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 

97 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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