FIELD INSPECTION AND TEST PROCEDURE *note: this is the sample document o! the !elated "o# onl$ *autho!: thep!ocedu!e%en&inee!'com
TA(LE OF CONTENTS
)' Scope ' Applica#le Code+ Standa!d And Speci,ca-on .' /ene!al 0' 1ate!ial Inspec-on 0') 1ate!ial Recei2in& Inspec-on 3' 1ate!ial T!acea#ilit$ Cont!ol 3') E4tent o T!acea#ilit$ Cont!ol 5' Dimensional Inspec-on 5') Founda-on Recei2in& Inspec-on 5' Loca-on 1a!6 Chec6 5'. Fit7up Inspec-on 5'0 Roundness 5'3 Plum#ness 5'5 Local De2ia-on 8' Nondest!uc-2e E4amina-on 8') 9isual Inspec-on 8' NDE P!ocedu!e 8'. Radio&!aphic Radio&!aphi c E4amina-on RT; 8'0 Li
8'8 Repai! and Re7e4amina-on =' >$d!osta-c Test =') P!e7test Chec6 =' ?ate! Fillin& ='. Se@lement 1onito!in& ='0 >$d!osta-c Test ='3 Cleanin& ='5 >$d!osta-c Test o! >ea-n& Coil ' Fi4ed Roo Test Test )B' Paint Inspec-on ))' Tan6 Cali#!a-on )' Final Inspec-on ).' ?itness Inspec-on )0' 1anuactu!e!s Data Repo!t
)' Scope This document co2e!s the inspec-on and test !e
' Applica#le Code+ Standa!d And Speci,ca-on The olloin& standa!ds+ code+ and speci,ca-ons ha2e #een used as a sou!ce o ino!ma-on in the p!epa!a-on o this document' API Standa!d API 53B7th Ed' )3 : ?elded Steel Tan6s o! Oil Sto!a&e AS1E CODE AS1E SEC' 9III DI9') : Rules o! Const!uc-on o P!essu!e 9essels AS1E SEC'9 : Nondest!uc-2e E4amina-on AS1E SEC'I : ?eldin& and (!ain& Guali,ca-ons
8'8 Repai! and Re7e4amina-on =' >$d!osta-c Test =') P!e7test Chec6 =' ?ate! Fillin& ='. Se@lement 1onito!in& ='0 >$d!osta-c Test ='3 Cleanin& ='5 >$d!osta-c Test o! >ea-n& Coil ' Fi4ed Roo Test Test )B' Paint Inspec-on ))' Tan6 Cali#!a-on )' Final Inspec-on ).' ?itness Inspec-on )0' 1anuactu!e!s Data Repo!t
)' Scope This document co2e!s the inspec-on and test !e
' Applica#le Code+ Standa!d And Speci,ca-on The olloin& standa!ds+ code+ and speci,ca-ons ha2e #een used as a sou!ce o ino!ma-on in the p!epa!a-on o this document' API Standa!d API 53B7th Ed' )3 : ?elded Steel Tan6s o! Oil Sto!a&e AS1E CODE AS1E SEC' 9III DI9') : Rules o! Const!uc-on o P!essu!e 9essels AS1E SEC'9 : Nondest!uc-2e E4amina-on AS1E SEC'I : ?eldin& and (!ain& Guali,ca-ons
?>S SPECIFICATION : Const!uc-on E!ec-on; P!ocedu!e Specici,ca-on : NDT Non Dest!uc-2e P!ocedu!e; : Scheme o! ?ate! Fillin& Test and Se@lement 1easu!ement : Gualit$ Plan
.' /ene!al ); Unless othe!ise speci,ed in this speci,ca-on+ inspec-on and tes-n& shall #e pe!o!med in acco!dance ith ?>s Gualit$ Plan and applica#le codes+ standa!ds and PTS'
; Field GC pe!sonnel shall ca!eull$ ollo the const!uc-on and tes-n& o tan6s+ and shall ma6e su!e that it complies in all details ith desi&n+ const!uc-on+ inspec-on and tests speci,ed #$ the applica#le codes+ standa!ds and speci,ca-on' speci,ca-on'
0' 1ate!ial Inspec-on 0') 1ate!ial Recei2in& Inspec-on 9isual inspec-on o incomin& mate!ial includin& the a#!icated tan6 mate!ial sent !om the shop+ shall #e made #$ the ,eld GC pe!sonnel to ensu!e that the!e is no in"u!ious deect on the su!ace and cut ed&es' Chec6 on the iden-,ca-on num#e! o !a mate!ial shall #e made a&ainst mate!ial ce!-,cates' ce!-,cates' Chec6 on the e!ec-on ma!6 o a#!icated a#!icated tan6 mate!ial shall #e made a&ainst the co!!espondin& d!ain&s'
3' 1ate!ial T!acea#ilit$ Cont!ol 3') E4tent o T!acea#ilit$ Cont!ol The olloin& tan6 components a!e !e
5' Dimensional Inspec-on
5') Foundaton Receiving Inspecton:- All the sta&e o !ecei2in& tan6 ounda-on+ the ,eld GC pe!sonnel shall !e2ie the ounda-on inspec-on !epo!t' Spot chec6 o actual dimension and #ench ma!6 shall #e made a&ainst the !epo!t'
5' Locaton Mark Check:- P!io! to the p!ima!$ la$in&7don o! e!ec-on o (o@om Plate+ (o@om S6etch Plate+ Shell Plate+ Roo St!uctu!es and Roo Plate+ the ,eld GC pe!sonnel shall chec6 the loca-on ma!6in& in acco!dance ith the !elated o!ienta-on d!ain&s' Simila!l$+ p!io! to ma6e the NoleH1anhole openin&+ the loca-on ma!6in& o openin& shall #e ensu!ed'
5'. Fi-up Inspecton:7?eld p!epa!a-on and dimensional accu!ac$ shall #e chec6ed p!io! to sta!t eldin&' (u@ elds o Shell "oints shall #e matched accu!atel$ and !etained in posi-on du!in& eldin& ope!a-on' 1isali&nment o Shell eld "oint shall not e4ceed the olloin& tole!ance' a' In completed shell 2e!-cal "oint Shell Plate )3'= mm th6 : )'5 mm #' In completed shell ho!ion@al "oint Uppe! Plate )3'= mm th6 : )'5 mm Fo! (o@om Annula! #u@ eld+ the tole!ances o 2e!-cal "oints shall #e applied'
