CWB LEVEL 2 QUESTIONS WITH
CORRECT ANSWERS
What cis cthe cdescription cof cdamage cof ca cbrittle cfracture? c- cCORRECT
cANS✔✔Sudden crapid cfracture cunder cstress c(residual cor capplied) cwhere cmaterial
cexhibits clittle cor cno cevidence cof cductility cor cplastic cdeformation
What ctype cof cSteel care cof cprimary cconcern cwith cbrittle cfractures? c- cCORRECT
cANS✔✔Carbon cand clow calloy csteels. c400 cseries cSS care calso csusceptible
What chas ca csignificant cinfluence con ctoughness cand cresistance cto cbrittle cfractures?
c- cCORRECT cANS✔✔Steel ccleanliness cand cgrain csize
In cmost ccases cbrittle cfractures coccur conly cat cwhat ctemperature? c- cCORRECT
cANS✔✔Below cthe ccharpy cimpact ctransition ctemperature.(or cductile-to-brittle
ctransition ctemperature)
The cpoint cat cwhich cthe ctoughness cof cthe cmaterial cdrops coff csharply
What ckind cof cequipment cor cunits ccan cbe caffected cfor cbrittle cfractures? c-
cCORRECT cANS✔✔*Can coccur cduring cambient ctemperature chydro ctesting cdue cto
chigh cstresses cand clow ctoughness cat cthe ctesting ctemperature
*Most cprocesses crun cat celevated ctemperature cso cthe cmain cconcern cis cduring
cstartup, cshutdown, cor chydro/tightening ctesting.
What cis cthe cappearance cof ca cbrittle cfracture? c- cCORRECT cANS✔✔Typically
cappear cstraight, cnon cbranching, cand clargely cdevoid cof cany cassociated cplastic
cdeformation. c(Although cfine cshear clips cmay cbe cfound calong cfree cadge cof cthe
cfracture cor clocalized cnecking caround cneck cof ccrack.
What cis cthermal cfatigue ca cresult cof c? c- cCORRECT cANS✔✔Cyclic cStress ccaused
cby cvariations cin ctemperature.
In cthermal cfatigue cdamage coccurs cas ccracking, cwhere cmay cthis coccur? c-
cCORRECT cANS✔✔Can coccur canywhere cin ca cmetallic ccomponent cwhere crelative
cmovement cor cdifferential cexpansion cis cconstrained. cParticularly cunder crepeated
cthermal ccycling.
What ctype cof cmaterial ccan cthermal cfatigue chappen con? c- cCORRECT cANS✔✔All
cmaterial cof cconstruction.
, What care ca ccouple cbut cnot call ccritical cfactors cfor cthermal cfatigue? c- cCORRECT
cANS✔✔*Key cfactors caffecting cthermal cfatigue care cthe cmagnitude cof cthe
ctemperature cswing cand cthe cfrequency c(number cof ccycles)
*Damage cis calso cprompted cby crapid cchanges cin csurface ctemperature cthat cresults
cin cthermal cgradient cthrough cthe cthickness cor calong cthe clength cof ca ccomponent.
What care csome caffected cunits cor cequipment cof cthermal cfatigue? c- cCORRECT
cANS✔✔*Major cproblem cin ccoke cdrum cshells
*another cexample cis cthe cmix cpoint cof chot/cold cstreams csuch cas chydrogen cmix
cpoints cin chydroprocessing cunits.
*locations cwhere ccondensate ccomes cin ccontact cwith csteam csystems csuch cas cde-
superheating cor cattemporating cequipment
What cis cthe cappearance cof ca cthermal cfatigue ccrack? c- cCORRECT cANS✔✔*Usually
cinitiates con cthe csurface. cGenerally cwide cand coften cfilled cwith coxides cdue cto
celevated ctemperature cexposure. c*May coccur cas csingle cor cmultiple ccracks
*usually cpropagate ctransverse cto cthe cstress cand care cusually cdagger cshaped,
ctransgranular, cand coxide cfilled. c
*Can calso csometimes cbe caxial, cor ccircumferential cor cboth cat cthe csame clocation.
How cis cthermal cfatigue cbest cprevented? c- cCORRECT cANS✔✔Through cdesign cand
coperation cto cminimize cthermal cstresses cand cthermal ccycling. cMethods cof
cprevention cinclude cbut cnot call:
Control crate cof cheating cand ccooling cduring cstartup cand cshut cdown
Design cthat cincorporates creduction cof cstress cconcentrators, cblend cgrinding cof cweld
cprofiles c& csmooth ctransitions cshould cbe cused.
What care c3 cmethods cof cinspection cfor cthermal cfatigue? c- cCORRECT
cANS✔✔*Visual cInspection
*MT
*PT
Define cErosion? c- cCORRECT cANS✔✔Accelerated cmechanical cremoval cof csurface
cmaterial cas ca cresult cof crelative cmovement cbetween, cor cimpact cfrom csolids, cliquids,
cvapors cor cany ccombination cthereof.
Define cErosion-Corrosion? c- cCORRECT cANS✔✔description cof cthe cdamage cthat
coccurs cwhen ccorrosion ccontributes cto cerosion cby cremoving cprotective cfilms cor
cscales, cor cby cexposing cthe cmetal csurface cto cfurther ccorrosion cunder cthe ccombined
caction cof cerosion cand ccorrosion.
What ckind cof cunits/equipment care caffected cby cErosion,
Erosion-Corrosion? c- cCORRECT cANS✔✔All ctypes cof cequipment ctat care cexposed
cto cmoving cfluid cand/or ccatalyst care csubject cto cerosion, cerosion-corrosion.
