Choosing gaskets - betech.site

Choosing gaskets

Compendium

2 2 Herlev +45 4485 8100 • Bramming +45 7656 2600 • www.betech.dk Herlev +45 4485 8100 • Bramming +45 7656 2600 • www.betech.dk

Page

What are gaskets? 3

Definition of static and dynamic seals 3

Gaskets can be grouped in three main categories 4 1. Non-metallic gaskets 4 2. Semi-metallic gaskets 5 3. Metallic gaskets 5

Extensive product range 6

Gasket properties 7

Crucial factors when choosing gaskets or gasket materials 8

Approvals 9

Examples of Betech’s standard gasket materials and approvals 9

Contact stress 10

Gasket thickness 10

Requirements on flange roughness 11

Gasket materials and contact stress 11

Gasket parameters to DIN 2505 E 4/90 12

Calculations for ASME boilers and pressure vessels 13 Gasket materials and sealing surfaces 13 Effective width of sealing surface 14

Designations 15

DIN 2505 calculation 15

Applications: aggressive chemicals, steam 16

Applications: standard chemicals, air, water and gases 17

Fitting gaskets and Storing gaskets 18

Trouble Shooting 19

Bolt tightening sequences 20

Bolt tightening sequences 21

Gaskets – and a lot more 22

In short – advantages and contacts 23

ConTenTS

Herlev +45 4485 8100 • Bramming +45 7656 2600 • www.betech.dk 3Herlev +45 4485 8100 • Bramming +45 7656 2600 • www.betech.dk 3

What are gaskets?Gaskets are materials or material combinations specially designed for fitting between two flanges in order to create a level of tightness which can: • preventleakageofamediumbetweenthemat-

ing surfaces;• preventtheingressofdust,dirt,liquidorforeign

matter between the mating surfaces; • retainapressureorvacuumwithinthesealed

assembly; • serveacombinationofthesepurposes.

Definition of static and dynamic sealsGaskets are basically a means of closing (sealing) openings or protecting joints against the ingress or egressofliquidsorgases.Sealscanbegroupedintwomaincategories:staticanddynamic.

• Static seals Static seals seal two surfaces which do not move inrelationtooneanother(staticapplications).

• Dynamic seals Dynamic seals seal two surfaces which move in relationtooneanother,e.g.therotarymovementof a shaft in a housing or the reciprocating mo-vement of a rod or piston in a cylinder (dynamic applications).Somesealswhichwereinitiallydesigned for dynamic applications are, however, alsousedforstaticapplications.

Tightness In static applications, tightness is obtained through contact stress, while in dynamic applications me-diumpressurealsocontributestotightness.Forfurther information on applications and fitting, plea-serefertoourO-ringcatalogue.

pakninger


Gaskets can be grouped in three main categories1.Non-metallicgaskets2.Semi-metallicgaskets3.Metallicgaskets

1. Non-metallic gasketsNon-metallic gaskets are made of a variety of polymer materials, rubber cork, various fibre systems, gasket laminatesorPTFEmaterials.

• Rubbergasketsheetsareproducedintraditionalpolymer types: NBR, HNBR, EPDM, CR, NR, VMQandFPM.

• Rubbercorkisproducedfromcorkgranulesofvarying size, bonded by means of a polymer of NBR,CR,EPDMorVMQ.

• Fibresystemsconsistofcellulosefibres,aramidfibres, a combination of fibreglass and aramid, carbonfibresorvermiculite.Fillersareadded

to the fibres before the material is bonded with rubber.

• Laminatedgasketsconsistofastainlesssteelcore coated with gasket material on either side toenhancethetensilestrengthofthematerial.Graphite, mica and vermiculite are often used

asfacingmaterials.

• PTFEmaterialsincludeeverythingfrompurePTFE to mono or multi directional types, pro-ducedaseithersheetsorexpandedmaterial.

Sheet materials are normally used in applications where pressure is low to intermediate, where ag-gressive chemicals are present or where tempera-turesarehigh.