5'0 Roundness P!io! to commencement o shell to (o@om S6etch plate eld+ the tan6 inte!nal !adius shall #e measu!ed' The ho!iontall$ measu!ed tan6 !adius at .BB mm a#o2e the #o@om co!ne! eld shall not e4ceed the olloin& tole!ances' Tan6 J ) m diamete! : K ). mm 5'3 Plum#ness The ,!st cou!se shell plate shall #e chec6ed o! plum#ness+ le2el and !oundness #eo!e eldin& in acco!dance ith ?>s const!uc-on p!ocedu!e to ensu!e that the tan6 ill #e completed ithin the speci,ed dimensional tole!ances' Plum#ness o Shell shall #e inspected ae! comple-on o all Shell elds' The out7o plum#ness shall not e4ceed )HBB o the total tan6 hei&ht' 5'5 Local De2ia-on Local de2ia-on shall #e inspected+ i the!e is an$ no-cea#le disto!-on ae! comple-on o shell eld' The Local de2ia-on shall not e4ceed the tole!ance o ). mm' 5'8 All nole and couplin&s di!ectl$ connected ith pipin& shall #e at the co!!ect ele2a-ons !om the su!ace o #o@om plate and !adial posi-ons ae! comple-on o eldin&
and e!ec-on and !emain at the olloin& tole!ance' Ele2a-on o nole : K )B mm Radial posi-on o nole : K )3 mm Nole p!o"ec-on : K )B mm Inclina-on o Man&e ace : K B'3
8' Nondest!uc-2e E4amina-on
8') Visual Inspecton:- Re&a!dless an$ othe! nondest!uc-2e inspec-on method applied+ all the site elds shall #e su#"ected to 2isual inspec-on+ and meet the !e
8' NDE rocedure :7/ene!al !e
Speci,ca-on : Nondest!uc-2e Test P!ocedu!e'
8'. Radiographic E!a"inaton #R$% :7The olloin& RT shall #e pe!o!med' a' Shell 2e!-cal H ho!iontal "oints and #o@om annula! !adial "oints shall #e !adio&!aphed in acco!dance ith the !eea-n& coil #u@ "oints shall #e !adio&!aphed on spot #asis' 1inimum 3 #u@ "oints o hea-n& coil elded #$ each elde! shall #e ull$ !adio&!aphed' #' Radio&!aphs shall #e "ud&ed in acco!dance ith API 53B Sec' 5 pa!a 5')'3' c' ?hen a spot !adio&!aph ail to compl$ ith the acceptance standa!d+ addi-onal !adio&!aphs shall #e ta6en in acco!dance ith the !e
8'0 Li&uid eneran E!a"inaton #$% :-The olloin& PT shall #e pe!o!med' a' The a@achment elds o nole H manhole elded to shell at site shall #e e4amined #$ PT' #' The acceptance standa!d shall #e in acco!dance ith API 53B sec' 5 pa!a 5'0'0'
8'3 Vacuu" 'o! $es #V'$%:- The olloin& 2acuum #o4 test shall #e pe!o!med' a' All (o@om elds+ i'e' (o@om7to7(o@om+ S6etch (o@om S6etch7to7(o@om S6etch+ (o@om S6etch7 to7Shell "oints+ shall #e inspected' #' An$ lea6a&e o#se!2ed #$ 9(T is unaccepta#le'
8'5 neu"atc Leak $es #L$%:7The olloin& pneuma-c lea6 test shall #e pe!o!med'All a@achment eld o !eino!cement plate on each shell openin& elded at site shall #e inspected in acco!dance ith API 53B An$ lea6a&e o#se!2ed #$ LT is unaccepta#le'
8'5 neu"atc Leak $es #L$%:7The olloin& pneuma-c lea6 test shall #e pe!o!med'All a@achment eld o !eino!cement plate on each shell openin& elded at site shall #e inspected in acco!dance ith API 53B An$ lea6a&e o#se!2ed #$ LT is unaccepta#le'
=' >$d!osta-c Test
=') re-es Check:-a' (eo!e ,llin& ate! into the tan6+ it shall #e ensu!ed that all inspec-on on (o@om+ Shell and Roo includin& a@achment elds shall #e completed' #' An$ o!ei&n a!-cles shall not #e le in the tan6'
()* +aer Filling
a' The ate! ,llin& !ate shall #e decided ith conside!a-on &i2en to tan6 sie+ pump acili-es+ ate! suppl$ a2aila#le+ sta#ilit$ o ounda-on se@lement+ and othe! ma@e! !ela-n& to saet$' #' ?hen ounda-on se@lements a!e ne&li&i#le o! si&ni,cantl$ &!eate! than e4pected se@lement+ ate! ,llin& !ate ma$ #e chan&ed' c' Du!in& the en-!e ,llin& and empt$in& ope!a-on+ !oo manhole andHo! othe! openin&s shall #e 6ept open' d' Du!in& the ate! ,llin&+ the Moa-n& !oo shall #e chec6ed !e
(), e.le"en Monioring
a' Se@lement !eadin& shall #e ta6e at a minimum o 0 points a!ound the #ase o tan6' #' Se@lement !eadin& shall #e ta6en and !epo!ted to Cont!acto! at least once a da$ hile the tan6 is #ein& ,lled ith ate! and emp-ed'
()/ 01drosatc $es
a' ?ate! shall #e ,lled to the speci,ed test le2el as ?> Spec'
#' Ae! the tan6 ,lled to test ate! le2el+ all elds in the shell+ includin& shell to #o@om S6etch Plate elds+ shall #e 2isuall$ inspected o! ate! -&htness' c' ?ate! shall #e maintained at the test le2el o! minimum o 0 hou!s ae! hich ate! ma$ #e discha!&ed' d' P!io! to sta!-n& the ate! discha!&in&+ ensu!e that the !oo openin&s a!e opened'
()2 Cleaning:-a' Du!in& and ae! the tan6 is emp-ed+ the inside o tan6 shall #e cleaned'
