Company: TRENERGY INCWORK PROCEDURE FOR GENERAL WELDINGPREP By A.GHAPPD. By J.BullCONTENTSPURPOSE/SCOPEThe purpose of this procedure is to define the general plant welding requirements includingwelding consumable and welding repair for TRENERGY INC.DEFINITIONSINSPECTOR: A person who performs inspection activities to verify conformance to specifiedrequirements.INSPECTION: Examination or measurement made to verify whether an item or activity conformsto specified requirements.SHALL: This term is used to indicate that a provision is mandatory.SHOULD: This term is used to indicate that a provision is not mandatory but is recommended asgood practice.MAY: This term is used to indicate that a provision is optional.WJCS (Welding Joint Control System) or WCS (Welding Control System): A databaseestablished to control welding, NDT, PWHT, Welders, Spools and hydrostatic test package.WPS: A WPS is a written qualified welding procedure specification prepared to provide directionfor making production welds to code requirements.PQR: A PQR is a record of welding data used to weld a test coupon for procedure qualification.WQT or WPQ: The demonstration of a welder/welding operator's ability to produce weldsmeeting prescribed standards.REFERENCESCodes and standards for welding activities shall be in accordance with the latest revision of thosespecified in the contractual documents, specifications and COMPANY official instructions asfollows:ASME Sec. I Sec. II Part C Welding Rods, Electrodes and Filler MetalsASME Sec. V Nondestructive ExaminationASME Sec. VIII Rules for Construction of Pressure VesselsASME Sec. IX Welding and Brazing QualificationRESPONSIBILITIESSubcontractor is responsible for executing, monitoring and quality control of welding activities,and preparing the related documents.The production departments are responsible for managing welding activities. The fieldexecutive engineer or supervisor is responsible for preparation and execution of welding work.The field QA/QC manager is responsible for assuring and overall quality controlling of weldingactivities.The QC inspector is responsible for quality control, inspection and documentation of the weldingwork.Inspectors responsible for acceptance or rejection of metals fabrication, inspection and testing ofwelding works shall be qualified.GENERAL REQUIREMENTSProduction welding shall only start when qualified welding procedures and welders have beenapproved .Production welding shall be done in accordance with Approved WPS by qualified welders/weldingoperators.Surfaces to be welded shall be clean and free from paint, oil, dirt, scale, oxides and othermaterials detrimental to welding. Cleaning shall be done in a manner that will not lead tocontamination of the weld or base metal. Only stainless steel brushes and tools shall be used onstainless steels, nickel and non-ferrous materials. Grinding discs containing sulfur (iron sulfite) orother harmful components shall not be used on stainless steels, nickel or non- ferrous materials.Welding shall not be done when the quality of the weld would be impaired by the prevailingweather conditions such as below:a) when surfaces are wet or exposed to rainb) welding personnel are exposed to inclement conditions- Welding shall be performed by completion of each layer before starting next layers.- Weld passes shall not start or stop at the same point.- Permanent backing rings and consumable inserts shall not be used.- Temporary welds shall be minimized. Welding shall be performed with the same materials,electrodes, minimum preheat and procedures as for the production welding.- The temporary welds shall be subsequently removed and ground flush with the base materials.- The method of removing attachments shall not injure base metal. They shall not be removed byhammering off.- The metal surfaces at the area of temporary weldment shall be inspected by MT or PT afterattachments' removal, if material is susceptible to crack.- Peening of welds is not permitted.- Welding is not permitted on the pressure retaining shell after hydrotest.- Arc strikes shall be avoided outside the weld bevel. Should this occur, the deposit shall becarefully removed by smooth grinding. In serious cases, the removal areas shall be subject to MTor PT.WELDING CONSUMABLE CONTROLGeneral- All welding electrodes shall conform to Part C of ASME Sec. II or Approved equivalent andrelated specifications.- TRENERGY should keep manufacturers test certificates for each heat, lot or batch ofelectrodes as required in related specification. Mill test certificates should show chemical andmechanical properties.- Trenergy shall assign welding material controllers and weldingforemen to meet the anticipated work load under supervision of their QC crew. They shallcheck all electrodes to be incorporated into the work and confirm that the correct electrodesare using.- The welding material controller shall be conversant with the scope of welding techniques andwelding consumables, and shall be able to identify the different types of electrodes andwelding rods, so as to recommend appropriate handling methods.