We elding Faabricatio on Proceedure API – 65 50 Storaage Tankks
Doc. #: AK KE/WFP/001 Rev.: 0 Page 1 of 6
TABLE OF O CONT TENTS
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PURPOSE AND D SCOPE .................................................. ..................................................................... 2 REFERENCES ............................................................... ..................................................................... 2 WELDER QUA ALIFICATION ........................................... ..................................................................... 2 WELDING PRE EREQUISITES................................................................................................................. 2 MATERIALS ................................................................. ..................................................................... 2 BASE MATERIIAL JOINT PRE EPARATION ....................... ..................................................................... 3 BASE MATERIIAL JOINT CLE EANING ............................. ..................................................................... 3 JOINT FIT-UP AND ALIGNM MENT .................................. ..................... ................................................ 3 PREHEAT ..................................................................... ..................................................................... 3 TACK WELDSS .............................................................. ..................................................................... 4 BACKPURGE/B BACKING GAS ........................................ ..................................................................... 4 INTER-PASS TEMPERATURE E ........................................ ..................................................................... 4 WELDING TEC CHNIQUE................................................. ..................................................................... 4 INTERRUPTION N OF WELDIN NG ....................................... ..................................................................... 5 INSPECTOR QUALIFICATION U N ........................................ ..................................................................... 5 ACCEPTANCE CRITERIA FO OR COMPLETE ED WELDS .............................................................................. 5 WELD REPAIR RS.................................................................................................................................. 6 POST WELD HEAT TREATM MENT .................................. ..................................................................... 6 ATTACHMENT T WELDS ................................................. ..................................................................... 6 ATTACHMENT TS....................................................................................................................................... 7
Weld ding Fab brication n Proced dure API – 650 A 0 Storagge Tankss
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PUR RPOSE AND SCOPE 1.
This Wellding Fabricaation Procedu ure (WFP) shhall govern thhe welding of componentss to the requiremen nts of API 650. The Code edition and aaddenda for thhis proceduree shall be the latest in effect or ass otherwise sp pecified by th he client.
22.0
REFERENCES
1. API 650, “Weld “ Steel Tanks T for Oil Storage” S 2. ASME Secction IX, “Weelding and Brazing Qualifiications”
33.0
WEL LDER QUAL LIFICATIO ON A.
Welder/weld ding operatorss shall be currently c certtified, havingg performed qualificationn tests in acccordance witth API – 650.
44.0
WEL LDING PRE EREQUISITE ES A. All A welding sh hall comply with w the requireements speciffied in the Weelding Proceddure Specification S (WPS). (
B. Welding W shall not be perforrmed when th he ambient tem mperature in tthe immediatee vicinity of tthe weld is lo ower than 0° F or when surrfaces are wett or exposed tto rain, snow,, dust, or highh wind. The w welder and weld w joint shalll be sufficien ntly protected d from inclem ment conditionns. Care shall be taken to aassure that moisture m has not n been trapp ped between members m thatt are to be weelded and thatt moisture haas not been in ntroduced intto previously y fit-up joints prior to fiinal welding.. Preheatingg above the minimum teemperature sp pecified in thee Welding Pro ocedure Spec ification (WP PS) may be necessary to reemove any en ntrapped moiisture. The ad dditional preh heat should bee applied if thhere is reasonn to believe m moisture is prresent.
55.0
MAT TERIALS A. Base B Materialss
B. Only O the materrials specified d shall be used d.
1. Filler Mateerials
W filler materials to be b used with this t proceduree are specifiedd in the Weldding C. Welding Prrocedure Specification (W WPS. D. Requirements R for f procurement and contro ol of filler maaterials shall bbe in accordannce with WPS. W E. Welding W filler materials (eleectrodes, baree filler wire, oor consumablee inserts) musst be utilized bby welders w makin ng weldments with this proccedure. Weldders shall not perform weldds autogenoussly.
