7 - Installation - Bracketing and System

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1 HDPE drainage Installation guidelines Pipe fixing system 6 Pipe fixing system 6.1 Choice of pipe fixing system The choice of the pipe f ixing system is essential to install the pipe system correctly. Depending on the temperature of the medium, the ambient temperature and the building constraints there are the following options: 1 Installation i n guide bra ckets with co rrection for axial movemen t of the pipe by means of: - Snap-expansion sockets - Deflection leg - A combination of both 2 Rigid installation 3 Embedding in concrete 4 HDP E systems belo w gr ound 6.2 Installation in guide brackets With compensation for axial movement of the pipe with snap- expansion sockets The axial movement is caused by the linear expansion of the pipe. The total expansion l triggered by the temperature difference can be calculated using formula 6.2.1 or can be taken from diagram 6.2.1. l t = L pipe . αt . t max . 10 3  The maximum length change which can be accommodated by the expansion sockets can be found in table 6.2.1. Equation 6.2.1 Length change caused by temperature difference l t = lenght change (mm) L  pipe = total lenght of pipe (m) αt = linear expansion coefficient (mm / mºK) t max = temperature difference in ºC Diagram 6.2.1 Length change caused by temperature difference d 1 (mm) Total length (mm) Min. insertion depth 20ºC (mm) Max. expansion (mm) 32 130 74 56 40 132 76 56 50 132 76 56 56 132 76 56 63 132 76 56 75 132 76 56 90 134 78 56 110 134 78 56 125 135 79 56 160 140 84 56 200 230 120 110 250 250 125 125 315 270 126 144 Table 6.2.1 length change with expansion sockets

Transcript of 7 - Installation - Bracketing and System

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HDPE drainageInstallation guidelines

Pipe fixing system

6 Pipe fixing system

6.1 Choice of pipe fixing system

The choice of the pipe f ixing system is essential to install the pipe systemcorrectly. Depending on the temperature of the medium, the ambient

temperature and the building constraints there are the following options:

1 Installation in guide brackets with correction for axial movement of

the pipe by means of:

- Snap-expansion sockets

- Deflection leg

- A combination of both

2 Rigid installation

3 Embedding in concrete

4 HDPE systems below ground

6.2 Installation in guide brackets

With compensation for axial movement of the pipe with snap-

expansion sockets

The axial movement is caused by the linear expansion of the pipe.

The total expansion ∆l triggered by the temperature difference can be

calculated using formula 6.2.1 or can be taken from diagram 6.2.1.

∆lt= L pipe . αt . t max . 103 

The maximum length change which can be accommodated by the

expansion sockets can be found in table 6.2.1.

Equation 6.2.1

Length change caused by temperature

difference

∆l t  = lenght change (mm)

L pipe = total lenght of pipe (m)

αt = linear expansion coefficient (mm / mºK)

t max  = temperature difference in ºC

Diagram 6.2.1 Length change caused by temperature difference

d1

(mm)

Total

length

(mm)

Min. insertion

depth 20ºC

(mm)

Max.

expansion

(mm)

32 130 74 56

40 132 76 56

50 132 76 56

56 132 76 56

63 132 76 56

75 132 76 56

90 134 78 56

110 134 78 56

125 135 79 56

160 140 84 56

200 230 120 110

250 250 125 125

315 270 126 144

Table 6.2.1 length change with expansion sockets

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Installation guidelines

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HDPE drainage

Pipe fixing system

The general rule regarding the number of expansion sockets to be used is

as follows:

Every expansion socket can accommodate the expansion and contraction

of a 5 meter pipe. In every pipe section the required expansion sockets

have to be installed. The number can be derived as follows (see example):

Example:

Length pipe section (L1+L2 +L3) = 18m

Installation temperature: 5°C

Temperature medium: +15°C / +75°C

Temperature difference: 75-5 = 70°K

Total expansion: 18 m x 0.18 mm/mK . 70K = 227mm

In a pipe section of 110 mm diameter this results in 227/56 = ~4.1 = 5

expansion sockets.

This general rule can be used for pipe sections of 5 meter length andlong term temperature differences ≤ 37,5°C.

With short term temperature differences, for example the emptying of a

bathtub, a reduction factor of 0.5 can be applied to the temperature

difference. In the example this would result in 0.5x227/56 = ~2.1 =

3 expansion sockets.

The general rules can be applied for pipe lengths ≤ 5 meter in most drai-

nage applications. With extreme high temperatures possibly in combi-

nation with a complex route the number of expansion sockets needs to

be calculated.

6.3 Installation in guide brackets

With correction for axial movement of the pipe with a

deflection leg

For computing the length of the deflection leg the formula 6.3.1 can be

used or table 6.3.2 and 6.3.3, depending on temperature of installation

and operation.

LB ≥ 10 x √∆l x d1,2

First the length change ∆L has to be determined at a temperature

difference ∆tmax (see paragraph 6.2.1).