- It shall be the responsibility of welding material controller to monitor the drying anddistributing electrodes.- Subcontractor welding material controller shall record baking status of welding electrodes. Noelectrodes shall be distributed until confirming completion of baking process.- welding Inspectors shall have full authority to monitor and check theactual welding consumable control activities at any time.- No welding consumables shall be left in the work site upon completion of the day's work.- Filler rods for inert gas tungsten arc welding shall be cleaned immediately before use.Electrode wire for inert gas metal arc welding shall be protected from contamination duringuse and special particularly between non-working periods.- The shielding gases to be used for welding and for back purging may be either Argon, helium oroxygen, to a sufficient purity. Pure Nitrogen may be also considered. The gas is tobe maintained till at least two layers of weld have been completed. Adequate time for preweldpurging should correctly be calculated so that oxidization is prevented. All relativerequirements of WPS shall be met.For GTAW rods, an empty box used to supply rods from the supplier may be used. It shall beprohibited to store different types of electrodes or rods in a dryer or box labeled for a differentelectrode/rod classification.Considering humidity of weather conditions, when hermetically sealed containers electrodes(vac.pac) are to be used, it shall preferably be kept in portable oven during use.Warehouse and Storage ConditionsStorage of electrode, wire and flux shall be in accordance with manufacturers instructions.Moreover, Storage conditions of welding consumables shall be as follows:1) The packages of electrodes, fluxes and welding rods shall be protected from any physicaldamage which will cause contact between containment and surroundings.2) The packages of electrodes and welding rods shall not be in direct contact with the ground.3) The packages should not be opened until just prior to use.- Welding electrode, flux and rod shall be kept clean and dry in an individual warehouse. Thewelding consumable warehouse shall have sufficient facilities to control humidity asrecommended by manufacturer.- Electrodes and welding rods shall be segregated by type and stored with identifying labels ormarkings, so that they can be easily identified and mixing of different types can be avoided.- Electrode storage warehouse, holding and drying ovens shall be controlled by weldingmaterial controller under supervision of welding Inspector.- No electrodes, filler wires or fluxes that are damaged, damp, greasy or oxidized may be used.Any electrode deemed unsuitable for use shall be removed from the site. Subcontractor shallbe responsible for discarding them prior to any distribution made.- Low hydrogen electrodes which have been in direct contact with water shall be definitelyrejected and removed from the site.- Traceability of consumables should be checked before commencement of productionwelding.6.3 Drying Equipment6.3.1 General6.3.1.1 trenergy shall provide the necessary drying and holding ovens, and shall alsoprovide the portable dryer for special materials.6.3.1.2 The baking and holding ovens shall be clearly marked to show the type of electrodescontained and the re-drying or stock locations.6.3.1.3 The temperature accuracy of measuring system for main ovens shall be checked using acalibrated thermometer as required.6.3.2 Baking/Main Drying Oven6.3.2.1 The main drying oven shall be used for drying and re-drying the electrodes.6.3.2.2 The main drying oven shall be provided with an automatic control device of dryingtemperature. The baking temperature and its time shall be carefully recorded.6.3.2.3 In the event of the required drying conditions being the same (in accordance withmanufacturer recommendation), several types of electrodes may be dried at one time,provided that they are kept clearly segregated by type.6.3.3 Holding Oven6.3.3.1 TRENERGY has sufficient number of holding ovens appropriate for thequantity of welding electrodes to be used.6.3.3.2 The holding oven shall be used to store those electrodes that conform to the provisions of6.4.1.6.3.3.3 The baking oven may be permitted to use as holding oven provided that it fulfill allrequirements for holding conditions.6.3.4 Welder Portable Oven6.3.4.1 Each welder shall be provided with at least one portable dryer on which welder's stampnumber prominently marked in order to prevent the inadvertent mixing of electrodes. It isnecessary that one dryer be individually used for each type of welding electrode.6.3.4.2 Each welder shall store the welding electrode in a portable dryer or electrode bag (ifpermitted for a specific type) so as to prevent the take-up of humidity, electrode damageand the mixing with different types of electrode.6.3.4.3 Each welder shall be responsible on the completion of the day's work for returning theportable dryer issued to him to the place designated as the welding consumable controlroom. This important job shall be controlled by welding foreman.6.4 Baking/Holding Process6.4.1 The baking and holding requirements shall be as per manufacturer