basic quality induction programme for welders`,fitters & engineers

8/8/2019 Basic Quality Induction Programme for Welders`,Fitters & Engineers

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Project-overview

IOCL VGM Spurline project , a venture in its pride to escalatetechnology in the Oil business to the next shift making CAIRNEnergy India Ltd.L&T`s construction contract for this project valued over Rs.10 Cr,

where, both Pipeline & Piping activities included, Launcher in VGMTerminal and Receiver at IOCL Terminal.Project Pipeline spans for over 2.5km, bridging Cairn and IOCLterminal; Piping scopes over 2200inch-dia with 5 packages.This Projects construction with elevated measures in Safety, Quality

& Stringent accomplishments with sophistication in each level of thisexecution.A Paramount in its possession, scope consists of Procurement,Fabrication, Construction, Installation, Pre-commissioning, Testing,Commissioning and Performance test run.


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ROLLER COASTER RIDE ACCIDENTOne of the theories was due to the failure of a weld (car onto rollingmember). This speeds up more than 80kmph. It is reported that anaverage of 900 fatalities are reported each year in spite of constantinspection and most of theories were fatigue weld failures.


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LEARNER INDUCTION PROGRAM

Welders are to be taught about the WPS, explained to depths in themanner he understands;

To ensure that he practices surface preparation; Fit-up checks like high-low, vertical/horizontal alignment and to re-

ensure that he abides welding by the approved WPS; Qualified Filler wire/Electrode to be made to use and their storageconditions to be checked; Use of Owen for Low Hydrogen Electrodes(E-7018) and their effect on

the weldments. Effect of Pre-heating & Stress Relieving on the weldments are to be

defined in detail. Forbid multiple Fit-ups; Restrict Support tack-welds (over parent material) to a minimum; All welders must bear their ID`s on site.


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Welding Procedure SpecificationThis directs the welder/welding operatorto weld by the rules/parameters as per

the code requirements

ESSENTIAL VARIABLES

These variables are a must duringexecution and subject to changes/re-

qualification of WPS/PQR, when thesevariables are changed. All that derive

changes in the mechanical property areessential variables listed in the PQR

SUPPLEMENTARY VARIABLES

These are variables that are termed with

specificity of their requirement, anychange in the variables will summon for

re-qualification/re-certification of theWPS/PQR

NON-ESSENTIAL VARIABLES

Variables can be changed without re-qualifying the WPS


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P number

Assigned based on the BASE metalcharacteristics towards Weldability,Composition & Mechanical properties;

G numberApplied for steel & steel alloys that

belong to a group of P-numbers for thepurpose of procedure qualification,

where, notch toughness requirementsare specified and metallurgical

compatibilities should be considered;

F numberApplied for grouping of electrodes

based on their usability characteristics;Grouping done to reduce voluminous

WPS/PQR and metallurgical

compatibilities should beconsidered;


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WELDING POSITIONS


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CLASSIFICATION CURRENT ARC/PENETRATION ELECTRODE COATING

E XXX0 DCEP DIGGING/DEEP CELLULOSE - Na

E XXX1 AC/DCEP DIGGING/DEEP CELLULOSE - K

E XXX2 AC/DCEN MEDIUM/SHALLOW RUTILE Ti & Na

E XXX3 AC/DCEN/DCEP SOFT/SHALLOW RUTILE Ti & K

E XXX4 AC/DCEN/DCEP SOFT/SHALLOW RUTILE Ti & Fe powder

E XXX5 DCEP MEDIUM/SHALLOW BASIC LOW H 2 - Na

E XXX6 AC/DCEP MEDIUM/SHALLOW BASIC LOW H 2 - K

E XXX7 AC/DCEN/DCEP MEDIUM/SHALLOW IRON OXIDE - Fe powderE XXX8 AC/DCEP MEDIUM/SHALLOW BASIC LOW H 2 - Fe powder

E XXX9 AC/DCEN/DCEP MEDIUM/SHALLOW RUTILE IRON OXIDE- Fe powder

ELECTRODE CLASSIFICATION

E (electrode) 70 (x1000 psi Tensile Strength) 1 (Welding Position) 8 (Coating, Penetration & Current)1 Flat, Horizontal, Vertical (up), Overhead

