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BRITISH STANDARD BS 3958-2:1982

Specification for

Thermal insulation

materials

Part 2: Calciumsilicate preformedinsulation

UDC662.998:666.96:661.842.65

CONFIRMED

DECEMBER 2007

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BS 3958-2:1982

This British Standard, havingbeen preparedunderthedirection ofthe Refrigeration,

Heating and Air ConditioningStandards Committee,waspublishedunderthe authorityofthe Board ofBSI andcomesinto effect on31August1982

BSI07-1999

First published December 1965

First revision February1970

Second revision August1982

The following BSI referencesrelatetothework onthis

standard:Committee reference RHE/9

Draft for comment80/77466

ISBN0580 12598 X

Cooperating organizations

The Refrigeration, Heating andAir Conditioning Standards Committee,underwhose directionthis British Standardwas prepared, consists ofrepresentatives fromthe following:

Association ofManufacturers of Domestic Electricity Supply Industry in England and

ElectricalAppliances wales*

Association ofConsulting Engineers Heating and Ventilating Contractors

Boiler and Radiator Manufacturers Association

Association Limited Hevac Association

British Combustion Equipment Institute ofEnergy

Manufacturers Association Institute ofRefrigeration*

BritishGas Corporation* Institution ofGas Engineers*

British Refrigeration and Air Conditioning Lloyds Register ofShipping

Association* Manufacturers Association ofRadiators and

Building Services Research and Information Convectors Limited

Association Ministry ofDefenceChartered Institution ofBuilding Services* NationalCoalBoard

Department ofEnergy (Energy Technology) Society ofBritish Gas Industries

DepartmentofHealthandSocialSecurity* Water-tubeBoilermakers Association*

Departmentofthe Environment (PSA)

The organizations markedwith an asterisk inthe above list,togetherwiththefollowing,were directly represented onthe Technical Committee entrustedwiththe preparation ofthis British Standard:

Albury Laboratories Limited EPS Association

AsbestosCement Manufacturers Eurisol (UK) Association ofManufacturers of

Association Limited Mineral Fibre Insulation

British Ceramic Research Association Fibre Building Board DevelopmentBritish Rubber Manufacturers OrganizationLimited

Association Gypsum Products Development Association

Combustion Engineering Association Institution ofMechanical Engineers

CranfieldInstitute ofTechnology Process Plant Association

Department ofIndustry (National Physical RoyalInstitute ofBritishArchitects

Laboratory) StructuralInsulationAssociation

Departmentofthe Environment (Building Thermal Insulation Manufacturers and

ResearchEstablishment) Suppliers Association (TIMSA)

Department ofthe Environment (Housing Thermal Insulations ContractorsAssociation

and Construction) Yarsley Testing Laboratories Limited

EnergyIndustries Council Coopted member

Engineering Equipment Users Association

Amendments issuedsince publication

Amd. No. Date of issue Commentspy

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BS3958-2:1982

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Contents

Page

Cooperating organizations Inside front cover

Foreword ii1 Scope 1

2 References 1

3 Definitions 1

4 Classification 1

5 Sampling andtesting 1

6 Composition 1

7 Moisture content 1

8 Physical requirements 1

9 Chemical requirements 2

10 Identification ofasbestos-free material 2

11 Standardshapes andsizes 212 Dimensionaltolerances 3

13 Marking 3

Appendix A Method oftest for alkalinity 4

Table 1 Thermal conductivity values 1

Publications referredto Inside back cover

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Foreword

This revision ofthis Part ofthis British Standard is one ofaseries publishedunderthe direction ofthe Refrigeration, Heating andAir Conditioning StandardsCommitteetospecify requirements for a particular range of insulating materials.

It supersedes the 1970 editionwhich is withdrawn.

Other Parts ofthis standard are:

Part1: Magnesiapreformed insulation;

Part 3: Metal mesh faced mineralwool mats and mattresses;

Part 4: Bonded preformed man-made mineral fibre pipesections1);

Part 5: Bonded mineralwoolslabs (foruseat temperatures above 50C);

Part 6: Finishing materials; hardsettingcomposition,self-settingcementand gypsum plaster.

