Design Calculations Manual

Design Calculations Manual

CPV Ltd Woodington Road, East Wellow Romsey, Hampshire, SO51 6DQ Tel: 01794 322884 Web: www.cpv.co.uk/hiline www.cpv.co.uk/hiline

Table of Contents

1.

Introduction ................ ........................ ................. .................. ................. ................ ................. ................. ................ ................. .................1 ........1

1.1

Subject ....................................... .................... .......................................... .................................... .............................. .............................1 ............1

1.2

Scope Of Application ................. ......................... ................. ................. ................. ................. ................ ................ ................. .............1 ....1

1.3

Construction plans and specifications................. specifications......................... ................ ................. ................. ................ ................. ..........1 .1

2.

Basic parameters ................. ......................... ................. ................. ................. ................. ................ ................ .................. .................. ..........1 ..1

2.1

Geometric properties ................ ........................ ................. ................. ................. ................. ................ ................ .................. .............1 ...1

2.2

Loads, shearing force, load bearing capacity................... capacity........................... ................ ................. ................. ...............2 .......2

2.3

Stresses and strengths ................ ........................ ................. .................. ................. ................ ................ ................. .................. ...........2 ..2

2.4

Material constants, factors and others .................. .......................... ................ ................ ................. ................. ...............2 .......2

3.

Materials and products ................. ......................... ................. .................. ................. ................ ................ ................. .................. ...........3 ..3

3.1

Carrier Carrie r pipe ........................................ .................... .......................................... ............................................ ..................................... ...............3 3

3.2

Casing pipe ................ ......................... ................. ................. ................. ................. ................. ................ ................ .................. ................3 ......3

3.3

Rigid polyurethane foam ................ ......................... ................. ................ ................. ................. ................ ................ .................3 .........3

3.4

Pipe unit ........................................ ..................... ......................................... ............................................ ......................................... ...................4 4

4.

Design input data ...................................... ................... ......................................... ............................................ ..................................5 ............5

5.

Design principles. princi ples....................... .......................................... .......................................... ......................................... ..............................6 ...........6

5.1

Dimensioning method ................ ........................ ................. ................. ................. ................. ................ ................ .................. .............6 ...6

5.2

Loads...........................................................................................................6

5.2.1

Soil-induced load on a buried pipe ................. ......................... ................. ................. ................ ................ .................. .............6 ...6

5.2.2

Friction force on side surface .................. .......................... ................ ................ ................. ................. ................. ................. .........6 .6

5.2.3

Carrier pipe axial force [n] .................. .......................... ................ ................. ................. ................ ................ .................. .............6 ...6

5.3

Forces resulting from carrier pipe internal pressure ................. ......................... ................ ................. .................7 ........7

5.4

Computed loading capacity of a carrier pipe cross section ................ ........................ ................ ................. ..........7 .7

6.

Designing CPV Hiline-ZPUM Systems................... Systems........................... .................. ........................ ....................... .................. ............8 ...8

6.1

Method 1 – natural natur al ....................................... .................... ......................................... ......................................... ..............................8 ...........8

6.1.1

Maximum straight assembly length [lmax] ................ ......................... ................. ................ ................ ................ ...............8 .......8

6.1.2

Pipeline Pipeli ne expansion expan sion.................... ....................................... ......................................... ......................................... .............................11 ..........11

6.2

Method 2 – Pre-stressed System ............... ....................... ................ ................ ................ ................. .................. ................. ........ 13

6.2.1

Elongation [δln] of an unburied pipe ................ ........................ ................. .................. ................. ................ ................ .......... 13

6.2.2

Elongation (shortening) [δlz] of an unburied pipe ................. ......................... ................. ................. ................. ......... 14

6.3

Method 2a – initial stresses if single use elongation joints are considered ................ ...................... ...... 14

6.4

Change in pipeline routing ................ .......................... .................. ................ ................ ................. ................. ................. ............ ... 15

6.4.1

Pipe route alteration by scarfing steel pipe at a joint ................ ........................ ................ ............... .............. ....... 15

6.4.2

Pipe route alteration by using preinsulated elbow units ................ ........................ ................ .................. ............ 15

6.4.3

Pipe route alteration by elastic bending of pipe........ pipe ................ ................ ................. ................. ................. ............ ... 16

6.4.4

Rerouting by means of preinsulated bend pipe ................. .......................... ................. ................ ................ ............ .... 17

7.

Elongation compensation ................. .......................... ................. ................ ................. ................. ................ ................ ............... ....... 19

7.1

The l-shape system ................ ........................ ................. .................. ................. ................ ................ ................. .................. ............. .... 19

7.2

The z-shape system ................ ........................ .................. .................. ................ ................ ................. ................. ................. ............ ... 24

7.3

The u-shape system ................ ........................ .................. .................. ................ ................ ................. ................. ................. ............ ... 26

7.4

Compensation zones.................. zones.......................... ................. ................. ................. ................. ................ ................ .................. ............ 26

8.

An actual preinsulated fixed point .................. .......................... ................ ................ ................. ................. ................. ............ ... 27

8.1

Calculation of forces affecting a fixed point ................. .......................... ................. ................ ................ ............... ....... 27

8.1.1

Relieved fixed point ................ ........................ .................. .................. ................ ................ ................. ................. ................. ............ ... 27

8.1.2

Partially relieved fixed point ................. ......................... ................. ................. ................ ................ .................. .................. ........ 28

9.

Pipe laterals and wall transitions.................... transitions............................ ................ ................ ................. ................. ................. .............31 ....31

10.

Preinsulated pipe connected to a traditional pipe (underground utilities) ................ ..................... ..... 33

11.

Steel fittings and fixtures ................ ......................... .................. ................. ................ ................ ................. .................. ............. .... 33

12.

Technical information ................ ........................ ................. .................. ................. ................ ................ ................. .................. ......... 34

13.

Trade information ................ ........................ ................. ................. ................ ................. ................. ................ ................. ............... ...... 34

Design Calculations Manual I

1.

Introduction

1.1

Subject

The purpose of this document is to provide methods of making calculations and designs of buried pre-insulated pipeline systems.

