Rubber expansion joints

General description of rubber expansion joints

Expansion joints are used in appli-

ances, machinery, apparatus and

pipe systems where space is limited:

■ to compensate for movement

■ to compensate for expansion

caused by dif

ferences in tempera-

ture

■ to reduce tension

■ to absorb noise and vibration

transmission

■ to compensate for ground, and

foundation settlement

■ to compensate for pipeline

movement aboar

d ships

■ as adapters to compensate for

installation inaccuracies

■ as dismantling pieces for fittings

■ as elastic sealing elements, where

pipelines pass thr

ough walls

Rubber expansion joints are used in a

variety of industrial applications:

■ Machine engineering

■ Domestic industry

■ Processing plant engineering

■ Power station technology

■ Shipbuilding

STENFLEX

rubber expansion joints

have served with distinction for more

than 45 years. They are the preferred

flexible pipe connection elements of

choice in manufactured appliances,

machinery, apparatus and piping en-

gineering.

Constant further development and

innovations update our product range

to meet the needs of current and

changing markets. Numerous patent

applications and on-going optimiza-

tion of the formulae for our rubber

grades ensure that our customers

always receive state-of-the-art pro-

ducts; highly reliable and of superior

durability.

The large-scale industrial manufac-

ture of the rubber bellows, constant

control of compliance with all manu-

facturing, business and quality

processes in line with EN ISO

9001:2008 and decades of experi-

ence in the development and manu-

facture of rubber expansion joints: all

this guarantees a uniform product of

the highest standard. It underlines

the STENFLEX

Quality Claim.

Nearly all nuclear plants throughout

Europe are equipped with

STENFLEX

expansion joints. Many

of our rubber expansion joints have

Purpose

been used in a large variety of appli-

cations. They have served on site in

trouble-free

operation for decades. STENFLEX

rubber expansion joints have passed

national and international type ap-

provals and suitability tests and are

certified by numerous classification

societies.

Our engineers in the fields of me-

chanical-, and processing-plant engi-

neering work hand-in-hand with our

modern R & D department. They are

always available for technical consul-

tation and ready to help in solving

specific application problems at any

time.

www.integflex.co.uk

Rubber expansion joints

General description of rubber expansion joints

Rubber bellows

Material qualities

STENFLEX

rubber bellows are made

of elastic synthetic elastomers. Their

wide range of industrial applications

are covered with combinations of the

four standard elastomer qualities

EPDM, CIIR, NBR and CR together

with tensile reinforcing elements.

Elastomers are basic materials that

are processed by adding sulphur,

fillers, plasticizers and aging protec-

tion agents to produce rubber com-

pounds suitable for vulcanization.

Under the influence of temperature

and pressure the vulcanization

process (cross linkage) converts the

rubber compounds into rubber grades

– with their typical elastic properties.

Material properties such as hardness,

elasticity, tensile strength, tempera-

ture resistance, etc., are rated to the

corresponding application. Docu-

ments detailing media resistance of

the rubber grades are available on re-

quest.

Structure

STENFLEX

rubber bellows have

been optimized by calculation and

verified by experimentation to pro-

duce highly elastic pressure-resistant

bellows with flow contours to meet

demanding absorption tasks.

Rubber bellows have a three-ply wall

structure:

■ inner ply (core) of medium-resis-

tant rubber compound

■ intermediate ply of rubber com-

pound with tensile elements for r

inforcement

■ outer ply (cover layer) of weather-

oof rubber compound

The arrangement of the tensile rein-

forcing elements is ascertained by

calculation and experimentation to

ensure that the force of pressure with-

in the bellows can be absorbed. A

permanent bond exists between the

embedded tensile reinforcing ele-

ments and the rubber material.

The rubber grades used for the inner-

and outer ply are empirically defined

rubber compounds rated to certain

properties (media resistance, ozone

resistance, UV resistance, elasticity,

wear-proof characteristics, etc.)

Properties

Applications

Rubber

grade

EPDM

Ethylene

propylene

diene

rubber

CIIR

Chloro

isobutylene

isoprene

rubber

NBR

Nitril-

butadiene

rubber

Polychloro-

prene

rubber

Water, hot water, cooling water,

sea water, steam, acids, lyes,

pickling lyes, hypochlorite so-

lutions etc. Special type AS in

heating systems (as per DIN

4809 up to +110 °C)

Recommended for drinking

water supply systems

Municipal gas, fuel oil, mineral

oil, blast furnace waste gas,

compressed air systems,

cooling water with antifreezing

compound

weather-proof outer ply (cover

layer)

Heat- and weather-proof rubber grade with special resis-

tance to highly oxidizing media and very many chemicals

(not oil-resistant). Temperature resistance in continuous op-

eration* from –40 °C to +100 °C.

