7/24/2019 Flare Systems Major Thrust Points for Stress Analysis
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lare systems: Major thrust points
for stress analysis
June 15, 2015 No Comment ᄃ
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Introduction:
Flare system is a means of safe disposal of waste gases y urning
them under controlled conditions! Flare piping generally comprises of
"#$s outlet piping, su header piping % main header piping! &esign
conditions considered for stress analysis are as per "%I&s, line list
and specific information related to flare if any y process!
' typical flare system consists of:
• "#$ outlet pipes, su header connected to main flare header ,
main flare header connected to (noc( out drum , outlet of flare
(noc( out drum to flare stac(!• ' (noc(out drum to remo)e and store condensale and entrained
li*uids!
• ' single or multiple urner units and a flare stac(!
+he major thrust points which a stress engineer should consider
carefully are listed elow:
7/24/2019 Flare Systems Major Thrust Points for Stress Analysis
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• luid &ensity:Fluid density has to e ta(en from list list
"rocess &epartment-! In asence of data, 1./rd water filled
weight can e assumed for aesar input!
•+est Method:Flare lines are normally pneumatic tested! #o,
hydrotest weight is not re*uired to e considered! owe)er in
specific cases water filled weight has to e considered hec(
with "rocess department-!
• #upporting:Flare lines are normally pro)ided with slopes as
per "roject specification! #o general practice is to support with
#hoe.saddle supports! #upporting span to e maintained such than
sustained sagging should not eceed /35 mm! #tructure elow pipe
support . shoe height is to e planned to meet piping sloping.free
draining re*uirement!
•#I : 4ormal industry practice is to ta(e 5 degree.60 degree
ranch connections from Flare eader: "roper #IF oth inplane and
outplane- should e incorporated at ranch connections while
entering data into aesar II! #IF s can e calculated using Fe3
#IF, 4o77le "ro, or some other type of F8' software! #ometimes
reinforcement may e re*uired to reduce #IF )alue!
•+emperature 9radient:
In a flare system sometimes temperature
gradient or profile may eist when the hot contents flow into the
suheader . main header which is at a lower temperature
confirmation with process if re*uired -!
• le2iility:"iping shall e e)aluated for fleiility! If
necessary epansion loops shall e pro)ided! 8pansion joints to
e a)oided! Flare piping loops are planned in hori7ontal plane &
ends- in order to ensure pipe slope.free draining re*uirement!
owe)er no of loops should e minimised as much as possile!
• Flare line routing and supporting to e planned in such a way
that forces and moments on flare (noc( out drum no77le connections
are minimi7ed!
• #ometimes Flare line may consist of two phoase flow! #o
$iration.'ccoustic analysis is re*uired to e performed and
supporting to e strengthened!
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