716WELDING OF

New Hampshire Department of Transportation Standard Specifications – 2016

ALUMINUM ALLOYS FOR HIGHWAY STRUCTURES General

1.1Description. These specifications apply to the welding of aluminum alloys used in bridge railing, structural supports for

highway signs, luminaires, traffic signals, and the like.

1.2Specifications.

1.2.1 The welding terms used in these specifications shall be interpreted in accordance with the definitions given in the latest edition of Welding Terms and Definitions, ANSI/AWS A3.0. 1.2.2 The welding symbols used on the plans will be thoses hown in the latest edition of Symbols for Welding, Brazing and Nondestructive Examination, ANSI/AWS A2.4. Special conditions will be fully explained by added notes or details. 1.2.3 The welding of aluminum bridge railing shall conform to Section 10 of the ANSI/AWS D1.2 “ Structural Welding Code – Aluminum” including Part E “ Workmanship Class II Structures ”. The fabrication and erection of bridge railing shall conform to Section 6 of the Specifications for Aluminum Structures, published by the Aluminum A ssociation. 1.2.4 The welding of aluminum sign supports, luminaires, and traffic signals shall conform to Section 10 of the ANSI/AWS D1.2 “ Structural Welding Code – Aluminum” including Part D “ Workmanship Class I Structures”. The fabrication and erection of aluminum sign supports, luminaires, and traffic signals shall conform to the requirements of the AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals. Special consideration may be given to certain support structures, which may be fabricated according to the provisions of 1.2.3. Base Metals

2.1The aluminum alloys to be welded under these specifications may be any of the following alloy designations:

Wrought non-heat-treatable alloys Alloy 3003 Alloy 3004 Alloy 5052 Alloy 5083 Alloy 5086 Alloy 5456 Wrought heat-treatable alloys Alloy 6061 Alloy 6063 Cast heat-treatable alloy Alloy 356.0

2.2Material used for permanent backing shall be at least equivalent in weldability to the base metal being welded .

Welding Processes.

3.1These specifications include provisions for welding by the gas metal -arc process and the gas tungsten -arc process. Other

processes may not be used except as permitted. Filler Metal.

4.1Bare wire electrodes for use with the gas metal -arc process and welding rods for use with the gas tungsten -arc process shall

conform to the requirements of the latest edition of Specification for Bare Aluminum and Aluminum Alloy, Welding Electrodes and Rods, ANSI/AWS A5.10.

4.2Tungsten electrodes for the gas tungsten-arc process shall conform to the requirements of the latest edition of Specification

for Tungsten and Tungsten Alloy Electrodes for Arc Welding, ANSI/AWS A5.12.

4.3Filler metals to be used with particular base metals shall be as shown in Table 1. Other filler metals may be used as approved.

New Hampshire Department of Transportation Standard Specifications – 2016 Table 1 - Filler Metal Guide for Gas Shielded Arc Welding Base Metals Filler Metal 3003 to 3003 ER1100 3004 to 3004 ER4043 5052 to 5052 ER5654* 5083 to 5083 ER5183* 5086 to 5086 ER5356* 5456 to 5456 ER5556* 6061 to 6061 ER4043* 6063 to 6063 ER5356* 356.0 to 6061 ER4043 356.0 to 6063 ER4043 * ER5183, ER5356, and ER5556 may be used interchangeably for these base metals.

4.4Filler metals shall be kept covered and stored in a dry place at relatively uniform temperatures. Original rod or wire containers

shall not be opened until ready for use. Rod and wire shall be free of moisture, lubricant, or other contaminants. Spools of wire temporarily left unused on the welding machine shall be ke pt covered to avoid contamination by dirt and grease collecting on the wire. If a spool of wire is to be unused for more than a short length of time, the spool shall be returned to the carton, and the carton shall be tightly resealed. Shielding Gases.

5.1Shielding gases shall be welding grade or better.

5.2Shielding gas for gas metal-arc welding shall be argon, helium, or a mixture of the two (at least 50 percent helium).

5.3Shielding gas for gas tungsten-arc welding done with alternating current shall be argon.

5.4Shielding gas for gas tungsten-arc welding done with direct current, straight-polarity, shall be helium.

5.5Hoses used for shielding gases shall be made of synthetic rubber or plastic. Natural rubber hoses shall not be used. Hoses

that have been previously used for acetylene or other gases shall not be used. Preparation of Materials.

6.1Joint details shall be in accordance with design requirements and detail drawings. The locations of joints shall not be changed

without approval.

6.2Edge preparation shall be by sawing, machining, clipping, or shearing. Gas tungsten- arc or gas metal arc cutting may also

be used. Cut surfaces shall meet the ANSI surface roughness rating value of 1000. Oxygen cutting shall not be used.

6.3Surfaces and edges to be welded shall be free from fins, tears, and other defects which would adversely affect the quality of

the weld.