recommendation.6.4.2 Electrode re-baking shall not be more than twice. Moreover, re-baking of electrodes isprohibited for those electrodes where it is restricted by manufacturer.6.4.3 All stock or unused welding electrodes shall be stored separately for re-drying by weldingmaterial controller. Electrodes which have been re-dried and held for long time shall befirst delivered for production welding.7.0 WELDING INSPECTION7.1 General7.1.1 This work instruction and the following two articles provide details for performing visualinspection for fit-up, welding in progress and completed weldment.7.1.2 The components to be welded shall be in accordance with Approved drawings and WPS.7.1.3 There shall be sufficient lighting to allow proper interpretation of visual inspection.7.1.4 Welded surfaces to be inspected must be clean and dry.7.1.5 All welds shall be visually inspected prior to any subsequent NDT.7.1.6 Welding procedure specification, contract AFC drawing and erection welding schedule orequivalent shall be used for inspection judgment.7.1.7 All inspections required for weld assemblies shall be performed in accordance withApproved ITP. Moreover, it is necessary that Subcontractor QC Inspector visually checkall fit-up and welded joints before issuance of any notification.7.2 Marking of Welds7.2.1 All joints shall be marked with identification number of welder(s) or welding operator(s).7.2.3 If more than one welder welds a joint, each shall apply his symbol in a manner to indicatethe part of the joint he welded.7.3 Fit-up Inspection7.3.1 The surface to be welded shall be smooth and free from deep notches, irregularities,scale, rust, oil, grease and other foreign materials detrimental to welding.7.3.2 Cleaning shall be done in a manner that will not lead to contamination of the weld or basemetal.7.3.3 Only stainless steel brushes and tools shall be used on stainless steels, nickel and nonferrousmaterials. Grinding discs containing sulfur shall not be used for these materials.7.3.4 All pipes shall be internally cleaned from any foreign material.7.3.5 The root opening of components to be jointed shall be adequate to provide acceptablepenetration.7.3.6 In fillet welds, the parts to be jointed shall be brought as close to contact as practical,although in most instances a small opening between the parts is desirable.7.3.7 Immediately prior to welding, the bevel and adjusting area of joint for a minimum distanceof 25mm shall be thoroughly cleaned of paint, rust, adhesions, dirt and any other foreignmatter by use of power brush or disc wheel.7.3.8 Weld bevels shall conform to the joint design shown in the WPS and/or Approveddrawing.7.3.9 Weld bevels shall be made by machining, grinding or thermal cutting and the beveledends shall be reasonably smooth and uniform.7.3.10 The hardened surface shall be removed by machining or grinding.7.4 Weld Visual Inspection7.4.1 General7.4.1.1 During welding operation, the following items shall be checked by qualified Inspectors.a) Ensure the required minimum preheat temperature is applied and established duringwelding.b) Ensure correct electrode / filler metal is used for welding.c) Ensure the correct interpass temperature is maintained.d) Ensure proper cleaning of weld between beads.7.4.1.2 Flux, slag and weld spatters shall be completely removed from weld beads andadjoining base material.7.4.1.3 For visible defects such as pin-holes, incomplete fusion or penetration, undercut,porosity and other marked defects refer to acceptance criteria described hereafter.7.4.2 PROCESS PIPING Acceptance criteria according to RP-2224-999-6300-001 & ASME B31.37.4.2.1 Crack and lack of fusion are unacceptable.7.4.2.2 Undercut exceeding 1/32 in (0.8mm) and TW/4 in depth, whichever is less isunacceptable.7.4.2.3 Surface porosity or exposed inclusion are not permitted.7.4.2.4 Concave root surface (suckback) is acceptable if total joint thickness including weldreinforcement is more than TW.7.4.2.5 Weld reinforcement or internal protrusion shall be as below:Table 7.1 Maximum weld reinforcement or excess for piping components Note (1)(TW) Wall Thickness mm (in.) Height mm (in.)T < 6 (1/4) h 25 (1) h < 5 (3/16)Note (1): Applicable for M, Normal, and Sever Cyclic. For category D, limits are twice theapplicable value above.7.4.3 PIPELINE Acceptance criteria according to RP-2224-999-6300-008&9 and API 11047.4.3.1 In the areas of weld preparation such as pipe ends, fusion faces and branches,planar defects are not acceptable, whatever the size.7.4.3.2 The weld shall fuse the pipe at the root without protruding excessively into the borepipe. The maximum permissible penetration of the root bead into the bore of the pipeshall be 3 mm, although an occasional local slight excess of penetration is allowable.7.4.3.3 Weld reinforcement shall be uniform and not less than 1.0 mm nor more than 3.0 mmin height.7.4.3.4 Cracks of any kind are not permitted. Welds found with cracks (other than cratercracks) shall be cut out.7.4.3.5 Arc strike is not acceptable on the base metal.7.4.3.6 Porosity7.4.3.6.1 Cluster porosity (CP) that occurs in the cap pass shall be considered a defectwhen