Segmented gaskets If gaskets are required that are larger than the size of the material used for the application in question, segments are first produced and then joined by means of adhesive bonding, vulcanisa-tionordovetailjoints.Wheregraphitematerialsareconcerned, dovetail joints can be strengthened usinggraphitetape.WherethematerialisFJ2815,a paste is used to enhance the tightness of the joint.

gaSkeTS

D

d S


2. Semi-metallic gasketsSemi-metallic gaskets consist of a metal mate-rialjoinedtoeithergraphite,PTFEorvermiculite.Semi-metallic gaskets can be spiral wound gaskets (SWG), serrated gaskets or metal reinforced gas-kets(MRG).

• Spiralwoundgasketsconsistofahelicalprofiledmetal strip interspersed with graphite, PTFE or the heat-resistant material thermiculite, which actsasthesealingelement.Dependingonoper-ating conditions, gaskets can be equipped with innerandouterrings.

• Serratedgasketsconsistofamilledmetalcorewith a coating of graphite, PTFE or vermiculite as thesealingelement.

• Metalreinforcedgasketsconsistofasteelcorewith a coating of graphite or PTFE as the sealing element.

In semi-metallic gaskets, the metal part gives the gasket strength while the facing material ensures tightness.Suchgasketsareusedinapplicationswithlow,intermediateorhighpressure.Thetemperaturethey are capable of withstanding depends on the qualityofthesteelandonthefacingmaterialused.

3. Metallic gasketsMetallic gaskets can be produced in numerous shapesandsizesfromvariousmetalalloys.Theyare primarily used in applications with high pres-sureorhightemperature.Metallicgasketsrequirehigh contact stress in order for the gasket to be compressedwithintheflangejoint.

gaSkeTS


For a gasket to function satisfactorilyit is important that the three elements of a flange joint – the gasket, the flange and the torque – are correctly designed and capable ofmeetingtherequirementsofthejoint.

Use of unsuitable flange or unsuit-able material Use of unsuitable material may cause the joint to leak, resulting in serious environmental consequencesintheformofpollutionorfire.Unnecessary down-time may also have major economicconsequences.

Gaskets should therefore never be judged on the basis of price but on their ability to seal the joint during its entire service life.

Flange joint elements:1.Gasket2.Flange3.Torque/bolt

Extensive product rangeBetech offers a comprehensive product range, in which we supplement our own products with prod-uctsfromtheworld'sleadingmanufacturers.Aswedevelop, manufacture and supply products, we are an obvious sparring partner should you require sound advice on which product best meets your particularneeds.

We are always pleased to discuss the possibilities as early as the design phase and work closely with our customers'developmentdepartments.Thisapproachensures the best, most reliable and highest quality solutions, which, at the end of the day, lead to sig-nificantsavingsandsuperiorproducts.

gaSkeTS


Gasket propertiesGasketsarenotonlyusedtocreateseals.Theycanalso be used to protect a product or its surroundings fromwearandscratching,e.g.inafashionsimilartofeltpads.Numerousfoammaterialscapableofdampeningnoiseand/orvibrationarealsoavailable.If the foam material is very porous in structure, it can alsobeusedforairorliquidfilteringpurposes,e.g.incookerhoods,etc.

By combining the material with wire gauze or similar, a filter gasket can be produced which is capable of capturing large or small particles dependingonthemeshdiameterofthegauze.The gasket can also prevent foreign matter from enteringthesystemconcernedviaairducts,etc.

Applications which require low contact stressFoamed or expanded materials of rubber or plastic are used in applications with low contact stress, e.g.coversealsformotors,electricalcabinets,etc.Assuchcoversareoftenmadeofplasticwithrelatively large distances between the bolts, a material with high compressibility at low contact stressisrequired.Thejointshouldbeequippedwith compression stops in order to prevent the materialfrombeingsubjectedtoexcessivestress.

Controlled compressionCombination gaskets can be manufactured from various materials for joints where contact stress is insufficient or where controlled compression ofthegasketmaterialisrequired.Withsuchso-called "sub" gaskets, the available contact stress is used to create the seal while the combination material is used to relieve stress, thus preventing the compressed part of the gasket from being subjectedtoexcessivestress.

Differences in contact stressIn applications with pressed metal flanges or large distances between the bolts, it may be advantageous to use materials with controlled

swellingproperties,i.e.materialscapableofcompensating for insufficient contact stress between the bolts by swelling on contact with the mediumtobesealed.