#' All sand+ slud&e and !u##ish on the tan6 #o@om shall #e !emo2ed'
()3 01drosatc $es 4or 0eatng Coil:- >ea-n& coil shall #e tested h$d!osta-call$ at a p!essu!e
speci,ed in applica#le d!ain&'
' Fi4ed Roo Test ?hile the tan6 is maintained at the test ate! le2el+ elds on the ,4ed !oo shall #e pneuma-call$ lea6 tested' Non7p!essu!e tan6 !oos shall #e tested to p!essu!e not e4ceedin& the ei&ht o the !oo plates ith comp!essed ai! and lo7p!essu!e tan6 !oos shall #e tested to a p!essu!e e
)B' Paint Inspec-on Paint inspec-on shall co2e! the olloin& items' a' paint mate!ial chec6 #' su!ace p!epa!a-on chec6 c' paint applica-on chec6 d' d!$ ,lm thic6ness DFT; chec6 e' 2isual inspec-on o completed su!ace ' pinhole test o! tan6 inte!nal linin& The ma&ne-c pull7o t$pe &au&e o! ,4ed p!o#e ma&ne-c Mu4 t$pe &au&e shall #e used o! DFT !eadin&s' Fo! each coat o paint+ the DFT shall #e ta6en at a !e
Tan6 cali#!a-on and p!epa!a-on o &au&e ta#le shall #e pe!o!med #$ a specialied ,!m in acco!dance ith inte!na-onall$ accepted method and ith local statuto!$ !e
)' Final Inspec-on P!io! to tan6 #o47up+ the inside o tan6 shall #e tho!ou&hl$ ensu!ed clean' Flan&e su!aces o NoleH1anhole shall #e ca!eull$ inspected o! deects hich ma$ caused and lea6a&e' It shall #e also ensu!ed that all o!6s !e
).' ?itness Inspec-on The scope o inspec-on #$ 9endo!+ CONTRACTOR+ and O?NER is indicated in Scope o Inspec-on' The Inspec-on and Test Plan shall #e p!o&!essi2el$ olloed #$ the inspecto! th!ou&hout site const!uc-on'
)0' 1anuactu!es Data Repo!t 1DR; The site po!-on o 1DR shall #e compiled at site as the const!uc-on is p!o&!essin&' The completed site 1DR shall #e su#mi@ed to CONTRACTOR+ hile a o!i&inal cop$ ill #e sent to ?> home oQce o! !etainin&' As a minimum+ the olloin& inspec-on !eco!ds shall #e included in the site 1DR as pe! Gualit$ Plan' a' Inspec-on Ce!-,cate #' As7#uilt S6etch o Shell Plate c' ?elde!s 1ap o Shell and (o@om PlateH?PS PGRH?elde!s Guali,ca-on Reco!ds d' NDE Reco!d o RT+ PT+ 9(T and LT e' Dimensional Inspec-on Reco!d o Tan6 Founda-on+ Roundness and Plum#ness ' >$d!osta-c Test Reco!d includin& se@lement data &' Roo Test Reco!d h' Paint Inspec-on Reco!d
Figure 1: Worldwide LNG imports [1] LNG is Liquefied Natural Gas, in which the main ingredient, methane, is liquefied at the extremely low temperature of minus 161.5 °. Liquefied natural gas ta!es up 1"6##th the $olume of natural gas in a gaseous state, ma!ing possi%le the mass transportation and storage %y LNG ships and tan!s. &dditionally, as natural gas emits '#()# * less +' than other fossil fuels such as petroleum and coal, it is widely considered a form of clean energy. &s a result, LNG consumption is forecast to steadily increase as seen in igure 1, which shows the recent growth of worldwide LNG imports.
-*Ni steel is commonly used for a%o$eground LNG tan!s
Figure 2: The boiling points of various liue!ed gases and appli"able metals for storage tan#s$ here are two types of LNG tan!s, one for oceangoing LNG ships and the other for onshore storage. &s for LNG storage tan!s, they can %e %uilt either a%o$e or %elow ground. &%o$eground tan!s usually ta!e the form of a dual shell structure that is cylindrical in shape with a flat %ottom, while underground tan!s are of the mem%rane type. /ecause the inner tan! is directly exposed to LNG at minus 161.5 °, it must ha$e a high le$el of notch toughness. he inner tan!s of a%o$eground storage tan!s are therefore commonly made of -* Ni steel or aluminum alloy, while those of underground tan!s are made of 0#) and"or 0#)L austenitic stainless steels. he choice of material depends on the %oiling point of the rele$ant gas 2efer to igure '3 %ecause the liquefaction of the gas requires such a particular low temperature. he rest of this article will introduce a%o$eground LNG tan!s with inner tan!s made of -* Ni steel and discuss related welding consuma%les and procedures.
Figure %: & "ross se"tional view of '(LNG storage tan# [2]$ igure 0 shows an a%o$eground, flat(%ottomed, cylindrical LNG storage tan! !nown as a 4LNG. his structure, widely adopted in o$erseas countries, has a surrounding wall made of pre(stressed concrete 43, an outer shell and roof made of low temperature ser$ice car%on steel, an inner shell made of -* Ni steel, and an inner aluminum dec! that is suspended from the car%on steel dome roof on the -* Ni cylindrical shell.
