Procedure to Repair the Rear Frame on 14M Motor Graders{7050, 7051} Caterpillar

Procedure to Repair the Rear Frame on 14M Motor Graders{7050, 7051}

Usage:

14M B9J

Motor Grader:: 14M (S/N: B9J1-1450; R9J1-540)

Introduction

This Special Instruction provides the information and the procedures that are necessary in order to repair cracks in the top plate of the articulation hitch on the reare frame of 14M Motor Graders.

Important Safety Information

Do not perform any procedure in this special instruction until you have read this special instruction and you understand this information. Use only proper tools and observe all precautions that pertain to the use of those tools. Failure to follow these procedures can result in personal injury. The following procedures should also be observed.

Work safely. Most accidents that involve product operation, maintenance, and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs.

A person must be alert to potential hazards. This person should also have the necessary training, skills, and tools in order to perform these functions properly.

Safety precautions and warnings are provided in this instruction and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard.

Therefore, the warnings in this publication and the warnings that are on the product are not all inclusive.

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Personal injury or death can result from machine movement.

Place blocks in front of and behind the wheels to make sure the machine does not move while the parking brakes are disengaged.

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Personal injury or death can result from fumes, gases and ultraviolet rays from the weld arc.
Welding can cause fumes, burn skin and produce ultraviolet rays.
Keep your head out of the fumes. Use ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing area. Wear eye, ear and body protection before working.
Protect yourself and others; read and understand this warning. Fumes and gases can be dangerous to your health. Ultraviolet rays from the weld arc can injure eyes and burn skin. Electric shock can cause death.
Read and understand the manufacturer's instructions and your employer's safety practices. Do not touch live electrical parts.
See "American National Standard Z49.1, Safety in Welding and Cutting" published by the American Welding Society.
American Welding Society
2501 N.W. 7th Street
Miami, Florida 33125

See "OSHA Safety and Health Standards, 29 CFR 1910", available from U.S. Department of Labor.
U.S. Department of Labor
Washington, D.C. 20210

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Personal injury can result from flame cutting or welding on painted areas.
The effect of gasses from burned paint is a hazard to the person doing the cutting or welding.

Do not flame cut or weld on painted areas.

References

ReferenceRefer to Special Instructions, REHS1841, "General Welding Procedures" for additional welding information.

ReferenceRefer to General Service Information, SEBD0512, "Service Welding Guide" for additional welding information.

General Repair Of Mild Steel Plate

The following procedure is written in order to perform general repair welding to cracks in mild steel plate. This procedure contains separate sections for the following repairs.

"Repair welding a through crack with an open root and access to one side of the crack."
"Repair welding a through crack with access to one side and using a permanent backup strip."
"Repair welding a through crack with access to both sides of the crack."
"Repair welding a crack that is not full depth."

Welder Qualification and Safety

All welders must be qualified for the material, the process, and the welding position in accordance with one of the following guides.

Caterpillar weld specification
A recognized national specification that is applicable to the product that is being manufactured
A recognized international standard that is applicable to the product that is being manufactured

Personal protection equipment should be worn. The personal protection equipment that is being used must meet the requirements of local safety policies. The welder must be familiar with both the air carbon arc gouging (CAC-A) and grinding processes. The welder must also be familiar with safety procedures for these processes.

Cleaning

Use a grinder, a sander, or a rotary steel wire wheel in order to clean the area around the crack. Clean the area in order to remove oil, grease, paint, and other contaminants. The area that is cleaned should extend 152 mm (6 inch) beyond the crack on all sides. Care should be taken in order to ensure that minimal thickness of base material is removed.

Preheating

The area that is surrounding the repair should be preheated to a temperature of 200° C (392° F) in order to remove any grease. Preheating will also remove any oils that may have been absorbed into the crack during service.

The amount of preheat that is required for any application depends on the following factors.

Chemistry of the base metals
Thickness of the plates
The restraint and the rigidity of the members
The heat input of the process

No guide can be applicable because of various factors of rigidity and restraint in assemblies. Therefore, these recommendations are posed as minimum preheat requirements and the recommendations should be accepted. Quenched steel and tempered steel may be damaged if the preheat temperature is too high. Generally, as the carbon equivalency increases, there is greater need for the following.

Preheating
Maintaining an interpass temperature
Using low hydrogen electrodes

Use the carbon equivalence formula in order to determine the carbon equivalency (Ceq). Refer to Illustration 1 for the carbon equivalence formula.

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Illustration 1	g01833303
(C) Carbon (Mn) Manganese (Ni) Nickel (Mo) Molybdenum (Cr) Chromium (Cu) Copper

The formula in Illustration 1 is only valid when the alloy content is less than the following values.