Inner ringGasket materials which are primarily used for manifolds and exhaust systems are often equipped with an inner ring of steel or copper on the side of thejointfacingthemedium.Suchinnerringsservetwo purposes: Firstly, as high-temperature materials are often relatively permeable to gases, they improvethegastightnessofthematerial.Secondly,they allow high contact stress on the side of the jointfacingthemedium.

An additional advantage of fitting an inner ring to a gasket is that the gasket material is not in physical contact with the medium and is thus protected from wear and chemical and temperature dependent deterioration.Itisthereforepossibletobroadenthe range of applications for which specific gasket materials can be used, both from the point of view oftemperatureandmedium,byfittinganinnerring.

Fibreglass and ceramic productsVarious types of fibreglass and ceramic products are ideal for packing and insulation at very high temperatures, including cords, tapes, tubes, sheets,paper,blanketsandcloths.Suchproductsare used in electrical equipment and machines, for thermal insulation of combustion chambers, and in thesteelandsmeltingindustries.Thematerialsaresuitablefortemperaturesofupto1200°C.

For applications which require high gas tightness, laminated gaskets based on mica and vermiculite areused.Suchmaterialscanwithstandtemperaturesofupto900°C.

gaSkeTS


Crucial factors when choosing gaskets or gasket materials

The most important requirements on the gasket or material concern: 1.tightness2.durability3.loosenability4.thermalconductivity5.elasticity

The way in which these factors affect the choice of gasketmaterialisdescribedbelow.

1. TightnessEvery gasket must provide a certain degree oftightness.However,gasketsareusedinanextremelywidevarietyofoperatingconditions.Most importantly, gaskets must be capable of withstandingcertainpressuresandtemperatures.They must also be capable of resisting the effects ofvariousmedia,e.g.superheatedsteam,engineexhaust,air,oil,chemicals,etc.

Furthermore, it is important to ensure that the chosen gasket can resist the mechanical stress to which it is subjected – in particular the internal pressure it must seal.Itmustalsobecapableofwithstandingthechemicals to which it is exposed, preventing it from being corroded or dissolved, and the temperatures towhichitissubjected,highorlow.

As the various gasket materials are capable of resisting different maximum contact stress, it is important to consider the relationship between the part of the gasket subjected to stress and the materialthickness.

If the gasket is to be used in screwed connections, itmayeasilybecomewarpedorbuckled.Thismusttherefore also be taken into account when choosing asuitablematerial.

When designing and dimensioning a joint, force lines in the assembly must be considered in order toensurethebestpossibleconnection.

Before choosing a gasket material, it is thus important to know the mechanical, chemical and temperature-related stresses it must be capable of resisting.

2. DurabilityIt is important that the physical properties of the gasketmaterialdonotchangeduringuse.Ifanunsuitable material is chosen the gasket may gradually lose its elasticity, become brittle or disintegrate.

Longservicelifecanonlybeassuredbychoosinga material which is suitable for the intended purpose.

Thanks to technological advances, a correctly chosen gasket can now be expected to last for as longasthemachinepartsitisdesignedtoseal.

3. LoosenabilityIn many cases, it is important that the gasketed jointmustbeloosenable,i.e.thatthegasketcanberemovedwithoutdamagingthecontactsurfaces.As standard, most gasket materials are treated with siliconetoprovidea"non-stick"surface.Inspecialcircumstances this may be replaced with a coating ofgraphiteorPTFEononeorbothsides.

4. Thermal conductivityWhen choosing gasket material, it is sometimes necessary to take into account whether the gasket is to act as a heat conductor or to provide insulationagainstheatloss.Gasketmaterialswithawide range of thermal and electrical conductances arethusavailable.

The consequences of choosing an unsuitable gasket material or type may be catastrophic – both with respect to safety and to the environment (pollution, fire, etc.).

5. ElasticityThe elasticity of the gasket material can also play animportantroleinitsuse.Ifthematerialistoprovide a tight seal throughout its expected service life, it must be capable of compensating for small flangemisalignments,surfacedefects,etc.,partlyby means of the contact stress applied and partly throughitselasticity.

gaSkeTS


ApprovalsThe various materials have various approvals or meet the requirements of public or other testing authorities:

DVGW Germanapprovalofmaterialsusedingasapplications.