1.2

Scope of Application

Calculations and design parameters must be followed in the drawing up of piping configuration and technical specifications for systems constructed from preinsulated pipe and fittings.

1.3

Construction Plans and Specifications

Construction plans and specifications should be drawn up in accordance with the Local Building Standards/Regulations and methods presente d in the study.

2.

Basic Parameters

2.1

Geometric Properties A

carrier pipe cross section area

DN

carrier pipe nominal diameter

D z

carrier pipe external diameter

D zp

jacket pipe nominal diameter

t

carrier pipe wall thickness

t p

casing pipe wall thickness

H

pipeline axis over full height of backfill

Hp

pipeline backfill height

L, C, D compensating arm lengths L

pipeline segment length

L max

pipeline assembly length

ε

pipeline unit elongation

∆L

buried pipeline L long elongation

∆ Ln

elongation of unburied pipeline [Ln] long heated up to a temperature of [Tp], free elongation

∆ L z

buried elongation (shortening) of pipeline heated up to a temperature of [T]

L n

length of unburied pipeline

l

preinsulated pipe length

r

preinsulated pipe bend radius

β

preinsulated pipe bend angle

Hiline-ZPUM Design Calculations -- Page 1 of 37 -- Rev no. HZ DC 2510 CPV Ltd, Woodington Mill, Woodington Road, East Wellow, Romsey, Hants, SO51 6DQ Website: www.cpv.co.uk -- Email: [email protected] -- Telephone: +44 01794 322884


2.2

Loads, Shearing Force, Load Bearing Capacity V F N N max N PS N RC p

2.3

Stresses and Strengths σ τ Re R m R r R s σ tr σ H σ x f d f dT f d ′

2.4

jacket pipe unit soil stress jacket pipe surface side friction axial force maximum axial force fixed point axial force rated load bearing capacity at compaction carrier pipe pressure

axial stress tangential stress yield point specified by manufacturer (rated) tensile strength specified by manufacturer breaking strength crushing strength compressive stress at transport hoop stress axial stress reduced rated steel strength reduced rated steel strength at increased temperatures rated steel strength

Material Constants, Factors and Others E ET v α λ γ µ ρ T T 0 T p ∆T A 5 ρS ρ PE ψ k

Young’s modulus Young’s modulus at temperature T Poisson’s ratio coefficient of linear expansion thermal conductivity load factor friction factor backfill soil density service temperature assembly temperature preheating temperature temperature difference percent of minimum elongation steel density hard polyethylene density rated cross section load reductibility ratio coefficient accounting for friction force between pipe and subgrade



3.

Materials and Products

3.1

Carrier Pipe

In accordance with standards: DIN-1626/84, DIN-1629 mechanical properties in accordance with: PN-90/B-3200, DIN-1629 Mechanical properties Product Steel marking Re Rm A5 MPa MPa % Spiral or longitudinal seam St 37.0 350 pipe 235 25 Rolled pipe R-35 345 Rolled pipe galvanised R-35 Steel material constants:

fd´ MPa 210

E = 205 GPa

= 0,3 = 1,2 · 10 -5/ºC 3 ρS = 7850 kg/m ν

α

Other types of carrier pipe:

3.2

copper pipe polyethylene pipe polypropylene pipe post-chlorinated PVC pipe

Casing Pipe Product

Rigid polyethylene pipe

Marking

σH MPa

PEHD

4,0

PEHD material constants:

friction force between pipe and subgrade coefficient

Mechanical properties Rr RS MPa MPa 24,0

3,0

E = 1,0 GPa λ = 0,43 W/mK α t = 0,2 · 10 -5/ºC ρ PE = 950 kg/m3 µ = 0.3-0.5

Other types of casing pipe:

3.3

37,0

σtr MPa

SPIRO galvanized sheet or aluminium pipe (for overhead networks), PVC or steel pipe

Rigid Polyurethane Foam

Rigid polyurethane foam meets the requirements of standard density radial compression strength at a 10% relative strain MDI index Thermal conductivity index at λ50: CO2 foaming system (without freon) CO2/cC5 foaming system (pentane)

EN-253 total min 80 kg/m3 core min 60 kg/m3 min 0,3 MPa min 130 0,0302 W/mK 0,0268 W/mK



3.4

Pipe Unit Pipe unit – preinsulated pipe complies with standard EN-253

thermal conductivity index at carrier pipe temperature = max 0.033 W/mK min 30 years

80ºC

expected life duration axial shear strength (at 20ºC) (at 140ºC) circumferential shear strength

min 0.12 MPa min 0.08 Mpa min 0.20 MPa

CPV Hiline-ZPUM offers preinsulated pipe up to a nominal diameter of DN 1000. Table 1 gives dimensions of preinsulated pipe up to DN 600. Unit heat losses for a preinsulated pipeline are presented in Table 2.

Preinsulated Pipe Dimensions

Table 1

Steel Carrier Pipe DN

Dext

mm

mm

welded

seamless

PEHD Jacket Pipe

PEHD Jacket Pipe

Standard insulation

Insulation Plus

g

g

Dext

gp

Dext

gp

mm

mm

mm

mm

mm

mm

20

26,9

2,6

2,9

75

3,0

90

3,0

25

33,7

2,6

2,9

90

3,0

110

3,0

32

42,4

2,6

2,9

110

3,0

125

3,0

40

48,3

2,6

2,9

110

3,0

125

3,0

50

60,3

2,9

3,2

125

3,0

140

3,0

65

76,1

2,9

3,2

140

3,0

160

3,0

80

88,9

3,2

3,6

160

3,0

200

3,2

100

114,3

3,6

4,0

200

3,2

225

3,4

125

139,7

3,6

4,0

225

3,4

250

3,6

150

168,3

4,0

4,5

250

3,6

315

4,1

200

219,1

4,5

6,3

315

4,1

355

4,5

250

273,0

5,0

7,1

400

4,8

450

5,2

300

323,9

5,6

7,1

450

5,2

500

5,6

350

355,6

5,6

8,0

500

5,6

560

6,0

400

406,4

6,3

8,8

560

6,0

630

6,6

450

457,0

6,3

10,0

560

6,0

630

6,6

500

508,0

6,3

11,0

630

6,6

710

7,2

600

610,0

7,1

-

800

7,9

900

8,7

DN – steel pipe nominal diameter;

ext

D

– external diameter

g, gp – wall thickness



Unit Heat Losses for a Preinsulated Pipeline [W.m] Soil temperature = 8ºC

Hp = 0,6 m

Table 2 Dz

DZP

mm

mm

Pipeline Temperature 150°C

130°C

110°C

90°C

70°C

50°C

26,9

75

20,2

17,3

14,5

11,7

8,8,

6,0

33,7 42,4 48,3 60,3 76,1 88,9 114,3 139,7 168,3 219,1 273,0 323,9 355,6 406,4 457,0 508,0 610,0