Resistant to hot water up to +100 °C.

Rubber grade complying with the latest hygiene directives

for drinking water systems as per KTW recommendation

by the German Health Department (KTW = Plastics for

drinking water). Impermeable to gas.

Temperature resistance in continuous operation* –40 °C to

+90 °C. Resistant to hot water up to +90 °C.

Quality with excellent oil resistance, very resistant to

swelling, e.g. even in contact with petrol/benzole mixture,

impermeable to gas for hydrocarbons. Temperature resis-

tance in continuous operation* –30 °C to +100 °C, resis-

tant to hot water up to +70 °C.

Multi-purpose rubber grade with good oil, weather and

flame resistance, very good resistance to ageing. Resistant

to various organic and inorganic chemicals. Impermeable

to gas for hydrocarbons. Temperature resistance in contin-

uous operation* from –30 °C to +100 °C, resistant to hot

water up to +70 °C.

Trade

name

Buna AP

Keltan

Vistaton

Butyl

Perbunan

Neoprene

Baypren

orange

white

red

STENFLEX®

colour code

*The given temperature for continuous operation refers solely to the rubber grade. When reinforcements or other filling material is embedded, the temperature

resistance in continuous operation increases.

www.integflex.co.uk

Universal rubber expansion joints

Structure:

Rubber bellows with connection parts (flange or thread)

Movement absorption:

Axial, lateral, angular and simultaneous movement absorption is possible. Uni-

versal expansion joints with two bellows and a connecting pipe are used to ab-

sorb large movement.

Fixed points:

To absorb axial force a pipe’s fixed points must be robust. Pipe routing must be

correct.

Lateral rubber expansion joints:

Structure:

Rubber bellows with flanges and laterally movable restraints.

Movement absorption:

Lateral shift of the expansion joints is possible. The restraint absorbs axial re-

action force and relieves the pressure on the pipe’s fixed points. In double joints

the type of restraint allows for movement on one plane; in ball joints it allows for

all-around movement. Lateral expansion joints with two bellows and a connect-

ing pipe are used to absorb large movement.

Fixed points:

Only light fixed points are required to absorb force from lateral movement and

friction force.

Angular rubber expansion joints:

Structure:

Rubber bellows with flanges and hinge restraint. The rotating axis of the hinge re-

straint is in the middle of the bellows.

Movement absorption:

Angular movement of the expansion joint is possible. The angular joints regulate a

defined angular movement, absorb axial reaction force and relieve the pressure on

the pipe’s fixed points.

We differentiate between angular expansion joints with a hinge (bellows’ angular

movement guided on one plane) and angular expansion joints with a cardan hinge

restraint (bellows movement guided on two planes). Angular expansion joints with

connecting pipe are used to compensate large movements.

Fixed points:

Only light fixed points are required to absorb angular movement force and friction force.

Development/Design

STENFLEX

rubber expansion joints

are rated by state-of-the-art comput-

ing techniques (which include the Fi-

nite Element Method). They are opti-

mized under experimental conditions.

Our development engineers use the

most up-to-date development tools

throughout the development stage to

validate the construction process in

terms of form, function and installa-

tion. This means we offer our cus-

tomers the following advantages:

■ Design and development in line

with the specific r

equirements, re-

sulting in safe and extremely

durable expansion joints

■

Efficient products by incorporating

superior pr

oduct functionality

■ Structures that are easy to install

■ Reduced lead times for special de-

signs

Versions

axiallateralangular

The excellent features of STENFLEX

rubber expansion joints include out-

standing absorption of movement

and good vibration damping proper-

ties. Depending on the particular ex-

pansion joint type, a maximum of the

forces produced by the pipe internal

pressure is absorbed by the specific

design of the expansion joint itself,

and not passed on to neighbouring

system components.

Rubber expansion joints differ accord-

ing to the following criteria:

■ type (universal/lateral/angular ex-

pansion joints)

■ pipe connection type (flange,

thr

ead)

■ rubber quality of the bellows (rated

to the media transported in the

pipes)

■ bellows structure (rated to the

essure and temperature load)

Our expansion joints are delivered

ready to install. Together with the

standard versions featured in the

catalogue, special versions can also

be developed and produced on re-

quest for special operating condi-

tions. Connection parts (that deviate

from DIN) such as ISO, ANSI, BS, VG

and SAE standards etc. are also pos-

sible.

