 2600"F but are within the claimed range.

Points 132-139 can be explained in that compositions in this area, are difficult to fiberize and thus do not define a viable fiber.

Points 41 and 74 are considered as within experimental error or simply anomalies. Assuming correct shrinkage and composition no.e testing the exact compositions defined by points 95-97 and 108-111 would be excluded from the claimed range due to excessive shrinkage above 51. at 2600*F. That is, claim 1 defines fibers within the claimed composition limits and which exhibit the defined shrinkage levels. Applicants have melted and tested 139 data points in order to define the present claimed range.

The high temperature refractory fiber described herein is commercially available from Manville Building Materials Corporation under the tradename of "CERACHEH". Both the fiber in bulk form and in blanket are usable to 2600*F (1426*C). In order to compare this fiber to other fiber rated to 2600*F, blanket samples of CERACHEM@ S25 (having a formulation of 49.7. Si0 2 34.7% Al203 and 15.01 *2 2 3 ZrO were tested for shrinkage in side-by-side furnace tests to a) a commercially available refractory fiber blanket having the formulation A 1203-54%, SiO2-461; b) a commercially available refractory fiber blanket which has undergone a heat treatment has been preshrunk) and has a composition of 511 alumina, 491 silica; and c) a commercially available refractory fiber blanket with the formulation of Si02-51.61, Al 203-47.71, the blanket having subsequently received a surface treatment of 1/21 chromium oxide.

Strips of these four blanket samples were tested for shrinkage in a manner performed in the previous tests. Measured lengths of blanket were placed in a kiln at 2550°F (1400°C) and -11remeasured after each of 25, 50 and 75 hours. The percent shrinkage was computed by dividing the change in length by the original length and multiplying by 100. Due to the relatively small amount of shrinkage change between the 50 and 75 hour measurements, subsequent tests run at 2600°F (1426°C) and 2700°F (1482°C) were run only to hours. The results of these tests appear in TABLE V.

TABLE V 1 Linear Shrinkage Temperature: 2500"F 2600°F 2700'F Sample 25 Hr 50 Hr 75 Hr 25 Hr 50 Hr 25 Hr 50 Hr CERACHEKM 3.0 3.1 3.1 3.2 3.2 5.7 5.7 54/46 formulation 4.2 4.9 5.0 5.0 5.7 4.8 5.7 51/49 formulation 3.4 3.6 3.6 4.6 4.6 6.7 6.9 Chrome treated 3.6 3.9 4.0 4.1 4.3 10.5 11.2 15 These tests show the superiority of CERACHEM@ to these three other commercially available fibers. When taken in conjunction with the difficulties of fiberizing a high alumina composition, problems associated with chromia treatment, the aforestated improvements in pour rate and fiber recovery rate as against other silica/alumina melts, the high temperature formulation of the present invention is clearly superior to other known refractory fiber compositions.

In formulating these various compositions, it is necessary to use ingredients that have a certain degree of purity. In fact, in order to insure the high temperature performance of this fiber, impurity levels, particularly for alkali metal oxides and alkaline earth oxides, must be kept at or below levels normally desired for high temperature silica-alumina refractory fibers. Suitable batch ingredients include Zircon sand (-325 mesh flour) available from Continental Minerals as 582 W.S. Zircon, a 200 mesh ground silica available from Wedron Silica Company, and any number of 200 mesh aluminas, for example, normal soda grade alumina such as Cl grade available from Kaiser Corporation or A-l grade available from Aluminum Company of America.

Various changes, alternatives and modifications will be apparent following a reading of the foregoing specification. For example, it is contemplated that the addition of up to 2.51 chromia -12to the #3 formulation may be beneficial in improving refractoriness.

Also, although only one fiberization technique has been discussed, this refractory fiber may be formed using any other commercial technique, such as blowing, for example. In addition, while the use S of the fiber herein disclosed and claimed may be in module form as discussed above, the fiber of the present invention may be used for any high temperature insulating purpose. For example, this fiber may be used in bulk- form for a spray-on refractory system such as disclosed in U.S. Patent No. 4,547,403. The fiber could also be used in manufacturing products such as is disclosed in U.S. Patent No. 4,014,704. Accordingly, it is intended that all such changes, alternatives and modifications within the scope of the appended claims be considered part of the present invention.

a *o e a a 4 a o 9 4& a 94* 4 99 -13-

Claims (2)

1. A high temperature refractory glass fibre exhibiting shrinkage of 5% of less when subjected to temperatures of about 2600 F for about 4 hours, said fibre, subject to (i) and having a composition, in percent by weight, of: from 41 to less than 56% SiO 2 from 27 to 42% Al 2 0 3 and from more than 10% up to and including 23% ZrO 2 said composition excluding: those compositions having from 46 to 52% SiO 2 from 32 to 38% Al203 and from 13 to 18% ZrO 2 and having a silica to zirconia ratio in the range of from 2.6 to 3.8; and (ii) those compositions having from 45 to 76% SiO 2 from 12 to 32% Al 0 and from 5 to 30% ZrO and having 2 3 2 a silica to alumina ratio of from 1.8 to o. as

2. A method for insulating a structure from exposure to S. high temperatures comprising the steps of: forming a high temperature refractory glass fibre 20 exhibiting shrinkage of 5% or less when subjected to temperatures of about 2600 F for about four hours, said fibre, subject to provisos and having a composition, in percent by weight, of: from 41 to less than 56% SiO 2 °from 27 to 42% Al 0 and 2 3 from more than 10% up to and including 23% ZrO 2 said composition excluding: those compositions having from 46 to 52% SiO 2 from 32 to 38% Al203 and from 13 to 18% ZrO 2 and having a silica to zirconia ratio in the range of from 2.6 to 3.8; and (ii) those compositions having from 45 to 76% SiO 2 from 12 to 32% Al203 and from 5 to 30% ZrO 2 and having a silica to alumina ratio of from 1.8 to DATED: 28 JUNE, 1990 PHILLIPS ORMONDE FITZPATRICK Attorneys For: MANVILLE SERVICE CORPCrA RTf>. 1174Z -14-