66.0
BASE E MATERIA AL JOINT PREPARAT TION A. The T edges of plates may be b sheared, machined, m chippped, or machhine oxygen cut. Shearingg shall be limited to 3/8 in n. thickness of o plates for butt-welded b jjoints and 5/8 in thickness for lap- weldded joints. When W edges of plates are oxygen o cut, th he resulting suurface shall bbe uniform annd smooth and shall be frree of scale an nd slag accum mulations befo ore welding. Circumferentia C al edges of ro oof and bottom m plates mayy be manuallyy oxygen cut.. Kerf or gouuge marks
Weld ding Fab brication n Proced dure API – 650 A 0 Storagge Tankss
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on n the joint bev vel deeper thaan 1/8” (0.125 5) shall be reppaired prior too fit-up and taack welding.
77.0
BASE E MATERIA AL JOINT CLEANING G A. Prrior to weldin ng, surfaces fo or welding shall be clean annd free from ppaint, oil, russt, scale, slag, grease, an nd other foreiign s that are detrimental d to o welding.
B. A fine film of rust r adhered to t the joint ed dges need not be removed pprior to weldiing.
C. Weld-through W primers, e.g., Deoxaluminite, Spatter-w weld, or Carbooweld 11, needd not be remooved prrior to weldin ng.
1. Solvents ap pproved for use u on the base material andd weld materiials are methyyl alcohol, ethhyl alcohol, iso opropyl alcoh hol, acetone, methyl m ethyl kketone, toluenne, Varson 4, Dowanol EB B, and Stoddard solvents. s
88.0
JOIN NT FIT-UP AND ALIGN NMENT A. The T root openiing and fit-up tolerances sh hall be as speccified in WPS S. Iff the tolerancees cannot be achieved, a the end preparatiions may be bbuilt up by weelding or re- pprepped by y machining or o grinding.
B. Plates to be joiined by butt welding w shall be b matched acccurately andd retained in pposition durinng th he welding op peration (see paragraph p 15.A.3).
C. During D the wellding operatio on, plates shalll be held in cclose contact aat all lap jointts.
D. Sh hell plates maay be aligned by metal clip ps attached to the bottom plates, and the shell may bee tackwelded w to the bottom b beforee continuous welding w is staarted between the bottom edge of the sheell plate an nd the bottom m plates.
99.0
PREH HEAT A. When W the basee metal temperrature is below w the minimuum preheat te mperature specified in the Welding Prrocedure Specification (WPS). The basse metal shall be heated succh that the surrfaces to be w welded are att or above thee minimum prreheat temperature prior to welding.
B. The T preheat tem mperature shaall be maintaiined for a disttance of at leaast 3 inches onn each side off the weld jo oint and in adv vance of the welding. w Preh heat temperatture above 125° F shall be checked by uusing a su urface pyromeeter, “Tempilstik,” or non-mercury-typee thermometeer. Indicating ccrayons shall not be ussed directly in n the weld zon ne.
100.0
TAC CK WELDS A. Tack T welds shaall be made by qualified welders w in accoordance with the Welding P Procedure Sp pecification (WPS.
B. Defective D tack welds shall be b removed orr repaired prioor to welding.
C. Tack T welds useed in the assembly of vertical joints of ttank shells shaall be removeed and shall noot reemain in the finished f joint when w the join nts are weldedd manually.
D. Tack T welds in the bottom, ro oof, and circu umferential jooints of the tannk shell need not be removved prrovided they are a sound and d the subsequeently applied weld beads aare thoroughlyy fused into thhe taack welds.
Weld ding Fab brication n Proced dure API – 650 A 0 Storagge Tankss
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111.0 BACKPURGE/B BACKING GAS
Not ap pplicable.