2 Flat, Horizontal4 Flat, Horizontal, Overhead, Vertical (down)WELDING POSITION


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WELDING ELECTRODES A STUDY

CELLULOSE RUTILE BASIC

MECHANICAL PROPERTY GOOD GOOD EXCELLENT

WELD-ABILITY &PENETRATION EASY & DEEP MEDIUM & SHALLOW DIFFICULT & MODERATE

ARC-STABILITY STRONGER & HARDER, MORESPATTERS, SPRAY-FORMLIGHTER & EASIER, LESSSPATTER, SPRAY-FORM

LIGHTER & EASIER,REDUCED SPATTER, DROP-

FORM

COATING THICKNESS THIN / MEDIUM MEDIUM THICK & HYGROSCOPIC(BAKING NECESSARY)

DE-SLAGGING MEDIUM DUE TO STRONGERARC INTENSITY EASY DIFFICULT-MORE VISCOUS

WELDING POSITION &ANGLE

DEEP-PENETRATION AT ALLPOSITIONS & 45to 60

VERY GOOD AT VERTICAL-DOWN & 45to 60

FLAT, HORIZONTAL &VERTICAL-UP & 75to 90

WELD METAL DEPOSITION 85% 65% 115%

PARAMETERS DC(-) & DC(+) for SHALLOW &DEEP PENETRATION AC / DCDC preferred for continuous

ARC-STABILITY


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ARC WELDING - SAFETY CONCERNS

Rays from Arc-Welding ranges from 2500C to 6500C, hence,direct eye-view would cause corneal aberration, IR heating- causingdistortion of cartilaginous lens;

Sparks and molten spatters impinge on the skin with high velocity-causing burns & fire hazard;


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Electrical Hazards In-sufficient safety-wears-gloves, goggles, shoes,un-insulated / damaged holders, bare live cables and proper earthingwith soil conductivity is also a factor;

Fumes Confined areas, electrode certification through OSHAS/othersafety standards are a must, as toxicity is a major issue;


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Equipment operation familiarity is a concern & Safety is a prioritymeasure; Use of Flash-back arrestors & tarpaulin overs which arenot fire-proof;

Site Management-evaluating working / conditions of clothing and

different areas of work-nature, Usage of safety-wears in the rightmanner; committing to provide thoughts to the fellow workers.


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1. Make sure machine is properly grounded (earth-ing);

2. Never permit live electric parts to touch bare skin;

3. Do not cool electrode holders by immersing in water;4. Turn off power supply when welder is not in use;

5. Do not stand on wet areas while welding;

6. Wear leather gloves;7. Make sure that cables are not open-striped off making the inner bare

wire naked;

8. Make certain that electrode holders are properly insulated;


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1. Protect eyes and face from flying particles of slag by use of safetyglasses or face shield.

2. Wear adequate protective clothing.

3. Always wear leather gloves.

4. Wear high top shoes.

5. Keep collar, shirt pockets, etc buttoned.

6. Do not touch the electrode or metal where welding has taken place.

7. Handle hot metal with pliers or tongs.

8. Keep electrode stubs properly disposed of.


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1. Use a welding helmet with the correct shade lens for each weldingprocess, in good condition.

2. Wear suitable clothing do not leave bare skin exposed to the rays of the arc.

3. Do not strike the arc without covering the face and eyes. Givewarning to others before striking the arc.

4. Avoid looking directly at the arc where others are welding withoutproper eye protection.

5. If administered seeing the arc with the naked eyes, immediately washeyes with water.


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1. Work only in well-ventilated, clean areas.

2. Use great care when working on metals covered with lead or zinc.

3. If working in a confined area use respirator or other approvedbreathing devices.

4. In confined spaces, presence of toxic gases and ventilation for gasesduring welding should be checked initially.

5. Necessary precautions to be taken when welding near combustiblematerials of any kind.

6. Never weld on covered containers which may have held combustiblematerials without first taking adequate safety precautions. For

example, fill them with water, steam clean or fill with an inert gas.