0.50% C
1.60% Mn
3.5% Ni
0.60% Mo
1.00% Cr
1.00% Cu

The method for preheat depends on the plate thickness, size of weld, and the equipment that is available for heating. A furnace is the most satisfactory method for preheating small assemblies. Another common method for preheating is the oxyacetylene torch. On large weldments, banks of heating torches or electrical strip heaters may be used. The Cooperheat system is an example of an electrical strip heater. Refer to Illustration 2.

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Illustration 2	g01833494
Typical Cooperheat heating unit

The minimum preheat temperature should be established at a distance that is at least equal to the thickness of the thickest member, but not less than 75 mm (3.0 inch) in all directions from the point of welding. Heat the side that is opposite of the weld in order to ensure that the area that is surrounding the joint is fully heated. Measure the surface temperature that is next to the joint. If the temperature can only be checked on the side that was heated, the heat source should be removed and the temperature should be allowed to equalize. Allow one minute for each 25 mm (1.0 inch) of material thickness.

Finally, the interpass temperature should be checked in order to verify that the minimum preheat temperature has been maintained prior to initiating the arc for each pass. The preheat temperature and the interpass temperature can be measured with temperature indicating crayons, infrared thermometers, or thermocouples. Refer to Illustration 3, Illustration 4, and Illustration 5.

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Illustration 3	g01833495
Temperature indicating crayons

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Illustration 4	g01833497
Infrared thermometer

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Illustration 5	g01833499
Thermocouple (2) Type K thermocouple wires

Removing the Weld Defect

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Illustration 6	g01833756
(1) Crack (A) Section thickness

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Illustration 7	g01833776
(1) Crack (3) Gouging depth (A) Section thickness (C) 4 mm (0.16 inch)

Use air arc gouging in order to evacuate the crack. Do not gouge the full thickness of the plate. Refer to Illustration 6 and Illustration 7 for guidance on the gouging profile and depth.
Note: Use a depth gauge or a steel ruler in order to measure the gouging depth. Maintain a 4 mm (0.16 inch) minimum of material thickness at the root of the gouge.

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Illustration 8	g01833855
(1) Crack

Illustration 8 is a pictorial view of the partially ground area around the repair prior to the final removal of the crack.

Go to section ""Repair Welding A Through Crack With An Open Root And Access To One Side Of The Crack" " when the crack extends through the full thickness of the plate with access to one side of the crack.

Go to section ""Repair Welding A Through Crack With Access To One Side And Using A Permanent Backup Strip" " when the crack extends through the full thickness of the plate with access to one side of the crack.

Go to section ""Repair Welding A Through Crack With Access To Both Sides Of The Crack" " when the crack extends through the full thickness of the plate with access to both sides of the crack.

Go to section ""Repair Welding A Crack That Is Not A Through Crack" " when the crack does not extend through the full thickness of the plate.

Repair Welding A Through Crack With An Open Root And Access To One Side Of The Crack

This section assumes that the following steps have been performed.

Cleaning
Preheat
Removal of the defect in the weld

Removal of the Weld Defect, Inspection, Verification, and Preparing the Joint

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Illustration 9	g01833913
Final crack removal with a cutoff wheel (A) Section thickness (B) 4 mm (0.16 inch) minimum material thickness at the root (C) 4 mm (0.16 inch) root opening (1) Crack (2) 3 mm (1/8 inch) cut-off wheel (3) Gouging depth

Use a 3 mm (0.125 inch) thick abrasive cutoff wheel in order to remove the final portions of the crack. This will produce a consistent root opening.
Most cracks do not propagate in a straight line. When a crack does not propagate in a straight line, the root opening will be larger than the thickness of the cut-off wheel. The root opening should be approximately 4 mm (0.16 inch) wide. However, conditions may arise when this will be slightly larger. Refer to Illustration 9.

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Illustration 10	g01834053
Cross section view of anticipated grinding (A) Section thickness (D) 2 mm (0.08 inch) minimum material thickness at the root (C) 4 mm (0.16 inch) root opening (3) Gouging depth (4) Prepared surface after final grind

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Illustration 11	g01834054
Cross section view of a prepared joint (C) 4 mm (0.16 inch) root opening (D) 2 mm (0.08 inch) minimum material thickness at the root (E) 70 Degree (F) 35 Degree (4) Prepared surface after final grind

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Illustration 12	g01834055
Longitudinal view of prepared joint (A) Section thickness (D) 2 mm (0.08 inch) minimum material thickness at the root (G) 45 Degree

Use a grinder or a sander in order to achieve the desired configuration of the weld joint. Refer to Illustration 10, Illustration 11, and Illustration 12.

