ABN 69 003 696 526

Welding Of Mill AppliedGalvanized Steel Sections

TGN-BC-03Rev: 0Date: 1 March 2006Pages: 19

1. ScopeThis guidance note discusses the key elements for the successful welding of mill applied in-linegalvanized steel sections. It contains a compendium of welding and brazing procedures that havebeen developed to produce successful welds in galvanized rolled hollow sections. It is not applicableto the welding of hot dip galvanized fabricated structures.

2. ReferencesAS/NZS 1163 Structural steel sectionsAS/NZS 2312 Guide to protection of iron and steel against exterior atmospheric corrosionAS/NZS 4791 Hot-dip galvanized (zinc) coatings on ferrous open sections, applied by an in-

line processAS/NZS 4792 Hot-dip galvanized (zinc) coatings on ferrous hollow sections, applied by a

continuous or a specialized processWTIA TN 7 Health & Safety in WeldingWTIA Guidance Note 13 - Structural Hollow Sections: Mill Galvanized Steel Products

3. Background to Galvanized SteelsIn terms of life-cycle cost many designers are turning to pre-formed galvanized steel sections inpursuit of more economical structures. However to realise this benefit there must be cost-effectivewelding solutions.

Galvanizing is simply a zinc coating applied to the steel substrate. In Australia it is common practicefor structural steels manufactured to AS/NZS 1163 to have their resistance to environmental corrosionconsiderably extended by the use of a zinc coating which forms a barrier between the steel and theenvironment. In addition to this barrier protection the zinc is electrochemically more reactive than steeland thus offers sacrificial protection when the surface of the zinc is damaged during handling orservice.

A guide to the selection and specification of coating systems for protection against atmosphericcorrosion is provided in AS/NZS 2312. AS/NZS 4680, AS/NZS 4791 and AS/NZS 4792 providespecific requirements for the mass, quality and testing of zinc coatings. WTIA Guidance Note 13provides a matrix of the detailed galvanized product specification against trade name, as offered bytwo leading product suppliers.

4. Source of Welding DifficultyThe fundamental reason why poor quality welds can arise during welding of galvanized steels isbecause the zinc vaporises before the steel melts with a tendency for arc instability and reduced weldquality. This can be explained by reviewing the difference in the physical properties of steel and thezinc as shown in Table 1.

Table 1 – Comparison of melting and boiling temperatures of steel and zinc

MetalMelting Point

( C)Boiling Point

( C)Zinc 419 908Steel (iron) 1535 3070

Problems that are encountered include porosity, wormholes, coating damage adjacent to the weld,high spatter and high levels of fume.

5. Successful welding of Galvanized steelsSuppliers of galvanized steel sections have gone to great lengths to produce zinc coated productsthat can be successfully welded. It is important that the fabricator understands the designrequirements, assesses the suitability of the various welding processes and develops the processparameters and welding technique most appropriate for the specific application. The followingsections provide information on three key areas, welding technique, welding process and weldingfume.

5.1 Welding TechniqueArc instability is a potential undesirable effect and depends on the thickness and location of the zinccoating. In general more arc instability occurs when the coating thickness increases and in locationswhere the vapour has difficulty to escape. Additionally, for the same weld parameters, edge wettingand penetration is reduced compared to uncoated steels

The key to successful welding is to direct the wire to the centre of the weld pool and allow time for thecoating to vaporize at the leading edge of the weld pool. Higher arc energies and tight focussed arcsare also important.

For butt welds it is better to direct the arc to the shoulder of the section and not the edge as shown inFigure 1 below.

Aim wire at corner

Approx.20-22mm

Approx.15-18mm

Coating

Figure 1 – Butt welding

The fillet weld can be more problematic than the butt weld because the galvanized edge ofone plate is butted against another galvanized surface and the vapour cannot escape easilyand instead can be blown into the weld pool and create porosity. Nevertheless, with optimumsettings and skill there is no need for any additional preparation for fillet welds.