2egulations and standards for LNG tan!s & wide range of regulations and standards define the design, construction, inspection and maintenance of LNG tan!s made of -* Ni steel. ome of the rele$ant &7, &48, / 7N, and 98 standards are pro$ided %elow. 13 &7 ec. :888, ;i$. 1< ;esign and fa%rication of pressure $essels= ;i$. '< <ernati$e rules. '3 &48 tandard 6'#< ;esign and construction of large, welded, low(pressure storage tan!s= &ppendix >< Lowpressure storage tan!s for liquefied hydrocar%on gases at temperature not lower than ?'@#° ?16A°3. 03 / 7N 1)6'#(1'##63< ;esign and manufacture of site %uilt, $ertical, cylindrical, flat(%ottomed steel tan!s for the storage of refrigerated, liquefied gases with operating temperatures %etween #° and ?165°, 4art 1< General. )3 98 /A'65'#1#3< onstruction of pressure $essel ― General principles= 98 /A'6@'##A3< onstruction of pressure $essel. he most commonly applied regulations and standards worldwide are &7 ec. :888 and &48 6'#. a%le 1 pro$ides a comparison of allowa%le stresses on a%o$eground LNG tan!s made of -* Ni steel. ;epending on what standard is applied, the allowa%le stress $aries and thus the plate thic!ness of the shell differs accordingly. &s seen in a%le 1, &7 and 98 calculate the allowa%le stress %y the strength of the welded %utt Boint, whereas &48 uses the strength of the weld metal. a%le 1< &llowa%le stresses of a%o$eground LNG
tan!s made of -* Ni steel
ode or standard
&48 6'# &ppendix >
&7
ormula to
tandard
calculate
strength
allowa%le stress
4a3
le stress 4a3
)1
maller $alue
σ/
%etween 1"0
66#
)1
&llowa%
D
)2
σ/
σC
and '"0 σC)2
06#
;i$. 1
1"0.5 σ/)%
σ/
;i$. '
1"'.) σ/)%
σ/
/
1") σ/)%
D
''#
)%
1-#
)%
'A#
D 66#
ec. :888
D 66#
1-#
A'65 )%
98
σ/
/
)%
1"0.5 σ/
D 66# 1-#
A'6@ )1: Tensile strength of weld metal$ )2: 'roof strength of weld metal$ )%: Tensile strength of welded butt *oint$
Ehen calculating the allowa%le stress of -* Ni steel as per &48 6'# &ppendix >, the lower $alue of the strength %etween the plate e.g. quenched(and( tempered & &550 ype 8< σ/ D 6-# 4a= σC D 5A5 4a3 and the weld metal e.g. 98 F 0''5 ;-Ni(1< σ/ D 66# 4a= σC D 06# 4a3, namely the strength of the weld metal, is adopted as the standard strength in general. 8n addition, he &ppendix > allows to use the tensile strength of 6-# 4a and the proof strength of )## 4a as the maximum perm itted $alues for determining the allowa%le stress, though they must %e tested and pro$en. hus, &48 allows adopting the higher strength design, which ma!es the reduction of plate thic!ness possi%le. 8n 1-6#, a destructi$e test in$ol$ing a large(sied pressure $essel made of -* Ni steel was carried out in the H& that pro$ed that -* Ni steel could %e used safely without postweld heat treatment for stress relief. ince then, large capacity tan!s made of -* Ni steel ha$e %een constructed widely. +$er time, as tan! capacities ha$e %een getting larger, the applied plate thic!ness has also %een increasing. Ehile tan!s with a capacity of A#,### !ilo liters !l3 would ha$e a -* Ni steel inner shell with a maximum plate thic!ness of 0# mm, 1)#,### !l tan!s require plate that is )# mm thic!. urrently, the design of '##,### !l tan!s is under in$estigation= these would require plates with thic!ness of 5# mm, reaching the maximum tan! capacity.
pecifications and features of -* Ni steel
a%le '< & and 98 specifications for -* Ni steel &
tandard
98 G 01'@
&550 &050
ype
L-N
L-N
5'#
5-#
8
ax. plate thic!.
5#
5#
5#
1##
Ieat treatment
NN
>
NN
>
*3
J #.10
J #.1'
i *3
#.15(#.)#
J #.0#
n *3
J #.-#
J #.-#
4 *3
J #.#05
J #.#'5
*3
J #.#05
J #.#'5
Ni *3
A.5#(-.5#
A.5#(-.5#
mm3
#.'*4 4a3
4a3
D 515
6-#(A'5
7l *3, t< hic!.mm3 D '#.#
8: 93 at ?1-6° L70 mm3 at ?1-6°
D 5A5 D 5'#
D 5-#
6-#(A0#
D '1 6 J t J 163 D '5 t K 163
)1
D '1 t K '#3
)2
D 0)
D 0)
D #.0A
(
)1
D )1
)1: With a plate+t,pe spe"imen as per -./ 0 221 No$ 3GL: mm4$ )2: With a round spe"imen as per -./ 0 221 No$ 5 3GL: mm4$ )%: Lateral e6pansion$
-* Ni steel is ferritic, possessing excellent mechanical properties at the cryogenic temperatures as well as good cutting, %ending and welding characteristics. a%le ' shows the & and 98 specifications for -* Ni steel.
he steels applied in LNG tan! construction are mainly & &050 and &550 ype 8, and 98 G01'@ L-N5'# and L-N5-#. &050 and G01'@ L-N5'# are stated as dou%le(normalied and tempered material NN3, while &550 ype 8 and G01'@ L-N5-#, are listed as quenched and tempered material >3. ompared with NN, the > material has the higher #.'* proof strength as well as higher impact toughness on thic!er plate. /ecause of these factors, > material is mainly used, particularly for the hea$y duty parts such as the shell and the %ottom. here are two important precautions to %e considered when handling -* Ni steel %efore it is pro$ided for welding. 13 Ehen the processing strain of -* Ni steel in the cold wor!ing process exceeds 0*, the impact property sharply drops in proportion to the strain rate, and in this case, post heat treatment is recommended as specified in &48 6'# &ppendix >. '3 -* Ni steel has the disad$antage of %eing easily magnetied. &ttention is necessary to pre$ent it from %ecoming magnetic during manufacturing, transport and processing such as cutting and %ending. ;uring transportation, it is especially ad$isa%le to a$oid the use of magnetic cranes for lifting and to !eep the -* Ni steel plate away from high $oltage power ca%les. he residual magnetism in -* Ni steel will cause magnetic arc %low, ma!ing for an unsta%le arc during welding. ome fa%ricators prefer to specify their own limit of 5# Gauss or less when accepting -* Ni steel fr om plate suppliers. ¬her solution for magnetic arc %low is to apply & welding for &E, already widely accepted %y fa%ricators.