The 1970 edition ofthis Part specified requirements for calciumsilicatepreformed insulation for use up to at least 650C. This edition includes bothmediumtemperature and hightemperaturetypesforuseupto atleast 650C

and 950C respectively,with appropriate requirements for eachtype.

A British Standard doesnotpurport to include allthe necessary provisionsof acontract. Users ofBritish Standards are responsible fortheir correct application.

Compliance with a British Standard doesnot of itself confer immunityfrom legal obligations.

Summary of pages

This document comprises a front cover, an inside front cover, pagesi and ii,pages1to 4, an inside back cover and a back cover.

This standard has beenupdated (see copyright date) and may have hadamendments incorporated. This will be indicated inthe amendment table onthe

inside front cover.

1) In course of revision.

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1 Scope

This Part ofthis British Standardspecifies

composition, moisture content, physical andchemical requirementsfortwotypes of calciumsilicate preformed insulation (see clause4).

2 References

Thetitles ofthe publications referredto inthisstandard are listed onthe inside back cover.

3 Definitions

Forthe purposes ofthis Part ofthis BritishStandard,the definitions given in BS 874, BS 2972,BS 3533, BS 5422 and BS 5970 apply.

4 Classification

This standard covers twotypes ofcalciumsilicatepreformed insulation as follows.

Type I: slabs, radiused and bevelled lags andpipesections foruse at temperatures upto 650C orsuch highertemperaturesrecommended by the manufacturer.

Type II:slabs and flat bevelled lags foruseupto 950C or at such highertemperaturesrecommended by the manufacturer.

5 Sampling andtestingSampling andtestingshall be in accordancewiththe appropriate clause in BS 2972 unless otherwisestated inthis standard. Forthermal conductivitydeterminations a flat slabshall beused forthetests.

6 Composition

The materialshall be composed predominantly ofreacted hydrous calciumsilicate reinforcedwithsuitable fibres (see9.2, note 2).

7 Moisture content

When conditioned at medium humidity inaccordancewith40.3 ofBS 2972:1975,the moisturecontent ofthe materialshall not exceed 7.5 % bymass.

8 Physical requirements

8.1 General. Inthe application ofthe physicalrequirementsof8.3to8.6, 95 % confidence limitsshallapply.

8.2 Thermal conductivity. Whentested inaccordancewiththe appropriate method oftest for

thermal conductivitygiven in BS 874, at a cold facetemperaturewithinthe range of 10Cto 50C,thethermal conductivity shall not exceedthevaluesgiven in Table 1.

Table 1 Thermal conductivity values

NOTE BS874 requires thetest report tostatewhich method oftest wasemployed,the bulk density ofthe material,the hot facetemperature and cold facetemperature,the conditioningprocedure andthe moisture content before and afterthetest.

8.3 Bulk density. The bulk density ofthe drymaterialshall lie withinthe range:

type I: 180kg/m3to 240kg/m3;

type II: 210kg/m3to 280kg/m3.

8.4 Flexuralstrength. The flexuralstrengthshallbe not less than:

type I: 250 kN/m2;

type II: 250 kN/m2.

8.5 Compressivestrength

8.5.1Dry.The reduction inthickness shall notexceed 5 %under a compressive load of:

type I: 500kN/m

2

;type II: 550kN/m2.

The minimum load at onset of disruption2)shall be:

type I: 500kN/m2;

type II: 550kN/m2.

8.5.2 Wet.After 18 h immersion inwater,thereduction inthickness shall not exceed 5 %under acompressive load of:

type I: 170kN/m2;

type II: 170kN/m2.

Type I Type II

Meantemperature

Thermalconductivity

Meantemperature

Thermalconductivity

C

100

150

200

250

300

350

400

425

W/(m.k)

0.061

0.067

0.074

0.080

0.087

0.094

0.102

0.106

C

200

250

300

350

400

450

500

W/(mk)

0.074

0.080

0.087

0.094

0.102

0.110

0.120

2) This is indicated by a noticeable change intheslope ofthe graph obtained from an automatic recording ofthickness versus

load, accordingto 2.5.3 b) ofBS 2972:1975.