However, should problems arise alternative approaches are available. Creating a gap ofapproximately 1.5mm between the two parts will help the vapour escape. Alternatively, usinga slight bevel of approximately 15 or even removing the coating from one surface willimprove the weldability.

a) No preparation b) With gap of 1.5m c) With 15 bevel

Figure 2 – Various approaches to welding a fillet joint

5.2 Welding ProcessGalvanized steels are commonly welded with GMAW and FCAW processes. MMAW is occasionallyused for small one-off jobs or site work. An emerging joining process is Gas Metal Arc Brazing whichis particularly tolerant to the zinc coating and produces very little coating damage as a result of thejoining process. The challenge for the fabricator is to find the optimum operating window for theprocess employed. Excessive heat input will increase vapourisation and hence arc instability andfume. Additionally higher heat inputs will remove more protective coating resulting in the need forgreater remedial action.

GMA and FCA welding offers the potential of increased productivity with advances in power sourcesproviding increased opportunities for fabricators. When welding with the traditional spray mode thecoating has less influence on arc instability but the disadvantage is relatively high heat input. Pulsedpower sources provide good penetration and fusion characteristics and positional welding capabilitieswith reduced heat inputs that minimise distortion & spatter. The hot arc zone allows for good coatingpenetration and the controlled heat input allows for excellent fusion with less risk of burn through.Specific current waveforms have been developed so that many new power sources contain presetconditions for particular applications, so set up is much easier. These types of power sources areused with GMAW and FCAW.

With FCAW a variety of gas shielded and self shielded consumables are available. Examples oftypical weld procedures for the FCAW process are shown in the compendium

In GMAW, most shielding gases use combinations of Ar/CO2 or Ar/CO2/O2 and are capable ofproducing uniform weld beads with good external appearance depending on appropriate selection ofthe operating conditions. Gases low in CO2 content (eg. Ar with approx. 15% CO2) produce high arcstability in the low current, low voltage ranges, and result in a low fusion area. Therefore, low CO2content gas is suitable for welding thin (<3mm) coated steel sections.

Welding of thicker section zinc coated steel requires the use of a higher CO2 gas with high wire feedrate and high inductance level in order to achieve satisfactory fusion. Within the GMAW processsuitable electrode wires are ES4 and ES6. Examples of typical weld procedures for the GMAWprocess are shown in the compendium.

With Gas Metal Arc Brazing a silicon bronze filler material, typically SG-CuSi3 or SG-CuAl8 is usedwithout the need for any flux. These types of filler materials melt around 900-1100°C and hence lesszinc vaporises. In addition, the low heat input avoids fusion of the base metal and results in far lessdistortion. Pure argon is the shielding gas most often used in GMA brazing although mixed gases withan active component of up to 1 % CO2 or oxygen, for example, are advantageous for a large numberof applications. This technique offers good gap bridging and less coating damage and results insmooth weld beads with excellent corrosion resistance. However it should be recognised that the filleryield strength is typically 170MPa compared to around 400 MPa for a steel filler and therefore thesuitability must be assessed.

With MMAW the choice of consumable is dependent upon the material specification of the substrate.Typically in applications where strength and toughness are important the electrodes conforming toE4816-2 of AS/NZS 1553.1 can be used. In less stringent applications E4112 can be used. Howeverwhen using these consumables a post weld coating treatment using a proprietary paint, rich in zincmust be used to render the weld and adjacent area protected against environmental corrosion.

5.3 Welding FumesIn common with all welding applications, welders should keep their heads out of the vapour plumeand employers should arrange welding activities such that the resulting welding fume is out of thebreathing zone. Should a welder finds white dust (zinc oxide) inside the welding helmet weldingconditions need to be adjusted or they have not positioned themselves correctly. Either wayimproved fume control will be required.

As a minimum a respirator mask should be worn but additional means of improving the ventilationand environment around the welder are available and should be considered. Further guidance onfume control and all aspects of welding health and safety is provided in WTIA TN 7.

6.0 Compendium of Welding and Brazing ProceduresThe following pages provide industry standard welding and brazing procedures for coated steel.These have been developed for the joining of rolled hollow sections and represent current bestpractice when using semi automatic GMA and FCA welding processes.

