MAN B&W S65ME-C8.2-GI-TII, Руководство по проекту, Страница: 191 / 395

MAN B&W
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MAN Diesel
7.07
MAN B&W ME-GI TII engines 198 86 37-7.2
Gas piping
For delivery of high-pressure gas to the ME-GI
main engine, double-wall gas pipe can be used in
both open and enclosed spaces and is required
for interior piping.
Moreover, double-wall gas pipe requires ventila-
tion in the annular space as described in Section
7.09.
Single-wall gas piping can only be used in exterior
locations in free open space. In all other locations,
double-wall gas piping is required.
Double-wall piping
Design guidelines:
Bosses must be fitted for every 5 meters for in-
spection of outer duct, inner pipe and supports.
Bosses shall also be fitted next to every pipe
bend on each side.
Inner pipe support must be placed with a distance
of 1,8 m of each other to prevent natural frequency.
On vertical piping, two supports must be placed
in the horizontal pipe right before the bend to the
vertical pipe.
Pipes to be cold-drawn in order to obtain a proper
inner surface finish of the outer pipe.
Pipe installation must be able to absorb deflection
from hull and engine due to heat and vibration,
therefore flexible elements must be installed.
Leakage test is to be carried out at shop test and
at commisioning of the vessel.
For more information contact MAN Diesel & Turbo,
Copenhagen.
Outer pipe for double-wall piping
Design in accordance with IGF code, chapter 9.8.
The tangential membrane stress of a straight pipe
should not exceed the tensile strength divided by
1.5 (Rm/1.5) when subjected to the critical pres-
sure. The pressure ratings of all other piping com-
ponents should reflect the same level of strength
as straight pipes.
Temperature range: .......................÷55ºC to +60 ºC
Total Pressure loss (max):
Must be constructed in a way to be compliant
with MAN Diesel & Turbo’s ventilation specifica-
tion, see Section 7.09, ‘General data for ventilation
system’.
Critical pressure: ......................................... 174 bar
(Based on 320 bar design pressure for inner pipe)
Material
The recommended material is Duplex EN 1.4462
or Stainless steel 316L (EN 1.4404). Selection of
this material is based on corrosion resistance and
required strength, resistance to cold exposure.
Therefore long maintenance intervals can be of-
fered with this material.
Duplex Steel EN 1.4462:
Ultimate tensile stress (UTS) .................... 680 MPa
Yield stress ................................................450 MPa
Stainless steel 316L (EN 1.4404):
Ultimate tensile stress (UTS .....................500 MPa
Yield stress ................................................200 MPa
Sizing of outer pipe
The table below provides pipe dimension guidelines
based on standard pipe sizes for EN 1.4462, and in
compliance with the above mentioned formula.
Pipe dimension guidelines based on standard pipe sizes for EN 1.4462
Power
range
Pipe OD Thickness,
t
NPS Test
pressure
Stress resulting from
critical pressure
MW mm mm inch Bar Mpa
0-45 114,30 3,05 4 175 317
>
45
168,28 4,50 6 175 308