CORRECT ANSWERS
What cis cthe cdescription cof cdamage cof ca cbrittle cfracture? c- cCORRECT
cANS✔✔Sudden crapid cfracture cunder cstress c(residual cor capplied) cwhere cmaterial
cexhibits clittle cor cno cevidence cof cductility cor cplastic cdeformation
What ctype cof cSteel care cof cprimary cconcern cwith cbrittle cfractures? c- cCORRECT
cANS✔✔Carbon cand clow calloy csteels. c400 cseries cSS care calso csusceptible
What chas ca csignificant cinfluence con ctoughness cand cresistance cto cbrittle cfractures?
c- cCORRECT cANS✔✔Steel ccleanliness cand cgrain csize
In cmost ccases cbrittle cfractures coccur conly cat cwhat ctemperature? c- cCORRECT
cANS✔✔Below cthe ccharpy cimpact ctransition ctemperature.(or cductile-to-brittle
ctransition ctemperature)
The cpoint cat cwhich cthe ctoughness cof cthe cmaterial cdrops coff csharply
What ckind cof cequipment cor cunits ccan cbe caffected cfor cbrittle cfractures? c-
cCORRECT cANS✔✔*Can coccur cduring cambient ctemperature chydro ctesting cdue cto
chigh cstresses cand clow ctoughness cat cthe ctesting ctemperature
*Most cprocesses crun cat celevated ctemperature cso cthe cmain cconcern cis cduring
cstartup, cshutdown, cor chydro/tightening ctesting.
What cis cthe cappearance cof ca cbrittle cfracture? c- cCORRECT cANS✔✔Typically
cappear cstraight, cnon cbranching, cand clargely cdevoid cof cany cassociated cplastic
cdeformation. c(Although cfine cshear clips cmay cbe cfound calong cfree cadge cof cthe
cfracture cor clocalized cnecking caround cneck cof ccrack.
What cis cthermal cfatigue ca cresult cof c? c- cCORRECT cANS✔✔Cyclic cStress ccaused
cby cvariations cin ctemperature.
In cthermal cfatigue cdamage coccurs cas ccracking, cwhere cmay cthis coccur? c-
cCORRECT cANS✔✔Can coccur canywhere cin ca cmetallic ccomponent cwhere crelative
cmovement cor cdifferential cexpansion cis cconstrained. cParticularly cunder crepeated
cthermal ccycling.
What ctype cof cmaterial ccan cthermal cfatigue chappen con? c- cCORRECT cANS✔✔All
cmaterial cof cconstruction.
, What care ca ccouple cbut cnot call ccritical cfactors cfor cthermal cfatigue? c- cCORRECT
cANS✔✔*Key cfactors caffecting cthermal cfatigue care cthe cmagnitude cof cthe
ctemperature cswing cand cthe cfrequency c(number cof ccycles)
*Damage cis calso cprompted cby crapid cchanges cin csurface ctemperature cthat cresults
cin cthermal cgradient cthrough cthe cthickness cor calong cthe clength cof ca ccomponent.
What care csome caffected cunits cor cequipment cof cthermal cfatigue? c- cCORRECT
cANS✔✔*Major cproblem cin ccoke cdrum cshells
*another cexample cis cthe cmix cpoint cof chot/cold cstreams csuch cas chydrogen cmix
cpoints cin chydroprocessing cunits.
*locations cwhere ccondensate ccomes cin ccontact cwith csteam csystems csuch cas cde-
superheating cor cattemporating cequipment
What cis cthe cappearance cof ca cthermal cfatigue ccrack? c- cCORRECT cANS✔✔*Usually
cinitiates con cthe csurface. cGenerally cwide cand coften cfilled cwith coxides cdue cto
celevated ctemperature cexposure. c*May coccur cas csingle cor cmultiple ccracks
*usually cpropagate ctransverse cto cthe cstress cand care cusually cdagger cshaped,
ctransgranular, cand coxide cfilled. c
*Can calso csometimes cbe caxial, cor ccircumferential cor cboth cat cthe csame clocation.
How cis cthermal cfatigue cbest cprevented? c- cCORRECT cANS✔✔Through cdesign cand
coperation cto cminimize cthermal cstresses cand cthermal ccycling. cMethods cof
cprevention cinclude cbut cnot call:
Control crate cof cheating cand ccooling cduring cstartup cand cshut cdown
Design cthat cincorporates creduction cof cstress cconcentrators, cblend cgrinding cof cweld
cprofiles c& csmooth ctransitions cshould cbe cused.
What care c3 cmethods cof cinspection cfor cthermal cfatigue? c- cCORRECT
cANS✔✔*Visual cInspection
*MT
*PT
Define cErosion? c- cCORRECT cANS✔✔Accelerated cmechanical cremoval cof csurface
cmaterial cas ca cresult cof crelative cmovement cbetween, cor cimpact cfrom csolids, cliquids,
cvapors cor cany ccombination cthereof.
Define cErosion-Corrosion? c- cCORRECT cANS✔✔description cof cthe cdamage cthat
coccurs cwhen ccorrosion ccontributes cto cerosion cby cremoving cprotective cfilms cor
cscales, cor cby cexposing cthe cmetal csurface cto cfurther ccorrosion cunder cthe ccombined
caction cof cerosion cand ccorrosion.
What ckind cof cunits/equipment care caffected cby cErosion,
Erosion-Corrosion? c- cCORRECT cANS✔✔All ctypes cof cequipment ctat care cexposed
cto cmoving cfluid cand/or ccatalyst care csubject cto cerosion, cerosion-corrosion.