any of the following conditions exist:a) The diameter of the cluster exceeds 13 mm.b) The aggregate length of CP in any continuous 300 mm length of weld exceeds 13 mm.7.4.3.6.2 Hollow-bead porosity is not acceptable, whatever the size.7.4.3.7 Undercut7.4.3.7.1 Cap undercut exceeding 0.5 mm in depth is unacceptable and shall be blended outby light grinding prior to radiography. Grinding shall not reduce the pipe wallthickness below the minimum specified.7.4.3.7.2 Root undercut and shrinkage groove with depths exceeding 0.4 mm and lengthexceeding 20 mm in any continuous weld length of 300 mm is unacceptable.7.4.3.8 Root ConcavityRoot concavity is permitted (up to 1.2 mm in depth) if there is no lack of root fusionand if the thickness of the weld (including cap reinforcement) is not less than thespecified wall pipe thickness.7.4.3.9 Incomplete Root Penetration and Lack of Root FusionCumulated length not to exceed 15 mm in any continuous weld length of 300 mm,with no single defect exceeding 10 mm in length.7.4.4 ATMOSPHERIC STORAGE TANKAcceptance criteria according to RP-2224-999-2500-001&API 6507.4.4.1 Cracks and arc strikes are not permitted.7.4.4.2 Maximum permissible undercut is 0.4 mm (1/64 in.) in depth for vertical butt joints,vertically oriented permanent attachments, attachment welds for nozzles, manholes,flush-type openings, and shell-to-bottom welds. For horizontal butt joints, horizontallyoriented permanent attachments, and annular-ring butt joints, the maximumpermissible undercut is 0.8 mm (1/32 in.) in depth7.4.4.3 The frequency of surface porosity in the weld shall not exceed one cluster (one ormore pores) in any 100 mm (4 in.) of length, and the diameter of each cluster shallnot exceed 2.5 mm.7.4.4.4 The reinforcement of the welds on all butt joints on each side of the plate shall notexceed the following thicknesses:Table 7.2 Maximum weld reinforcement for tank shell in generalPlate Thickness mm (in.)Maximum Reinforcement Thickness mm (in.)Vertical Joints Horizontal Joints 13 (1/2) 2.5 (3/32) 3 (1/8)> 13 (1/2) to 25 (1) 3 (1/8) 5 (3/16)> 25 (1) 5 (3/16) 6 (1/4)7.4.4.5 The reinforcement need not be removed except to the extent that it exceeds themaximum acceptable thickness or unless its removal is required by radiographicexamination. In this case, the finished surface of the weld reinforcement at thelocation of the radiograph shall either be flush with the plate or have a reasonablyuniform crown not to exceed the following values:Table 7.3 Maximum weld reinforcement for shell where RT requiredPlate Thickness mm (in.) Maximum Reinforcement Thickness mm (in.) 13 (1/2) 1.5 (1/16)> 13 (1/2) to 25 (1) 2.5 (3/32)> 25 (1) 3 (1/8)7.4.5 LPG DOUBLE WALL TANK Acceptance criteria according to RP-2224-999-2550-001 & BS 7777The welds shall be visually inspected in accordance with EN 970. The defects shall bewithin the specified limits of applicable level in EN 25817 (ISO 5817) and following visibleitems:(a) Crack; not permitted(b) Lack of fusion; not permitted(c) Lack of penetration; not permitted(d) Undercut; h 1 mm for horizontal but joints and fillet welds. h 0.5 mm for other joints.(e) Single pore; d 0.3s for butt welds, 0.3a for fillet welds and max. 3 mm.(f) Localized porosity; same as (b) except that maximum size of cluster limits to 2 mm.Legend:a: nominal fillet weld throat thicknessd: diameter of poreh: size (height or width) of imperfections: nominal butt weld thickness or the prescribed depth of penetration7.4.6 STEEL STRUCTURAL WORK Acceptance criteria according to RP-2224-999-1882-001 & AWS D.1.17.4.6.1 Time of InspectionVisual inspection of welds in all steels may begin immediately after the completedwelds have cooled to ambient temperature. Acceptance criteria for ASTM A 514, A517, and A 709 Grade 100 and 100W steels shall be based on visual inspectionperformed not less than 48 hours after completion of the weld.7.4.6.2 CrackAny crack shall be unacceptable, regardless of size or location.7.4.6.3 Crater Cross SectionAll craters shall be filled to provide the specified weld size, except for the ends ofintermittent fillet welds outside of their effective length.7.4.6.4 Weld and Base Metal FusionThorough fusion shall exist between adjacent layers of weld metal and between weldmetal and base metal.7.4.6.5 Undersized WeldsThe size of a fillet weld in any continuous weld may be less than the specifiednominal size (L) without correction by the amounts (U) prescribed in table 7.4.Table 7.4 Undersized WeldL USpecified nominal weld size in. (mm) Allowable decrease from L, in. (mm) 3/16 (5) 1/16 (2)1/4 (6) 3/32 (2.5)5/16 (8) 1/8 (3)In all cases, the undersize portion of the weld shall not exceed 10% of the weld length.On web-to-flange welds on girders, under-run shall be prohibited at the ends for alength equal to twice the width of the flange.7.4.6.6 Undercut7.4.6.6.1 For material less than 1 in. [25 mm] thick, undercut shall not exceed 1/32 in. [ 1mm], with the following exception: undercut shall not exceed 1/16 in. [2 mm] forany accumulated length 2 in. [50 mm] in any 12 in. [300 mm].7.4.6.6.2 For material equal to or greater than 1 in. thick, undercut shall not exceed 1/16 in.