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Isoplus® Static Calculation<br />

Program Installation<br />

This program needs at least the following configuration to work properly:<br />

Hardware configuration: PC 486 66Mhz with 8 MBytes of RAM, 3 MBytes of free disk space,<br />

SVGA video card.<br />

Software configuration: Windows 95 / NT.<br />

To install the program, insert the disk number 1 in the floppy disk drive; within Windows, select<br />

'Execute/Run'. A blank prompt will appear asking the command line; write a:\setup.exe and then press<br />

enter on the keyboard. The program will automatically create the icons and the group in the program<br />

menu list.<br />

Please note: this software is provided with two languages, German and English, and the images found in<br />

this manual are taken from the English version only. The contents are the same for both languages.<br />

Starting Isoplus® Static Calculation<br />

The first window you will see is the following:<br />

It informs the user that upon the field experience some limits should be observed during the pipe design,<br />

the first in the dilatation and the second in the deflection. So when using compressible dilatation zones<br />

with PUR or PE cushions the suggested limits are the following, which depend themselves upon the<br />

diameter of the pipes involved in the calculation: for a pipe between DN 20 and 200 dilatation and<br />

deflection should not exceed 40.0 mm; for a pipe between DN 225 and 300 the limit is set to 50.0 mm<br />

and finally over DN 300 the limits are 60.0 mm. With a deflection greater than 65.0 mm the use of a<br />

stonework trench is recommended. These limits are, however, changeable every time and they will


emain in the program memory: it is possible to change every limit simply inserting the new value in the<br />

corresponding text field. Every time these limits will be exceeded an appropriate warning message will<br />

be displayed (see after). It is also possible to disable all the warnings simply checking the "Ignore these<br />

limits" button. Pressing the OK button will let you to proceed with the next window:<br />

With this window you will set the default ground type that will be used in the next calculations. Please<br />

note that the you will be able to change the ground type anytime during the work. After having selected<br />

the default ground type (and having pressed the button) the main program window will be displayed.


The selectable menus are the following<br />

Exit:<br />

the exit menu lets you close the application.<br />

Language: With this menu it is possible to switch between german and english language. All the<br />

changes are simultaneous and will affect also the output (i.e.: the printed sheets will be in the selected<br />

language.) The selected language will be maintained in the next program run.<br />

View detailed static calculations: a windows with in-depth static calculations will be showed.<br />

Normally this window is hidden and is detailed in the "Further Calculations Window" section.


Print: the print menu lets you examine, print and export the data sheet. The first time you push<br />

this button, a window with all the data will be displayed. The window shows roughly the data as they<br />

will be printed on the paper sheet. In the left-upperside window corner another 'Print' menu will be<br />

prompted: clicking on this menu another window will appear (the contents reflect the window's<br />

language):<br />

Using this window you'll be able to select how many copies, the kind of printer you are going to use and<br />

so on.<br />

Compensations: four kind of compensations are actually available:<br />

Selecting L, Z or U compensation simply change the data in the compensation window (see below);<br />

selecting the axial compensation will force the program to take the data set out in the main window<br />

'Pipes laying with L-Z-U compensation' and to transfer them in the 'Axial Compensation' window. So<br />

switching from L-Z-U compensation to axial compensation will take the main values present in the L-<br />

Z-U window (Norm, Stress, DN, Steel Type, Design Pressure and Temperature and so on) and will<br />

use them for the calculations in the axial window. Switching from the axial window back to the L-Z-<br />

U the values will be maintained.