90 110 110 125 140 160 200 225 250 315 400 450 500 560 630 710 800

24,7 25,5 29,3 33,0 39,3 40,7 42,7 49,9 59,6 65,1 62,5 72,3 70,1 74,6 74,7 72,0 88,6

21,2 21,9 25,2 28,3 33,8 35,0 36,7 42,8 51,2 56,0 53,7 62,1 60,2 64,1 64,2 61,9 76,1

17,7 18,3 21,1 23,7 28,2 29,2 30,7 35,8 42,8 46,8 44,9 52,0 50,4 53,6 53,7 51,8 63,6

14,3 14,7 16,9 19,0 22,7 23,5 24,7 28,8 34,4 37,6 36,1 41,8 40,5 43,1 43,2 41,6 51,2

10,8 11,1 12,8 14,4 17,2 17,8 18,6 21,8 26,0 28,4 27,3 31,6 30,6 32,6 32,6 31,5 38,7

7,3 7,5 8,7 9,8 11,6 12,0 12,6 14,7 17,6 19,3 18,5 21,4 20,7 22,1 22,1 21,3 26,2

4.

Design Input Data

L ] and In the calculations of friction force [ F ], axial force [ N ], maximum assembly length [max elongations [ ∆L] for CPV Hiline ZPUM pipelines the following loads and material constants were used: pipeline depth H = 1m compacted backfill density ρ =1650 kg/m3 carrier pipe-soil friction factor µ = 0,35 passive soil pressure K = 0,6 pipeline working pressure p = 1,6 MPa reduced calculated steel strength f d = 150 MPa service temperature input T = 135ºC return T = 80ºC assembly temperature T 0 = 8ºC Young’s modulus accounted at temperature T E T = 204 GPa coefficient of linear elongation for 0-100ºC range α T = 1,2·10 -5/ºC for 0-150ºC range α T = 1,22·10 -5/ºC load factors load upper point γ = 1,1 service upper point γ = 1,0 Poisson’s ratio ν = 0,3



5.

Design Principles

5.1

Dimensioning Method

Dimensioning is performed by means of finite element method for loads and use in compliance with standard PN-76/B-03001 showing that in service the pipeline will meet the load condition.

5.2

Loads

Buried preinsulated pipe is loaded by: • friction forces acting on the outside of the casing pipe; • soil pressure on the pipe casing; • internal carrier pipe pressure response, and is additionally subject to temperature changes inside the carrier pipe. Thus, a static system with a limited degree of free elongation, where carrier pipe temperature drops and rises, this will generate axial forces dependent on friction forces and internal carrier pipe pressure.

5.2.1

Soil-induced Load on a Buried Pipe

The unit passive soil pressure exerted on a buried pipe should be determined in accordance with standard PN-83/B-03001 from the formula : 2 V z = γ· H ·ρ· g • vertical component: [N/m ] 2 [N/m ] V x = γ· H ·ρ· g· K 0 • horizontal component: where: γ H ρ g K 0

load factor pipeline axis depth backfill density gravitational acceleration passive pressure coefficient

[m] 3 [kg/m ] 2 [m/s ]

To determine the unit soil pressure evenly distributed circumferentially an average value is taken into calculation and calculated from the formula : V = 0.5·(V z+V x )

5.2.2

Friction Force on the Outside of the Casing

Friction force per pipe length unit [F] is calculated from the formula: where:

F = µ·V ·π· D zp µ friction coefficient between casing pipe and soil V casing unit soil pressure D zp casing pipe external diameter

5.2.3

[N/m ] [m]

2

Carrier Pipe Axial Force [N]

Axial force [N] in carrier pipe of a length of [L] generated by friction forces is calculated from the formula: N = F· L

where: F friction coefficient between jacket pipe and soil L jacket pipe unit soil pressure


2

[N/m ]


5.3

Forces Resulting from Carrier Pipe Internal Pressure

It is assumed that the load generated by the heating medium is taken over by the carrier pipe, where the following stresses will appear:

(

p D z -t

•

hoop stresses:

σ H

•

axial stresses:

σ

=

2 t

(

p D z -t =

x

)

)

4⋅ t

2

[N/m ]

2

[N/m ]

where: 2

carrier pipe pressure jacket pipe external diameter carrier pipe wall thickness

p D z

t

[N/m ] [m] [m]

Axial force derived from internal pipe pressure, being the axial stress here is: N x

=

σ x

⋅ A

⋅

where: 2


A

[m ]

The effect of the axial force resulting from the internal carrier pipe pressure on the computed cross section loading is minimal, therefore it can be neglected in further calculations.

Computed Loading Capacity of a Carrier Pipe Cross Section

5.4

If standard PN-90/B-03200 is to be complied with, then the pipe axial force cannot exceed the pipe computed loading capacity, namely: N − N − N ≤ x Once N = F L, N = x ·

σ · A x

[N]

RC

and N

= RC

ψ· A f ·

the resultant equation is:

d

,

F L ·

A σ x·

≤ ψ· A f d ·

where: F

unit friction force

L

pipeline section length rated cross section load reductibility ratio carrier pipe cross section reduced rated steel strength

ψ

A

f d σ x

axial stress


[N/m] [m] 2

[mm ] [MPa] 2 [N/m ]


Designing CPV Hiline-ZPUM Systems

6.