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8.6 Heat stability. Whentestedin accordancewithBS 2972 under conditions ofsoaking heat at

increasingtemperatures the materialshall bedeemedsuitable for normaluse at operatingtemperatures at whichthe following requirementsare met.

a) Maximum linearshrinkage:

type I: 2%

type II: 2%.

b) Reduction inthickness not exceeding 5%undera compressive load of:

type I: 400kN/m2;

type II: 400kN/m2.

c) Minimum load at onset of disruption

3)

of:type I: 400kN/m2;

type II: 400kN/m2.

9 Chemical requirements

9.1 Alkalinity.Whentested by the methoddescribedinAppendixAthe pHvalue recordedshallbe between 9.5 and 11.0.

9.2 Corrosive attack. The materialshall notincludesignificant quantities ofsubstances that willpromote corrosive attack onthesurfaces withwhichit is to be in contact. Where necessary,trace

quantitiesofwater-soluble chlorides shall beestimated in accordancewithsection22 ofBS 2972:1975.

NOTE 1 Water-soluble chlorides are normally present intracequantities in commercial calciumsilicates as in most thermalinsulating materials. Inthe presence ofmoisture and oxygen andunder certain adverse metallurgical conditions chloride ions arecapable of initiatingstress corrosion cracking insusceptiblemetal alloys suchas austeniticstainless steels.

It isnot practical to indicate asafeupper limit for chloridecontent sincewater can leach out soluble chlorides fromsubstantialvolumes of insulating materials and allow themto beconcentrated at themetal-insulation interface. In addition,waterfrom outside sources such as the process itself or wind-drivenspray cansubstantially increasethe chloride content oftheinsulation.

In conditions potentially conducivetostress corrosion cracking,appropriatesafeguards should be adopted (see BS 5970).

Special forms ofcalciumsilicate incorporating corrosioninhibitors are commercially available.

NOTE2 Some organic matter may be present either in fibrousform or as a bonding agent. It is suggestedthat the compositionofthe product be checked withthe manufacturer for use inprocess conditions where organics may present a hazard,e.g. processesinvolving powerful oxidizing agentsorthermalinsulation on pipework and plant in a flammable atmosphere.

10 Identification of asbestos-freematerial

10.1 In orderto identify those materials which arenot subject to control by Governmentregulations,(see note), asbestos-free calcium silicate preformedinsulation, manufactured in accordancewith Part 2ofthis standard,shall be distinctively colouredyellow. The colouring mattershall remainsufficiently stable and permanent underserviceconditions to permit the ready identification oftheoutersurface ofthe insulation.

NOTE Government regulations4) concerningasbestos-containing insulation requirethat special precautionsbe observed in ordertosafeguardthe health of individuals whoare handling these materials orwho are working inthevicinity.

10.2 Materials which contain asbestos fibreshallnot be otherthanself-coloured.

11 Standardshapes andsizes

11.1 Preformed calciumsilicateshall besupplied inthe form of flat slabs, bevelled lags, pipesections orradiused and bevelled lags, complyingwiththefollowing.

NOTE Not allsuppliers providethe full range ofstandardshapes andsizes listed ina)to d). Conversely other shapes andsizes may be available. Suppliers literatureshould be consultedfor details ofthe range offered.

a)Flat slabs:types I andII

Length: 600mmto 1 000mm

Width: 150mmto 1 000mm

Thickness: 25 mmto 100mm;

b)Pipesections:typeIonly

Length: 914 mm

Diameter:to fit standard mildsteel pipes ofexternal diameterupto 329 mm

Wallthickness: 25 mmto 75 mm.

c)Flat bevelled lags:types I andII

Length: 600mmto 1 000mm

Majorwidth: 150mmto 166mmThickness: 25 mmto 100mm.

d)Radiusedandbevelled lags:typeIonly

Length: 914 mm

Width of outer curvedsurface:approximately140mmto 170mm depending onradius ofcurvature,thickness and number oflags to fit circumference

Thickness: 25 mmto 100mm.