Settings: with this menu, it will be possible to select the 'Limits' window<br />

This window is responsible for setting/resetting the dilatation and/or deflection limits for different pipe<br />

dimensions. When the 'Ignore this limits' flag is set, the program won't inform the user about the<br />

limits exceeding.<br />

There are other windows on the screen, depending from which kind of compensation is used. In the<br />

following sections each window type will be discussed. When a L-Z-U compensation is used, on the<br />

screen the following windows are visible:<br />

Header Data:<br />

data sheet general informations<br />

Ground Samples: basis settings for different kinds of ground<br />

T-pieces: calculates the dilatation values for a side derivation (*)<br />

Further Calculations: global static values in the pipe - normally hidden<br />

Expansion/Deflection: find the pipe lenghts for a specified expansion or deflection (*)<br />

L/Z/U compensator: displays the values for the specified compensator type (*)<br />

Main comp. window: set the environmental variables for L/Z/U compensation<br />

(*) These windows are not visible when axial compensation is used<br />

In the next section the detailed explanation for the single windows will follow.


The Header Data Window<br />

The L-Z-U or Axial compensation windows share a common part which defines the data sheet general<br />

informations:<br />

These informations (Customer, Order, Plan n° and so on) will be always printed on the top of the data<br />

sheet. It isn't compulsory to fill all the data: blank fields won't be printed.<br />

The Ground Samples Window<br />

This window is simply a list of different materials, and it is possible to insert the correspondent values in<br />

the main window by clicking anywhere in the correspondent row.<br />

Clicking, for example, in the fourth row will set in the main window Kd = 0.7, re = 1800 and m = 0.45.<br />

The last entry in the list is the "standard ground setting", which is the default one for all the calculations.


The T-Pieces Dilatation Window<br />

It is possible to calculate the T-pieces dilatation by putting the distance (in m.) from the beginning of the<br />

selected section (one or two, pushing the grayed button) and choosing the T-piece DN.<br />

To calculate the necessary cushion and the piece dilatation, the program will work this way: first, it will<br />

set the other section length to 0.0 m.; then it calculates the T-piece distance from the pipe's middle<br />

section (Neutral Point) and will use that length doubled for all the successive calculations.<br />

This length will give thus the T-piece dilatation: please note that this dilatation will be calculated using<br />

the main pipe's DN. To calculate the branch arm cushion the program will use the T-piece DN with the<br />

found dilatation giving thus the closest approximation possible.<br />

Thus:<br />

ls1 m total length section 1<br />

tls1 m T-piece position from the beginning of sect. 1<br />

dl1 mm dilatation of sect. 1<br />

tdl help 1 mm dilatation calc for help<br />

tdl1 mm dilatation at T-piece position<br />

If tls1 > ls1/2 then tls1 = ls1 – tls1; that means we always have to take the shortest way from one end to<br />

the T-piece:<br />

Example:<br />

ls1 = 300m<br />

if tls1 = 25m then we don’t make any calculation, else if tls1 = 270m let tls1= 300 – 270 = 30m, so we<br />

calculate with 30m. Please note that tls1 never can be negative or longer than ls1, that always is<br />

incorrect.<br />

Dilatation calc.:<br />

Dilatation for the total length<br />

DN100<br />

90°C<br />

10°C<br />

ls1 = 300mm<br />

dl1 = 25.909mm


Dilatation for a fictitious length of (2* tls1)<br />

DN100<br />

90°C<br />

10°C<br />

tls1 = 25m (dilatation of 50m)<br />

tdl help 1 = 18.343mm<br />

Dilatation at T-piece<br />

tdl1 = dl1 - tdl help 1 = 25.909 – 18.343 = 7.566mm the dilatation at the T-piece is 7.566mm<br />

The 'Further Calculations' Window<br />

The L-Z-U or Axial compensation windows share another window, the 'Further Calculations' window in<br />

which there is an entire set of data concerning dilatations and stresses in the two pipe sections:<br />

The meaning of these variables will be explained in the next pages. It is important to notice that every<br />

change in the main window will force the recalculation of the entire data sheet; hence, the values present<br />

on the screen are always the most up-to-date ones. Please note that normally this window is hidden and<br />

will be displayed only by selecting the entry "view detailed static calculation" in the "Program" menu.


