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Stress Analysis

Method and Emphasis points

David Cohen – 29/09/14



• The Most important reason stress analysis is carried out is : SAFETY

• This is achieved by designing a Code Compliant System.

• There are also Financial Saving to be made:

• Correct pipe support spans

• Material sizes and thicness !hich are correctly speci"ied.

2

General

IdealFlo!hart



3

Dangers

"i#hpress$re Flamma%l

e

Good practice engineering, Quality controls,Experienced engineers, and correct installation shouldavoid dangerous consequences



4

Dangers

&$ried 'ipes ( alon# roads and in!ivil areas) "IDDE* DA*+E,S

sho$ld %e !onsideredserio$sly



5

• #esign and Analysis should tae into account also construction "easibility

• The designer should run di""erent analyses according to speci"ying steps.



6

Codes

• $oading Codes:• Seismic $oads: S%&'()

• *ind $oads: S%&'('

• Tra""ic and Earth $oads: ASCE&+uidelines "or the design o" buried steel pipe

, +eotechnical -eport

• iping Codes:

• ASME /)(.)

• ASME /)(.0

• S%&122'

• 3E3 )214



Sources for generation of stress in a Piping System:•Weight

•Internal/External Pressure

•Temperature change

•Occasional oa!s !ue to "in!# seismic !isturbances# PS$ !ischarge etc.

•%orces !ue to $ibration.

&.Sustaine! Stresses are the stresses generate! by sustaine! loa!s. 'e.g. Pressure # Weight(. These loa!s are present

continuously throughout plant life.

).*esisti+e force arising out of sustaine! stresses balance the external forces ,eeping the system in e-uilibrium. Excee!ing

sustain allo"able stress +alue causes catastrophic failure of the system.

.s per S0E 1 &.# 'clause 2)..3( 4 The sum of the longitu!inal stresses# S# in any component in a piping system#

!ue to sustaine! loa!s such as pressure an! "eight# shall not excee! the pro!uct Sh x W 5. Where# Sh61asic allo"able

stress at maximum metal temperature expecte! !uring the !isplacement cycle an! W6"el! 7oint strength re!uction factor.

8.Pressure Stresses are ta,en care of by calculating an! selecting proper pipe thic,ness. The pressure thic,ness 't( of a

straight pipe can be obtaine! as per S0E 1&. from the e-uation '9lause 28.&.)(.



Seismic Loadה א



M)-) .,o$re) i$

Seismic Loadה א

ateral +ro$nd Disp

"i#h Seismi! area(Sol$tions

David Cohen


http://slidepdf.com/reader/full/stressanalysismethod-141208025453-conversion-gate02 11/22David Cohen11

The SI-414 is giving a very detailed methodor calculating !ind orces on roundelements

WIND Loadה א



WIND Loadה א



TRAIC Loadה א



Soil!"i#e In$erac$ion



S%##or$s De&ini$ion

3he s$pports sho$ld %e ina!!ordan!e ith a!t$alstr$!t$res and not 5in theair6

3he s$pports sho$ld%e pla!ed !orre!tly



17

Coe7!ient o8 8ri!tion 8a!tor dependin# $pon the s$pportin#inter8a!e i)e :$n!tion %eteen 3op o8 Steel and &ottom o8 'ipeor &ottom o8 Shoe/Cradle; shall %e applied at all verti!alrestraint <= or = s$pports; lo!ations as mentioned %elo)

Car%on Steel to Car%on Steel( 0)>

'olished Stainless Steel to 'olished Stainless Steel/+raphite(0)1? 3e@on to 3e@on/ 'olished Stainless Steel( 0)10Con!rete to Car%on Steel( 0)4'ipe to ,oll S$pport( 0)01 3e@on to Car%on Steel( 0)2

S%##or$s ric$ion



From 'ipin# desi#n to stressanalysis :$st !he! that anydesi#n pro%lem ill o!!$r)'I'I*+ ,edesi#n ill #enerate ane stress analysis pro!ess)

Chec' $he (odel



)*

From Soil ,eport

Soil Data sho$ld %e inserteda!!ordin# to soil report pipediameter and pipe depth)

Inser$ Da$a



+,

A ine *$m%ers sho$ld %eritten.nly on main lines not 8orvents;

A S$pports sho$ld %e ithdierent name !he! d$pli!ityline stop sho$ld %e the sames$pport name;

Inser$ Da$a



+)

Anal-sis Se$$ings



++

Che! the hi#hest displa!ementval$e ( D,

Inser$ Da$a

Che! the hi#hestS$pport/An!hor ,ea!tion +lo%alF,

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