Designing consists in determining: pipeline assembly section [L

], for which the maximum axial force in a carrier pipe [Nmax] does not exceed its rated load [NRC]; pipeline extension [∆L] and its compensation in a natural way using changes in the pipe-

•

max

•

line routing (expansion joints) or

Method 1 – Natural

6.1

A pipeline having been assembled and tested is buried.

Maximum straight assembly length [L

6.1.1

]

max

In accordance with Point 5.4 the rated load of a cross section of pipe is determined by the formula: F L – σ x· A≤ψ· A f d ·

·

where: F

unit friction force

L

pipeline section length rated cross section load reductibility ratio carrier pipe cross section reduced rated steel strength

ψ

A

f d σ x

If L

=

L

equals:

[N/m] [m] 2

[mm ] [MPa] 2 [N/m ]

axial stress

and providing

ψ

= 1 (class 1 of cross section ), then the maximum assembly length [ L max

L max = =

A ⋅⋅ ( f d

+ σ x

)

F

Maximum assembly lengths [ L ] for the carrier pipe diameters and wall thickness specified in Table 3 and 4 assume that a pipeline axis is buried a t H = 1.0 m and at the initial data assumed in design. max


]


Table 3

R – 35 Carrier Pipe Dz

t

mm

mm

26,9 33,7 42,4 48,3 60,3 76,1 88,9 114,3 139,7 168,3 219,1 273,0 323,9 355,6 406,4 457,0 508,0

2,9 2,9 2,9 2,9 3,2 3,2 3,6 4,0 4,0 4,5 6,3 7,1 7,1 8,0 8,8 10,0 11,0

A mm2

219 281 360 414 574 733 965 1386 1705 2316 4212 5931 7066 8736 10992 14043 17175

Jacket Pipe Dzp

Friction Force F

Assembly Length L max

mm

N/m

m

75 90 110 110 125 140 160 200 225 250 315 400 450 500 560 630 710

1410 1410 1723 1723 1958 2193 2506 3132 3524 3916 4934 6265 7048 7831 8144 8771 9867


24 31 32 38 46 53 61 71 79 97 140 156 168 187 211 239 260


Table 4 Jacket Pipe

26,9 33,7 42,4 48,3 60,3

2,6 2,6 2,6 2,6 2,9

198 254 325 373 523

75 90 110 110 125

Friction Force F N/m 1410 1410 1723 1723 1958

76,1 88,9

2,9 3,2

667 862

140 160

2193 2506

49 55

114,3 139,7 168,3 219,1 273,0 323,9 355,6 406,4 457,0 508,0 610,0

3,6 3,6 4,0 4,5 5,0 5,6 5,6 6,3 6,3 6,3 7,1

1252 1539 2065 3034 4210 5600 6158 7919 8920 9930 13448

200 225 250 315 400 450 500 560 630 710 800

3132 3524 3916 4934 6265 7048 7831 8144 8771 9867 12530

65 72 88 104 115 137 138 158 161 162 197

St 37.0 Carrier Pipe

Dz

t

A

Dzp

mm

mm

mm2

mm

H i

Hi

The assembly length L max

and unit friction force F

Assembly Length

L max m

for a pipeline laid at a depth of H i

22 28 29 34 42

can be de-

termined from the formula: H

i L max

e.g. for:

=

Lmax

Hi

F

H i

zD = 26.9 mm

.

=

06

=

⋅

as per Table 3

F = 1 410 N/m

24

06

L max

F ⋅ H i

g = 2.9 mm

L max = 24 m

for Hi = 0.6 m

=

40 m

F

0.6

= 1410 0.6 = 846 N/m ·

.

In the case when a steel carrier pipe of a cross section area of [A] different than the dimensions specified in Tables 3 and 4 is used, L has to be changed pro rata. max



6.1.2

Pipeline Expansion

The expansion by [∆L] of a preinsulated buried pipeline whose assembly length is [L] is defined as a difference between free thermal expansion and expansion due to friction forces, and is calculated from the formula:

∆ L = α t (T − T 0 ) ⋅ L − where:

F ⋅ L 2

2 ⋅ ET ⋅ A

[1/ºC] coefficient of linear expansion service temperature [ºC] assembly temperature [ºC] pipeline segment length [m] unit friction force [N/m] Young s Modulus at Temperature T [N/m2 ] carrier pipe cross section area [m2] Once initial data are input (see Table 4) a simplified formula determining elongation, expressed in millimetres, [ ∆ L] is obtained: 2 [ ∆ L] = 0.864· L – W · H · L [mm] for T = 80ºC [ ∆ L] = 1.548· L – W · H · L 2 [mm] for T =135ºC αT T T 0 L F ET A

'

where: 0.864 and 1.549 are constant W coefficient dependent on carrier pipe cross H L

section specified in Tables 3 and 4 pipeline buried at pipeline segment length

[mm/m] [mm/m3] [m] [m]



Table 5 Insulation STANDARD

St 37.0 Carrier Pipe

Dz

g

A

Coeffcient W

mm

mm

mm2

mm/m3

26,9 33,7 42,4 48,3 60,3 76,1 88,9 114,3 139,7 168,3 219,1 273,0 323,9 355,6 406,4 457,0 508,0

2,9 2,9 2,9 2,9 3,2 3,2 3,6 4,0 4,0 4,5 6,3 7,1 7,1 8,0 8,8 10,0 11,0

219 281 360 414 574 733 965 1386 1705 2316 4212 5931 7066 8736 10992 14043 17175

0,0144 0,0112 0,0107 0,0093 0,0076 0,0067 0,0058 0,0050 0,0046 0,0038 0,0026 0,0024 0,0022 0,0020 0,0017 0,0014 0,0013

Insulation PLUS Coefficient W mm/m3 0,0176 0,0137 0,0121 0,0105 0,0085 0,0076 0,0072 0,0057 0,0051 0,0047 0,0029 0,0026 0,0025 0,0021 0,0018 0,0016 0,0014 Table 6