SVGW Swissapprovalofmaterialsusedingasapplications.ÖVGW Austrianapprovalofmaterialsusedingasapplications.KTW Germanapprovalofmaterialsusedincoldandhotwaterapplications.W270 GermansupplementtoKTWconcerningmicrobiologicalapplications.WRAS Britishapprovalofmaterialsusedinhotandcoldwaterapplications.FDA USrequirementsonmaterialsusedwithfood.

UP401 Gasketsforhighthermalloadsinfittingsandflangesofgasmetresandpressurecontrolequipment.HTB GasketsforgasmeterconnectionstoDIN3376Parts1and2,withreferencetoDIN3374.

Fire Safe Test TÜV

Dutchinstituteatwhichgasketmaterialsaretested.

BAM Approvalofgasketmaterialsforflangejointsinoxygenpipingandfittings.TA Air MaterialswhichcomplywiththerequirementsofVDI2440.

Examples of Betech's standard gasket materials and approvals

FJ no. DVGW SVGW ÖVGW KTW W270 WRAS FDA VP401 BAM HTB TA Air

2634 x x x x x x x x x x x2639 x x x x2662 x x x x x x x x2663 x (x) (x) x x

2677 x (x) x x x x

26902698

2912C x2912D x2912C x

(X) Presently being tested

gaSkeTS


Contact stress A gasket material will shrink considerably if subjectedtoexcessivecontactstress.Theelasticityof the material is thus affected, preventing it from compensatingforfluctuationsincontactstress.

Maximum permissible contact stressIndividual gasket materials have their own specific maximum permissible contact stress depending ontemperatureandmaterialthickness.Thingasketmaterials can always withstand higher contact stressthanthickmaterials.Thethinnerthematerial,the higher are the requirements on flange joint parallelismandsurfaceroughness.

Blow outIf the gasket material is soft, the pressure between the gasket and flange must provide sufficient friction to prevent the gasket from being extruded fromthejoint,aphenomenonknownas"blowout".

Hydrostatic end forceWhen a joint is subjected to internal pressure, the pressure will attempt to force the joint apart, thus reducingthecontactstressonthegasket.Suchinternal pressure, also known as "hydrostatic end force", must be taken into consideration when calculating the minimum contact stress during operation and the testing stress, which in the majority of cases will be much higher than the operatingcontactstress.

Bolt tightening and lubricationTo ensure the correct contact stress, bolts should be tightenedusingatorquewrench.Inaddition,bolts,nuts and washers should be lubricated in order to reducefrictionandenhanceboltpreloading.

The estimated friction coefficient of lubricated joints is0.14whilethatofnon-lubricatedjointsis0.3.

Gasket thicknessGaskets should always be as thin as possible in order to achieve maximum strength and minimum leakagethroughthegasketmaterial.

The necessary material thickness is determined by the following parameters:

• Surfaceroughness:thelowertheRavalue,thethinnerthegasket.

• Compressibility:thelowerthecompressibility,thethickerthegasket.

• Contactstress:thehigherthecontactstress,thethinnerthegasket.

gaSkeTS


Requirements on flange roughness

Gasket type Gasket cross section Flange surface finish, microinch Ra

Flange surface finish, micrometre Ra

Spiral wound gaskets 125 – 250 3.2 – 6.3

Flexpro gaskets 125 – 250 3.2 – 6.3

Metallic serrated gaskets

Max. 63 Max. 1.6

MRG 125 – 250 3.2 – 6.3

Solid metal gaskets Max. 63 Max. 1.6

Metal jacketed gaskets 100 – 125 Max. 2.5

Soft cut sheet gaskets Material thickness < 1.5mm

125 – 250

Material thickness < 1.5mm

3.2–6.3

Material thickness ≥ 1.5mm

125 – 500

Material thickness ≥ 1.5mm

3.2–12.5Important-Undernocircumstancesshouldflangesealingsurfacesbemachinedinamannerwhichleavestoolmarksextendingradiallyacrossthesealingsurface.Suchtoolmarksare

practicallyimpossibletosealregardlessofthetypeofgasketused.

Gasket materials and contact stressThe usual contact stress ranges of various gasket materials are listed below.Note,however,thatmediumpressure,temperatureandgasketthicknessmustalsobetakenintoaccount.