6.4Dirt, grease, forming or machining lubricants, or any organic materials shall be removed from the areas to be welded by

cleaning with a suitable solvent or by vapor degreasing.

6.5On all edges and surfaces to be welded, the oxide shall be removed just prior to welding by wire brushing or by other

mechanical methods, such as rubbing with steel wool or abrasive cloth, scraping, filing, rotary planing, or sanding. If wire brushing is used, the brushes shall be made of stainless steel. Hand or power driven wire brushes which have been used on other mater ials shall not be used on aluminum.

6.6Where mechanical methods of oxide removal are found to be inadequate, a standard chemical method shall be used. Welding

shall be done within 24 hours after chemical treatment.

New Hampshire Department of Transportation Standard Specifications – 2016

6.7When gas tungsten-arc welding with direct current, straight polarity, is being used, all edges and surfaces to be welded shall

have the oxide removed by a standard chemical method.

6.8Welding shall not be done on anodically treated aluminum unless the condition is removed from the joint area to be welded.

Welding Procedure.

7.1All butt welds requiring 100 percent penetration, except those produced with the aid of backing, shall have the root of the

initial weld chipped or machined out to sound metal before welding is started from the second side. Butt welds made with the use of backing shall have the weld metal thoroughl y fused with the backing. Where accessible, backing for welds that are subject to computed stress or that are exposed to view on the completed structure, and that are not otherwise parts of the structure, sh all be removed and the joints ground or machined smooth. In tubular members, butt welds subjected to computed stresses shall be made with the aid of permanent backing rings or strips.

7.2The procedure used for production welding of any particular joint shall be the same as used in the procedure qualification for

that joint.

7.3All welding operations, either shop or field, shall be protected from air currents or drafts so as to prevent any loss of gas

shielding during welding. Adequate gas shielding shall be provided to protect the molten metal during solidification.

7.4The work shall be positioned for flat position welding whenever practicable.

7.5In both shop and field, all weld joints shall be dry at the time of welding.

7.6The size of the electrode, voltage, amperage, welding speed, gas or gas m ixture, and gas flow rate shall be suitable for the

thickness of the material, design of joint, welding position, and other circumstances attending the work.

7.7Gas metal-arc welding shall be done with direct current, reverse polarity.

7.8Gas tungsten-arc welding shall be done with alternating current or with direct current, straight polarity.

7.9When the joint to be welded requires specific root penetration, the Contractor shall make a sample joint and a macroetched

cross-section of the weld to demonstrate that the joint welding procedure to be used attains the required root penetration. The sample joint shall have a length of at least 1 ft. ) and shall be welded with the electrode, polarity, amperage, voltage, speed, gas mixture, and gas flow rate that are proposed to be used in production welding. The Engineer, at his discretion, may accept evidence on record in lieu of the preceding test.

7.10Where preheat is needed, the temperature of preheat shall not exceed 350 ºF for heat-treated alloys and 600 ºF for non-heat-

treated alloys. The temperature shall be measured by temperature- indicating crayons or by pyrometric equipment. Heat -treated alloys shall not be held at the maximum preheat temperature or at temperatures near the maximum for more than 3 0 minutes. Weld Quality.

8.1Regardless of the method of inspection, the acceptance or rejection of welds shall be determined by the following conditions:

Aluminum” will not be acceptable.

8.2Undercut shall not be more than 0.01” deep when its direction is transverse to the primary stress in the part that is undercut.

Undercut shall not be more than 1/32” deep when its direction is parallel to the primary stress in the part that is undercut.

8.3No overlap shall be allowed.

8.4All craters shall be filled to the full cross-section of the welds.

8.5Welds having defects greater than the levels of acceptance specified above shall be considered as rejected u nless corrected

in accordance with 716.10. Inspection.

9.1To determine compliance with Section 7, all welds shall be visually inspected, and in addition, all welds subject to computed

stress shall be inspected by the dye penetrant method except as specified in 9.4.

9.2For truss-type highway sign structures, the dye penetrant method shall be used on butt welds in columns and main chord

members, on fillet welds connecting columns to bases and main chord members, including the associated flanges, gussets, or main load carrying brackets or members, and also on fillet welds connecting flanges to the main truss chord members. On pole type and

New Hampshire Department of Transportation Standard Specifications – 2016 common light standards, the dye penetrant method shall be used on butt welds in columns and on fillet welds connecting c olumns to bases.

9.3The dye penetrant tests shall be performed in accordance with the requirements of ASTM E 165, Method B, Procedures B-2

or B-3.

9.4Dye penetrant inspection may be omitted provided that the Inspector examines each layer of weld metal wi th a magnifier of

3X minimum before the next successive layer is deposited. Corrections.

10.1In lieu of rejection of an entire piece or member containing welding that is unacceptable, the corrective measures listed below

may be permitted by the Engineer, whose approval shall be obtained prior to making each repair.