pecifications and features of welding consuma%les a%le 0< &E and 98 specifications for welding consuma%les related to -* Ni steel 4roces
&E standard
s
pecifications for
nic!el and nic!el alloy &E
&5.11"&5.11<'## 5
welding electrodes for shielded metal arc welding
&E
&5.0)"&5.0)<'#
nic!el(alloy electrodes for
#@
flux cored arc welding
G&E
&5.1)"&5.1)<'## nic!el and nic!el alloy
G&E
5
&E
%are welding electrodes and
rods
4roces s
&E
98 standard
F 0''5<1---
pecifications for
co$ered electrodes for -* nic!el steel
filler rods and solid wires G&E
F 000'<1---
for 8G welding of -* nic!el steel
su%merged arc welding solid &E
F 0000<1---
wires and fluxes for -* nic!el steel
he welding consuma%les that are generally used for welding -* Ni steel are high Ni alloy such as the 8nconel type Ni(r alloy3, and the Iastelloy type Ni( o alloy3 though their chemical compositions are quite different from those of -* Ni steel. <hough the strength of high Ni alloy is lower than that of -* Ni steel, it does not cause %rittle fractures, e$en at cryogenic temperatures, %ecause of its full austenitic microstructure. he first application of -* Ni steel in 9apan occurred in 1-66 for a liquefied oxygen tan!, on which 8nconel type electrodes were used. ince then, with continual impro$ements in welding automation, crac! resistance and strength of weld metal, Iastelloy type welding consuma%les Ni(o alloy3 ha$e increasingly %een put into practice. oly%denum o3 in Iastelloy type welding consuma%les has %een found effecti$e in pre$enting hot crac!s. &E specifies the welding consuma%les for -* Ni steel in &5.11, &5.1) and &5.0) as part of the specifications for nic!el and nic!el alloy welding consuma%les. /y contrast, 98 sets forth specific regulations for welding consuma%les to %e used with -* Ni steel in F 0''5, F 000' and F 0000 as shown in a%le 0. +nly in regards to &E does 98 not directly specify the consuma%les to %e used with -* Ni steel.
o$ered electrodes for -* Ni steel /oth &E and 98 specifications for co$ered electrodes for welding -* Ni steel are shown in a%le ), and Mo%e teels recommended co$ered electrodes, in a%le 5. a%le )< &E and 98 specifications for co$ered electrodes for -* Ni steel
&E &5.11
98 F 0''5
lassif i( 7Nire(
7Niro(
7Nio(
;-Ni(
;-Ni(
-
6
A
1
'
*3
J #.15
J #.1#
J #.1#
J #.15
J #.1#
i *3
J #.@5
J 1.#
J #.@5
J #.@5
J #.@5
n *3
1.#().5
'.#().#
J 1.5
Ni *3
D 55.#
D 55.#
D 6#.#
12$+17$
12$+17$
#.5(0.5
o *3
'.5(5.5
5.#(-.#
17$+2$
J -.#
E *3
J 1.5
1.#('.#
'.#().#
(
#.5(0.#
#.5('.#
(
J 1'.#
J #.1#
J #.1#
J #.15
(
(
(
D 06#
D 65#
D 6'#
D 65#
D 66#
D '5
D 05
D '5
D '5
(
(
(
cation.
r *3
N%Oa *3 e *3
1.#(
J 0.#
).#
D 55.#
1$+
D 6#.#
(
17$
1$+ 22$
1.5( 5.#
#.0(
(
0.#
J 1'.#
#.'*4 4a3 4a3 7l *3 #8: 93 at+189(
&$ D 0) 7ach D '@
a%le 5< 4278&2TM co$ered electrodes for -* Ni steel and their deposited metal properties rade desig.
N8(@#
N8(@#I
N8(1
&E &5.11
7Nire(-
7Niro(6
7Nio(A
98 F 0''5
;-Ni(1
(
;-Ni('
8nconel
8nconel
Iastelloy
type
type
type
&
&
&
NM)1
(
NM)1
eature 4olarity hip class appro.
*3
#.#-
#.#A
#.#0
i *3
#.'6
#.)'
#.)-
n *3
'.'6
'.A5
#.'A
Ni *3
[email protected]
6A.1
6A.6
r *3
10.-
1'.-
1.-
o *3
0.@
@.1
1A.6
E *3
#.6
1.'
'.-
N%Oa *3
1.@
#.-
(
e *3
-.A
5.5
6.A
#.'*4 4a3
)0#
)6#
))#
4a3
@#5
@'5
@0#
7l *3
)1
)'
)A
8: 93 at (1-6°
6'
@@
A0
)1: N; stands for Nippon ;ai*i;,o#ai$
4278&2TM N8(@#I is a newly(de$eloped co$ered electrode that shows much higher #.'* proof strength and tensile strength than other con$entional co$ered electrodes for -* Ni steel.
lux(cored wires for -* Ni steel a%le 6< 4278&2TM Es for -* Ni steel and their deposited metal properties rade desig. &E &5.0)
;E(N@# (
;E(N@#-4 7Nio10(3 )1 ▪ Iastelloy
type
for all &pplica%le for eature
downhand welding
position welding. ▪ 7xcellent
hot(
crac! resistance and +; $alues.
hielding gas
A#*&r( '#*+2
A#*&r('#*+2
*3
#.#5
#.#'
i *3
#.'#
#.'1
n *3
5.-1
'.@5
Ni *3
6'.6
6'.1
r *3
16.A
6.-
o *3
1#.'
