2009/01/14
Weld Joints
ME 538 – Welding Design, Fabrication & Quality Control
Weld Types
[Cary: Modern Welding Technology, 1998]
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Fillet Welds
correction
ME 538 – Welding Design, Fabrication & Quality Control
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Groove Welds Directing electrode at side wall of the joint will help ensure good sidewall fusion in deep welds
Provide base metal for root and prevent blow through Ensure full penetration
ME 538 – Welding Design, Fabrication & Quality Control
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Examples of Groove Welds
Edge Weld ME 538 – Welding Design, Fabrication & Quality Control
CWA W59 Appendix E
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Butt Joint & Applicable Weld Types
[AWS Handbook, 9th ed., Vol.1, Chap.5, and CSA W59-M1989 Standard] ME 538 – Welding Design, Fabrication & Quality Control
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Corner Joint & Applicable Weld Types
[AWS Handbook, 9th ed., Vol.1, Chap.5, and CSA W59-M1989 Standard] ME 538 – Welding Design, Fabrication & Quality Control
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T – Joint & Applicable Weld Types
[AWS Handbook, 9th ed., Vol.1, Chap.5, and CSA W59-M1989 Standard] ME 538 – Welding Design, Fabrication & Quality Control
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Lap Joint & Applicable Weld Types
[AWS Handbook, 9th ed., Vol.1, Chap.5, and CSA W59-M1989 Standard] ME 538 – Welding Design, Fabrication & Quality Control
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Edge Joint & Applicable Weld Types
[AWS Handbook, 9th ed., Vol.1, Chap.5, and CSA W59-M1989 Standard] ME 538 – Welding Design, Fabrication & Quality Control
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2009/01/15
Standard Locations of Elements of a Welding Symbol
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Handbook, Vol. 1, also ANSI/AWS Standard A2.4-98]
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The Weld Joint & Reference Line
ME 538 – Welding Design, Fabrication & Quality Control
[Cary: Modern Welding Technology, 1998]
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Groove Weld Symbols
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Handbook, Vol. 1, also ANSI/AWS Standard A2.4-98] 12
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Fillet and Other Weld Symbols
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Handbook, Vol. 1, also ANSI/AWS Standard A2.4-98]
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Supplementary Symbols
Finishing Codes ME 538 – Welding Design, Fabrication & Quality Control
[AWS Handbook, Vol. 1, also ANSI/AWS Standard A2.4-98]
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Welding, Brazing & Soldering Process Designations
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Handbook, Vol. 1, Chap. 8]
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Example: Welding Symbols with Multiple Reference Lines
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Handbook, Vol. 1, Chap. 8]
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Example: Welding Symbols for Intermittent Fillet Welds 1/4 1/4
1/4 1/4
All units are Inches ME 538 – Welding Design, Fabrication & Quality Control
[AWS Handbook, Vol. 1, Chap. 8]
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Example: Brazing & Soldering Symbols
FS
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Handbook, Vol. 1, Chap. 8]
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2009/01/19
Selection of the Joint Type The most appropriate joint type for an application will depend on: 1. 2. 3. 4.
The required part geometry The ability of the joint to transfer the load The welding position Accessibility of the joint for welding and inspection 5. Joint preparation and welding costs 6. Governing code and qualification requirements (Fabrication) ME 538 – Welding Design, Fabrication & Quality Control
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Selection of Weld Types Selection of the most appropriate weld type for a joint is based on the ability of the weld to safely transfer the load in service and on the cost of making the weld. The designer can choose: 1. Plug or slot welds 2. Fillet welds for jjoints subject j to lower stress or less demanding service conditions 3. Full penetration groove welds for joints in critical service conditions, e.g., high stress or cyclic loading ME 538 – Welding Design, Fabrication & Quality Control
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Prohibited Applications of One One--sided Fillet Welds
F
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Handbook, Vol. 1, Chap. 8]
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Example: CSA W59 Required Fillet Lap Joints in Tension
F F
ME 538 – Welding Design, Fabrication & Quality Control
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Welding Positions
More Favored
Less Favored
Easier, Faster, Higher Deposition Rates, L Less Cost
Harder, Slower, Lower Deposition Rates, More Cost
ME 538 – Welding Design, Fabrication & Quality Control
[Cary: Modern Welding Technology, 1998]
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Groove & Fillet Welds Positions
ME 538 – Welding Design, Fabrication & Quality Control
[CSA W59-M1989 Standard]
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Pipe Welding Positions
[Cary: Modern Welding Technology, 1998]
ME 538 – Welding Design, Fabrication & Quality Control
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Examples of Poor Weld Accessibility POOR
POOR
POOR
BETTER
POOR BETTER
POOR ME 538 – Welding Design, Fabrication & Quality Control
[J. Hicks, A Guide to Designing Welds, 1989]
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More Examples of Weld Accessibility
ME 538 – Welding Design, Fabrication & Quality Control
[J. Hicks, A Guide to Designing Welds, 1989]
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Economics of Groove Welds • Square groove welds: Lowest Cost but thickness is limited – From one side 1/4” to 3/8” (6 to 10 mm) max. – From both sides 1/4 1/4” to 1/2” 1/2 (6 to 12 mm) max.