The L-Z-U Compensation Window<br />

This window presents all the environmental variables the user can change:<br />

These are the variables' meanings and their possible range of values:<br />

Pipe Norm (P Norm ):<br />

It is the pipes' set from the list ranging from 1 to 3.<br />

Default: 1<br />

Pre Stress (P Stress )<br />

With this box it is possible to force the pipes' pre-stressing: this affects the laying temperature as<br />

explained later.<br />

Default: No<br />

Ground Cover ( h o )<br />

It is the depth of soil covering, ranging from 0.60 to 2.50 m.<br />

Default: 1.0 m.<br />

Steel Type ( S Type )<br />

The pipe steel types implemented in this version are: steel 37, steel 44 and steel 52.<br />

Default: Steel 37


Design Temperature (T d )<br />

The design temperature (or working temperature) ranges from 0°C to 150°C with 5°C step.<br />

Default: 90°C<br />

Alternative Temperature (T alt )<br />

It is possible to define the value for the laying temperature (T l ) by changing the Talt value. The<br />

installation could be set with or without prestressing: this affects the laying temperature in this way:<br />

Without pre-stressing: T l = T alt or, if this one is 0, T l = 10 °C<br />

With pre-stressing: T l = T alt or, if this one is 0, T l = (T d +T min )/2+5 °C<br />

Default: 20°C<br />

Minimum Temperature ( T min )<br />

This is the ground temperature, ranging from 0°C to 20°C with a 5°C step.<br />

Default: 10°C<br />

Design Pressure (P d )<br />

This is the maximum working pressure, ranging from 0 bar to 40 bar.<br />

Default: 14 bar<br />

DN<br />

The pipe's DN ranges from 20 to 800 as written in the standard Isoplus list.<br />

Default: 100<br />

r e<br />

It is the ground density ranging from 1700 to 2200 kg/m³ with a 50 kg/m³ step in the possible values.<br />

Default: 1900 kg/m³<br />

K d<br />

This is the compressive pressure coefficient whom values range from 0.4 to 0.95 with a 0.05 step.<br />

Default: 0.75<br />

m<br />

It is the friction factor, with values ranging from 0.2 to 0.95 with a 0.05 step in the values.<br />

Default: 0.4<br />

Please note that, as explained before, r e , K d and m are function of the first ground selection. The<br />

above values are true on ly if "Standard Ground" was selected in the "Select ground types" window. (Or<br />

enter was pressed)<br />

Deflection Angle (d)<br />

The deflection angle affects the maximum deflection for the pipe sections, and its possible values range<br />

from 5° to 90° with a 5° step.<br />

Default: 90°


Length of the Sections (L s1 and L s2 )<br />

This value represents the length of the two pipe sections (1 and 2): the value is free, but it cannot be<br />

bigger than the maximum installation length: in this case the lenght(s) in excess will be displayed in red<br />

and a question mark will appear on the left of the text box. If the user pushes the question mark, there<br />

will be the possibility to enter the axial compensation or to correct the lenghts.<br />

Default: 80.0 m for Section 1 and 20.0 m for Section 2<br />

Wall thickness of steel pipe (wt)<br />

It is possible to change the default value for the pipe ' s wall thickness. This value will be reset to the<br />

default every time the user changes the pipe's DN.<br />

Permissible Stress (s perm )<br />

The permissible reference stress for the pipe is based upon the steel type employed, and if a greater<br />

safety factor is wanted in the net design, it is possibe to change this value. If the user presses the 'R'<br />

button on the right side of the text cell, the value will be reset to the default.<br />

Algorithms used for the L-Z-U Compensation<br />

The following section explains which formulas where used for the L-Z-U calculations.<br />