(2 mm) for any length of weld.7.4.6.6.3 For Cyclically Loaded Nontubular Connections & Tubular Connections: In primarymembers, undercut shall be no more than 0.01 in. [0.25 mm] deep when the weldis transverse to tensile stress under any design loading condition. Undercut shallbe no more than 1/32 in. [1 mm] deep for all other cases.7.4.6.7 Porosity7.4.6.7.1 For Statically Loaded Nontubular Connections: CJP groove welds in butt jointstransverse to the direction of computed tensile stress shall have no visible pipingporosity. For all other groove welds and for fillet welds, the sum of the visiblepiping porosity 1/32 in. [1 mm] or greater in diameter shall not exceed 3/8 in. [10mm] in any linear inch of weld and shall not exceed 3/4 in. [20 mm] in any 12 in(300 mm)length of weld.7.4.6.7.2 For Cyclically Loaded Nontubular Connections & Tubular Connections: Thefrequency of piping porosity in fillet welds shall not exceed one in each 4 in. [ 100mm] of weld length and the maximum diameter shall not exceed 3/32 in. [2.5mm]. Exception: for fillet welds connecting stiffeners to web, the sum of thediameters of piping porosity shall not exceed 3/8 in. [10 mm] in any linear inch ofweld and shall not exceed 3/4 in. [20 mm] in any 12 in. [300 mm] length of weld.7.4.6.7.3 For Cyclically Loaded Nontubular Connections &Tubular Connections: CJPgroove welds in butt joints transverse to the direction of computed tensile stressshall have no piping porosity. For all other groove welds, the frequency of pipingporosity shall not exceed one in 4 in. [100mm] of length and the maximumdiameter shall not exceed 3/32 in. (2.5 mm).8.0 ARTICLE I - PRESSURE PIPING AND EQUIPMENT8.1 General8.1.1 This article shall specifically be applied for welding of piping and equipment componentsthat are governed by project specifications RP-22, 23& 24-999-6300-01~07.8.1.2 Materials which require preheat for welding shall be preheated in the same manner forthermal cutting or arc-air gouging as per WPS.8.1.3 When arc-air gouging is used, the surface shall have all carburized and hardenedsurfaces removed by grinding, and all such areas shall be inspected by theSubcontractor's quality control department for conformity prior to welding.8.1.4 Weld joining components of different material thicknesses shall be made in such amanner that the slope through the transition zone does not exceed 1/4.Fig. 8.1 Taper schematic8.1.5 For single-side welded butt joints: 1/48.1.5.1 In Carbon-Mo, Cr-Mo, and austenitic stainless steels, and welds located incompressor suction or lube oil systems shall have the root pass made by the GTAWor GMAW process with a back gas shielding protection.8.1.5.2 When the GTAW/GMAW processes are used for welding carbon-Mo, low-alloy andCr-Mo steels with a chromium content not exceeding 1.5%, back gas shielding maybe waived as per WPS.8.1.6 In double-side welded joints, the root pass shall entirely be removed by arc-air gouging,followed by grinding for final cleaning, prior to back-welding.8.1.7 All vertical welding shall be done vertical up (uphill progression).8.1.8 Only GTAW shall be used for pipe diameters less than 2 3/8 (60 mm).8.1.9 The maximum individual layer thickness for SAW shall not exceed 9.5 mm for materialsless than 32 mm thick, or 12.5 mm for thicker materials. Recycling of fluxes is notpermitted.8.1.10 The brand and grade of flux used for the production of SAW shall be the same as what isused in the procedure qualification test.8.1.11 The maximum weld width shall not exceed three times of the electrode diameter.8.1.12 Welding shall not be stopped before the second pass is completed and until the thicknessof the weld is at least equal to one third of the pipe wall thickness.8.1.13 Weld at the orifice flange shall de ground smooth on the inside.8.1.14 All tack welds shall be made in accordance with the Approved WPS and shall beperformed by qualified welders. Tack welds shall be of sufficient cross-section and lengthin order to avoid cracks, especially on high strength steel materials.8.1.15 Materials that require preheat for welding shall be preheated in the same manner beforetack weld.8.1.16 Tack welds shall be completely removed prior to welding.8.1.17 The temporary welds shall subsequently be removed and ground flush with the basematerial, and then inspected by MT or PT.8.2 Welding Processes8.2.1 For pressure containing parts, the following processes have been approved and anyother welding process requires CONTRACTORs approval before starting construction:a) Shielded metal arc welding (SMAW)b) Inert gas tungsten arc welding (GTAW)c) Submerged arc welding (SAW)8.3 Requirements for Location of Welds8.3.1 Distance between two successive girth welds shall not be less than one pipe diameter or50mm, whichever is greater.8.3.2 Attachments of non-pressure parts by welds which cross existing main or for which theminimum nominal distance between the toe of the attachment weld and the toe of theexisting main welds or branch welds is less than the smaller of twice the thickness of thepressure parts of 40mm, should be avoided.8.3.3 All longitudinal weld seams shall be located on the