112.0 INTE ER-PASS TEMPERATU E URE
A. In nter-pass temp perature shalll not exceed th he maximum value specified in the Wellding Proceduure Sp pecification (WPS and shaall be checked d on the surfacce of the com mponent usingg a surface pyrrometer, “T Tempilstik,” or o non-mercu ury-type therm mometer. Indi cating crayonns shall not bee used directlyy in the weld w zone.
B. Iff the temperatture of the weeld is above th he maximum iinter-pass tem mperature specified in the W Welding Prrocedure Specification (WPS) the weld shall be allow wed to cool doown below thhe maximum iinterpaass temperatu ure, but not beelow the minim mum preheatt temperature,, prior to resum mption of welding.
113.0 WEL LDING TEC CHNIQUE
A. Welding W voltag ge and amperrage shall be in n accordancee with the limiits specified oon the WPS. V Voltage an nd amperage range r gages located on thee welding pow wer supply aree for reference only and aree not mandatory m cheeck or hold po oints. Voltage and amp rangge checks forr documentatiion purposes sshall be peerformed by the t inspector using u calibratted voltage annd amp meterrs or approvedd welding parrameter reecording equip pment.
B. Cracks C or blow wholes that ap ppear on the su urface of a weeld bead shalll be removed by filing, grrinding, chipp ping, or air caarbon arc goug ging before deepositing the next bead. O Oxygen gouging sh hall not be useed on quench hed and tempeered steel.
C. Before B welding g over previou usly deposited d metal, all sllag and flux shall be removved, and the w weld and ad djacent base material m 1 incch on either side of the weldd shall be bruushed clean.
D. For double-weelded butt join nts, before app plying weld m metal on the ssecond side too be welded tthe root sh hall be prepaared by suitab ble methods such as chippping, grindinng, or air carrbon arc gougging to asssure sound metal. m
E. The T recommen nded weld beaad thickness shall s be 1/16 too 3/16 inches. P Passes shall bbe less than ½ inch th hick unless oth herwise speciified in the Welding W Proceddure Specification (WPS). b used to con ntrol distortion n or to relievee residual streesses. Peeningg shall not bee F. Peening may be n. depth of beevel has been deposited. P Peening shall nnot be appliedd to cover peerformed untiil at least 3/8 in paasses, base, or weld layers requiring non ndestructive eexamination. Peening shalll not be used to mask a defect.
G. After A being laid out and tack ked, bottom plates p shall bee joined by weelding the joinnts in the seequence proviided in Attach hment 2, unleess otherwise specified by tthe Client.
H. All A welding prrocesses may be b single passs or multiple ppasses per sidde unless otheerwise specifiied in n the Welding g Procedure Sp pecification (WPS).
I.
Welding W shall be performed d single arc un nless otherwisse specified inn the Weldingg Procedure Sp pecification (WPS.
114.0 INTE ERRUPTION N OF WELD DING
A. Welding W may be b interrupted d without restrriction, unlesss otherwise sppecified in thee Welding Prrocedure Specification (W WPS).
Weld ding Fab brication n Proced dure API – 650 A 0 Storagge Tankss
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115.0 INSPPECTOR QUALIFICAT U TION
A. The T Inspector who w performss welding insp pection for accceptance to th this proceduree shall be au uthorized by AL-KARRAR A R and approv ved by client.
116.0 ACC CEPTANCE CRITERIA FOR COMP PLETED W ELDS
A. Butt B Welds
1.. As-welded d surfaces are permitted; ho owever, the suurface of weldds shall be suufficiently freee from coarse ripp ples, grooves, overlaps, abrrupt ridges, annd valleys. 2. The surfacce condition of the finished d welds shall bbe suitable forr the proper innterpretation of radiograph hic and other nondestructiv n ve examinationns when nonddestructive exxaminations arre required. Butt-welded B joints j to be raadiographed shhall be preparred as followss:
a. Weld W ripples orr weld surfacee irregularitiess on both the inside and ouutside shall bee removed by y any suitable mechanical process p to succh a degree thhat the radiogrraphic contrasst ressulting from any a irregularities cannot m mask or be co onfused with the t image of any a objectionaable defect.