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Rubber Expansion joints

Program summary

Type DN

A-1

AR-1

AS-1

B-1

R-1

RS-1

DN 20-1000

DN 20- 400

DN 25- 400

DN 32- 400

DN 25- 300

PN 16

PN 25

PN 16

+90 °C

+110 °C

+90 °C

EPDM, NBR, CIIR

EPDM, NBR

EPDM, NBR, CIIR

EPDM, NBR

1.13

1.15

1.17

1.21

1.33

C-1

DN 300-2400

DN 300-2800

DN 300-3600

+90 °C

EPDM, NBR, CIIR

C-2 DN 300-2000

DN 300-2000

+90 °C

EPDM, NBR, CIIR

AG-5

AS-5

DN 20-50

DN 32-40

PN 16

+100 °C

+110 °C

EPDM, NBR, CIIR

EPDM, NBR

Universal rubber expansion joints

D-11

D-30

DN 300-7500

PN 0,7

EPDM, NBR

D-21

D-22

D-41

D-42

DN 150-7500

PN 0,7

+90 °C

EPDM, NBR

GR-

SAE

DN 40-125

NBR

+110 °C

PN 16

1.13

1.15

1.17

1.21

1.33

1.35

1.19

1.20

1.19

1.20

1.231.23

1.25

1.27

1.291.29

1.31

PN 16

PN 10

PN 4

PN 10

PN 4

PN 16

+90 °C

essure

rate

bar

Max. operating

temperature

Rubber grades

Connection

parts

Page

rotating

flanges

press-on

retaining

flange

female and/or

male thread

press-on

retaining

frame

rotating

SAE flange

press-on

retaining

flange

rotating

press-on

retaining

flange or

tightening

straps

VP-1

DN 40- 150

VG 85356

+90 º C

EPDM, NBR

VS-1

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Type DN

Pressure

rate

bar

Max. operating

temperature

Rubber grades

Connection

parts

Page

press-on

retaining

flange

rotating

flange with tie

rod restraint

press-on retaining

flange with tie rod

restraint on

segments

rotating

flange

rotating

flange

rotating flange

with hinge

restraint

press-on

retaining

flange with

hinge restraint

press-on re-

taining flange

with hinge

restraint on

counter flange

rotating

flange with tie

rod restraint

press-on

retaining

flange with tie

rod restraint

press-on retaining

flange with tie rod

restraint on

counter flange

W-1

W-2

DN 80-3400

DN 200- 800

PN 1

PN 2,5

+90 °C

EPDM, NBR

A-2

AR-2

AS-2

B-2

R-2

RS-2

DN 20-1000

DN 20- 400

DN 25- 400

DN 32- 400

DN 25- 300

PN 16

PN 25

PN 16

+90 °C

+110 °C

+90 °C

EPDM, NBR, CIIR

EPDM, NBR

EPDM, NBR, CIIR

EPDM, NBR

1.37

1.39

1.41

1.43

1.53

1.55

A-4

AR-4

AS-4

B-4

DN 20-1000

DN 20- 400

DN 25- 400

DN 32- 400

PN 16

PN 25

PN 16

+90 °C

+110 °C

+90 °C

EPDM, NBR, CIIR

EPDM, NBR

1.37

1.39

1.41

1.43

1.45

C-31 DN 300-1000

DN 300-1000

DN 300-2400

DN 2500-3600

PN 16

PN 10

PN 4

+90 °C

EPDM, NBR, CIIR

1.47

C-32 DN 300-3600 on

request

+90 °C EPDM, NBR, CIIR

1.48

C-35 DN 300-3600

request

+90 °C

EPDM, NBR, CIIR

1.49

1.51

1.57

1.59

E DN 20-250 PN 10

+90 °C

EPDM, NBR

DN 25-100

DN 125-250

PN 16

PN 10

+90 °C

EPDM, NBR

A-3

AS-3

DN 32-1000

DN 25- 400

PN 16

+90 °C

+110 °C

EPDM, NBR, CIIR

EPDM, NBR

1.61

C-41 DN 300-3600

request

+90 °C

EPDM, NBR, CIIR

1.62

C-42 DN 300-3600

request

+90 °C

EPDM, NBR, CIIR

Angular rubber expansion joints

Wall sealing expansion joints

Lateral rubber expansion joints

1.63

on request

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Technical annex

Movement and force at compensators

Before opting for a compensator type,

it is important to decide on how a

change in length of a pipe system is to

be compensated.

The choice of the compensator type

depends essentially on the securring

expansion, on the routing of the pip-

ing system and on the space avail-

able.

Pipe expansion can be absorbed by

shift and deflection of a certain type of

compensator.