[email protected]
E *3
(
'.)
N%Oa *3
'.#
(
e *3
1.A
@.@
#.'*4 4a3
)'5
)5#
4a3
@15
@1#
7l *3
)6
)6
8: 93 at ?1-6°
1#6
-#
(
1.)#
L7 mm3 at ?1-6°
)1: The "lassi!"ation of
& new &E specification &5.0) was esta%lished and made pu%lic in '##@ as shown in a%le 0. 8t specifies the chemical compositions and the tension tests in the same manner as &5.11 and &5.1). he application of flux(cored wires Es3 for LNG tan!s made of -* Ni steel had %een limited %ecause tight control of welding conditions in a narrow range was required to pre$ent hot crac!s, and the all(position welding was difficult. Iowe$er, as shown in a%le 6, Mo%e teel has de$eloped two types of the Es for welding -* Ni steel that sol$e these pro%lems, and recently they ha$e %een put into operation. 4278&2 TM ;E(N@# is designed for down( hand welding and a new E, 4278&2 TM ;EN@#-4, for all position welding as shown in a%le 6. ;E(N@#-4 is introduced here as &5.0) 7Nio10(3, %ecause there is not such a classification in &5.0) yet. &ccording to the latest information, the re$ised &5.0), which will co$er 7Nio10(, will %e issued %y &E soon. or more detailed technical information related to ;E(N@#-4, please see PMo%elco Eelding oday, :ol. 10 No. 1 '#1#.Q & %utt Boint welded on -* Ni steel %y ;E(N@#-4 yielded satisfactory results in tensile, impact, +;, and %end tests as shown in a%le @. he macrograph of the weld Boint and the appearance of the %end test specimens are shown in igure ). &nd igure 5 shows the 8+ crac! test result of ;E(N@#-4 weld metal. he crac!free one has %ecome much wider, e$en at faster welding speeds, when the suscepti%ility against hot crac! %ecomes quite critical.
Figure : F./(> "ra"# test results of PREMIARCTM DWN709SP weld metal? showing superior hot "ra"# resistan"e over "onventional F(W$ a%le @< Eelded Boint properties of 4278&2TM ;E(N@#-4 in 0G welding position 4roperties ensile strength at room temp.)1 8mpact toughness at ?1-6° +; at ?1-6° δ3 Longitudinal %ending, 1A#°
easurements @0A 4a ractured at weld metal3 AA, -1, A- &$. AA3 93 #.0-, #.0-, #.0A &$. #.0A3 Good
)1: @ase metal is &/T= &% T,pe .? 2Amm thi"#? double+B groove$
Figure 5: PREMIARCTM DW-N709SP e6hibits "omplete fusion in %G+position butt *oint and e6"ellent du"tilit, in bend test$
8G welding wire for -* Ni steel
a%le A< &E and 98 specifications for 8G wires for -* Ni steel and the properties of the matching filler wire 4278&2TM G(@#- rade
lassifications
4roperties
)1
98 F
&E &5.1) 72Nio(A
designation
000'
G(@#-
CG-Ni( '
▪ Iastelloy
type
wire eatures
(
(
and rod. ▪ uita%le
for
automatic G&E hip class
(
(
NM
*3
J #.1#
J #.1#
#.#'
i *3
J #.@5
J #.@5
#.#0
n *3
J 1.5
J 0.#
#.#0
Ni *3
D 6#.#
D 6#.#
@#.)
r *3
#.5(0.5
(
'.#
o *3
1@.#('#.#
15.#(''.# 1-.#
E *3
'.#().#
1.5(5.#
0.#
e *3
J 1#.#
J 1'.#
5.5
#.'*4 4a3
(
D 06#
)6#
4a3
(
D 66#
@0#
7l *3
(
D '5
)@
appro.
8: 93 at ?1-6°
&$ D 0), (
7ach D
16#
'@
)1: (hemi"al "ompositions are for wire$ =e"hani"al properties are for deposited metal$
7$er since Mo%e teels (8L process for automatic 8G welding was de$eloped in 1-@0, it has %een applied widely %y tan! fa%ricators, particularly in 9apan. +$erseas, it has %een adopted in more than 1# units of LNG tan!s made of -* Ni steel and in a%out 6# units in the 9apanese domestic mar!et. his efficient automatic 8G welding in$ol$es the application of a large welding current and the intentional defl ection of arc direction %y magnetic force, and it is a%le to maintain the soundness of weld metal, the principle ad$antage of G&E. 8t is two times more efficient than &E and four times
more than manual G&E. urthermore, the process reduced the defect ratio to almost ero and impro$ed the completion time, total cost and quality of the weld. &E and 98 specifications for 8G wires for -* Ni steel and the properties of the matching filler wire 4278&2 TM G(@#- are shown in a%le A.
&E wires and fluxes for -* Ni steel a%le -< &E specifications for &E wire and 98 specifications for &E wire and flux com%inations for -* Ni steel &E
98 F 0000
&5.1) lassification 72Nio(A
-Ni(
-Ni(
"C-Ni
I"C-Ni
&pplica%le to
wire
Eeld metal
Eeld metal
*3
J #.1#
J #.1#
J #.1#
i *3
J #.@5
J 1.5
J 1.5
n *3
J 1.5
J 0.5
J 0.5
Ni *3
D 6#.#
D 6#.#
D 6#.#
r *3
#.5(0.5
(
(
o *3
1@.#('#.#
1#.#('5.#
1#.#('5.#
E *3
'.#().#
(
(
e *3
J 1#.#
J '#.#
J '#.#
#.'*4 4a3 (
D 065
D 065
pa3
(
D 66#
D 66#
7l *3
(
D '5
D '5
8: 93 at
(
&$. D 0)
&$. D 0)
?1-6°
7ach D '@
7ach D '@
8n its &E specifications, the &E regulates wires only in &5.1) whereas 98 specifies the com%ination of wire and flux, as shown in a%le 0 and a%le -. Mo%e teels &E wire and flux com%inations are shown in a%le 1#. a%le 1#< 4278&2TM &E wire and flux com%inations for -* Ni steel and their deposited met properties rade
lassification
desig. lux"wire 3
hemical composition *3
&E
98
&5.1)
F 0000
eatures
H(@#-
72 Nio(A wire3
-Ni( "C-Nil
4ol.
class appro.