Given:<br />

de = external diameter of steel pipe [mm]<br />

DE = external diameter of jacket pipe [mm]<br />

wt = wall thickness of steel pipe [mm]<br />

se = wall thickness of jacket pipe [mm]<br />

r e = ground density [kg/m³]<br />

g = acceleration due to gravity [m/s²]<br />

h o = depth of soil covering<br />

K d = compressive pressure coefficient<br />

m = friction factor<br />

P v = r e * g * h o vertical ground press. on the superior / inferior pipe surface<br />

P h = K d * r e * g * (h o +DE/2) horizontal ground pression on the lateral pipe surface<br />

Fixed as:<br />

D list = de -2*wt internal steel pipe diameter [mm]<br />

A list = D list ² * p/4 internal steel pipe area [mm²]<br />

As = de²*p/4-Alist overall steel pipe cross sectional area [mm²]<br />

D lim = DE-2*se internal jacket pipe diameter [mm]<br />

A lim = D lim ²*p/4-de²*p/4 overall internal jacket pipe cross sectional area [mm²]<br />

Am = DE²*p/4-D lim ²*p/4 overall external jacket pipe cross sectional area [mm²]<br />

Being:<br />

r w<br />

= water density [kg/m³]


st<br />

r m<br />

r lim<br />

= steel density [kg/m³]<br />

= external jacket pipe density [kg/m³]<br />

= internal jacket pipe density [kg/m³]<br />

The overall pipe weight per meter is:<br />

mv = A list *r w +As*r st +A lim *r lim +A m *r m [kg/m]<br />

And the frictional force is derived from:<br />

F c = m*g* [DE²*p/4*K d * r e + mv] frictional force due to the pipe<br />

F h = m*g* [DE*p/2* r e *(1+K d )] frictional factor per ground meter<br />

So the frictional force per pipe meter is:<br />

Fr' = F c + h o *F h frictional force per pipe meter [N/m]<br />

Other variables of interest are the following:<br />

T d = design or operating temperature [°C]<br />

T l = laying temperature [°C]<br />

T alt = alternative temperature, which defines Tl (see after) [°C]<br />

T min = the pipes ' minimum temperature (ground temp.) [°C]<br />

P d<br />

= design water pressure [bar]<br />

The permissible reference stress for the pipe is based upon the steel type employed, and the following<br />

formula uses a safety factor of 1.225 as written in the Tab. A.1. for the DIN 1626 for steels 37,44 and<br />

52:<br />

Steel 37: If Td


where DT is the max abs. value between ( T d - T l ) and ( T l - T min )<br />

The average peripheral stress due to the internal pressure is:<br />

s up = (de/wt-1)*P d /2 = (D list *P d )/(2*wt) [N/mm²]<br />

While the longitudenal stress due to internal pressure is:<br />

s lp = A list *P d /As [N/mm²]<br />

The internal pressure generates an elastic radial dilatation in the pipe and a similar contraction in the<br />

longitudenal sense (e) but opposite in sign. The real dilatation is:<br />

e = (0.5-n)*s up /E<br />

n = steel trasversal contraction factor (0.3)<br />

The length of the sliding section at repeating temperature changes is:<br />

I ob = (a*E*(T d -T min )+t)*As/Fr' [m]<br />

t = s lp -0.3*s up [N/mm²]<br />

And the change of the length of the sliding zone due to the differential temperature is:<br />

DI ob = (a*(T d -T min )+t/E)*I ob /2<br />

[mm]<br />

When expansion is taken up in natural expansion bends, the longitudenal stress at the free end of the<br />

pipe is 0.5*s up ; hence, the length of the sliding section at T max is:<br />

I ow = (a*E*(T d -T l )+t)*As/Fr' [m]<br />

Consequently the change of the length of the sliding zone at T max is:<br />

DI ow = (a*(T d -T l )+t/E)*I ow /2<br />

[mm]<br />

When the pipe is cooled from T l to T min under atmospheric pressure, the length (and the change in<br />

lenght) of the sliding section at T min is:<br />

I ok = a*E*(T l -T min )*As/*Fr' [m]<br />

DI ok = -a*(T l -T min )*I ok /2<br />

[mm]<br />

For the following formulas it is important to consider Ix, the semi-length of the pipe section 1 (I 1 ) and<br />

section 2 (I 2 ) to the natural reference point: the object is to calculate the following:<br />