Illustration 6.2.2 Pipe section with expansion sockets

Illustration 6.3.1

Installation with deflection leg

Equation 6.3.1

bepaling buigbeenlengte

L A= Bracket distance

LB= Lenght deflection legL= Pipe lenght 

GL= Guide bracket 

∆l= Length change

LB = Length of deflection leg in mm

d 1 = diameter pipe

∆l = Lenght change caused by expansion

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HDPE drainageInstallation guidelines

Pipe fixing system

Figuur 6.3.3 length deflection leg at operation temperature -40°C - 25°C 

Figuur 6.3.2 length deflection leg at operating temperature 25°C - 100°C 

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HDPE drainage

Pipe fixing system

Remark:

If the calculated deflection leg is shorter than the available length there

will be no extra load on the pipe system. If this is not the case an additional

expansion socket needs to be installed (see paragraph 6.4).

Fixing system

Check: LB1 + LB2 ≤ Allowed L A 

When the distance between both guide brackets is larger than the allowedbracket distance La the deflection leg needs additional support to prevent

sagging.

This extra bracket should not hinder the working of the deflection leg. This

can be done by a pendulum bracket. Bracket distance LA can be found in

table 8.2.3.

6.4 Installation in guide brackets

With compensation for axial movement of the pipe with

combination of 6.2 and 6.3

When possible a combination of a deflection leg with expansion sockets

is recommended. It uses the advantages of both systems and saves

expansion sockets. In illustration 6.4.1 you will find an example:

Working temperature : +15°C / +75°CPipe lengths L1 - L4 ≤ 5m

The expansion sockets take up the expansion of pipe sections L3 and L4.

Several guide brackets have to be installed. The deflection leg LB1 and LB2

compensates the length change of L1 and L2 from pipe section L1 and L2.

When the expansion is more than can be compensated in one expansion

socket a number of expansion sockets with anchor brackets need to be

used.

Illustration 6.3.4

Check fixing systemIllustration 6.4.1 Installation with deflection leg and expansion sockets

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HDPE drainageInstallation guidelines

Pipe fixing system

6.5 Rigid installation with anchor points

In some applications the Akatherm HDPE drainage systems can also be

installed using the rigid installation method. The HDPE pipe is not free to

expand and the forces cause by the expansion will be transferred com-

pletely to the brackets. Because of the forces and resulting tensions in

the pipe, the applications are limited.

Illustration 6.5.1

 Anchor point load at ambient temperature -40°C - 25°C 

Illustration 6.5.2

 Anchor point load at ambient temperature >15°C 

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HDPE drainage

Pipe fixing system

When applying this installation method, the following aspects need to be

taken into account:

The force on the bracket depends on wall thickness and diameter of the

pipe. The length of the pipe is not part of the equation. When a the pipe

diameter is reduced an anchor point needs to be placed. (The occurring

force can be found in table 6.5.1 and 6.5.2). The guide brackets need to

be installed between anchor points to prevent the pipe from buckling

(snake effect). The bracket distances are in diagram 8.2.3. At higher

temperatures the bracket distance gets smaller (diagram 8.1.1). Small

diameters are recommended to be installed with support trays.

6.6 Embedding in concrete

By embedding the pipe system in concrete it acts as a rigid system. Short

pipe sections can be embedded without any problem. With long pipe

sections certain precautions have to be taken. There will be no connection

between the concrete and the HDPE. This means that the pipe can freely

contract and expand as a result of temperature changes when no precau-tions are taken.

To prevent the axial movement in long straight pipe sections, fittings like

the akafusion coupler can be installed to serve as an anchor point. As an

alternative for the installation of anchor points snap expansion sockets

can be used. They act as an anchor point on one side and absorb the

expansion on the other side of the socket. The snap-expansion socket

can accommodate the expansion and contraction of a 5 meter pipe.

All fittings installed in the pipe system act as an anchor point and are

subdued to the expansion force.

The following precautions have to be taken when installing 45° and

88,5° branches.

When the length change is smaller than the shrinkage of the concrete no

special precautions have to be taken (see illustration 6.6.1). This is very

rarely the case.

A branch is subdued to the expansion force Fvp. This force and a possible

deformation of the fitting can be counteracted by installing an akafusion

coupler (see illustration 6.6.2) or two snap-expansion sockets (see illu-

stration 6.6.3).

Illustration 6.6.2

Illustration 6.6.3

Illustration 6.6.1

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HDPE drainageInstallation guidelines

Pipe fixing system

Both the akafusion coupler and snap-expansion socket act as an anchor

point preventing the additional load to be transferred to the branch.

When the length of the branch is more than 2 meters special precautions

have to be taken there as well.

A fitting installed in a ceiling penetration acts as an anchor point as well.

In case branches are used in this place it is recommended to use an

akafusion coupler for the jointing and embed this coupler in the concrete

as well.

6.7 HDPE systems below ground

Due to its specific features like flexibility and temperature resistance

(frost) HDPE pipe systems are very suitable for underground use.

Necessary steps:

- The bedding (1) of the pipe needs to be free of stones and other

material that can damage the pipe. The bedding must be at least100 mm deep.

- The pipe must be fully supported by the bedding to prevent sagging

and point loads.

- The consolidation and protection layer (2) must get to at least

300 mm above the pipe.

- After the pipe has been laid with the correct slope it must be

underpinned before filling in the protection layer with sand.

The compacting needs to be done by hand.

- After filling the trench with the protection layer of sand the rest of the

excavated material can be filled in and mechanical compacting can be

used.

- The trench must be as narrow as possible (Pipe dimension + 400 mm)

to avoid additional load on the pipe.

- The pipes must be laid below the frost line.