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1. Be familiar with location and types of fire extinguishers.

2. Familiarity with the use of extinguishers;

3. Report any unsafe conditions that might start a fire.4. Do not weld near inflammable materials.

5. Do not weld on containers that has/had inflammable materials.

6. Do not weld near electrical fittings or lines.


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HEAT TREATMENT


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HEAT TREATMENT an Introduction

Pre-heating:Localized heating of the parent

material on either sides of the joint above theambient temperature before welding.

Post-heating:Localized heating of the welded joint

and the HAZ.


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Pre-Heating Decreases rate of thermal conductivity; Decreases the cooling rate after welding,

thereby, susceptibility towards cracking &martensitic transformation is meagre;

Reduces stress across the weld-parent metalinterface, thus, reduces distortion;

Reduces shrinkage and increases parent metalsurface wettability; Moisture evacuation; Usually, ranging between 10 C to 400 C.


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Pre-heat Temperature-Information Chiefly based on Carbon Equivalent values (Ceq) for carbon steels

dependent on the weight percentage of carbon presence.Ceq = C + Mn /6 + (Cr + Mo + V) /5 + (Cu + Ni) /15

Material thickness is a main factor to be considered in the evaluationof heat-treatments. Material with Large thickness dissipates heat orcools off sooner and Thinner materials tend to distort with largelinear/lateral variation and cools slowly as the volume for thermaldistribution is less.

Upon pre-heating, hydrogen emissivity is increased, thereby,reducing prone to Weld-metal, HAZ hydrogen cracking.

A welded joint on a high thickness job cools off immediately, as thevolume more is large to conduct/dissipate heat through the material.Therefore, pre-heating, will help the weld-puddle (molten weldbefore solidification) to cool at a slower rate. Therefore, shrinkage isminimized.


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MILD STEEL MEDIUM CARBON &ALLOYED STEELHIGH CARBON &ALLOYED STEEL

CARBONEQUIVALENT

CeqC

eq< 0.4 0.4< C

eq0.5

WELDABILITY EASY MEDIUM DIFFICULT

PRE-HEAT

10 C for thickness 1in as

per ASME B31.3 andOptional by BS 5135

150 C to 180 C as perASME B31.3 and 93 C

to 204 C by BS 5135

150 C to 400 C as perASME B31.3 and204 C to 370 C

by BS 5135

USE OF LOWHYDROGEN

ELECTRODESOptional for Thicker sections

Optional for Thinsections & Conditional

for thicker sections

Conditional for all size-dimensions

POST-WELD

HEATINGOptional for Thicker sections Conditional for thicker

sections at 1 hr/in

Conditional for all size-

dimensions at 2 hr/in

COOLING RATE AIR-COOLING SLOW VERY SLOW

HEATAFFECTED

ZONE (HAZ)Cracking

Not susceptible , if lowhydrogen electrodes are

used

Less susceptible , iflow hydrogen

electrodes are used

Higher susceptibility .Mandatory use of LowHydrogen Electrodes


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Post-weld Heat Treatment Post weld heat treatment (PWHT), defined as

any heat treatment after welding, is often used toimprove the properties of a weldment.

This process is commonly referred to stressrelief , so called because it is carried out attemperatures below the critical range of thebase metal, followed by uniform cooling.

PWHT-Stress Relieving: decreases hardness,increases ductility by decreasing yield strengthof the material.


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Post Weld Heat Treatment Relaxes residual stresses; Recovers cold work-deformations; Improves toughness;

Tempering to the required levels (softening), asin the case for Leaf springs used as suspensorin heavy vehicles ;

Re-crystallization & Spherodization for specialpurpose applications .

PWHT to be done within 14 days from the day ofwelding completion-as per ASME B31.3.