DI w = change of length at T max [mm]<br />

DI b = change of length due to the differential temperature [mm]<br />

DI k = change of length at T min [mm]<br />

s lw = longitudenal stress at T max [N/mm²]<br />

s lk = longitudenal stress at T min [N/mm²]<br />

There are two main cases and three sub-cases:<br />

1) the length of the sliding zone at T max (I ow ) is greater than the length of the sliding section at<br />

repeating temperature changes (I ob ):


a) the semi-length of the section (Ix) is greater than I ow and I ob :<br />

DI b = DI ob<br />

DI w = DI ow<br />

DI k = DI w - DI b<br />

s lw = -(I ow *Fr'/As-s lp )<br />

s lk = I ob *Fr'/As<br />

b) the semi-length of the section (Ix) is smaller than I ow and I ob :<br />

DI b = DI ob * Ix/I ob *(2-Ix/I ob )<br />

DI w = DI ow * Ix/I ow *(2-Ix/I ow )<br />

DI k = DI w - DI b<br />

s lw = -(Ix*Fr'/As-s lp )<br />

s lk = Ix*Fr'/As<br />

c) the semi-length of the section (Ix) is smaller than I ow but greater than I ob :<br />

DI b = DI ob<br />

DI w = DI ow * Ix/I ow *(2-Ix/I ow )<br />

DI k = DI w - DI b<br />

s lw = -(Ix*Fr'/As-s lp )<br />

s lk = I ob *Fr'/As<br />

2) the length of the sliding zone at Tmax (I ow ) is smaller than the length of the sliding section at<br />

repeating temperature changes (I ob ):<br />

a) the semi-length of the section (Ix) is greater than I ok and I ob :<br />

DI b = DI ob<br />

DI k = DI ok<br />

DI w = DI b +DI k<br />

s lw = -(I ob *Fr'/As-s lp )<br />

s lk = I ok *Fr'/As<br />

b) the semi-length of the section (Ix) is smaller than I ok and I ob :<br />

DI b = DI ob * Ix/I ob *(2-Ix/I ob )<br />

DI k = DI ok * Ix/I ok *(2-Ix/I ok )<br />

DI w = DI b + DI k<br />

s lw = -(Ix*Fr'/As-s lp )<br />

s lk = Ix*Fr'/As<br />

c) the semi-length of the section (Ix) is smaller than I ok but greater than I ob :<br />

DI b = DI ob<br />

DI k = DI ok * Ix/I ok *(2-Ix/I ok )<br />

DI w = DI b + DI k


s lw = -(I ob *Fr'/As-s lp )<br />

s lk = Ix*Fr'/As<br />

The expansion Dlx of the section is equal to the greater value between the change of length at T max<br />

(DI w ) and the change of length at T min (DI k ).<br />

The permissible longitudenal stress is based upon s st and the peripheral stress s up :<br />

_____________<br />

s lzul = s up - Ö s st ² - 0.75*s up ² [N/mm²]<br />

The semi permissible length without prestressing is then:<br />

I lzul = (s lp - s lzul )*As/Fr' [m]<br />

If I lzul is greater than the length of the sliding zone at T max (I ow ) or (s lw and s lk ) < s lzul the<br />

permissible installation length is unlimited; else it corresponds to 2*I lzul .<br />

The correspondent reference stress for the section is:<br />

_________________<br />

s v = Ö s lw ² + s up ² - s lw * s up [N/mm²]<br />

And the max deflection for the pipe sections is based upon the deflection angle d °:<br />

W 1 = Dl 1 /sind + Dl 2 / tand [mm]<br />

W 2 = Dl 2 /sind + Dl 1 / tand [mm]<br />

For the cushion thickness we have to consider the deflection angle and the expansion of both sections:<br />