WPS : 05-611-002 Welding Procedure REV: 1 Specification A Thermadyne Company

PAGE: 1 of 1 Cl ient:

CIGWELD

Purging Gas n/a Gas Flow Rate Arc Trans fer Mode CTWD (Electrode Stick Out) Wire Feed Speed Baking Temperature

R un No. Pas s Process D iam. Current Voltage Polarity WeaveTravel Speed Heat Input

(mm) (A) (V) (mm/m in) (kJ/m m)Transm ig 500P Prog 1. WFS 11.9mm/min V Ref 196Side 1&3 Butt Weld GMAW 0.9 140 22 DCEP 400 0.46

Side 2&4 Fi llet Weld GMAW 0.9 140 22 DCEP 400 0.46

Method None requiredn/a H eating Rate n/a15 0C H olding Temperature n/a15 0C C ooling Temperature n/a250°C R eleas e Temperature n/a

M.T: n/a P.T: n/a U.T: n/a R.T: n/a Notes:

NON DESTRUCTIVE TESTINGApplicable Code: AS/NZS 1554.1 VISUAL: yes

Heating Rate Preheat tem perature Fi ll Pas s es Max Interpass Temp.

PREHEATING POST WELD HEAT TREATMENT Method Flam e

Pres et Autocraft LW1-6

Autocraft LW1-6

Arc Strikes None perm ittedWELDING DETAILS

Cons umable

Interrun Cleaning Chip, wire brus h and/or grind Maximum weave

15 - 24 mm

n/a Hot Box Temperature n/a

Shielding Gas Argon 16% C O2, 2% O2

16-18l/min.Puls e MIG , Trans m ig 500P

Cons umable Detai ls 0.9 mm Manufacturer Cons umable Name Autocraft LW1-6

Welding proces s (s ) GMAW Cons umable Specification AS 2717.1ES6-GC/M-W503AH

AS 1163 AS1163WELDING PARAMETERS WELDING SEQUENCE

C 350LO/C450LO C 350LO/C450LO Material Group Material Group

MATERIAL SPECIFICATION Material 1 Material 2

Welding Posi tion D ow nhand (1G), Fil let Horizontal (2F) Back Gouging N ot required

Joint Preparation Saw Preparation Check

(H-C 1c) Thicknes s range tube to tube ,3.0 mm

JOINT PREPARATION

Qual ification Standard AS/N ZS 1554.1 (SP) Joint Configuration Single V Butt weld (welded one side)

Coated Tube Welded Joint ABN: 56 0 07 226 8 15 71, Gowe r St , Preston VIC 3072 Ph : +61-3- 947 4 7400 Fax: +61-3- 9474

APPLICABLE STANDARDS JOINT CONFIGURATION

side 2 & 4

0- 2mm

Side 2 & 4 3-4 mm fillet

Side 1&3

Side 1&3

WPS : 05-611-003 Welding Procedure REV: 1 Specification A Thermadyne Company

PAGE: 1 of 1 Cl ient:

CIGWELD

Purging Gas n/a Gas Flow Rate Arc Trans fer Mode CTWD (Electrode Stick Out) Wire Feed Speed Baking Tem perature

R un N o. Pas s Process D iam. Current Voltage Polarity WeaveTravel Speed H eat Input

(m m ) (A) (V) (m m/m in) (kJ/m m )Transm ig 500P Prog 1. WFS 11.9mm/min V Ref 196Side 1&3 Butt Weld GMAW 0.9 160 24 DCEP 400 0.6

Side 2&4 Fi llet Weld GMAW 0.9 160 24 DCEP 400 0.6

Method None requiredn/a H eating R ate n/a15 0C H olding Tem perature n/a15 0C C ooling Tem perature n/a250°C R eleas e Tem perature n/a

M.T: n/a P.T: n/a U.T: n/a R.T: n/a Notes:

Coated Tube Welded Joint ABN: 56 0 07 226 8 15 71, Gowe r St , P reston VIC 3072 Ph : +61-3- 947 4 7400 Fax: +61-3- 9474

APPLICABLE STANDARDS JOINT CONFIGURATION Qual ification Standard AS/N ZS 1554.1 (SP) Joint Configuration Single V Butt weld (w elded one side)

(H-C 1c) Thicknes s range tube to tube ,5.0 m m

JOINT PREPARATION Joint Preparation Saw Preparation Check Welding Posi tion D ow nhand (1G), Fil le t Horizonta l (2F) Back Gouging N ot requi red

MATERIAL SPECIFICATION Material 1 Material 2C 350LO/C450LO C 350LO/C450LO Material Group Material GroupAS 1163 AS1163

