GB2129368A

GB2129368A - Insulation sandwich

Info

Publication number: GB2129368A
Application number: GB08309182A
Authority: GB
Inventors: Trevor Alfred Oliver; Bernard Sidney Sadler
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-11-01
Filing date: 1983-04-05
Publication date: 1984-05-16
Also published as: GB2129368B

Abstract

An insulation sandwich, usually in the form of a pad for use by a plumber instead of asbestos, comprises an envelope 1 of glass fibre cloth which is tear resistant and a ceramic blanket 2 as core. The core has a relatively small thickness of about 6 mm and is capable of continuously withstanding gas torch flame temperature of 1260 DEG C. The envelope material normally has a lesser flame resistance, however, their combination in the sandwich withstanding 1000 DEG C temperatures over substantial periods during a long use life before the mechanical properties of the envelope become impaired. <IMAGE>

Description

SPECIFICATION Insulation sandwich The invention relates to a thermal insulation sandwich combining marked properties of exterior flame. resistance and mechanical damage resistance with overall thermal insulation of a high level. The sandwich of the invention is especially useful-as a thermal insulation pad for use in place of asbestos products in protecting surfaces .against fire damage and combustion risk, for example surfaces of combustible components adjacent to solder pipe joints. The sandwich is also envisaged to find application for other purposes, for example personnel and equipment protection, in industries such as the steel, foundry and glass industries.

According to'the invention, there is provided a thermal Insulation sandwich comprising a normally-thin core of ceramic insulation material enveloped by a teår-resistant retaining envelope at least afrontface-ofwhich is made of flame resistantmatedal (e.g. glass fibre cloth) preferably capable. of withstanding a 1 0000C flame for at least two minutes.

In.general; the core will have a thickness of less than 30 mm, usually 25 mm or less (e.g. from 1 to 20 mm). Typically, the core will be from 5 to 20 (e.g. from 5 to 1 5) mm thick, precise thickness depending on density of the ceramic insulating material and intended field of application. A preferred sandwich according to the invention will have a thickness of 6 to 12 mm, with the core conveniently comprised pf ceramic insulation material having a density of from 64 to 96 kg/m3.

Such a density gsjust mentioned will be typical in the sandwich of the invention although higher or smaller densities may be appropriate in some circumstances. Densities up to 1 28 kg/m3 are, for example, useful in some instances.

The ceramic insulation material may conveniently be- a deramic blanket, such material being readily available in the thicknesses and densities referred to above.

In general, the core will consist wholly of the ceramic insulation'material.

The tear-resistant envelope will in general be made dfwpven glass fibre cloth. Generally, such cloth will have a weight of 500 or more (e.g. 750 or more). gum2. A weight in the range 900 to 1100 g/m2 is suitable for most practical applications, although'higher weights, for example up to 3000 g/m2, may be appropriate in heavy service applications such as in foundry work. The envelope will normally be made wholly of a material examples of which have just been described since this provides reversibility and manufacturing convenience.However, a front face of the sandwich may be so made with a rear face made of another material, for example a lower grade of glass fibre cloth, either of woven or non woven type.

The woven glass fibre cloth usedifor flame resistance will generally be of monofilament type.

Plied yarn composition is preferred for both mechanical strength and flame-resistance. Cloth of weavelock construction is preferred for mechanical strength. Weave in any of the cloths just referred to may be plain or twill.

Graphite-impregnated woven glass fibre cloth is preferred in terms of flame-resistance.

Woven carbon fibre cloth or woven high temperature-resistant aramid fibre cloth (e.g. that sold under either of the trade names Kevlon and Normex) are alternatives to woven glass fibre cloth for use in envelope construction in sandwiches according to the invention.

In a preferred embodiment of the invention, an insulation pad comprises a sandwiched core of ceramic insulation material enveloped in a tearresistant envelope at least a front face of which is formed by woven glass fibre cloth having a weight of 750 to 1100 g/m2. The core is preferably 5 to 1 5 (e.g. 6 to 12) mm thick with a density of from 60 to 130 (e.g. 64 to 96) kg/m3. The pad will conveniently have a surface area on each of its flat faces of from 0.1 to 2 m2, preferably being of generally rectangular form, for example with approximately equally dimensioned sides.