▪ Iastelloy
4(N0"
echanical proper
hip i
n
Ni
r
o
E
e
#.'*4 4a3
7l
4a3 *3
type
consuma%les ▪ uita%le
for 1G
welding
&, ;74
(
#.#0 #.1' 1.@# 6).1 1.6 16.6 '.5 1).@ )##
6-#
))
NM
#.#0 #.@) #.5A 6).# 1.@ 1@.'
6A#
)0
position ▪ Iastelloy
4(N)" H(@#-
72 Nio(A wire3
-Ni( "C-Nil
type
consuma%les ▪ uita%le
for 'G ;74
'.@ 1).- )1#
welding position
Eelding procedures and control he !ey factor for the economical and qualitati$e tan! construction is to minimie the amount of on(site fa%rication wor!. his can %e achie$ed %y adopting modular design, in which each module is fa%ricated at a plant and deli$ered to the site for the connection wor! afterwards. 7$en the dome ceiling of an LNG tan! is fa%ricated at a plant and connected to the shell onsite %y using the airraising process. he welding Boints that are typically carried out on -* Ni steel components on(site is shown in igure 6. a%le 11 shows the welding procedures used on indi$idual Boints.
@
Figure 9: (ross se"tional view of t,pi"al welding *oints in the shell and bottom of a 8C Ni steel tan# in on+site fabri"ation$ 3Defer to Table 11 for individual welding pro"edures4 a%le 11< Eelding p rocedures f or indi$idual B oints 2efert o igure 6 for each Boint No.3
①
9oint No.
②
③
omponen
ide
ide
/ottom to
t
shell
shell
side shell
ype of
;ou%le : ;ou%le :
Boint
Eelding position)1
0G
&E
Eelding )2
process
&E &uto(8G
'G
;ou%le %e$el
'G
④
/ottom
Lap
' &E
&E
&E
&uto(8G &uto(8G
&E &uto( 8G
)1: %G 3Berti"al groove4E 2G 3oriontal groove4E 2F 3oriontal !llet4$ )2: ;obel"o auto+T.G welding euipment is available onl, in -apan$ [Note: .n"onel is a trademar# of /pe"ial =etals (orp$ astello, is a trademar# of a,nes .nternational$]
igure @ shows examples of groo$e configurations for &E, G&E, &E and &E in designated welding positions in the figure. igure A shows horiontal
fillet welding '3 on the roof of an LNG tan! with ;E(N@#-4 flux cored wire. igure - shows o$erhead %utt Boint welding )G3 along the %ottom plate of an LNG tan! with automatic 8G welding equipment using G(@#- 8G wire. hese pictures were ta!en at a construction site in 9apan where the maBor a%o$eground LNG tan!s use the flat(%ottom dou%le(shell cylindrical dome(roof structure igure 1#3. he dome roof is also made of -* Ni steel.
Figure 7: T,pi"al groove "on!gurations for /=&W? GT&W? /&W? and F(&W used for *oining 8C Ni steel "omponents in fabri"ation of an LNG tan#$
Figure A: oriontal !llet welding 32F4 on the roof of an LNG tan# is "arried out with PREMIARCTM DW-N709SP Hu6 "ored wire$
Figure 1: (ross se"tional view of the Hat+bottom doubleshell ",lindri"al dome+roof LNG tan# [%]$
Figure 8: >verhead butt *oint welding 35G4 along the bottom plate of an LNG tan# is "ondu"ted with automati" T.G welding euipment using PREMIARCTM TG-S709S T.G wire$
ips for %etter welding results on -* Ni steel Iigh Ni alloy welding consuma%les are hot crac! sensiti$e in general, and LNG tan!s typically require much dissimilar welding. he following special precautions against hot crac! and %ase metal dilution ha$e to %e ta!en. rater crac! must %e remo$ed< Mo%e teels welding consuma%les for -* Ni steel ha$e %een pro$en to %e adequate through the inspection %y 8+ crac! testing for hot crac! suscepti%ility. Iowe$er, %ecause crater crac!s one type of hot crac!3 are common and diff icult to a$oid, it is strongly recommended for the crater to %e ground off each time when the arc stops. ;ilution of %ase metal affects the mechanical properties of the weld metal< Ehen the %ase metal is diluted into the weld metal %y the arc, the weld metal
chemistries can change. hese changes can %e especially more significant in dissimilar welding, decreasing the tensile strength of the weld metal. 8t is ad$ised to chec! the welding conditions and to ensure that the tensile strength and #.'* proof strength fulfill the requirements in the procedure test in ad$ance.
he &/s of &rc Eelding Iow to calculate welding consumption
Ee recommend you to use the following diagrams for a quic! estimation of the consumption of welding consuma%les for welding ferritic steel %utt Boints and fillet Boints respecti$ely. 4lease follow the examples indicated %y gray arrows in the figures. igure ' shows the calculated consumption of welding consuma%les as a function of plate thic!ness, welding process, groo$e angle, and root opening for %utt Boints. Eith respect to fillet Boints, ig. 0 shows the calculated consumption of welding consuma%les as a function of fillet sie, welding process, and reinforcement sie. hese diagrams were de$eloped using the calculations o%tained %y the following equation for %oth groo$e and fillet welding Boints under the prerequisites gi$en %elow. R S&1 O &23 x L x G"7T x 1"1# Ehere < onsumption of welding consuma%les !g3 &1< &rea of ection & 1 weld metal mm 23 ― ig. 1 &2< &rea of ection & 2 reinforcement mm 23 ― ig. 1
igure 1. Eeld sies θ in deg., I, 2, and in mm3 L< Eeld length m3 G< pecific gra$ity of weld metal @.A5 g"cm %3 7< ;eposition 7fficiency *3 ― &E co$ered electrodes< 55* G&E solid"metal(cored wires< -5* &E flux(cored wires< -#* &E solid wires< 1##*
igure '.onsumption of co$ered electrodes in &E and solid"metal(cored wires in G&E of %utt Boints.