WELDING PARAMETERS W ELDING SEQUENCE Welding proces s (s ) GMAW Cons um able Specification AS 2717.1ES6-GC/M-W503AH Cons um able D etai ls 0.9 m m Manufacturer Cons um able N am e Autocraft LW 1-6 Shie ld ing Gas Argon 16% C O2, 2% O2

16-18l/min.Puls e MIG , Trans m ig 500P15 - 24 mm

n/a Hot Box Tem perature n/a Interrun Cleaning Chip, wire brus h and/or grind Maxim um weave Arc Strikes None perm itted

W ELDING DETAILS

C ons um able

Pres et Autocraft LW1-6

Autocraft LW1-6

PREHEATING POST W ELD HEAT TREATMENT Method Flam e Heating Rate Preheat tem perature Fi ll Pas s es Max Interpass Tem p.

NON DESTRUCTIVE TESTINGApplicable Code: AS/NZS 1554.1 VISUAL: yes

Weld sequence , butt weld s ide1, run 1, butt weld s ide 3, run 1, fi llet weld s ide 2, fil le t weld s ide 4 , Butt weld s ide 1 run 2 , butt weld s ide 3 run 2 .

s ide 2 & 4

0- 2mm

Side 2 & 4 5-6 mm fillet

Side 1&3

Side 1&3

DISCLAIMER: While every effort has been made and all reasonable care taken to ensure the accuracy of the material contained herein, the authors, editors and publishers of this publication shallnot be held to be liable or responsible in any way whatsoever and expressly disclaim any liability or responsibility for any injury or loss of life, any loss or damage costs or expenses, howsoeverincurred by any person whether the reader of this work or otherwise including but without in any way limiting any loss or damage costs or expenses incurred as a result of or in connection with thereliance whether whole or partial by any person as aforesaid upon any part of the contents of this publication. Should expert assistance be required, the services of a competent professional personshould be sought.

PO Box 6165, Silverwater NSW 1811Unit 50, 8 The Avenue of the Americas, Newington NSW 2127

Ph: +61 (0) 2 9748 4443 Fx: +61 (0) 2 9748 2858Email: info@wtia.com.au Webpage: www.wtia.com.au

WPS : 05-611-001 Welding Procedure REV: 1 Specification A Thermadyne Company

PAGE: 1 of 1 Cl ient:

CIGWELD

Purging Gas n/a Gas Flow Rate Arc Trans fer Mode CTWD (Electrode Stick Out) Wire Feed Speed Baking Tem perature

R un N o. Pas s Process D iam. C urrent Vol tage Polarity WeaveTravel Speed Heat Input

(m m ) (A) (V) (mm /m in) (kJ/m m )

Side 1&3 Butt Weld GMAW 0.9 115-120 16-16.5 DCEP 400 0.3Side 2&4 Fi llet Weld GMAW 0.9 115-120 16-16.5 DCEP 350 0.34

Method None requi redn/a H eating R ate n/a15 0C H olding Tem perature n/a15 0C C ooling Tem perature n/a250°C R eleas e Tem perature n/a

M.T: n /a P.T: n/a U.T: n /a R.T: n/a Notes:

Coated Tube Welded Joint ABN: 56 00 7 226 815 71, Gower S t , P reston VIC 3 072 Ph: +61-3- 9474 7 400 F ax: +61- 3-9 474

APPLICABLE STANDARDS JOINT CONFIGURATION Qual ification Standard AS/N ZS 1554.1 (SP) Joint Configura tion Single V Butt we ld (w elded one side)

(H-C 1c) Th icknes s range tube to tube , 1 .6 to 2 .0 m m

JOINT PREPARATION Joint Prepara tion Saw Preparation Check Vis ual Welding Posi tion D ow nhand (1G), Fil le t Horizonta l (2F) Back Gouging N ot requi red

MATERIAL SPECIFICATION Material 1 Material 2C 350LO/C450LO C 350LO/C450LO Material Group Material GroupAS 1163 AS1163

W ELDING PARAMETERS W ELDING SEQUENCE Welding proces s (s ) GMAW Cons um able Specifica tion AWS - SFA A5.7 Cons um able D etai ls 0 .9 m m Manufacturer Cons um able N am e Autocraft Silicon Bronze Shie ld ing Gas Argon

16-18 l/min. Spray15 - 24 mm

n/a Hot Box Tem perature n/a In terrun Clean ing Chip, wire brus h and/or grind Maxim um weave Arc Strikes None perm itted

W ELDING DETAILS

C ons um able

Sil icon BronzeSi licon Bronze

PREHEATING POST WELD HEAT TREATMENT Method Flam e Heating Rate Preheat tem perature Fi ll Pas s es Max Interpass Tem p.