b. Th he weld surfacce shall merge smoothly innto the plate ssurface.
c. Th he finished su urface of the weld w reinforceement may bee flush with thhe plate or maay have a reassonable unifo orm reinforcem ment not to exxceed the amoount shown inn Atttachment 1. ompleted vertiical butt jointss of tank shellls shall not exxceed 10% off the plate 3.. The misaliignment of co 1 thickness or o /16 inch, whichever w is th he larger. 4.. The upper plate in comp pleted horizon ntal butt jointss of tank shellls shall not prroject beyondd the face of the loweer plate at any y point by mo ore than 20% oof the thickneess of the uppper plate, withh a maximum of 1/8 inch exccept that a pro ojection of 1/116 inch is perm missible for uppper plates less than 5 /16 inch thiick.
5.. The edges of welds shalll merge with the surface oof the plate wiithout a sharpp angle. Theree shall be a maximum m permissiblee undercut of 1/64 inch of thhe base metal for vertical buutt joints and 1/32 inch for horizon ntal butt jointss. 6.. The thickn ness of the rein nforcement of the welds onn butt joints oon each side oof the plate shall not ex xceed the amo ount shown in n Attachment 1.
B. Fillet Welds
d surfaces are permitted; ho owever, the suurface of weldds shall be suufficiently freee from 1. As-welded coarse ripp ples, grooves, overlaps, abrrupt ridges, annd valleys. d welds shall bbe suitable forr the proper innterpretation of 2. The surfacce condition of the finished nondestrucctive examinaations.
117.0 WEL LD REPAIR RS
A. Defects found f in weld ds shall be callled to the atteention Client aand approval obtained prrior to repair.
Weld ding Fab brication n Proced dure API – 650 A 0 Storagge Tankss
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B. Weld W repairs sh hall be perforrmed using the original Weelding Proceddure Specificaation (WPS) tto reestore a weld to an acceptaable condition n.
C. Pinhole leaks or o porosity in tank-bottom joints j or rooff joints may be repaired by applying an ad dditional weld d bead over th he defective area. a Other deefects or crackks in tank botttom joints shhall be reepaired.
D. Cracks C and all defects in sheell joints or sh hell to bottom m joints shall bbe removed bby chipping, grrinding, mach hining, or air carbon c arc go ouging from oone or both siddes of the joinnt and re- wellded.
E. Repairs R of defeects discovereed after the tan nk has been ffilled with waater for test shhall be made w with the water w level at least l 12 inchees below the point p being reppaired or withh the tank emppty if the repaairs are on n or near the tank t bottom. Welding shaall not be perfo formed on anyy tank unless cconnecting linnes have beeen completely blanked offf.
F. Welded W repairss shall not be attempted on n a tank filled with oil, or on a tank that hhas previouslly co ontained oil, until u the tank has been emp ptied, cleanedd, and freed off gas or oil residue in a saffe manner. m Repairs shall not be b attempted on o a tank that has contained oil, except iin a manner ap pproved in wrriting by the Client. C
118.0 POST T WELD HEAT TREA ATMENT
A. Post P weld heeat treatment when indicaated in the W Welding Proccedure Speciffication (WP PS shall be peerformed in accordance a wiith API-650
119.0 ATTACHMENT T WELDS
A. Bars, B clamps, temporary t attaachments, etcc. welded to thhe base materrial shall be thhe same P- nuumber ass the base material. B.
When W applyin ng attachmen nts to materiaals of differennt thicknessees, the preheaat requiremennts of the th hicker materiaal shall govern n.
C. When W the engiineering speciification requ uires removal of temporaryy attachments, a method thhat will not daamage the baase material shall be utilizeed, e.g. cut, ggrind, or air ccarbon arc goouge the attacchment off an nd grind the area a flush.