topside of pipe when the piping iserected. Two successive longitudinal weld seams shall be staggered by 30 degreesminimum. When this requirement is not satisfied, each longitudinal weld seams are takenRT with 300mm length near circumference side to confirm soundness of welds.8.4 Heat Input Control8.4.1 Heat Input shall be restricted to the maximum values shown in the relevant WPS andPQR for ferritic materials that required impact testing at -46C or below and quenched &tempered steels.8.4.2 For austenitic stainless steel materials, heat input shall be kept within the limits ofWPS&PQR and not over 15 kJ/cm.8.4.3 The following parameters shall be carefully checked:a) Preheat temperatureb) Minimum and maximum interpass temperaturesc) Amperage and voltaged) Welding travel speed and weld width8.4.4 Measuring equipment shall be calibrated according to the related quality Procedure.8.5 Socket and Fillet Welding8.5.1 When socket weld fittings or valves are used, the pipe face shall be spaced minimum 1.5mm clear from the root face of socket to avoid bottoming.8.5.2 Socket welds shall be made with at least two passes.8.6 Seal Welding of Threaded Connectionsa) Hydrocarbon service:Threaded plugs on hydrostatic vents not provided with a valve shall be seal welded aftertesting has been carried out. Valve, vents, drains, and sample connections discharging toan open system shall only be seal welded upstream the first block valve. Caps shall not beseal welded. Threaded needle valves at sample connections shall not be seal welded.Galvanized piping shall not be seal welded.b) Other services: all threaded connections shall be sealed as follows:- 204C and below: PTFE thread tape (i.e. no seal-welding)- Above 204C: seal weld wherever possible, otherwise use pipe joining compound tomanufacturer's standard.c) Where seal welding of threaded joints is intended to be used, all following conditions shallbe met:- The materials shall be weldable.- The joints shall be made up clean and without the use of any tape or compound.- The weld shall cover all exposed threads.- The welding procedure shall not cause damage to the threaded fitting, e.g. valve softseats.- Welding shall only be carried out by qualified welders.- No other satisfactory means of jointing is available- The weld shall cover all exposed threads and shall be done with electrodes not inexcess of 3.2mm in diameter, unless otherwise agreed by TPA or COMPANY.8.7 Preheating and Interpass Temperature8.7.1 Preheating shall be in accordance with qualified WPS. In general, the followings shouldbe followed for carbon steel and low-alloy steels:a) Minimum 50C: When only moisture removal is required. When moisture removal isnot applicable, minimum temperature of metal shall be 0C for low-hydrogenelectrodes and 10C for other types.b) Minimum 100C: When the base material thickness exceeds 25 mm or when thecarbon equivalent exceeds 0.42.c) Minimum 150C: When the base material thickness exceeds 25 mm and the carbonequivalent exceeds 0.42.8.7.2 Minimum Preheat temperatures for other ferritic materials shall be as table 8.1.Table 8.1 - Preheat temperatures for other ferritic materials (1)Material(Nominal Analysis)ASMEP-No.Minimum PreheatTemperature (C)Manganese Molybdenum 3 150C-1/2 Mo, 1/2Cr-1/2 Mo 3 1001 Cr-1/2 Mo, 1 1/4 Cr-1/2 Mo 4 1502 1/4 Cr-1 Mo, 3 Cr-1 Mo, 5 Cr-1/2 Mo,7 Cr-1/2 Mo, 9 Cr-1 Mo 5 2002 1/2 Ni 9A 1503 1/2 Ni 9B 150 (1)Note (1): For piping welding, minimum 95C preheat is acceptable for thickness up to 10mm.8.7.3 For ferritic materials, when the required preheat temperature is 200C or higher, and forthickness greater than 50 mm, the metal shall be maintained at preheat temperature untilthe weld is post-weld heat treated.8.7.4 The above preheat temperature shall be maintained during all thermal operations such aswelding, thermal cutting and arc-air gouging.8.7.5 Preheat shall be applied uniformly around the circumferential weld using gas or electricalmeans.8.7.6 Temperature shall be measured using contact thermometer or indicating crayons of themelting type.8.7.7 In weld assembly of different base materials, preheat temperature shall be the highest ofthose which are requested for each material.8.7.8 Interpass temperature shall not be less than the minimum preheat temperature and shallnot exceed the maximum interpass temperature.8.7.9 Preheating shall be avoided for austenitic stainless steel materials. Moreover, interpasstemperature shall be minimized and be restricted to 150 C.8.8 Special Consideration to Repair Welding (for Piping)8.8.1 The repair work must be based on qualification testing (PQR) supporting a specific WPSfor each type of repair on materials which are subject to impact tests at temperaturesbelow 0C except austenitic stainless steels.8.8.2 For materials other than austenitic stainless steels which are subject to impact tests attemperatures below 0 C, or for stainless steels used in corrosion environment, a secondrepair of the same area on a given weld shall not be permitted. Should a defect berepaired on a previously repaired weld area, the whole weld shall be cut and reweldedafter having restored the base materials to