Insulation STANDARD R - 35 Carrier Pipe

Dz mm 26,9 33,7 42,4 48,3 60,3 76,1 88,9 114,3 139,7 168,3 219,1 273,0 323,9 355,6 406,4 457,0 508,0 610,0

g mm 2,6 2,6 2,6 2,6 2,9 2,9 3,2 3,6 3,6 4,0 4,5 5,0 5,6 5,6 6,3 6,3 6,3 7,1

A mm2 198 254 325 373 523 667 862 1252 1539 2065 3034 4210 5600 6158 7919 8920 9930 13448

Coefficient W mm/m3 0,0158 0,0124 0,0118 0,0103 0,0083 0,0073 0,0065 0,0056 0,0051 0,0042 0,0036 0,0033 0,0028 0,0028 0,0023 0,0022 0,0022 0,0021


Insulation PLUS Coefficient W mm/m3 0,0193 0,0151 0,0134 0,0117 0,0093 0,0084 0,0081 0,0063 0,0057 0,0053 0,0041 0,0037 0,0310 0,0029 0,0025 0,0025 0,0025 0,0000


6.2

Method 2 – Pre-stressed System

A pipeline having been assembled and tested prior to burying is subjected to a preheating. Once the requested elongation has been achieved, the pipeline is buried. The preheating temperature [T p] is set at such a point that when the buried pipeline is cooled down to the assembly temperature [T 0] and heated up to the service temperature [T ], the axial stress [σ ] does not exceed the computed compressive and tensile [ f d ] strength of a steel pipe.

Elongation [∆Ln] of an Unburied Pipe

6.2.1

A preheated [T 0] and unburied pipeline:

L1

∆L1

Elongation [ ∆ L] of a pipeline [Ln] long preheated to [T p], and unburied – in other words free elongation is computed according to the formula: ∆ L n = k·α1·(Tp – T 0 )· L n

where:

coefficient accounting for friction forces between k = 0,7÷0,8 pipe and soil α1 coefficient of linear expansion [1/ºC] T p preheating temperature [ºC] T 0 actual assembly temperature [ºC] L n unburied pipeline length [m] Free elongation of a preheated pipeline can be determined as a product of unit elongation [ε] and pipeline length [ L n]: ∆ L n = ε· L n [mm] k

Pipeline unit elongation: ε = α1·(T p-T 0 )

[mm/m]

Pipeline unit elongation ε [mm/m]


Graph 1


6.2.2

Elongation (Shortening) [∆Lz] of an Unburied Pipe

A buried and service temperature [T ] preheated pipeline:

L

L1

∆Lz

Lmax

Elongation, or shortening [ ∆ L z], of a buried pipeline is calculated from the formula:

∆ L z = α t ⋅ (T − T p )⋅ L max −

F ⋅ L 2 max

2 ⋅ ET ⋅ A

[m]

where: α t T T p L max F ET A

coefficient of linear expansion service temperature preheating temperature pipeline assembly length unit friction force Young s Modulus at Temperature carrier pipe cross section area '

[1/ºC] [ºC] [ºC] [m] [N/m] [N/m2 ] [m2]

T

When shortening is calculated from the above presented formula, proper temperature values have to be applied, while pipeline assembly length [ L max] has to be calculated from the formula presented in Point 6.1.1.

6.3

Method 2a – Initial Stresses If Single Use Compensator Joints Are Considered

A pipeline with compensator joints on it, having been subjected to tests, is subsequently buried except for places where the joints are, and then is preheated. Spacing between joints should not exceed twice the maximum assembly length [ 2· L max] determined as specified in Point 6.1, while the distance of the joints from either the actual or virtual fixed point should not exceed the assembly length [Lmax ] calculated from the formula in 6.1.1.

L

L1

∆Lz

Lmax

Compensator joint setting, allowing the joint to accommodate pipe elongation [ ∆ z L ], once the pipe has been preheated and put into operation at [T ] is calculated from the formula :

∆ L = α t ⋅ (T − T 0 ) ⋅ L −

F ⋅ L 2

4 ⋅ ET ⋅ A

[m]



where: α t

T T 0 L F

ET A

6.4

[1/ºC]

coefficient of linear expansion service temperature preheating temperature pipeline assembly length unit friction force

[ºC] [ºC] [m] [N/m]

Young s Modulus at Temperature T

[N/m 2 ]


[m2 ]

'

Change in Pipeline Routing

Pipeline rerouting can be effected by means of: • pipe end scarfing at the joint; • assembling using preinsulated elbows; • elastic bending of pipe at the site; • preinsulated bend pipes.

Where the pipe is bent at an angle less than 10º, such section is treated as a straight one. 6.4.1

Pipe Route Alteration By Scarfing Steel Pipe At a Joint

Slight rerouting at small angles (up to 10º) is obtained by scarfing steel pipe and subsequent assembling at an angle β ≤ 3º.

A minimum distance between scarfed ends should be at least 6,0 m.

β ≤ 3°

β ≤ 3°

6. 0 m m i n

6.4.2

Pipe Route Alteration By Using Preinsulated Elbow Units

Changes in a pipeline routing by inset elbows at angles of: 15º, 30º, 45º, 60º, 75º and 90º for the whole range of diameters. Elbow radii: r Diameter Steel Grade (bend radius) DN 20÷DN 80

R–35

3×Dz

DN 100÷DN 300

St 37.0

1,5×DN

D z – steel pipe external diameter



6.4.3

Pipe Route Alteration By Elastic Bending of Pipe

Assembled preinsulated pipe 6,00 or 12,00 m long is lowered into a trench and subjected to elastic bending. A minimum bending radius and the corresponding pipe bend angle [ β ], dependent on pipe diameter and pipe sections used, is specified in Table 7. Table 7

Steel Carrier Pipe Nominal DiExternal ameter Diameter DN Dz mm

mm

20 25 32 40 50 65 80 100 125 150 200 250 300 350 400 450 500 600

26,9 33,7 42,4 48,3 60,3 76,1 88,9 114,3 139,7 168,3 219,1 273,0 323,9 355,6 406,4 457,0 508,0 610,0