Movement

When choosing a compensator the

following types of movement must be

considered:

■ axial movement

■ lateral movement

■ angular movement

Rubber compensators

If both axial and lateral (superim-

posed) movement are simultaneously

introduced into a rubber compen-

sator, its maximum extension in the

axial direction and its ability to absorb

the highest rated movement are re-

duced (see diagram

).

The interrelation of superimposed an-

gular and axial movement is shown in

diagram

.

Steel compensators

If axial and lateral movement are si-

multaneously introduced into a steel

compensator (superimposed move-

ment), the lateral share is converted

by an equation into an equivalent axi-

al path and must not exceed 100 %

when added.

Please contact our Technical Consul-

tation Service.

Restriction of the lateral movement with simultaneous

axial movement (universal expansion joints)

Restriction of the angular deflection with simultaneous

axial movement (universal expansion joints)



angular angle



Rubber Expansion Joints:

Influence of temperature on the permissible

inner pressure

The maximum permissible operating pressure of rubber

expansion joints stated in the data sheets refers to a

temperature of 20 °C. The pressure must be reduced with

rising temperature as the strength of bellows materials

decreases with rising temperature (see table).

max. permissible operating pressure (bar)

*for brief periods (max. 100 hours)

50 % of max.

lateral movement

lateral travel

axial compression

axial extension

axial compression

axial extension

100

110

120

130

9.5

Temperature

°C

A, AG, B, R

bar

AS, RS

bar

GR-SAE

bar

E, G

bar

type series

100

2.5

2.2

1.7

2.5

2.2

1.7

3.8

3.5

2.8

1.5

1.5*

3.8

3.5

2.8

1.5

1.5*

5.5

2.5

2.5*

5.5

2.5

2.5*

5.5

2.5

2.5*

0.9

0.7

0.4

0.4*

9.5

Temperature

°C

bar

type series

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Connection parts

able pipes, flanges and threads.

Flanges

Flanges for rubber expansion joints in

the series A, AR, AS, B, E, G, GR-SAE

R and RS have a specially turned

groove designed to accommodate

the rubber rim. They are fitted in a ro-

tating position at the bellows to sim-

plify mounting to the pipeline.

STENFLEX

rubber expansion joints

in the series C, D, and W have press-

on retaining flanges.

The flanges have a stabilizing collar

on the side facing the bellows (mould-

ed bead or welded rim). This stabi-

lizes the rubber bellows and ensures

compliance with safety spacing be-

tween the ends of the screws and the

rubber bellows throughout the entire

range of pressure and movement. The

purpose is to eliminate the risk of

damage to the rubber bellows caused

by the screw ends. Special flanges

are fitted with stabilizer rings.

Standard screws can be used be-

cause the flanges are drilled for

through-bolts according to EN 1092

(DIN 2501). Other pitch circles and

The following special versions are

possible on request:

■ All-round machined flanges

■ Special materials deviating from the

standar

d data sheet (stainless

steels, aluminum, plastic, etc.)

Flanges made of unalloyed steels are

galvanized and blue chromated or

given an anti-corrosion prime coating.

Stainless steel is used to meet

tougher corrosion protection require-

ments. Other materials and forms of

corrosion protection (hot-dip galva-

nizing, special varnish, coating etc.)

can be supplied on request.

pumps, tanks etc., by flanges or

screwed union. The connections are

standardized to fit commercially avail-

STENFLEX

rubber expansion joints

are supplied ready for installation.

They are connected to pipes, fittings,

bores are possible e.g. to ANSI (ASA),

BS, SAE and for ventilation systems.

Flanges vary according to expansion

joint type (universal, lateral and angu-

lar expansion joints) and size as fol-

lows:

■ Standard flanges

■ Flanges with molded ears

■ Flanges with welded ears

■ Oval flanges

■ Flanges with two pitch circles

■ Flanges made to other standards

Standar

d flanges for rubber expan-

sion joints are machined to produce a

fit within the tolerances.

Abbreviation as per DIN EN (DIN)Flange material Material No. as per DIN EN

Unalloyed steel 1.0038 S235JR

1.0577 S355J2

Stainless steel 1.4541 X6CrNiTi18-10

1.4571 X6CrNiMoTi17-12-2

1.4404 X2CrNiMo17-12-2

Standard flange with turned groove

for rubber rim and stabilizing collar

(universal expansion joint)

Flange with second pitch circle for the

restraints (lateral expansion joints)

Oval flange (angular expansion joints) Flange as per SAE standard (type

GR-SAE)

Flange with molded ears for the re-

straints (lateral expansion joints)

Flange with welded ears or molded

ears for the restraints (lateral

expansion joints)