their initial condition (i.e. remove heat affectedzones, damaged surfaces, etc.) For all other welds, only two repairs shall be permitted onthe same area of a given weld. Should a third repair become necessary, then the wholeweld shall be cut as per above.8.8.3 Welds containing cracks shall be subject to additional non-destructive testing (ultrasonicor magnetic particle).9.0 ARTICLE II - PIPELINE9.1 General9.1.1 This article shall be applied to the site welding of carbon steel pipelines according toASME B31.4, B31.8 and API 1104 and project specifications RP-2224-999-6300-008 &009.9.1.2 The requirements of this procedure shall prevail over those of API 1104 and where thisprocedures states no overriding requirements, those of API 1104 shall be applied in full.9.1.3 Weld repairs to pipe or fitting body or bevels are not permitted.9.1.4 Basic coated low hydrogen electrodes shall be used for all fillet welds.9.1.5 For pipe diameters less than 150 mm and for all welds to valves, flanges or fittingsincluding fillet welds, the complete weld shall be vertical-up.9.1.6 For all tie-ins (closing welds), all welds where external line-up clamps are used, and for allRepair welds, vertical-up welding shall be applied for the root runs.9.1.7 When vertical-down welding is applied the second run (hot pass) shall be depositedimmediately after completion of the root run (stringer bead), and the time lapse shall notbe greater than that used in the procedure qualification test, with a max. of 15 minutes.9.1.8 For pipe to pipe welds, a minimum of four layers or one third of weld thickness, whicheveris less, shall be completed before cooling below preheat temperature. No welds onfittings, tie-ins and repairs shall be allowed to cool below preheat temperature prior totheir completion.9.1.9 The working clearance shall be such as to afford the welder maximum comfort duringwelding. A clearance of 400 mm with any surrounding obstacle shall be a minimum.9.2 Welding Process9.2.2 Only GTAW process shall be used for pipe diameters less than 2 3/8 (60 mm).9.2.3 Welding processes for anode connection welds or any other welds to electrically connectattachments shall have prior approval of CONTRACTOR.9.3 Pipe End Preparation9.3.2 All required field bevels on pipe line must be made with a beveling machine. Automaticflame beveling is acceptable for tie-ins only.9.3.3 Where pipes or fittings of unequal wall thickness are to be welded, the taper shall not besteeper than 1 in 4.9.4 Alignment of Pipe9.4.1 All joints with diameter over 150 mm shall be aligned with an internal line-up clampexcept for tie-in line-ups or under exceptional conditions approved by COMPANY, onwhich occasions an external line-up clamp may be used.9.4.2 Where external line-up clamps are used, all roots run shall be welded vertically-up. Rootruns for riser and expansion loop fabrication shall also be welded vertically up.9.4.3 When lining up longitudinally welded pipe, the pipe shall be positioned so that the seamwill be on the upper surface of the line and within that area of sixty degrees each side ofthe top center of the pipe, with a minimum offset of 200 mm except at vertical bends.9.4.4 Maximum misalignment or offset of surfaces shall not exceed 2.0 mm.9.5 Proximity of Weldsa) A diameter of Branch/Fittingb) Six (6) times wall thickness of thickest componentc) 150 mm9.6 Preheating and Interpass Temperature9.6.1 A minimum preheat of 100C shall apply to the welding of fittings, repair welds, tie-insand fillet welds (as per Approved WPS). Interpass temperature shall not exceed themaximum value achieved in the procedure qualification test, which in any case shall notexceed 250C.9.6.2 The preheat temperature required by the qualified WPS shall be maintained completelyduring welding.9.6.3 Preheat or warm up shall be applied in a uniform manner using gas burner or electricalmeans except that hand held torch heating shall not be permitted other than whereexternal line-up clamps are used.9.6.4 The minimum preheat temperature shall be maintained and measured over a distance ofat least 25 mm either side of the welding area.9.6.5 Temperature shall be measured using contact thermometer or indicating crayons of themelting type.9.6.6 The interpass temperature measured shall not be less than the minimum preheattemperature and shall not exceed the maximum interpass temperature recorded duringprocedure qualification.9.6.7 The preheat for repair welds shall be 20C greater than that used at qualification testsunless otherwise agreed by COMPANY.9.7 Tack Welds9.7.1 Tack welds shall be performed with a minimum of 50 mm long, with the same process asthe root run defined in Approved WPS by a relevant qualified welder. Where preheat isrequired, it also shall be applied prior to tack welding.9.7.2 Tack welds incorporated into the final weld shall be completely removed prior to welding.9.7.3 All tacks are to be welded vertical up.9.8 Special Consideration to Repair Welding (for Pipeline)9.8.1 The weld repair shall be carried out in accordance with the Approved repair WPS.9.8.3 Weld repairs are permitted for defects located in the filling and cover passes (i.e. partialpenetration repairs).9.8.5 Single-run repairs are permitted where the whole of the weld cap is replaced to theoriginal procedure. For any other single-run repair (internal or cap repair), qualificationtests are required.9.8.6 Weld repairs to pipe, fitting body or bevels are not permitted.10.0 REPAIR PROCEDURE (In addition to paragraphs 8.8 and 9.8)10.1 General10.1.1 For defects that are over the limits ASME sec I or ASME sec VIII and/or NDT procedures,Or customer specification Trenergy shall take such remedial action as is necessary to secure acceptance.10.1.2 For partial repairs, the cut-out portion shall be sufficiently deep and long to remove thedefect. At the ends and sides of the cut, there shall be a gradual taper from the base ofthe cut to the surface of the weld metal. The width and profile of the cut shall provideadequate access for rewelding.QA OR NDT shall fully record all repair works and provide documents that show allrequired NDE have been performed satisfactorily.10.1.5 The preheat and interpass temperatures shall be in accordance with Approved WPS.10.1.6 The repaired weld shall be subject to post-weld heat treatment as per WPS, if required.10.1.7 When PWHT is required, repairs shall be made before PWHT.10.1.8 PWHT, if required, shall be applied to the whole girth weld.10.2 Removal of Weld Defects10.2.1 Complete repair of a weldment shall include removal of the weld metal, beveling of newedges, and rewelding.10.2.2 Unacceptable defects shall be removed by chipping, grinding, machining or arc-airgouging. Where arc-air gouging is used, all carbon, copper and other debris, includingcarburized metal, shall be removed by grinding or other Approved mechanical methods.Oxygen gouging of quenched and tempered steels or other high strength steels is notpermitted.10.2.3 The removed portions shall be sufficiently deep and long to remove the defect. The widthand profile of the cavity shall be such as adequate access for re-welding is met.10.2.4 Special care shall be taken to remove weld defects located at the root in order to obtainan acceptable root gap.10.3 Progressive Examination for Defective Welds10.3.1 Piping and Pipeline10.3.1.1 An examined item (ORI) with one or more defects (imperfections of a type ormagnitude exceeding the acceptance criteria of the project) shall be repaired orreplaced; and the new work shall be reexamined by the same methods, to the sameextent, and by the same acceptance criteria as required for the original work.10.3.1.2 Additional welds shall be selected as follows:a) Two additional samples (AD-1) of the same kind (if welded or bonded joints, by thesame welder, bonder or operator) shall be given the same type of examination.b) if the items examined as required by (a) are acceptable, the defective item shall berepaired or replaced and reexamined, and all items represented by these twoadditional samples shall be accepted, butc) if any of the items examined as required by (a) reveals a defect, two further samples(AD-2) of the same kind shall be examined for each defective item found by thatsamplingd) if all the items examined as required by (c) are acceptable, the defective item(s) shallbe repaired or replaced and reexamined, and all items represented by the additionalsampling shall be accepted, bute) if any of the items examined as required by (c) reveals a defect, all welded joints (bythat welder or welding operator) shall be fully examined (AD-3) around welding date ofinitial defective joint (ORI) until his rejection rate drops to below 5%.A weld that fails to meet the criteria given in Para.7.4.4 shall be reworked beforehydrostatic testing as follows:Arc strikes discovered in or adjacent to welded joints shall be repaired by grinding andre-welding as required. Arc strikes repaired by welding shall be ground flush with theplate.a) Rewelding is required if the resulting thickness is less than the minimum required fordesign or hydrostatic test conditions. b) The repair weld shall visually be examined for defects.10.3.2.2 When a section of weld is shown by a radiograph to be unacceptable under theprovisions of Para. 8.1.5 of API 650 or the limits of the deficient welding are notdefined by the radiograph, two spots adjacent to the section shall be examined byradiography; however, if the original radiograph shows at least 75 mm (3 in.) ofacceptable weld between the defect and any one edge of the film, an additionalradiograph need not be taken of the weld on that side of the defect. If the weld ateither of the adjacent sections fails to comply with the acceptance criteria, additionalspots shall be examined until the limits of unacceptable welding are determined, orthe erector may replace all of the welding performed by the welder or weldingoperator on that joint. If the welding is replaced, the inspector shall have the option ofrequiring that one radiograph be taken at any selected location on any other joint onwhich the same welder or welding operator has welded. If any of these additionalspots fail to comply with the acceptance criteria, the limits of unacceptable weldingshall be determined as specified for the initial section.