Welding Codes (AWS)

Understanding primary welding standards:

AWS D1.1 (Structural Welding - Steel):

Scope:
- Structural steel welding
- Buildings, bridges, structures
- Carbon and low-alloy steels
- Most referenced structural code

Key Requirements:
- Prequalified and qualified procedures
- Welder qualification
- Inspection requirements
- Acceptance criteria

Related AWS Codes:
- D1.2: Aluminum
- D1.3: Sheet steel
- D1.5: Bridge welding
- D1.6: Stainless steel
- D1.8: Seismic supplements

ASME Section IX:

Scope:
- Welding and brazing qualifications
- Pressure equipment
- Used with ASME construction codes
- Most comprehensive qualification standard

Content:
- WPS/PQR requirements
- Welder performance qualification
- Essential variables
- Base metal groupings (P-numbers)

ASME Construction Codes:
- Section I: Power boilers
- Section VIII: Pressure vessels
- B31 series: Piping

API Standards:

API 1104:
- Pipeline welding
- Transmission and distribution
- Field welding focus
- Industry-specific

API 650:
- Storage tanks
- Atmospheric welding
- Tank construction

ISO Standards:

ISO 3834:
- Quality requirements for welding
- Comprehensive, intermediate, elementary
- System approach

ISO 15614:
- Welding procedure qualification
- International equivalent of ASME IX
- Multiple material parts

Other Codes:
- AWS D17.1: Aerospace
- NAVSEA: Naval shipbuilding
- EN standards: European
- Customer specifications

Documenting and qualifying welding:

Welding Procedure Specification (WPS):

Purpose:
- Written instructions for welding
- Tells welder how to make weld
- Based on qualified parameters
- Required for code work

Content:
- Joint design
- Base materials
- Filler metals
- Process parameters
- Preheat/interpass
- Post-weld heat treatment

Types:
- Prequalified (D1.1)
- Qualified by test

Procedure Qualification Record (PQR):

Purpose:
- Documents successful test weld
- Supports WPS validity
- Actual test parameters recorded
- Testing results documented

Process:
1. Prepare test plate per variables
2. Weld using proposed parameters
3. Perform required testing
4. Document results
5. Develop WPS from qualified range

Testing:
- Visual examination
- Mechanical testing (tensile, bend)
- Impact testing (if required)
- Radiography/UT (if required)

Essential Variables:

What They Are:
- Parameters affecting mechanical properties
- Change requires requalification
- Defined by code
- Examples: P-number, thickness, process

Categories:
- Essential: Change requires new PQR
- Supplementary essential: When impact required
- Nonessential: Change without requalification

Common Essential Variables:
- Base metal (P-number change)
- Significant thickness change
- Welding process change
- Filler metal F-number change
- Position change
- Heat input range
- Preheat reduction

Qualifying welding personnel:

Performance Qualification:

Purpose:
- Verify welder capability
- Required for code work
- Specific to variables
- Periodic maintenance

Process:
1. Weld test coupon per WPS
2. Visual examination
3. Mechanical testing (usually bends)
4. Or radiographic testing
5. Document qualification

Essential Variables:

Common Variables:
- Welding process
- Position
- Electrode/wire type
- Material group
- Thickness range
- Backing or no backing

Variable Limits:
- Position qualified extends to less difficult
- Thickness qualifies range (per code)
- Material qualifies group

Testing:

Bend Tests:
- Face and root bends
- Side bends (thick material)
- Evaluate ductility
- Discontinuity limits

Radiographic:
- Alternative to bend testing
- Internal soundness
- Per acceptance criteria
- Common for pipe

Fillet Weld:
- Break test
- Macro examination
- Size and profile
- For fillet-only qualification

Maintenance:

Expiration:
- Typically 6 months without welding
- Process/position specific
- Code specific rules
- Documentation required

Renewal:
- Continued work may extend
- Retest if expired
- Engineering may extend
- Documentation essential

Records:

Required:
- Welder identification
- Test date
- Variables qualified
- Test results
- Examiner/organization

Verifying weld quality:

Inspection Methods:

Visual Inspection:
- First-level inspection
- Per code requirements
- Before, during, after welding
- CWI often required

Non-Destructive Testing:

Radiography (RT):
- Internal soundness
- Volumetric (porosity, inclusions)
- Permanent record
- Radiation safety

Ultrasonic (UT):
- Internal soundness
- Planar defects (cracks, LOP)
- Portable, no radiation
- Operator-dependent

Magnetic Particle (MT):
- Surface and near-surface
- Ferromagnetic materials
- Cracks, undercut
- Quick, portable

Liquid Penetrant (PT):
- Surface defects
- Any material
- Non-porous surface
- Simple, portable

Acceptance Criteria:

Types of Criteria:

Workmanship:
- Visual requirements
- Surface condition
- Weld profile
- Dimension limits

Structural:
- Discontinuity limits
- Based on loading/service
- More rigorous where critical
- Fatigue considerations

Common Discontinuities:
- Porosity (limits vary)
- Incomplete fusion
- Undercut (depth limits)
- Cracks (generally unacceptable)
- Profile (reinforcement limits)

Rejection and Repair:

When Required:
- Exceeds acceptance criteria
- Per code repair procedure
- Retest after repair
- Documentation

Documentation:

Required Records:
- Inspection reports
- NDE reports
- Welder qualifications
- Procedure documentation
- Traceable to work

Career applications and code expertise are essential for quality welding.