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HEATTREATMENT PROCESS

COOLINGRATE

MECHANICALPROPERTIES

ANNEALINGHeated above UCT & soaked for1Hr for every 1in.Then, cooled in Furnace

SLOW

DUCTILITY TOUGHNESS

STRENGTH COARSE GRAINED

SUB-CRITICAL orSTRESS-RELIEF

ANNEALING

Heating around LCT (~635 C),depending on the steel and locality SLOW

ONLY RESIDUAL STRESSRELIEVED; NO CHANGE INGRAIN STRUCTURE

NORMALIZINGHeated above UCT & soaked for1Hr for every 1in.Then, cooled in Air

MEDIUM

DUCTILITY TOUGHNESS STRENGTH FINE GRAINED

TEMPERING(DRAWING)

Re-Heated(220 C to 723 C) toconvert the remaining Hardness intoToughness

MEDIUM

DUCTILITY

TOUGHNESS STRENGTH FINE GRAINED

HARDENINGHeated above UCT & soaked for1Hr for every 1in.

Then, cooled in QuenchingRAPID

DUCTILITY HARDNESS TOUGHNESS STRENGTH FINE GRAINED


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HEAT INPUT - INFORMATION Heat Input (H) is a relative measure of the amount of

Energy transferred during welding. Any change in values from the WPS will call for re-

qualification. Welding with High Q will weaken the HAZ due to its

high temperature & Slower cooling rate-coarser grainstructure.

H = Power / Velocity of motionduring welding, Watt-sec/mm ;

One Joule = One Watt-sec; Cooling Rate is conversely

proportional to the Pre-heattemperature and the Heat Input;


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If the HEAT-INPUT is large,

MECHANICALPROPERTIES

Reduced Tensile & Yield StrengthIncreased Ductility, Reduced Hardness

Notch Toughness for 1550 kJ/in for SMAW

Notch Toughness for 50110 kJ/in for SMAW

if S , Blow Hole, In-complete penetration, Porosity, Improper Beadsize, Ir-regular weave profile

if V A, Complex & profuse melting of electrode, localized weldlumps, reinforcement, under-cuts, pressurized-gouging arc,weak HAZ, forced slag entrapment

HAZLarge & Weak-HAZ/oxidation of the parent material,precipitation in some steels

COOLINGRATE

Lower cooling rate, Large metallurgical changes, Pre-heatrequired for some metals with low heat-input (faster cooling)

DISTORTION Depends on thickness & large variation-angular/linear


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Post Heating Method

Flexible Ceramic Pads (FCP) heatingelements- desired temperature up to 1150C

Burners- Infrared gas burners - smaller

sized objects.

- Oil burners or High Velocity gasburners- larger objects


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Heat Treatment Furnaces

Temporary furnaces Permanent furnaces High temperature

furnaces


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BASIC FIT-UP REGULATIONS Inside cleaning, Surface Buff, Paint/stain & foreign material removal; Groove-design, Face-width, Bevel taper & Angle-made as per the

approved procedure; Check for the appropriate material & thickness in use;

Material for tack-supports shall be the same as the parent materialmade in use & be restricted to 4 at each 90 of 10mm max; Wedge/Bridge inserts tacked between the grooves are better

preferred & After welding, De-tacks shall not be hammered out; Suspended pipings/Sand-bag supports tend to deviate, hence, mitre

possibilities are to be checked & counter alignment has to be made;; RF pads shall be drilled for a hole before welding onto pipes; Use of machining wheels-GRINDING/CUTTING for appropriate

applications; Punching/Tracing shall be made out before welding;


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Improper BEVEL-ANGLE ,Insufficient GAP and

DIS-QUALIFIED Branch Fit-up


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UN-REGULATED GAP(7mm) /MIS-MATCH FOUND, THIS

INVOLVES SUPPORT PIPE RE-LENGTHING & WELDING


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JOINT INVOLVING MORE THAN 4FIT-UP SPOTS; PARENT METALELECTRODE-STROKED; POOR

BEVEL & GROOVE DESIGN


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RESTRICT TACK WELDS TO AMINIMUM & EACH SHOULD

CONTAIN STITCH WELDS/ DROPSNOT TO EXCEED 10 mm


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De-LINEAR ALIGNMENT


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IMPROPER BRANCH CUTS FORWELDING OF OLETS INNER

DIAMETER DOEST NOT MATCH THE`OLET in FIG A; SQUARE CUTTING

BY GRINDING WHEELas in FIG B & C;