Material type Min. MPa Max. MPa

Rubber cork 2 7Rubber materials 2 10

Cellulose materials 5 70Fibre-based gasket materials 20-30 80-180

Graphite laminates/vermiculite 20 110-160

High-pressure graphite 30 500SIGMA 13 195

SWG graphite/PTFE/vermiculite 50 150SWG IR 50 300

Serrated gaskets, graphite/PTFE 20 500MRG gaskets, graphite 20 110

MetalgasketsRTJ,softiron 235 525RTJF5 400 900RTJAISI 335 750

gaSkeTS

12 12 Herlev +45 4485 8100 • Bramming +45 7656 2600 • www.betech.dk

GASKETS

Definitions: σvu Minimum required gasket stress during assemblyσvo Maximum permissible gasket stress during assemblyσBO Maximum permissible gasket stress during operation

Gasket parameters to DIN 2505 E 4/90

Material Thickness σvu σvo σbo 100°C σbo 200°C σbo 300°C

FJ 2639 1.5 18 95 60 152.0 23 80 55 103.0 25 70 50 10

FJ 2662 1.5 23 135 60 242.0 26 115 55 223.0 28 70 43 18

FJ 2663 1.5 20 255 113 672.0 22 240 102 633.0 28 150 84 52

FJ 2677 1.5 25 260 126 742.0 27 240 110 683.0 29 200 88 56

FJ 2634 0.5 35 250 140 901.0 35 220 120 802.0 30 180 100 60

3.0 20 160 90 40

FJ 2690 2.0 20 140 140 140 140FJ 2698 2.0 20 160 150 150 150FJ 2815 1.6 20 180 140 115 90FJ 2912C 2.0 13 195 130 70FJ 2912 D 2.0 16 228 164 100FJ 2912 D 2.0 16 190 135 80

N/mm2 N/mm2 N/mm2 N/mm2 N/mm2

gaSkeTS

Herlev +45 4485 8100 • Bramming +45 7656 2600 • www.betech.dk

Gasket materialGasketfactor

(m)

Minimumdesignseating

stress (y)(psi)

Sketches and slot groups

Seating width(see table)

group column

Elastomers without liner below 75 Shore A75 Shore A and above

0.501.00

0200

(1a), (1b)(1c), (1d)

(4), (5)

II

Elastomers with liner 1.25 400

Fibre-based gasket materials 1.75 1100

Graphite sheets FJ2695foilFJ2690FJ2698

2.002.002.00

900900

2500(1a), (1b)

MRG gaskets 2.0 2500 (1a), (1b)

Serrated gaskets 2.0 2500 (1a), (1b)

Spiral wound gaskets, standard type 3.0 10000 (1a), (1b)

Spiralwoundgaskets,LStype 3.0 5000 (1a), (1b)

Corrugated metal gaskets with gasket material or corrugated metal beaded with liner

Soft aluminiumSoft copper or brassIron and soft steelMonel with 4-6% chromiumStainless steel and nickel-based alloys

2.502.753.003.253.50

29003700450055006500

(1a), (1b)

Corrugated metal


2.753.003.253.503.75

37004500550065007800

(1a), (1b)(1c), (1d)

Smooth metal beaded with

liner


3.253.503.753.503.753.75

550065007600800090009000

(1a)2, (1b)2

(1c), (1d)

(2)

Machined metal


3.253.503.753.754.25

5500650076009000

10100

(1a), (1b)(1c), (1d)

(2), (3)

Pure metal gaskets


4.004.755.506.006.50

880013000180002180026000

(1a), (1b)(1c), (1d)

(2), (3)(4), (5)

I

Ringtypejoint(RTJ)gaskets

Iron and soft steelMonel with 4-6% chromiumStainless steel and nickel-based alloys

5.506.006.50

180002180026000 (6)

Note:

Thistableliststhemostcommonlyusedgasketmaterialsandsealingsurfaces.Thesuggesteddesignvaluesformandyhaveprovedtobesatisfactoryduringoperationwith

theeffectivesealingsurfaces(b)showninthetableonthefollowingpage.Thedesignvaluesandotherinformationgiveninthetableareforguidanceonlyandarenotobligatory.

