HPP final

1/23/2015 High Pressure Piping

High Pressure Piping

“Design of a High Pressure Pipe transporting live steam”

Project Supervisor:

Prof. Dr.-Ing. B. Jatzlau

Participants:

Manas Shidore

Ahmed Hussein

Hochschule Offenburg University of Applied Sciences

Operational data

• This high pressure pipe is applied to transport a live steam from the

boiler to the steam turbine in a conventional steam power plant.

1/23/2015 High Pressure Piping 2

Fluid flow rate “Q” Fluid quality “X” Point of operation (Press. &

Temp.)

555.555 kg/sec. at

operation conditions

X=1 (100% Steam) Super heated

steam

(Single-phase region)

Toper.= 550 C°, Tdesign= 565 C°

P= 26 Mpa, Ploss=1 Mpa


Fluid properties


Composition “SC” 1.0-2.0 µS/cm

Phase Gaseous (live steam)

Density “ ” 82.34 kg/m3

Viscosity “ ” 32.81E-6 Pa.s

Toxicity Nontoxic

Combustibility Nonflammable

Fluid group Group 2

Flow type Turbulent

Thermal conductivity “λ” 100.9*10-3 W.m-1.K-1

Compressibility Compressible (Psteam= 260 bar > 1.513 bar)


Material properties


Grade: X8CrNiMoNb 16-16 (Solution Annealed)

Number: 1.4981

Standard: EN 10302 : 2008 Creep resisting steels, nickel

and cobalt

alloys

Classification: Austenitic Steels

Nominal design creep strength (test) “Re” 215 N/mm2 (Mpa)

Tensile strength “Rm” 530/690 N/mm2 (Mpa)

Density “ ” 8.01 kg/m3

Verification by PED Quality grade lll

C Si Mn Ni P S Cr Mo N

0.04 - 0.1 0.3 - 0.6 max 1.5 15.5 - 17.5 max 0.035 max 0.015 13.5 - 17.5 1.6 - 2 max 1.2


Corrosive and abrasive properties

• In the range 500-800 degrees for any reasonable time there is a risk that

the chrome will form chrome carbides (a compound formed with carbon)

with any carbon present in the steel. This reduces the chrome available to

provide the passive film and leads to preferential corrosion, which can be

severe.

• Because of the high Nickel content in Austenitic materials which

gives it a relatively higher formability in higher temperatures and

because of stress corrosion cracking, preferential corrosion and

recrystallization dangers at high temperature ranges as well as taking

both partial and usage Factors of safety into considerations, the FOS

is chosen relatively high 1.5 (as it usually ranges from 1.05 - 1.5).



Calculations

• All calculations were done for only one train with the aid of the

MATLAB 7.0 as the main computing software


Number of trains Number of fittings (max.)

2 (parallel) 20

The number of trains has been limited to only 2 because of the

summation of the total losses at parallelized trains. A compromise

must be done for optimum design and fabrication between using few

numbers of trains with big diameters or using large numbers of trains

with small diameters.


Thickness calculations (Thin)

• Going for the calculations of smooth cylinderical thin pipe and at different

values for “Di” and “t”, Da/Di=1.33 and hence not satisfying the thin-walled

cylinderical pipe condition which is Da/Di≤1.2.



Thickness calculations (Thick)



Thickness calculations (Thick)

• Going for the calculations of smooth cylinderical thick pipe and according to

DIN-2917, Di=308.95 mm at v=45 m/sec.

• For both velocity and diameter value corrections, v at Di=320 mm equals to

41.94≈42 m/sec. and hence t=50 mm (according to DIN-2917).

• Choosing this specific velocity was based on the fact that the minor

losses (losses due to fittings) were relatively high at the same range

of velocity variations from 20-70 m/s. With the fact that major losses

increase at high velocities (smaller diameters), while the minor losses

increase at larger diameters (lower velocities), so a compromise has

been done for choosing this velocity.



Losses calculations


majorminorlosslossPPPP

elevationtotal

Major losses:


Losses calculations


Major losses Minor losses Elevation losses

3.73 bars 4.2 bars 0.072 bars


Stress calculations for T fittings

• For tees: di=Di/2=160mm, di=200 mm and hence ts=32 mm (according to

DIN-2917)



Flange calculations


1215.7 KN

1170.1

501.4

= 2887.27


Flange calculations

• Annular force:


= 164.66 KN

Total pressure force:

= 1380.36 KN

Gasket force:

1- assembly [using Metall-Flächdichtung (stainless steel) with strength = 350

N/mm2]

= 2.858 MN


Flange calculations

• 2- operation:


= 414.12 KN

= 2561.3 KN

3- safeguard against lifting flanges:

= 276.0 KN


Flange calculations

• 4- allowable gasket load:


= 4109.6 KN

5- forces on bolts:

= 3731.4 KN

= 2295.88 KN

= 5991.36 KN


Flange calculations

• 6- dimensions: @ assembly (class 8.8 at 20 C)


= 24.62+c mm, = 27.62 mm

@ initial operation (class 8.8 at 20 C)

= 31.2+c mm, = 29.33 mm


Flange calculations

• @ operation (class 8.8 at 300 C)


= 22.72+c mm, = 25.7 mm

So we choose M36 for class 8.8 (nearest bigger diameter is 30.5 mm)


Flange calculations

• External moments:


= 508354.8 N.mm

= 451258.4 N.mm


Flange calculations

• Moments of resistance:


= 6011761.6 mm3

= 26.54 mm

= 42.49 mm


Flange calculations


= 4077287.8 mm3

= 6630492.1 mm3


Life time calculations

Life (h)

cycle

% C° Allowed

load time

Factor

200 1 570 40000 5 5

1000 5 560 60000 3.3 16.66

2000 10 530 280000 0.714 7.14

3000 15 540 180000 1.1 16.6

15000 75 550 120000 1.6 125

20000 100 170.47


Damage expected by 200000/1.705 = 117302 h

After 100000 hrs. of operation, first repeated inspection should be done.


Questions ?

Finally


HPP final

Documents

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