igure 0. onsumption of co$ered electrodes in &E, fluxcored wires in &E, solid"metal(cored wires in G&E, and solid wires in &E of fillet Boints
he &/s of &rc Eelding > and &< 2ust on a stainless steel weld
>uestion< Ee deli$ered 0#)(type stainless steel Boints welded with the flux(cored wire, ;E(0#A. wo wee!s later, our customer complained that rust was forming on the surface of some of the weld %eads. Ehat causes this pro%lemU 8n addition, we found that the remaining wire of the ;E(0#A would stic! to a magnet. Ee thought that ;E(0#A would not stic! to a magnet. Ehat has happened with the wireU &nswer< 8t is often said that stainless steels do not rust. his is not true= howe$er, they are less li!ely to generate rust compared to con$entional car%on and special steels. 8t is helpful to understand the way that each type of steel forms rust. he case you descri%ed of r ust forming on the %eads was li!ely a type of ru st that forms on dissimilar metals li!e a com%ination of car%on steel and stainless steel. his type of rust can %e caused %y such external factors as car%on steel powders enerated %y near%y grinding and %rushing with car%on steel wire %rushes, adhering to the surface of the stainless steel weld %eads. herefore, we guess that some car%on steel powders that had adhered to the surface of the ;E(0#A weld %eads caused the ru st in your case. igures 1 and ' show examples of %ead appearance. he rusty %ead in igure 1 had %een %rushed with a car%on steel wire %rush, while the other metallic, lustrous one in igure ' had %een %rushed with a stainless steel wire %rush. he former one clearly has %rown rust e$en on the %ase metal. Cou can therefore understand that stainless steel wire %rushes are essential for %rushing stainless steel welded Boints. Cou might ha$e thought that the magnet and the wire were attracted to each other due to some ingredients contained in the ;E(0#A wire. he ;E(0#A wire indeed does react magnetically %ecause of the stress(induced martensite on the surface of the wire. he martensite structure is formed %y wor! hardening the surface of the wire during the process of drawing into the designated diameter. he stress(induced martensite, howe$er, has nothing to do with rusting. he ;E(0#A weld metal also %eha$es magnetically. his phenomenon is caused %y a small amount of ferrite contained in the weld metal. Eith the desire to !eep the crac!ing suscepti%ility of the weld metal as low as possi%le, ;E(0#A is designed to contain small amounts of ferrite in the weld metal. he ferrite tructure also has nothing to do with rust.
8f the rust pro%lem descri%ed a%o$e is not so serious, it can %e w iped off with a sponge or cloth soa!ed with neutral detergent or soapy water. areful washing with water is necessary afterward so as not to lea$e any neutral detergent or soapy water. Ehen it is serious, use an exclusi$e cleaning solution for stainless steel or 15* diluted nitric acid. 4olishing with sand paper or %rushing off with a stainless steel wire %rush is also eff ecti$e. Ehen followed %y cleaning with soapy water, it will %e perfect for o%taining %eautiful welds.
igure 1< 2usty appearance of a weld %ead aft er %rushing with a car%on steel wire %rush
igure '< etallic, lustrous appearance of a weld %ead %rushed with a stainless steel wire %rush
Eelding of Gal$anied teel heets
>uestion< Ee weld a $ariety of gal$anied steel sheets %y semi(automatic + 2 welding. Iowe$er we ha$e a hard time with postweld treatment and repair, %ecause pits occur often and a lot of spatter is generated. ould you please explain how porosity and spatter generate with gal$anied steel sheets and recommend a good welding wire to sol$e these pro%lemsU &nswer< Gal$anied steel sheets are widely used in many steel structures li!e cars, steel towers, %ridges and %uildings %ecause of their cost(effecti$eness due to excellent corrosion resistance and rust pre$ention. hey include hot(dip gal$anied steels, 5*&lalloyed hot(dip gal$anied steels, 55*&l(alloyed hot( dip gal$anied steels, electrogal$anied steels, and other gal$anied steels. he welda%ility of these steels is related to the amount of inc coating g"m 23. he thic!er the inc coating, the more the porosity pits and %lowholes3 and spatter that result in arc welding. 4orosity can %e understood %y noting that the inc coating decomposes in the arc heat and that the inc $apories at around -##° to %ecome a gas, causing %u%%les in the weld pool and porosity in the weld metal. &s to the increase of spatter, he force of the inc $apor Bet against the arc li!ely causes the metal droplet transfer to %ecome unsta%le, there%y expelling the metal droplets outside the arc as spatter. & $ariety of porosity(resistant low(spatter welding wires for gal$anied steel sheets ha$e %een de$eloped. hese wires ha$e sophisticated chemical compositions that suppress the growth of gas %u%%les trapped in the weld pool and sta%ilie metal droplet transfer. ars, electric machinery, office equipment, and $ending machines typically adopt electro(gal$anied steel sheets with 5#g"m 2 or less of coating and alloyed hot(dip gal$anied steel sheets with )#(1##g"m 2 of coating. or these thin(coated steel sheets, solid wires, such as G(1F for + 2 gas shielding3, 8V(1F for &r(+ 2 mixed gas shielding3, and 8V(1 for &r(+ 2 mixed gas shielding and pulsed current3 are recommended. a%le 1 shows the applications for and characteristics of the a%o$e( mentioned welding wires. 8f you ta!e into account the shielding gas composition and the power source output characteristics when selecting a