D

d S

D

d S

D

d S

D

d S

Calculations for ASME boilers and pressure vessels Gasket materials and sealing surfacesGasket factor (m), operating conditions and minimum seating stress (y)

GASKETS

13Herlev +45 4485 8100 • Bramming +45 7656 2600 • www.betech.dk 13

gaSkeTS


Calculations for ASME boilers and pressure vessels Effective width of sealing surface – see note (1)

Sketch of sealing surface,enlarged

Effective width of sealing surface, b0

Column I Column II

(1a)

N2

N2(1b)

See note (2)

(1c)

(1d)See note (2)

(2)

W + N4

W + 3N8

(3)

N4

3N8

(4)See note (2)

3N8

7N16

(5)See note (2)

N4

3N8

(6)

W8

Effective width of sealing surface, b

b = b0 if b0 ≤ 1/4”;b=0.5√b0 if b0 > 1/4”

Positioning gasket force

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N

W + T2

W + N4 max.( (

; W + T2

;

W ≤N

W ≤N

W ≤N/2

W ≤N/2

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N0.4mmelevation

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N

N N

N

W T

N

W T

W

W

W

W

HGG Gh

bO.D. på pakflade

For b > 6,35 mm0 For b < 6,35 mm0

HGG Gh

Ø Pakflade

N

N

N

N

N

N

W + N4 max.( (

0.4mmelevation

gaSkeTS

Notes:

(1)Gasketfactorsonlyapplytogasketswithinthebolts.

(2)Whereroughnessdoesnotexceed0.4mmindepthwith0.8mmdistanceinwidth,sketches(1b)and(1d)shouldbeused.


Symbol Designation UnitA Gasket area mm²bD Gasket width mm

dD

Gasket diameter in centre of gasket area

mm

d1 Inside diameter of gasket mmd2 Outside diameter of gasket mmF1 Internal pressure N

FDBU

Minimum required tightening force during operation

N

FDVU

Minimum required tightening force during assembly

N

FSBU Minimum bolt force during operation N

FDBO

Maximum permissible tightening force during operation

N

FDVO

Maximum permissible tightening force during assembly

N

S Safety factorp Internal pressure N/mm²

FSBO Maximum bolt force during operation N

σvu

Minimum required gasket stress during assembly

N/mm²

σvo

Maximum permissible gasket stress during assembly

N/mm²

σBU

Minimum required gasket stress during operation

N/mm²

σBO

Maximum permissible gasket stress during operation

N/mm²

m Gasket factorFSO Bolt force during assembly N

DIN 2505 calculation FDBU is the minimum required tightening force during operation if joint tightness istobeassured.Thesafetyfactor(S=1.2)allowsforunforeseenconditionsduringoperation.Asafetyfactorof1.3canbeusedforgasketsheets.

FDBU = dDxπxbD x σBU x S, where σBU = m x p

FDBO = dDxπbD x σBO

F1istheforcegeneratedbytheinternalpressure.

F1 = dD2xπxp/4

FSBU> = F DBU + F1

DesignationsDesignations of several characteristics relevant to the choice of gas-ketarelistedbelow.AlldesignationsarefromDIN28090September1995.

gaSkeTS


Aggressive chemicals

°C

Bar

0

5

10

15

20

25

30

35

40

45

25 50 75 100 120 125 150 175 200 225 250 260 275 300 325 350 400

FJ2815

FJ2698

FJ2912C

FJ2912D

Steam

0

5

10

15

20

25

30

35

40

45

25 50 75 100 120 125 150 175 200 225 250 260 275 300 325 350 375 400 425 450 475 500

°C

Bar

FJ2677

FJ2663

FJ2815FJ2698

FJ2639

FJ2662

FJ2634

ApplicationsThe specified gaskets can be used under the conditions shown without further testing if due regard is given tobolttightening.Seepage12.

Contact Betech

Contact Betech

gaSkeTS


ApplicationsThe specified gaskets can be used under the conditions shown without further testing if due regard is given tobolttightening.Seepage12.