FLOW OBSTRUCTION & SHOCKTURBULENCE MAY BE OBSERVED IN

DUE SERVICE


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`OLETS WELDED WITHFLANGES BEFORE WELDING

ONTO PIPES; HIGH RATEDFLANGES ARE HEAVY, WOULDPOSE A MIS-FIT IN ALIGNMENT

SIMULTANEOUS FIT-UPS-NOTADVICED; CAUSES RESTRAINT

AMONG THE MEMBERS


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FIG A & B : SUPPORTCHANNELS DIRECTLYWELDED TO THE PARENTMATERIAL WITHOUT ANYSANDWICH(SIMILAR TOPARENT METAL);FIG C : CS SUPPORTS AREGIVEN TO SS PIPINGS-REGRETTED;


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PRE/POST WELD REGULATIONS Welder ID/Qualification to be checked; Electrode-baking, Amperage controls, Pre-heat are to be checked; Earthing to be tight, blunt, insulated & clamped and should not be placed

over the parent metal; Welding cleats for fit-ups to be made by approved welder for the right

material; Conductivity check of the electrode be made over a scrap piece; For Socket welds, minimum 2 runs required & the start point shall not

coincide with the end point;

Post weld De-slagging, Re-capping be made if convex peeks, Under-cuts& removal of welded cleats are observed;

Arc-strikes must be restricted and if made should be filed-off; Weaving width shall not exceed 2.5D;


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OBSERVATION : RF PAD WELDED ONTO PIPE JOINT;CONSEQUENCE : HAZ WEAKENING or PRECIPITATION

SEGREGATION, JOINT INSPECTION IN-ABILITY, SERVICE LOADIMBALANCE;


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CLEATREMOVALUN-DONE

CRATERS ASSISTED WITH ELECTRODE DRAG &PENETRATED ARC-STRIKE

IN-COMPLETECAPPING,

UN-REGULATEDWEAVING


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DAMAGED-PIPE TACK WELD SPOTS

DAMAGES MADE BYFIT-UP TACKS &

GRINDING

POOR AMPERAGE CONTROLS & PARAMETERS


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POOR AMPERAGE CONTROLS & PARAMETERS

IN-COMPLETE PENETRATION

EXCESSPENETRATION


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ARC-STRIKES & INAPPROPRIATE EARTHING SPOTS


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NO SURFACE PREPARATION-WELDED OVERCOATING, RESULTING IN HEAVY OXIDATION DUE TO

HIGH HEAT INPUT & PIPE DAMAGE

SUPPORTPENETRATING

THRO` THE PIPE


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INSUFFICIENT OVERLAPPING OF BEADS


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LEAKS OBSERVED DUE TO ELECTRODEPENETRATION THROUGH THE THICKNESS OFTHE PIPE, INDISCIPLINED WELD LEAKSWITNESSED


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OBSERVATION: Leak during hydro-test, a 7 mmprotrusion (thro` thickness) found;REASON: Pipe welded with R-pad support, but, waspoorly welded with the electrode penetrating thro` thethickness;


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Stainless steel - AWARENESSAwareness:Heat Input (H) parameters to be checked as per the approved WPS, as

they vary from CS to SS (H,usually lower than CS);Pipes/Tubes 2 & below are to be welded by GTAW for shallowpenetration;

Inter-pass time delay for Distortion control in SS;Purging for SS avoids OXIDATION;Use of low/no chloride markers for markings on SS, as punching &materials/tools used in CS are regretted for use in SS;Use of the appropriate electrodes for SS;

Use of the appropriate SS materials for supports, fit-up cleats,grinding/buffing tools;

THERMAL BEHAVIOUR CS SSThermal Conductivity

Thermal Expansion & Distortion


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CRATER STROKES

UNDERCUT

OXIDIZATION of impurities present in thefiller / foreign material interference


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THANK U

basic quality induction programme for welders`,fitters & engineers

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