NON DESTRUCTIVE TESTINGApplicable Code: AS/NZS 1554.1 VISUAL: yes

side 2 and 4

2mm

Side 2 & 4 3 mm fil let

S ide 1&3

Document No:9.4.5QR-0001

Revision No: Rev 0Page 1 of 2

NDNPTECHNOLOGY

DIFFUSIONACTIVITY # 27

ABN 69 003 696 526NATIONAL DIFFUSION NETWORKS PROJECT

TECHNOLOGY QUESTIONNAIREBuilding & Construction Industry Group

“Welding of Mill Applied Galvanized Steel Sections”

Date: 21 Nov 2005

G:\USERS\guidance-notes\Questionnaires\Welding of Mill Applied Galvanized Steel Sections.doc

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As part of the WTIA National Diffusion Networks Project, the Building & Construction Industry Sector has identified theneed to provide their customers with more information on the welding of their mill applied galvanized sections. The WTIAhas prepared a Technical Guidance Note “Welding of Mill Applied Galvanized Steel Sections” to provide Australianfabricators both the best practice for carrying out such welding plus a compendium of proven welding procedures. As avalued technology expert in this area we would like you to be part of the Technology Expert Group to review this note.Please complete this questionnaire so that we can gauge the success of meeting this need.

Objective 1: Identify the need to increase efficiency of welded galvanized steel sectionsGalvanized steel sections in are being increasingly adopted in the building and construction industry. It is recognised thatthe industry needs to be able to make welded connections in an efficient and competitive manner. This guidance note isintended to provide the Building & Construction Industry with the welding advice plus ready to use welding procedures forsuch welding. How well does the document achieve these aims?

poor average good very good

Comments:

Objective 2: Identify appropriate technology receptors in the Building & Construction IndustryThis document was written for fabricators, designers, welders and welding coordinators in the Building & ConstructionIndustry. Are these people the appropriate individuals we should be targeting?

yes no

What other types of companies and/or personnel do you suggest we target?

Objective 3: Identify current best practice for welding mill applied Structural Hollow SectionsThe document was written to reflect current best practice for welding mill applied galvanized steel products. Do youenvisage opportunities for the use of this technology in the industry?

yes no

If yes, what and where, if no why not?

Objective 4: Is the information provided clear, concise and accurate?yes no

If not, why?

Objective 5: Broad dissemination of technology to the Building & Construction IndustryPlease indicate how best to disseminate this Technical Guidance Note to the appropriate Building & Construction IndustryRecipients

Free Website Download Poster Pocket Guide Pamphlet

If poster, what size? A1 A2 A3 Laminated What selling price? $

If a pocket guide, what selling price? $

Other format?

Document No:9.4.5QR-0001

Revision No: Rev 0Page 2 of 2

NDNPTECHNOLOGY

DIFFUSIONACTIVITY # 27

ABN 69 003 696 526NATIONAL DIFFUSION NETWORKS PROJECT

TECHNOLOGY QUESTIONNAIREBuilding & Construction Industry Group

“Welding of Mill Applied Galvanized Steel Sections”

Date: 21 Nov 2005

G:\USERS\guidance-notes\Questionnaires\Welding of Mill Applied Galvanized Steel Sections.doc

2

Objective 6: Continuous ImprovementPlease Identify areas where the document can be improved or return the document with your recommendedadditions/amendments. Alternatively, please use the area below to provide any additional comments.

Respondents Name: Company: Phone:

Fax: Email: Date:

Please Fax (02 9748 2858) or E-mail (j.baker@wtia.com.au) your response.

Your prompt response is appreciated.

The WTIA has joined forces with industry and government to create a 3.5 million dollar Technology Support Centres Network. This network will assist industry to identify and exploit world’s besttechnology and manufacturing methods to establish a vibrant Australian industry beyond 2006. Together we will be implementing a step by step process which will lead to ongoing viability and greaterprofitability for all concerned:

(1) Determine your technological and manufacturing needs;(2) Identify world’s best practice;(3) Draw upon the network to implement world’s best practice at your site