FJ2815

FJ2698

FJ2677FJ2912C

FJ2912D

FJ2663

FJ2662

FJ2639

General chemicals

0

5

10

15

20

25

30

35

40

45

25 50 75 100 120 125 150 175 200 225 250 260 275 300 325 350 375 400 425 450 475 500 525 550 575 600 625 650 675 700 725 750 775 800

°C

Bar

FJ2698

FJ2815

FJ2663FJ2662FJ2639

Air, water and gases

0

5

10

15

20

25

30

35

40

45

°C

Bar

25 50 75 100 120 125 150 175 200 225 250 260 275 300 325 350 375 400 425 450 475 500 525 550 575 600 625 650 675 700 725 750 775 800

Contact Betech

Contact Betech

gaSkeTS


Fitting gasketsTo obtain a reliable flange joint, it is imperative that thegasketbefittedcorrectly.

It is also important that the bolts and surfaces to be sealed are selected in accordance with the contact stress required by the chosen sealing material or gasket.

Clean the sealing surfaces thoroughly without scratching them and ensure that they are com-pletelydry.Checkthebolts,nutsandwashersfordefectsandrust.Cleanorreplaceifnecessary.

Bolts, nuts and washers should be lubricated on all load-transmittingsurfaces.

Check that the gasket has the correct shape, is made of suitable material and is free of imperfec-tionsandscratches.Alwaysusedrygaskets.

Positionthegasketcarefullybetweentheflanges.Neverusejointpaste,releaseagents,grease,etc.onthegasketorflanges.

Bring the flanges together and tighten the bolts with yourfingers.Wherelargeflangesareconcerned,awrenchshouldbeused.

Alwaysusesuitabletools,i.e.acalibratedtorquewrenchorotherapprovedtensioner.

To ensure uniform distribution of contact pressure, the bolts must be tightened in a cross-pattern se-quence to the recommended torque in five steps:

1)Tightentheboltsbyhand.

2)Tightentoapprox.30%oftherecommendedtorque.

3)Tightentoapprox.60%oftherecommendedtorque.

4)Tightento100%oftherecommendedtorque.

5) Re-tighten to 100% torque in a clockwise sequencetoensureuniformcontactstress.

Forsafetyreasons,neverreuseagasket.

Storing gasketsFibre-based gasket materials consist of various fibre systems, fillers and polymers, all of which aresubjecttoageing.Asaresult,themechanicalpropertiesofthegasketchangeovertime.

Gaskets should never be stored for more than two or three years and must:

• alwaysbestoredinacool,darkplace–protectedfrom sources of heat and direct sunlight;

• alwaysbestoredinadryenvironment;

• alwaysbestoredawayfromanysourcesof electrical discharge (ozone production);

• alwaysbestoredhorizontally;

• neverbehungfromanailorfolded.

Gaskets of PTFE or graphite are not subject to ageing in the same way as fibre-based gaskets, butshouldalsobestoredhorizontally.

gaSkeTS


Trouble Shooting

Good preparation ensures good performance

• Handlewithcare

• Keepinpackage

• Protectfromdamageandtheweather

• Stack;don’thang

• Checkflangesurfacesforcorrectfinish,blemishes,flatnessetc.