__________________<br />

Wd = Ö (Dl 1 /sind)²+(Dl 2 / tand)²<br />

The cushion thickness is calculated is calculated as follows:<br />

If W 1 is greater than Wd and W 2 , the cushion is proportional to W 1 ; if W 2 is greater than Wd and<br />

W 1 , the cushion is proportional to W 2 , else the cushion is proportional to Wd. The cushion cannot be<br />

greater than 150 mm. Let it be W X the quantity derived from the aforementioned calculation (being it,<br />

W 1 , W 2 or Wd ):<br />

If it is W X


The 'Set the Expansion or Deflection Amount' window<br />

This window is displayed under the main one and his purpose is to help the net design trying to find the<br />

best section lengths with a given expansion or deflection. Actually it is possible to enter the wanted<br />

deflection (or deflection) for a certain section and after a while the program will display the best value<br />

for the corresponding section. Clicking on the "Insert these Values" button will force the program to<br />

use the found values in the main window. This is also useful when dealing with deflection or deflection<br />

limits: whenever limits are used (unckecking the "Ignore these limits" square in the 'Set limits' window)<br />

the program will display a small button with a triangle inset everytime deflection or deflection for a<br />

section exceeds a certain pipe limit. These limits are set within the 'Set limits' window which appears<br />

everytime the program is run or by clicking the 'settings' menu in the main window. When limits are<br />

surpassed the main window will look as below:<br />

In this case both dilatation and deflection exceed the limits: clicking on the corresponding button the<br />

following request will be displayed:<br />

Clicking on the 'Yes' button will force the program to accept the suggested values for the dilatation. The<br />

same is for the deflection:


Z - Compensation<br />

When Z-Compensation is used, the following window will appear:<br />

The length of the sliding section at T max is based upon an average value (T max -T min )/2 :<br />

I ow = (a*E*(T d -T min )/2+t)*As/Fr' [m]<br />

Consequently the change of the length of the sliding zone at T max is:<br />

DI ow = (a*(T d -T min )/2+t/E)*I ow /2<br />

And DI w , change of length at T max ,<br />

is:<br />

[mm]<br />

DI w = DI ow * Ix/I ow *(2-Ix/I ow ) if the semi-length of the section (Ix) is less than I ow<br />

DI w = DI ow<br />

if the semi-length of the section (Ix) is greater than or equal to<br />

I ow<br />

The deflection is based upon DI w , as follows:<br />

W L1 = DI w1 /sind + DI w2 / tand<br />

W L2 = DI w2 /sind + DI w1 / tand<br />

[mm]<br />

[mm]<br />

Take note that the W L1 and W L2 values are not W 1 and W 2 , but they represent the maximum<br />

deflection possible, that is, the deflection coming from the greatest DT possible, T max -T min . We’ll use<br />

the W L1 and W L2 values instead of the W 1 and W 2 values.<br />

The expansion leg length DZ 1 for the compensator is function of the deflection: DZ 1 = ¦(W 1 +W 2 );<br />

hence DZ 2 is calculated as follows:<br />

DZ 2<br />

_______<br />

= 44.0 * de * W<br />

Where:<br />

de = external diameter of steel pipe [mm]


W<br />

= max between the W 1 and W 2 values<br />

The tests showed that the better approximation of the "real" world is given using the "stress"<br />

calculation, which involves the evaluation of values W L1 and W L2 . Thus for all the compensations the<br />

"stress" option is used, but for the clarity of calculations also the "normal" way is presented.<br />

L - Compensation<br />

When L-Compensation is used, the following window will appear:<br />

The length of the sliding section at T max is based upon an average value (T max -T min )/2 :<br />

