Flux cored Arc Welding- a productive process Abby Joseph, - PowerPoint PPT Presentation

Flux cored Arc Welding- a productive process Abby Joseph, voestalpine Bohler Welding India CII Welding Conference 2016, Mumbai- 16Nov 2016 voestalpine Böhler Welding voestalpine Böhler Welding www.voestalpine.com/welding

Market overview and trends Cored wire annual growth rate 6-8% [kto] Global growth cored wires  Shift from stick electrodes to cored wire and solid wire 395  Higher deposition rate , (23%) cored wire also applicable for positional welding  Ease to use  MIG/MAG equipment and gases getting cheaper Source: figure 2013 from BM; growth rate from F&S voestalpine Böhler Welding

Market overview – Indian scenario Highlights 1. Joining FCWs have a total market of 10,000MT/yr. and HF FCWs 2500MT/yr. 2. Industry segments- Pre-engineered buildings, Railways, Shipbuilding. 3. Structural steel joining is an early adopter of FCAW process, although SMAW still has a significant share. 4. FCAW has a good position in SS- mainly for cladding but also for high-thickness joining. 5. Oil & Gas segment has adopted FCAW utilizing the new features of low-H2, CTOD and NACE compliance. 6. LNG Tank construction use Ni-base FCWs for higher productivity in V-up welding voestalpine Böhler Welding

What is FCAW?  Principle of FCAW process  Slag systems  Parameter settings  Economical Aspects  Welding techniques  Wire production & QA/QC voestalpine Böhler Welding

Flux Cored Arc Welding (FCAW) Operating principle of the process voestalpine Böhler Welding

Slag System • With respect to the flux ingredients, the flux cored wire may be rutile based or basic based. • Rutile gives good slag detachability whereas basic gives good mechanical properties. • In rutile flux ingredients, the slag may be fast freezing or slow freezing. voestalpine Böhler Welding

Welding Techniques Pushing Neutral Dragging voestalpine Böhler Welding

Production of folded cored wires voestalpine Böhler Welding

Production of seamless cored wires Metal strip Manufacturing tube from solid strip using HF welding Annealing and Drawing to final dimension calibrating to filling and copper coating diameter Manufacturing agglomerated flux and Pre-drawing to annealing filling of the tube by diameter and annealing vibration of the filled tube voestalpine Böhler Welding

Quality Assurance voestalpine Böhler Welding

Quality Assurance Free for shipment Stopped for further Investigation voestalpine Böhler Welding

Types of cored wires Division by the filling cored wires for gas shielded welding Self-Shielded without slag slag formation Joining Hard facing rutile filler B M basic filler metal cored wires R P slow freezing slag fast freezing slag voestalpine Böhler Welding

Types of cored wires Division by production methods Seamless Cored Wires Folded Cored Wires Thicker tube (metallic coat) Higher filling ratio  optimal positioning of the wire  easier to optimize weldability for automatic welding 100% copper coated 100% homogenous filling  best current transition  uniform mechanical properties  and corrosion resistance lower deformation in production low hydrogen content in closed tube  enables production of high  no re-drying necessary alloyed and nickel base qualities voestalpine Böhler Welding

Equipment, Arc Types and Welding Positions Main Components of the Welding Machine voestalpine Böhler Welding

Welder skill requirement Comparatively lower 1. Semi-automatic process 2. CV against CC power source characteristics leads to nearly constant arc gap. 3. Much wider parameter window within the same dia. of wire lead to a lot of flexibility. 4. Advances in equipment/systems helps welder in self-correction while welding. 5. Modern equipment (programmable) helps welder in replicating the performance. 6. Less welder fatigue ensures consistent performance over long working hours Skilled Welders + Advanced FCAW power source = Less repair and high productivity voestalpine Böhler Welding

High Deposition Efficiency Weight of Weld Metal • Deposition efficiency = Weight of Electrode Used For FCAW: 85-90 % For SMAW: 55-60% Flux cored wires have a lower flux-to-metal ratio than coated electrodes, and thereby, a higher deposition efficiency. voestalpine Böhler Welding

Main properties of cored wires Process efficiency Gives information about the efficiency of the process [%] Solid wire FCAW Current transfer Cross section Current transfer Cross section Flux Isolator Weight Minus spatter, Weight Average Consumable wire slag etc. Weldmetal Process- wire- ø: 1,2 mm [g/m] [g/m] [g/m] efficiency 98 – 100 % Solid wire .. = 8,49 (98%) 8,68 -0,19 96 – 98 % Metal cored 8,30 -0,22 = 8,08 (97%) 85 – 94 % Basic 7,48 -0,43 = 7,05 (94%) 83 – 92 % Rutile 7,22 -0,85 = 6,37 (88%) voestalpine Böhler Welding