• Verifythatproperstudmaterialisbeingused

• Checkconditionofstudsandnut

• Ifwashersareusedtheymustbehardened

• Lubricatethreadsandbearingsurfaceofnuts

• Don’tapplyanycompoundsorpastesonthegasket

• Usethecorrect,new gasket

• Don’tsecurethegaskettotheflangewithducttape

• Useacrossboltingpatterninincrementalsteps;thengobolt-to-bolt

• Applysufficientload

gaSkeTS


Bolt tightening sequencesBolt Torque Sequence

8

4

6 2

7

3

51

8 Bolt

s 8

4

10

6 2

11

7

3

9

51

12

8

12

4

14

610

2

15

7

11

3

13

591

16

8

16

4

10

18

614 2

11

19

7

15

3

9

17

5131

12

20

16 B

olts

20

12

4

22

14

6

1810 2 23

15

7

19

11

3

21

13

517

912416

8

24 B

olts

12 B

olts

20 B

olts

gaSkeTS


Bolt tightening sequences

1 179

255

21

13

29

3

19

11

27

7

2315

3121810

26

6

22

14

30

4

20

12

28

8

2416

32 1 2 3 417

18

20

33

36

9

10

1228

2726

25424187

65

2122

23

24

37

38

39

40

13

14

19

11

35

34

4443

2916

15

323130

1 2 3 450

51

25

27

1011

41

1718

1920

338765

5655

5453

29

32

15

14

134546

47

52

44

9

28

3435

2221

48

3724

23

36

16

3130

12

4342

49

26

4039381 2

43

67

6364

910

111236353433

565554

5320

1918

1748

4746

4543

26 2728

6162

2544

66653231

3029

4039

3837

131415

1657585960

2122

2324

4950

5152

5 6 7 8 4241

68

32 B

olts

44 B

olts

56 B

olts

68 B

olts

Bolt Torque Sequence

gaSkeTS


1. The Development PhaseOur starting-point is always your specific project. It could turn out to be a very sound investment if you choose to involve us at an early stage and thereby combine your own particular insight with our comprehensive experience and highly specialized knowledge about every single one of our many products.

This also means that your R&D department can quickly and inexpensively test new designs, materials and thicknesses. We work with GPS tolerances for technical drawings and transfer your drawings to cutting programs without any need for tools. Our technical experts will help you choose the perfect material for your application and help design the flanges for the parts in order to ensure that the application ends up having the optimum sealing qualities.

2. The Production LineIn the manufacturing phase, our strong and comprehensive portfolio enables us to act as your total supplier so that you can make all your purchases in one place. This means, among other things, that you can save time and significantly reduce your logistics costs.

3. The Service PeriodWe can deliver very small batches of customer-specific top quality gaskets for very close tolerances without any wait at all (Kanban), and we can produce anything from a single prototype to grand batches. This means that your own service department can reduce their stock significantly.

This compendium is about gaskets, but Betech has a lot more to offer. Betech is also a total supplier of seals, mouldings, bellows, vibrations dampers and sheet metal working.

We specialize in solutions that include polymers and offer comprehensive technical consulting within all of the above-mentioned product areas. At Betech you will meet some of the most skilled and experienced specialists in the business, who will provide you with creative and solution-oriented consulting.

Betech was founded in 1922 and has become one of the leading suppliers in its field. As a supplier, we cooperate with the world’s most well-reputed manufacturers, among them Hallite, Flexitallic, Reinz and Barry Controls. At our factory in Bramming, Denmark, we produce customer-specific solutions within machine-made and handmade seals, and we also perform sheet and plate work on state-of-the-art machinery.

We strengthen your products and competitive performance

At Betech, it is our mission to strengthen the products and competitive performance of our customers. We aim to offer you capable, professional consulting and close cooperation all the way through the development and manufacturing of your products – throughout their entire life cycle.

gasketsand a lot more


Contacts for further information

For more information about gaskets, other products of Betech or our company in general please do not hesitate to contact us by phone or email:

Sales Department Tel. +45 4485 8100 – [email protected]

When you enter into a collaboration with Betech, you get:

• An experienced consulting team with some of Scandinavia’s most skilled technical experts

• An innovative and solution-oriented sparring partner all the way from design to manu - facturing and maintenance

• A total supplier with an extensive product portfolio and fast and flexible delivery

We strengthen your products and competitive performance

Our missiOnimproving your products

Sales

Product Life Cycle

Time

1 32 3+

1. Development•Broadbusinessexperience•Specializedproductknowledge•Quickmanufacturingofprototypes• Inexpensivetests

Betech offers:

2. Production•Allpurchasinginoneplace• Timesaved+lowerlogisticscosts• Topquality•Securityofsupply

3. Service•Shortdeliverytimes•Sparepartsondemand

512

DK

07-

2011

Betech A/S Industrivej 29 DK-6740 Bramming

Tel. +45 7656 2600 Fax +45 7510 1558

Betech A/S Vesterlundvej 4 DK-2730 Herlev

Tel. +45 4485 8100 Fax +45 4492 7800 [email protected]

See our catalogue collection on

www.betech.dk

...expresses the essence of our mission.Optimizing and enrichment of the customers’ products

are our challenging goals.

200

GB

03-

2010

200-

en/0

9-20

15

mailto:[email protected]

www.betech.dk

Choosing gaskets - betech.site

Documents

Transcript of Choosing gaskets - betech.site