3) This is indicated by a noticeable change intheslope ofthe graph obtained from an automatic recording ofthickness versus

load, accordingto 2.5.3 b) ofBS 2972:1975.4) Statutory Instruments 1969, No.690, Factories, The Asbestos Regulations 1969.

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11.2 Flat slabs shall be free fromwarp. Mating facesshall be plane and edges shall besquaretothe

surfaces andto one another.11.3Pipesections and lags shall be concentric andfree fromwarp. Mating faces shall be plane andends shall correspondwith a plane at right angles tothe long axis.

11.4Bevelled edges of radiused and bevelled lagsshall correspondwiththe radii ofthe curvedsurfaceto be insulated.

12 Dimensionaltolerances

The insulationshapes shall be in accordancewiththe dimensions stated by the manufacturer (or

supplier, as appropriate),subject tothe followingtolerances.

a)Slabs and lags

Length andwidth: 3mm

Thickness: 1.5 mm, + 3mm.

b)Pipesections

Length: 3mm

Inside diameter: 0mm, + 5 mm

Thickness (average): 1.5 mm, + 3mm

Uniformity:the localthickness at any point shallnot vary fromthe averagethickness by more

than 3mm.

13 Marking

Each packageshall be indelibly markedwiththe

following:

a)the manufacturers name, mark orsymbol;

b)the manufacturers type designation andmaximumservicetemperature limit: ifthematerial contains asbestos,this shall be clearlyindicated;

c)the nominal dimensions;

d)the number ofthis British Standard,i.e. BS 3958-25).

5) Marking BS 3958-2 on or in relationto a product is a claim by the manufacturerthat the product has been manufactured inaccordancewiththe requirements ofthestandard. The accuracy ofsuch a claim is thereforesolely the manufacturersresponsibility. Enquiries as tothe availability ofthird party certificationtosupport such claims should be addressedtotheDirector, Quality Assurance Division, British Standards Institution, Maylands Avenue, Hemel Hempstead, Herts HP24SQ inthe case of certification marks administered by BSI ortothe appropriate authority for other certification marks.

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Appendix A Method oftest foralkalinity

A.1 Preparation ofsample. Fromthe bulksample,taken in accordancewith BS 2972, cutfivepieces, each ofapproximate mass5 g, fromseparateunits. Crushthese pieces and mix thoroughly.

A.2 Determination of pH. Weigh 2g ofthecrushedsample andshakewell for 10 min

with 100mL ofdistilledwater at roomtemperature.Leavetosettle for 5 min and measurethe pH ofthemixture,using astandard pH meter(seeBS 1647 and BS 3145) and decantingthesolution if necessary. Repeat thetest on afurther 2g ofthesample and report the mean pHvalue.

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Publications referredto

BS 874, Methods for determiningthermal insulating properties,with definitions ofthermal insulatingterms.

BS 1647, pH

sca

le.BS 2972, Methods oftest for inorganicthermal insulating materials.

BS 3145, Specification for laboratorypHmeters.

BS 3533, Glossaryofterms relatingtothermal insulation.

BS 3958, Specification forthermal insulating materials6).

BS 3958-1, Magnesiapreformed insulation.

BS 3958-3, Metal mesh faced mineralwool mats and mattresses.

BS 3958-4, Bonded preformed man-made mineral fibre pipesections7).

BS 3958-5, Bonded mineralwoolslabs (foruse at temperatures above 50 C).

BS 3958-6, Finishing materials;hard settingcomposition,self-settingcement and gypsum plaster.

BS 5422, Specification fortheuse ofthermal insulating materials.

BS 5970, Code of practice for thermal insulation of pipeworkand equipment.

6) Referredto inthe foreword only.7) Incourse of revision.

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