Higher Operating Factor Arc Time (Hours) %age of a welder’s working day that = is actually spent welding Total Hours Worked SMAW 15% to 40% FCAW 40% to 50% Because of Higher ARC Time Because of Lesser ARC Time Operating factors ranging from 50% to values approaching 90% may be obtained depending on the degree of automation. Operating factor depends upon,  Machine set-up (electrode change, holder adjustment)  Operator Skill  Material Handling voestalpine Böhler Welding

Higher Current density Current density J [A/mm²] is the relation between the amperage I [A] and effective cross section A [mm²] of the wire: I I I A    J [ ]  d² π a  2 2 A (d d ) * π mm² i 4 4 FCAW Solid wire Current transfer Current transfer Cross section Cross section d d a d i Flux Isolator voestalpine Böhler Welding

Main properties of cored wires Current density Solid wire, Ø 1,2 mm welding current I = 220 A Shielding gas: M21 (18% CO2 + 82% Ar) 220 Α I Α J = d² = (1,2mm)² = 194  p  p 1 mm² 4 4 Rutile Flux Cored wire, Ø 1,2 mm welding current I = 220 A Shielding gas: M21 (18% CO2 + 82% Ar) Α I 220 A J = (d²-d²) = (1,2²-0,75²) mm² = 320  p 2  p mm² a i 4 4 Higher current density = Higher deposition rate voestalpine Böhler Welding

Penetration compared to solid wire  Flux cored wire have a wider arc  Operate therefore with a very safe penetration  The risk of lack of fusion is minimized Flux cored Solid wire voestalpine Böhler Welding

Cored wires welding parameters More flexible welding parameter settings 38 Spatter formation 36  Steady low spatter welding in Solid wire Ø 34 1.2 mm spray arc from approx. 150 A, 32 Voltage (V) 24V, 6.5 m/min. (solid wire Ø Flux- 30 cored 1.2 mm from approx. 210 A, wire Ø 0.9 28 mm 28V, 7 m/min) 26 Solid wire Ø 1.0 mm 24  Good welding behavior Flux- cored 22 remains constant over wide wire Ø 1.2 mm 20 range of currents and voltages Poor seam outflow 18 100 150 200 250 300 Current (A) voestalpine Böhler Welding

Comparison of deposition rates Flux cored wire ø 0,9 mm Theoretical deposition rate Flux cored wire ø 1,2 mm Flux cored wire ø 1,6 mm Solid wire ø 1,0 mm 100% d.c. (kg/h) Solid wire ø 1,2 mm Coated electrode Welding position: 1G PA Amperage (A) voestalpine Böhler Welding

Comparison of weld length Flux-cored wire Solid wire Flux cored wire Covered electrode E316LT1-4(1) E316L-(Si) A = 180 E316L-17  EAS 4 PW-FD EAS 4 M-IG (Si) V= 27,5 FOX EAS 4 M-A  Ø 1,2 mm Ø 1,0 mm Ø 3,2 mm WS = 8,3 m/min  M 21 M 12 L = 220 mm/min  [cm] [cm] 30 30 Solid wire pulsed [cm] A = 100  25 30 25 V = 20  25 20 20 WS = 5,5 m/min  20 L = 145 mm/min  15 15 15 Covered electrode 10 10 10 A = 90  5 5 V = 26 5  L = 75 mm/min  0 0 0 voestalpine Böhler Welding

Fabrication Codes & FCAW process AWS D1.1  FCAW process is deemed as qualified processes as per Section 3.0 – Prequalification of WPS.  With respect to welder qualification, a 3G qualification qualifies for all other positions except Overhead position. ASME SEC IX  QW-255 covers the welding variables for procedure qualification for GMAW and FCAW.  QW-355 covers the welding variables for welder qualification for GMAW and FCAW processes. ASME SEC VIII  UHT-82 clause describes the welding requirements per process  For FCAW, the consumable should conform to SFA 5.29 and SFA 5.36 voestalpine Böhler Welding

Fabrication Codes & FCAW process API RP 582: Welding Guidelines for the Chemical, Oil and Gas Industries  As per its section 5.1 FCAW is an acceptable welding process  FCAW-G (Gas shielded) may be used for either groove or fillet welds for pressure boundary or structural welding  For use of FCAW consumables in pressure containing equipment, diffusible hydrogen limit should be met as specified in Table 5-1 (H4 or H8) API 1104: Welding of Pipelines and Related Facilities  As per Section 12 – FCAW Automatic Welding is an acceptable process  For each process details of essential variable is given in its sub section 12.5 voestalpine Böhler Welding