Jacket Pipe External Diameter Dzp mm

75 90 110 110 125 140 160 200 225 250 315 400 450 500 560 630 710 800

Bend Radius r m

17 20 24 28 34 42 49 65 76 97 123 153 182 200 224 251 283 343

Bend angle Pipe Length 6.00 m 12.00 m β β deg

deg

20,0 17,0 14,0 12,0 10,0 8,0 7,0 5,3 — — — — — — — — — —

— — 28,0 24,0 20,0 16,4 14,0 10,6 9,0 7,1 5,6 4,5 3,8 3,4 3,1 2,7 2,4 2,0



6.4.4

Rerouting by Means of Preinsulated Bend Pipe

Straight preinsulated sections 6,00 and 12,00 m long are bent on special machines at a requested angle. Preinsulated bent pipes have to be used where routing optimisation is sought and can substitute elbows. The permissible minimum radius [ r min] and the corresponding bend angle [ β ] for a pipe 12,00 m long depending on steel carrier pipe diameter [ D ] and depth of trench [ H ], provided steel pipe stress does not exceed f = d 150 MPa, is presented in the Table. z

Table 8

Steel Carrier Pipe

Soil Layer Depth [m]

Nominal

External

External

Diameter

Diameter

Diameter

DN

Dz

Dzp

r

β

r

β

mm

mm

mm

m

deg

m

deg

20 25 32 40 50 65 80 100 125 150 200 250 300

*)

Jacket Pipe

26,9*) 33,7*) 42,4 48,3 60,3 76,1 88,9 114,3 139,7 168,3 219,1 273,0 323,9

0,5

0,6

0,7 r m

75 90 110 110 125 140 160

6,5 8,4 8,8 10,1 12,3 14,0 16,2

— — — — — — —

5,4 7,0 7,3 8,4 10,3 11,7 13,5

— — — — — — —

4,7 6,0 6,3 7,2 8,8 10,1 11,6

200 225 250 315 400 450

18,5 20,3 24,8 25,8 28,2 33,3

37 34 28 27 24 21

15,5 16,9 20,7 21,6 23,6 27,9

44 41 33 32 29 25

13,3 14,6 17,8 18,5 20,2 23,9

0,8

0,9

β

r

β

deg

m

deg

r

11,7 12,7 15,6 16,2 17,7 21,0

59 54 44 42 39 33

β

m deg

— 4,1 — 5,3 — 5,5 — 6,3 — 7,7 — 8,8 — 10,2 52 47 39 37 34 29

1,0 r

β

m

deg

3,6 4,7 4,9 5,6 6,9 7,8 9,0

— — — — — — —

3,3 4,2 4,4 5,0 6,1 7,0 8,1

— — — — — — —

10,4 11,4 13,9 14,4 15,8 18,7

66 61 50 48 43 37

9,3 10,1 12,4 12,9 14,1 16,7

74 68 56 53 49 41

bend radii refer to 6.0 m long pipes.



Auxiliary formulae and guidelines on pipe routing if bend pipe or elastic bending is used.

a

β

a

lg

r

β

r

The β rerouting angle is determined from the design. Tangent length is obtained from: bend radius from:

⋅ a = r tan r =

β 2

360 ⋅ l g 2 ⋅ ⋅ β ̟

[m] [m]

The pipe length [l ] g over the arch section has to be treated as a multiple of preinsulated pipe section 6.00 m long for nominal diameter of 20 and 25, and 12.00 m long for diameters 32 and more, respectively. In the case of elastic bending the arch pipe length [l g] is determined once the rerouting angle has been specified in the design.



7.

Elongation Compensation

σ ] and pipeline elongation [∆L] when buried and operated at temperature The state of axial stress [σ [T ], and having an assembly length [Lmax] at which the carrier pipe cross section reduced rated steel strength [ f d ] is not exceeded is shown in the diagram below:

σ = f d

Lmax The length of straight pipe sections should not exceed twice the maximum length [ L max ], the elongation [∆L] being zero in the span middle, and a virtual (conventional) fixed point is set up – the pipe is fixed – and the free pipe ends will extend by [∆L].

σ = f d

σ

∆L

Lmax

Lmax

∆L

Pipe elongation is set off by pipe rerouting (natur al compensation) or by mounting elongation joints. Depending on the geometric configuration of a route, natural compensation is achieved through: • an L-shape system; • a Z-shape system; • a U-shape system.

7.1

The L-Shape System

L-Shape Systems alter a route by an angle of 45º to 90º.

≥ 45°

Elongation and compensation arm calculation Hiline-ZPUM Design Calculations -- Page 19 of 37 -- Rev no. HZ DC 2510 CPV Ltd, Woodington Mill, Woodington Road, East Wellow, Romsey, Hants, SO51 6DQ Website: www.cpv.co.uk -- Email: [email protected] -- Telephone: +44 01794 322884

≤ 90°


The L90 System – rerouting by 90º

∆L1

L1 L′1

∆L 2

L′2 L2

L1 < Lmax L2 < Lmax

Compensation arm length is calculated from:

L′1 = 1 . 2 ⋅

L 2′ = 1 . 2 ⋅

1 .5 ⋅ ET f d

1 .5 ⋅ ET f d

⋅ D z ⋅ ∆ L 2

[m]

⋅ D z ⋅ ∆ L1

[m]

where: D z f d ET ∆ L1 ∆ L 2

external carrier pipe diameter reduced rated steel strength Young s Modulus at Temperature '

[m] T

[MPa]

L1 section elongation (as per 6.1.2) [m] L2 section elongation (as per 6.1.2) [m] ’ [ L ] compensation arm lengths for carrier pipe diameters [ D z] to be used and conditions in which the pipeline is to be laid depending on elongation [∆ L] can be obtained from graph 2 (page 20).