I ow = (a*E*(T d -T min )/2+t)*As/Fr' [m]<br />

Consequently the change of the length of the sliding zone at T max is:<br />

DI ow = (a*(T d -T min )/2+t/E)*I ow /2<br />

And DI w , change of length at T max ,<br />

is:<br />

[mm]<br />

DI w = DI ow * Ix/I ow *(2-Ix/I ow ) if the semi-length of the section (Ix) is less than I ow<br />

DI w = DI ow<br />

if the semi-length of the section (Ix) is greater than or equal to<br />

I ow<br />

The deflection is based upon DI w , as follows:<br />

W L1 = DI w1 /sind + DI w2 / tand<br />

W L2 = DI w2 /sind + DI w1 / tand<br />

[mm]<br />

[mm]<br />

The expansion leg length DL x for the compensator is function of the deflection: DL x = ¦(W x ).<br />

_______<br />

DL x = 55.0 * de * W x


Where:<br />

de = external diameter of steel pipe [mm]<br />

W x = W 1 and W 2<br />

U - Compensation<br />

When U-Compensation is used, the following window will appear:<br />

The length of the sliding section at T max is based upon an average value (T max -T min )/2 :<br />

I ow = (a*E*(T d -T min )/2+t)*As/Fr' [m]<br />

Consequently the change of the length of the sliding zone at T max is:<br />

DI ow = (a*(T d -T min )/2+t/E)*I ow /2<br />

And DI w , change of length at T max ,<br />

is:<br />

[mm]<br />

DI w = DI ow * Ix/I ow *(2-Ix/I ow ) if the semi-length of the section (Ix) is less than I ow<br />

DI w = DI ow<br />

if the semi-length of the section (Ix) is greater than or equal to<br />

I ow<br />

The deflection is based upon DI w , as follows:<br />

W L1 = DI w1 /sind + DI w2 / tand<br />

W L2 = DI w2 /sind + DI w1 / tand<br />

[mm]<br />

[mm]<br />

Take note that the W L1 and W L2 values are not W 1 and W 2 , but they represent the maximum<br />

deflection possible, that is, the deflection coming from the greatest DT possible, T max -T min . We will<br />

use the W L1 and W L2 values instead of the W 1 and W 2 values: i.e. the program will show the resulting<br />

dilatation zone length for both the dilatation and deflection components.


The crown length DU 2 is equal to twice the leg length of the standard 1x1 bends, while the lengths DU 3<br />

have relatively little effect on the permissible amount of expansion; so the Dilatation Zone Length DU 1<br />

is function of the deflection: DU 1 = ¦(W 1 +W 2 ), length DU 3 is calculated as follows:<br />

_______<br />

DU 3 = 31.0 * de * W 2<br />

where de = external diameter of steel pipe [mm]


The Axial Compensation Window<br />

When the axial compensation is used only these windows are used: the 'Further Calculation' window, the<br />

'Axial Compensator' window and the 'Select Ground Type' window.<br />

All the controls are the same as in the L-Z-U window, with the exception of the pre stress box which is<br />

not used. The alternative temperature is now effectively the laying temperature wanted and there is the<br />

pre heating temperature box in which the pre heating temperature is calculated. It is also possible to<br />

change the wall thickness and the permissible reference stress. The main changes are in the lower part of<br />

the window: in the total line length box it is possible to enter the installation length. The program will<br />

calculate (as detailed below) the maximum sections' lenghts, then it will reduce the Section 2 until the<br />

total line length is reached. For example, in the page before a total line length of 800 m. was entered.<br />

The program defines the maximum values for the sections, S 1max = Section B + Section A = 103.16 m,<br />

while S 2max = 2 * Section A = 99.32 m.<br />

The Ideal Lengths of Section A and B represent the maximum extent possible for these single sections<br />

in an ideal condition ( with a pipe of infinite length), meanwhile the Real Length is the one in a pipe of<br />

finite extent (in this example, the 1000 m. in the total line length box).<br />

The pipes will be placed as for the following figure:


So for a total line lengh of 1000 m., we will have:<br />

Sect 1 (103.16 m) + 8 * Sect 2 (99.32) + Sect 1 (103.16 m) = 1000.88 m<br />

Please note that all the values for dilatation, reference stress, etc are referred to the real sections<br />

length, not to the ideal ones.<br />

section 1<br />

section 2<br />

<br />

B<br />

A A A A<br />

h<br />

<br />

p<br />

<br />

preheat<br />

Kompensator<br />

B<br />

hot<br />

zul<br />

<br />

p<br />

<br />

cold<br />

zul<br />

<br />

L B<br />

L<br />

A<br />

To calculate the dilatation, stresses and section lengths the first step is the mean permissible stress:<br />

s st mean = (s st (T ins ) + s st (T max ))/2<br />

Where:<br />

s st mean = mean permissible stress [N/mm²]<br />

s st (T ins ) = permissible stress at T ins [N/mm²]<br />

s st (T max )<br />

= permissible stress at T max [N/mm²]<br />

Secondly the preheating temperature (T pre ) is the lower between:


T pre = T ins + s st mean /(a*E) (rounded down) and<br />

T pre = (T max )* 0.9<br />

Where:<br />

T pre = preheating temperature [°C]<br />

T ins = temperature at installation [°C]<br />

s st mean = mean permissible stress [N/mm²]<br />

Formula for section B<br />

L b =( s st mean * As)/Fr´<br />

Length of Section B [m]<br />

Where:<br />

As = de²*p/4-Alist Overall steel pipe cross sectional area [mm²]<br />

Fr' = F c + h o *F h Frictional force per pipe meter [N/m]<br />

s st mean<br />

Formula for section A<br />

Mean permissible stress [N/mm²]<br />

L a =( 2 * s st mean - a * E * ( T max - T ins ))* As/F<br />

Length of Section A [m]<br />

Where:<br />

As = de²*p/4-Alist Overall steel pipe cross sectional area [mm²]<br />

Fr' = F c + h o *F h Frictional force per pipe meter [N/m]<br />

a = (11.4 + Td/129)* 10 -6 Expansion coefficient [1/°C]<br />

E = (21.4 - Td/175)* 10 +4 Young's modulus [N/mm²]<br />

s st mean<br />

mean permissible stress [N/mm²]<br />

And then the correspondent max length for the sections A and B is<br />

I 1 = L b + L a [m]<br />

I 2 = L a + L a [m]<br />

At this point, all the calculations are made at design temperature Td with a laying temperature T pre (i.e.<br />

all the calculations are made with T l = T pre ): as a result we'll find the dilatations DL 1 and DL 2 . When<br />

axial compensation is used, the sand on the B-side will compensate for a »20% of the total expansion:<br />

the residual 80% will be reduced by the axial compensator, so that the expansion joint range will be:<br />

DZ 1 = DL 1 * .8 + DL 2 + DL 2 For the first section<br />

DZ 2 = DL 2 + DL 2 For the other sections


Index<br />

Isoplus® Static Calculation ................................................................................................................... 1<br />

Program Installation ........................................................................................................................... 1<br />

Starting Isoplus® Static Calculation ................................................................................................... 1<br />

The Header Data Window .................................................................................................................. 6<br />

The Ground Samples Window ............................................................................................................ 6<br />

The T-Pieces Dilatation Window ........................................................................................................ 7<br />

The 'Further Calculations' Window ..................................................................................................... 8<br />

The L-Z-U Compensation Window .................................................................................................... 9<br />

Algorithms used for the L-Z-U Compensation .................................................................................. 11<br />

The 'Set the Expansion or Deflection Amount' window..................................................................... 16<br />

Z - Compensation ............................................................................................................................. 17<br />

L - Compensation ............................................................................................................................. 18<br />

U - Compensation ............................................................................................................................ 19<br />

The Axial Compensation Window .................................................................................................... 21<br />

Index ................................................................................................................................................... 24

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