Thermal insulation sandwiches according to the invention typically are non-tearable so as to withstand use (for example, by a plumber engaged in pipework installation, as protection for surfaces local to a heat-formed pipe joint) and mechanical force over a substantial service life. The sandwich construction resists flame temperatures in the region of 1 0000C for substantial periods without degradation of mechanical properties. In some cases, continuous flame exposure for as much as 50 minutes can be withstood, a period several times larger than the period over which the envelope material itself can withstand such exposure in the absence of the ceramic core. The sandwiches are generally thin and accordingly can easily be handled and used as insulation pads by tradesmen such as plumbers.

The following is a description of a preferred form of such a pad, reference being made to the accompanying drawing which shows the pad in cross-section and in part only.

The pad shown in the drawings comprises an envelope 1 of woven glass fibre cloth and totally enclosing within its cavity a ceramic blanket 2.

The cloth of envelope 1 is made of monofilament glass fibre plied yarn woven in a weavelock construction. The cloth has a weight of 900 g/m2 and a thickness of approximately t mm.

The core ceramic blanket 2 is approximately 6 mm thick and has a density of 96 kg/m3. The material is capable of withstanding continuous exposure to a 1 2600C flame from a gas torch.

The envelope is of one-piece construction, folded over to sandwich the ceramic blanket 2 and stitched using glass fibre yarn where the over and under tiers meet along three edges.

The dimensions of the pad shown in the drawing are approximately 24 mm by 21 mm.

The pad material of the envelope is capable of withstanding exposure continuously to a 1 0000C flame from a gas torch for 2 to 3 minutes.

The completed pad was tested under exposure to a 1 0000C gas torch flame and found to retain its mechanical properties substantially unimpaired after 45 minutes exposure. Exposure times of approximately 5 minutes were resisted on a large number of separate occasions without loss of mechanical properties. Test simulating practical use by a plumber over a period of one month gave consistently satisfactory results in terms of insulation and protection of surfaces from heat damage and at the end of the tests the pad remained untorn and intact, and ready for further use. The pad proved slightly better in performance and durability than a conventional asbestos product, avoided the possible health hazards associated with asbestos and was cost-effective in terms of manufacture.

Other cloths which may be used as envelope material in any of the forms of the invention described earlier include woven ceramic cloth, Siltemp and Fortress T matting. Successful results have also been obtained with other infills (e.g.

ceramic paper, glass paper such as Fortress T, Pyronap felt and ceramic felt).

The invention as described earlier without reference to the drawing may include any one or more features of the invention as described with reference to the drawings.

Claims

1. A thermal insulation sandwich comprising a thin core of ceramic insulation material enveloped by a tear-resistant retaining envelope at least a front face of which is made of flame-resistant material.

2. A thermal insulation sandwich as claimed in Claim 1 and in the form of a pad for use in place of asbestos products in protecting surfaces against flame damage and combustion risk in solder jointing of pipes.

3. A thermal insulation sandwich as claimed in Claim 1 or Claim 2 wherein the core has a thickness of from 5 to 20 mm.

4. A thermal insulation sandwich as claimed in any one of Claims 1 to 3 which has a thickness of from 6 to 12 mm.

5. A thermal insulation sandwich as claimed in any preceding claim wherein the retaining envelope is made of woven glass fibre cloth.

6. A thermal insulation sandwich as claimed in Claim 5 wherein the cloth is made of monofilament fibre plied yarn woven in a plain or twill weavelock construction.

7. A thermal insulation pad comprising a sandwiched core of ceramic insulation material enveloped in a tear-resistant envelope at least a front face of which is formed by woven glass fibre cloth having a weight of 750 to 1100 g/m2, the core having a thickness of from 5 to 15 mm and a density of from 60 to 130 kg/m3.

8. A thermal insulation sandwich substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.

9. A method of performing a plumbing operation using heat application to a pipe in the vicinity of a combustible surface which method comprises covering said surface for protection purposes with a pad of thermal insulation sandwich as claimed in any preceding claim and then applying heat to said pipe.