ALUMINUM WELDING


 

GENERAL REQUIREMENTS

 

The welding qualification requirements for fabrication and/or repair of any aluminum sign support structures for highway signs, light poles and traffic signals shall be in accordance with the requirements of the Structural Welding Code – Aluminum  AWS D1.2/D1.2M: 2003, Aluminum Welding Code for Class III Structures and the requirements of Article 2423 of the standard specifications.

 

WELDING PROCESS

 

All welding shall be done by the following process:

       GMAW - Gas Metal Arc Welding

       Other processes may be approved by the Engineer.

 

BASE METAL

 

Base Metal shall conform to ASTM B221, Alloy Group 6061-T6.

 

PROCEDURE QUALIFICATION

 

A Welding Procedure Specification (WPS) shall be required and shall be submitted for approval. WPS shall be prepared in accordance with Section 3 and Annex E of the AWS D1.2 Structural Welding Code.

 

Qualification of the WPS shall be in accordance with Section 3, Part C using the Base Metal, Procedure Qualification Record (PQR), joint preparation, surface preparation, cleaning and limiting variables from Part C, Section 3.14 of the AWS D1.2 Structural Welding Code.

 

ELECTRODES

 

Electrodes shall be of the type specified on the plans or in the AWS D1.2/D1.2M: 2003 as listed in Table 4.2. Certificate of Conformation shall be required and shall be submitted for review and verification.

 

ACCEPTANCE CRITERIA – GROOVE WELDS PLATE & PIPE (AWS D1.2, 3.6.2)

 

The visual examination of the test weldment shall satisfy the following acceptance criteria:

  1. Both the face and the root surfaces shall be free of cracks.
  2. All craters shall be filled to the full cross section of the weld.
  3. The edges of the weld shall blend smoothly with the base metal.
  4. Underfill shall not exceed 0.01”
  5. The root shall show:
    1. Complete fusion for CJP groove welds.
    2. Penetration equal to or greater than the weld size specified for PJP groove welds.
  6. The maximum melt through on groove welds in pipe or in tubing shall not exceed 1/8” (3 mm).
  7. The root cavity shall not exceed 1/16”.
  8. Total weld thickness shall be equal to or greater than the thickness of the base metal but the weld reinforcement shall not exceed the following values:

 

Thickness

Maximum Reinforcement

inch

inch

t 3/8

3/32

3/8 < t 3/4

1/8

t > 3/4

3/16

note: The above indicated values for a given plate thickness joint welded from both sides.

 

 

Thickness

Maximum Reinforcement

inch

inch

t 1/4

3/23

1/4 < t 1/2

1/8

1/2 < t 1

5/32

t > 1

3/16

note: The above indicated values for a given plate thickness joint welded from one side.

 

The tensile and yield strength for temper T6, Alloy 6061 shall be as follows: 38 Ksi (Tensile),

 

When fracture occurs in the weld metal, a minus 5% tolerance shall be allowed, if fracture occurs outside the weld metal.

 

ACCEPTANCE CRITERIA – FILLET WELDS FOR PLATE AND PIPE (AWS D1.2, 3.6.3)

 

The visual examination of the test weldment shall satisfy the following acceptance criteria:

  1. Surface of the welds shall be free from any cracks.
  2. All craters shall be filled to the full cross section of the weld.
  3. The edges of the weld shall blend smoothly with the base metal.
  4. Underfill shall not exceed 0.01”.
  5. The weld shall exhibit complete fusion in the root and to the base metal by the macroetech test.
  6. The leg length shall meet the requirements of the WPS.
  7. Root surface concavity (suck-back) shall not exceed 1/32”.

 

GROOVE WELDS – PLATE, PIPE AND CASTINGS

 

 

POSITION AND TESTS FOR PROCEDURE WELDS

 

Each WPS shall be qualified by positioning and welding test plates as follows:

Note: These positions are classified as (1) Flat, (2) Horizontal, (3) Vertical, or (4) Overhead

Note:   Plate – Groove – 1G (Flat), 2G (Horizontal), 3G (Vertical), 4G (Overhead)

            Plate – Fillet – 1F (Flat) 2F (Horizontal), 3F (Vertical), 4F (Overhead)

Pipe – Groove – 1G (Horizontal Rotated), 2G (Vertical Fixed), 5G (Horizontal Fixed), 6G (Inclined Fixed)

Pipe – Fillet – 1F (Inclined Rotated), 2F (Vertical Fixed), 2FR (Horizontal Rotated), 4F (Overhead Fixed), 5F (Horizontal Fixed)


 

 


WELDER PERFORMANCE

 

 

LIMITATION OF VARIBLE

 

 

FILLET WELD QUALIFICATION

 

Fillet welds between parts having dihedral angle of less than 75 degrees, the welder shall be required to weld a groove weld test plate. Parts having a dihedral angle of 75 degree to 135 degrees, shall be required to weld a fillet weld test plate.

 


 

Performance Accepting Criteria for Groove welds:

 

Visual examination shall be required for appearance and dimensions shall be in accordance with Part B, Section 3.6.3

 

The guided bend surface of the weld and the heat affected zone shall have no discontinuities exceeding the following dimensions:

a.     1/8” measured in any direction

b.     3/8” for the sum of all the discontinuities exceeding 1/32”, but less than or equal to 1/8” for 1 ½” wide specimens.

c.      Ό” maximum for corner cracks, except when this crack has resulted from a visible inclusion or other fusion type of discontinuities, then 1/8” maximum shall apply.

 

Fillet Welds Fracture Test Requirements:

 

The 6 inch performance specimen, center section shall be examined visually on the broken surface.  In order to pass, it must show complete fusion to the root and have no inclusion or porosity larger than 3/32” in the greatest dimension. The sum of greatest dimensions of all inclusions and porosity combined shall not exceed Ύ” in the 6” length.

 

Note:  The macroetch specimen for the fillet weld test (option #1) shall show complete penetration to the root of the joint.