L-45º-plus compensation: rerouting at an angle ≥ 45º



L′1

∆1

L′2

L1 L2

∆2

The length of compensation arms [ L´ 1] and [ L´ 2], provided the reduced elongations ∆1 and ∆ 2 have been accounted for, is obtained from the formula:

L′1 = 1 . 2 ⋅

L 2′ = 1 . 2 ⋅

1 .5 ⋅ ET f d

1 .5 ⋅ ET f d

⋅ D z ⋅ ∆ 2

[m]

⋅ D z ⋅ ∆1

[m]

where: D z f d ET ∆ L1 ∆ L 2

[m]

external carrier pipe diameter reduced rated steel strength Young s Modulus at Temperature '

[MPa] T

reduced elongation of section L1 reduced elongation of section L2

[m] [m]

Reduced elongation is obtained from:

∆ L 2 ∆ L1 + tan α sin α ∆ L 2 ∆ L1 ∆ 2 = + sin α tan α ∆1 =

[mm] [mm]

where: α ∆ L1 ∆ L 2

obtuse angle L1 section elongation (as per 6.1.2) L2 section elongation (as per 6.1.2)

[m] [m]

The length of compensation arms [ L´ 1] and [ L´ 2] for applicable carrier pipe diameters [ Dz] [ 1] and [∆ 2] can be determined from graph 2. depending on reduced elongations ∆

Specific requirements A system needs no compensation if its route is altered by an angle between 8º and 45º. Such a system should be protected against overloads by means of a fixed point at a distance of maximum L = 6,0 m or by an L-90 system at a distance not exceeding 0,5·L max.



a)

max 6.0 m m a x 6 . 0 m < 45°

b)

90° < 45° 90°

c)

90°

m a x 6 . 0 m

< 45°

L-Shape System The compensation arm length [ L´ 1] in relation to elongation [∆ L]

L

∆L E = 204 GPa f d = 150 MPa



Graph 2



7.2

The Z-Shape System ∆L1

L1 L′1

C

L′2

∆L 2

L2

For a Z-Shape System, the length of compensation arms [C] is obtained from:

C =

1 .5 ⋅ ET f d

[m]

⋅ D z ⋅ ∆ L

where:

[m]

external carrier pipe diameter reduced rated steel strength

D z f d ET

[MPa]

Young s Modulus at Temperature T ∆ L = ∆ L1+∆ L 2 '

∆ L1 L1 section elongation (as per 6.1.2) [m] ∆ L 2 L2 section elongation (as per 6.1.2) [m] The length of [ L’] compensation arms in a Z-Shape System for applicable carrier pipe diameters and initial data depending on elongation [∆ L] can be obtained from Graph 3.

Z-Shape System The compensation arm length [C] in relation to elongation [∆ L]

∆L1 C E = 204 GPa f d = 150 MPa

∆L2



Graph 3



7.3

The U-Shape System

A U-Shape System is seen as a system where the arms length remains within the following limits: B
∆L1

L1

- -

∆L2

L2

L′1

L′2

C B For a Z-Shape System, the length of compensation arms [D] is obtained from:

C = 0 .7 ⋅

1 .5 ⋅ ET f d

[m]

⋅ D z ⋅ ∆ L

where: D z f d ET

[m]

external carrier pipe diameter reduced rated steel strength

[MPa]

Young s Modulus at Temperature T ∆ L = ∆ L1+∆ L 2 '

∆ L1 L1 section elongation (as per 6.1.2) [m] ∆ L 2 L2 section elongation (as per 6.1.2) [m] The length of [C] compensation arms in a U-Shape System for applicable carrier pipe diameters and initial data depending on elongation [∆ L] can be obtained from Graph 3.

7.4

Compensation Zones

A compensation zone has to be seen as a space along a pipeline, limited by the length of a compensation arm [L’] and existing elongations [∆ L] where a pipeline section or elbows are to be relieved from the pressure a pipeline exerts on the soil. We suggest filling the compensation zone over a stretch equaling L = 2/3 L’

∆L L′′ L′

d

d



We suggest: In order to have a compensation zone properly filled in with for instance mineral wool mats or foam claddings, subsequent layers have to be stepped, assuming that if one mat layer of thickness [ d ] is to take over part of elongation [∆ L] over length [ L’], then the following mat should be [ L˝ ] long equaling:

L =

8.

∆ L − d ⋅ L′ ∆ L

[m]

Preinsulated Fixed Points

Preinsulated fixed points in thermal networks are used to: • relieve other preinsulated structural members not fitted to carry loads, that is for instance preinsulated tees, wall transition sleeves, points where traditional transmission modes are replaced with preinsulated solutions; • form desired elongations within thermal networks, for example where a preinsulated elbow compensation arm, calculated basing on actual elongation does not carry over such an elongation due to topographic conditions.

8.1

Calculation of Forces Affecting a Fixed Point

8.1.1

Relieved Fixed Point

A fixed point completely and on one side relieved is such which is subjected to axial force acting on one side. A case of a one side load on a f ixed point is when there runs a straight section on one side, whilst on the other the route is altered by means of for instance a 90º elbow. It is essential that this straight section between the 90º compensation elbow [ A] and the fixed point is negligibly short, which is illustrated below:

P.S.

Tj=const N PS = T j × L

(A)

(B) L

The axial force [N PS] affecting the fixed point is expressed by : N PS = T j × L

[N]

where: T j L

unit friction force affecting preinsulated pipe [N/m] pipe length between f.p. and compensation elbow [B] [m]



Partially Relieved Fixed Point

8.1.2

A partially relieved fixed point is a one where axial force resulting from friction between a preinsulated pipe jacket and the sand surround, and affecting the fixed point: N PS1 =T × [N] j L 1 and taken over from an L1 length between the fixed point and the compensation elbow at [ B] is a partially reduced axial force which acts in an opposite direction to soil friction forces affecting the point: N PS2 =T × [N] j L 2 taken over from an L 2 length between the fixed point and the compensation elbow at [ A] This situation is shown in the diagram below:

Tj=const

P.S. N PS 2

=

T j × L2

N PS 1

=

T j × L1

(B)

(A) L2

L1

A total axial force [ N PS] affecting the fixed point is expressed as: N

N

=N PS

–N PS1

-L PS= T ×(L j 1 )2

PS2

[N] [N]