• Single V or single bevel welds: – Thickness is equal or less than 3/4” (18 mm)
• Double V or double bevel welds: – Up to 40 mm gives lowest distortion
• Single and double J groove welds: – Less weld metal is required, but requires machining operation
• Single and double U groove welds: – Less weld metal is required, but requires machining operation ME 538 – Welding Design, Fabrication & Quality Control
Welding & Metal Fabrication, Mar. 1977, pp. 85-91
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Rule of Thumb for Fillet Welds Weld strength is proportional to the weld throat area Throat Area = 0.707 S x L To double the strength:
Weld Throat
1) Double the size, S, but the volume of weld metal required increases in proportion to S2, i.e., the volume of weld metal required increases by 4 times! 2) Double the length and the volume only doubles
Rule of Thumb for Fillet Welds: Always make a fillet weld small and long Note: there are usually minimum allowed fillet weld sizes in codes due to metallurgical limitations ME 538 – Welding Design, Fabrication & Quality Control
[Cary: Modern Welding Technology, 1998]
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Minimum weld sizes in steel welding codes are to avoid formation of martensite at the fusion boundary due to high cooling rates in small welds on large plates.
2009/01/21
Volume of Weld Metal for TT-Joints
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
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Equal Throat/Strength TT-Joint Welds
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
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Typical Corner Joint Designs
ME 538 – Welding Design, Fabrication & Quality Control
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Corner Welds => D&E groove welds used for larger plates *E can be a problem with structural steel due to lamilar tearing
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Deposition Rates
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
ME 538 – Welding Design, Fabrication & Quality Control
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Deposition Rates SMAW
GMAW
FCAW
SAW
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
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EXXXX
UTS
Additives Position
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Operator Factor
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
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2009/01/22
Some General Weld Joint Design Guidelines 1. Designed weld strength must be greater than or equal to the required joint strength 2. Use standardized jjoints whenever p possible 3. Use complete penetration welds for joints in tension or fatigue (CP) 4. Always choose a joint preparation that minimizes machining costs and the amount of weld metal and welding time required 5. Always use the smallest fillet or partial penetration weld ld size i allowed ll d 6. Use intermittent fillet welds whenever possible, but be aware of minimum length & pitch requirements 7. Always try to reduce the number of welds required 8. Avoid overwelding ME 538 – Welding Design, Fabrication & Quality Control
[Cary & Helzer: Modern Welding Technology, 2005]
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Some General Weld Joint Design Guidelines 9. Remove material in butt joints between different thicknesses for better transition (don’t add material) 10. Try to avoid using double T or cruciform joints 11. Always bevel the thinner member of corner joints 12. Avoid plug or slot welds in highly stressed members 13. Use flat welding position whenever possible 14 Welding in an enclosed area must be well ventilated 14. 15. Always ensure accessibility 16. Weld symbols must be clear and unambiguous
ME 538 – Welding Design, Fabrication & Quality Control
[Cary & Helzer: Modern Welding Technology, 2005]
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Practical Welding Design Principles 1. Secondary Member: There is no secondary member in a welded structure 2. Transverse Forces: Always provide a path so that a transverse load can enter part/parts of the weldment that lie parallel to the load 3. Force Redirection: Always provide a component p when a force changes g direction 4. Weld Details vs. Welder’s skill: Always avoid a joint design where the skills of the welder determine the weld’s integrity ME 538 – Welding Design, Fabrication & Quality Control
[Cary & Helzer: Modern Welding Technology, 2005]
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Examples: CSA W59 Minimum Allowed Weld Sizes for Welded Steel Construction
ME 538 – Welding Design, Fabrication & Quality Control
[CSA W59-M1989 Welded Steel Construction] 39
Examples: Secondary Members Backing bars butted together => Incipient crack Discontinuous Backing Bar
Solution: Weld backing bars together or use continuous length ME 538 – Welding Design, Fabrication & Quality Control
Keep weld away from joint 40
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Examples: Transverse Forces A force applied transverse to a member will ultimately enter a p portion of the section that lies p parallel to the applied force
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
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Provision for Transverse Force
Poor Design Better Design ME 538 – Welding Design, Fabrication & Quality Control
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
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Example: Attachments with Transverse Loads
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
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Example: Attachments with Transverse Loads
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
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Example: Attachments with Transverse Loads
ME 538 – Welding Design, Fabrication & Quality Control
[AWS Welding Handbook, Vol. 1 (9th Ed.)]
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Example: Designing for Transverse Forces
Poor Design
Better: Add External Gusset Plates ME 538 – Welding Design, Fabrication & Quality Control
Best: Add Internal Stiffener Plates [Blodgett, Eng. J. - AISC, 1980, 17(4), pp. 106-119]
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Force Redirection
ME 538 – Welding Design, Fabrication & Quality Control
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Weld Details vs. Welder’s Skill
Poor Design ME 538 – Welding Design, Fabrication & Quality Control
Better Design O.W. Blodgett, Eng. J.-AISC, 17(4),1980,106-119
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Weld Details vs. Welder’s Skill
A weld must start and stop so no crater is left at points of high stress (AWS Standard D1.1 and CSA W59 Welded Steel Construction)
ME 538 – Welding Design, Fabrication & Quality Control
O.W. Blodgett, Eng. J.-AISC, 17(4),1980,106-119
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