10.2Defective welds shall be corrected by removing and replacing the entire weld, or as follows:

means, then remove the crack throughout its length and depth, and rewelded .

10.3The defective areas shall be removed by chipping or machining. Oxygen cutting shall not be used. Before rewelding, the

joint shall be inspected to ensure that all of the defective weld has been removed. If dye penetrant has been used to inspect the weld, all traces of penetrant solutions shall be removed with solvent, water, heat, or other suitable means before rewelding. Qualification of Procedures, Welders, and Welding Operators.

11.1Joint welding procedures that are to be employed in executing Contract work under these specifications shall be previously

qualified by tests presc ribed in Section 5 of the ANSI/AWS D1.2 “ Structural Welding Code – Aluminum”. The qualifications shall be at the expense of the Contractor. At the Engineer’s discretion, evidence may be accepted of previous qualification of the joint welding procedures to be employed. The fabrication shop shall maintain a file of certificates of qualification for its welders and welding operators and make th e file available to the Engineer upon request. Each certificate of qualification shall state the name of the welder or welding operator, the name and title of the person who conducted the examination, the kind of specimens, the position of the welds, the results of the tests, and the date of the examination. Upon request, the fabrication shop shall submit a letter of compliance to the Engineer listing by name all welders and welding operators employed on the fabrication of material for the project. The letter shall certify that these welders or welding op erators have been prequalified and that they have been continuously engaged in gas metal -arc or gas tungsten-arc welding with no lapse in such employment in excess of six months since being prequalified.

11.2All welders and welding operators to be employed under these specifications shall be previously qualified by tests as

prescribed in Section 5 of the ANSI/AWS D1.2 “ Structural Welding Code – Aluminum”. At the Engineer’s discretion, evidence may be accepted of previous qualification of the welders and welding operators to be employed. The same process and type of equipment that are required for execution of the construction work shall be used in qualifying welders and welding operators.

New Hampshire Department of Transportation Standard Specifications – 2016

Description. Retroreflective sheeting shall consist of a retroreflective microprismatic system having a smooth outer surface.

When adhesive backing is used, the sheeting shall have a pre- coated adhesive on the back side protected by an easily removable liner.

Detail Requirements. Reflective sheeting and overlay film shall be selected from the Qualified Products List (QPL).

Reflective sheeting and overlay film products will be included on the QPL after the Department determines conformance to the specifications and the manufacturer has supplied written information indicating conformance to the warranty requirements as noted under the acceptance criteria of the QPL. Determination of conformance will include, but will not be limited to, the evaluation of test data from AASHTO’s National Transportation Product Evaluation Program (NTPEP) or other Department approved facilities except when otherwise indicated. Retroreflective sheeting shall conform to the requirements of ASTM D 4956 including supplementary requirement and any exceptions and/or additions included herein.

Retroreflective sheeting used on all Type A, AA, B, BB, C and CC signs, shall conform to the requirements of Type IV

material except those specifically indicated otherwise herein. 3.1.1 Retroreflective sheeting for the copy, border, and shields on overhead structures including bridge mounts shall conform to Type IV, VIII, IX, or XI material unless otherwise noted in the plans.

3.2Blank.

3.3Fluorescent Retroreflective sheeting for the following signs shall conform to Type VIII, IX, or XI material.

• Fluorescent yellow sheeting shall be used for all Horizontal Alignment Warning signs as defined by the MUTCD. • Fluorescent orange sheeting shall be used on permanent orange construction and maintenance activity signs as prescribed under Section 619.

3.5Overlay films shall consist of highly durable, transparent, acrylic colored films coated with a transparent pressure sensitiv e

adhesive protected by a removable translucent, synthetic, release liner. 3.5.1 Test Methods: Testing conditions and panels for the following test shall follow ASTM D 4956. 3.5.1.1 Color Requirements. When electronic cuttable film is applied to retroreflective sheeting, the resulting color of the composite sheeting will conform to Federal Specification FP-92, Section 718.01 and ASTM D 4956. 3.5.1.2 Coefficient of Retroreflection, R A. When transparent colored electronic cuttable film is applied per the manufacturer’s recommendations over white retroreflective sheeting, the colored compo site will conform to the percentage specified in Table 1. The coefficient of retroreflection shall be determined in accordance with ASTM E -810. Table 1 Coefficient of Retroreflection RA * for applied Overlay Films (expressed as % of white retroreflective sheeting background ) Transparent Color Minimum Maximum Green 13.0 20 Blue 6.5 20 Red 14 24 Yellow 60.0 80 Orange 30 - Brown 5.0 - RA (cd/lux/m2) measurements shall be made at 0.2º observation angle, - 4º entrance angle, and 0º rotation, per ASTM E - 810. The ratio of the R A (color) to R A (white) shall be calculated and converted to a percentage to determine the film transmission values.