(indexes as in the previous diagram) Table 12 shows maximum dimensions of fixed point concrete blocks. Axial forces acting on a fixed point were derived from the following assumptions: pipe axis depth is below soil level H = 1,0 m; fixed point is totally relieved on one side; the section length over which axial forces affecting the fixed point were collected is , steel grade is St-3.0, insulation STANDARD; L in dimensioning concrete blocks the axial force assumed was twice that of [ N PS] due to the action of the feeding and return carrier pipe on the concrete block; in dimensioning a concrete block the unit passive soil pressure was assumed to be 150 kPa in accordance with standard PN-81/B-3020. Fixed point foundation blocks have to be designed and cast in concrete of class at least B-15, reinforced with rebars grade A-III, 34 GS. • • •

max

•

•



Fixed Point Concrete Block Dimensions A

B/2

DN

Dzp B

B/2

Fixed point stop y Pierścień oporowy collar punktu stałego

H

X X+Dzp



Concrete Block Reinforcement L1 5

n””pieces "n" szt.

 NR 1 5

4 a

10

10

a

a L3

NR 2 a a 4 5

b

 NR 1

a

2 NR L2

5

L4

b

Maximum Dimensions of Fixed Point Concrete Blocks - - k x e c i E m e i a h s p D T l s i e P l l l a a n e n W e r / t e r e S t t

- r x e E t e e m p a i P i t D e l k a c n a r e J t

y k e b c c o r d l o e B F t l t e a i t e m m s r i x n c n a a r o M T C

k t c o s n l n i o o B i P e s n d t e e e r m x c i n i F o D C

Fixed Point Concrete Block Reinforcement

Dz/g

Dzp

[NPS]

A

B

H

mm/mm

mm

dN

cm

cm

cm

1

26,9/2,6

75

6030

80

50

30

2

33,7/2,6

90

7530

105

50

30

3

42,4/2,6

110

10800

110

60

30

4

48,3/2,6

110

11730

130

60

30

5

60,3/2,9

125

15870

150

70

40

6

76,1/2,9

140

20580

165

80

40

7

88,9/3,2

160

27520

170

100

50

8

114,3/3,6

200

40970

205

120

70

9

139,7/3,6

225

48430

240

125

70

10

168,3/4

250

65050

280

140

80

11

219,1/4,5

315

90760

390

150

100

o N r a b e R

r e t e m a i D

mm

y t i t n a u Q

pcs

1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1

8 6 8 6 8 6 8 6 10 6 10 6 10 6 10 6 10 6 12 8 10

4 5 4 6 4 5 4 5 5 6 6 7 8 7 10 8 10 9 10 11 12

2 1

8 14

15 14

12

273,0/5

315

124863

446

180

100

2

10

17

13

323,9/5,6

450

173730

541

190

150

1 2

14 10

16 20

L1 cm

70

L2 cm

20

100

20

30

155

30

60

230

60

70

435

90


22

42

22

52

22

52

22

62

32

72

32

92

42

112

62

117

62

132

92

142

92

172

92

182

142

90

380

530

42

40

195

270

cm

20

140

160

cm

L4

20

95

120

L3

140


Note: Foundation dimensions have to be customized accounting for pipeline axial force value, computational passive soil upper limit pressure and stability of the foundation-subgrade conditions as specified by standard PN-81/B-3020.

9.

Pipe Laterals and Wall Transitions

Pipelines in CPV Hiline ZPUM have to be br anched off by means of tees. Laterals are affected by mains elongation (as in the diagram); moreover, a lateral will be subject to thermal elongation, affecting this way the mains. The length of a compensation zone [L’] and elongation [∆L] are calculated as for an L-90 Compensation System.

L

∆L

L

Thermal elongation exerted by a lateral on the mains can be set off by: 1. Setting up a fixed point within the lateral no more than 9,0 m away from the mains axis:

L

∆L

L

2. Fitting in a Z-Shape Compensation System within the lateral no more than 24,`0 m away from the mains axis:



L′ max 24.0 m

C

3. Fitting in a lateral parallel to the mains over a 2/3 L max from the fixed point (or a conventional one): L max 2/3 L max L'

∆L1

L1 Conventional fixed umowny or lubactual rzeczywisty point

punkt stały

L'

The compensation arm length [ L’] on a lateral is calculated in the same way as for the LShape Compensation, i.e. elongations [∆ L] over the section L1 are calculated and the compensation arm length [ L’] is read out from the [∆ L] axis in Diagram 2 on page 22. 4.

If a lateral makes an extension of the mains, a half of a U-Shape Compensation System should be considered in designing. mains rura

lateral rura odgałęźna

główna

D

B/2

A preinsulated section parallel to a thermal network cannot be worked out as a mains extension by means of a parallel tee. The diagram below shows an incorrectly designed thermal network section.



lateral

rura odgałęźna

rura główna

mains

5. No shutoff, venting, strain nor preinsulated laterals can be included in compensation zones.

10.

Preinsulated Pipe Connected To a Traditional Pipe (Underground Utilities) Effect of preinsulated pipe elongation are set off by fitting in a fixed point or a Z-Shape System distanced no more than 9.0 m from the traditional pipeline axis or connection.

max 9.0 m

max 9.0 m



max 9.0 m

max 9.0 m C

11.

C

Steel Fittings and Fixtures

When designing preinsulated steel fittings and fixtures like: shutoff valves, shutoff valves with a single venting (straining) valves, shutoff valves with straining and venting functions the following should be observed: • • • •

fittings should not be located in the vicinity of compensation elbows (L-, Z-, and Ucompensating joints); shutoff vent spindle should be accessible from a street box and jacket pipe or a manhole should be built in concrete tube at least 600 mm in diameter; the spindle of a buried shutoff valve should be protected with compensation mats; straining and venting shutoff valves should be in concrete tube manholes of a diameter at least 10000 mm or in concrete chambers;

Steel shutoff fittings and fixtures are used to cut off the flow of a medium in a given section of a pipelines thermal utilities. Strain valves should be fitted in the lowest network points, while venting ones in the topmost sections and next to straining, a erating and venting shutoff valves.


Design Calculations Manual

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