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Illustration 13	g01834056
Prepared weld joint

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Illustration 14	g01834057
Close up view of a properly prepared weld joint

Illustration 13 and Illustration 14 are pictorial views of a properly prepared weld joint.

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Illustration 15	g01834873

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Illustration 16	g01834876

A 152 mm (6 inch) electric grinder with a 0.64 mm (0.025 inch) cutting wheel and a 178 mm (7 inch) pneumatic grinder with a 36 grit sanding pad are the recommended tools in order to prepare a weld joint. Illustration 15 and Illustration 16 are pictorial views of a cutting disk and an electric grinder.
Note: A reciprocating saw with a metal cutting blade may be used on a crack that has branched out at several angles. Some cases will require the use of a reciprocating saw and a cutting wheel.
Note: Tip: Leave a larger root face 5 ± 0.5 mm (0.12 ± 0.02 inch) with larger root openings 2.5 mm to 3 mm (0.10 inch to 0.12 inch).

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Illustration 17	g01834879

Visually verify that the entire crack has been removed. Use magnetic particle inspection (MT) or dye penetrant testing (PT) after the visual test (VT) in order to ensure that the entire crack has been removed. Refer to Illustration 17 for a pictorial view of a portable magnetic yoke that is used in the MT.
Note: MT inspection may be completed while the part is at an elevated temperature. However, PT requires the part to be at room temperature or near room temperature. In order to reduce the rework time, use magnetic particle inspection with dry, visible, magnetic particles with a color that enhances the component for inspections of parts that are in process.

Ensure that the area is free of debris, rough edges, and pockets that will trap magnetic particles in order to eliminate false indications. Follow Step 6.a through Step 6.e in order to verify that the entire crack has been removed.
1. Place one leg of the yoke on each side of the excavated crack. Obtain good contact with the steel component.
1. During the energizing of the yoke, gently apply dry magnetic particles with a bulb type applicator.
1. Remove the yoke from the area and visually inspect the area for indications of particles.
1. Apply additional particles to the area as you energize the yoke along the length of the evacuation. Energize the yoke along the length of the excavation in increments that are equal to the distance between the legs of the yoke. Do not wash away the areas that were previously magnetized.
1. Continue to excavate the crack and grind the profile until the crack has been removed.

Note: The entire crack must be removed. The component may be cooled down and a dye penetrant may be used if there is any question.

Note: Obtaining a quality open root weld may be difficult if the root opening is larger than 5.5 mm (0.22 inch). Go to Section ""Repair Welding A Through Crack With Access To One Side And Using A Permanent Backup Strip" " or Section ""Repair Welding A Through Crack With Access To Both Sides Of The Crack" " for a root opening that is larger than 5.5 mm (0.22 inch).

Welding the Root Pass

The surface tension transfer (STT) was developed by the Lincoln Electric Company for open root welding on pipe and plates. Surface tension transfer (STT) is achieved through inverter technology and specially designed waveforms. This allows the operator to control the heat input and the weld puddle at a relatively low current. Refer to Illustration 18 and Illustration 19 for a pictorial view of a typical Invertec STT II power supply and a typical wire feeder at Caterpillar.

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Illustration 18	g01834895

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Illustration 19	g01834897

Refer to Table 1 for the STT welding parameters that will provide the necessary heat input and the arc characteristics for a good sidewall fusion with a minimal root reinforcement in an open root joint. Refer to Table 2 for the electrode requirements.

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Table 1
Welding Parameters
Root Opening	3 - 4 mm (0.12 - 0.16 inch)	4.5 - 5.5 mm (0.18 - 0.22 inch)
Peak current	280 amp	250 amp
Background current	60 amp	50 amp
Wire feed speed	4318 mm (170 inch) per minute	3810 mm (150 inch) per minute
Tailout	5	5
Hot start	5	5

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Table 2
Electrode Requirements
Electrode	ER70S	0.90 mm (0.035 inch) diameter
Shielding Gas	75/25 (Ar/Co2)	40 Cubic feet per hour (CFH)
Electrical Stickout		6.4 to 9.5 mm (0.25 to 0.375 inch)

2500 mm (inch)

The progression of welding is a vertical down weld. Use a 25 degree to 45 degree travel angle with a slight weave when necessary.

Welding in the flat position can be accomplished with either the push or the pull welding technique. Use a 5 degree to 15 degree travel angle with a slight weave when necessary.

Note: Ensure that the voltage sensing lead is attached close to the area around the repair prior to welding.

Note: The root pass of the weld should not be interrupted. Use a cutoff wheel in order to taper the end (crater) of the weld if the weld is interrupted. This will ensure a proper tie-in weld.

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Illustration 20	g01835056
STT open root pass

Illustration 20 is a pictorial view of an STT root pass that was welded in the vertical position and using the recommendations that are listed above.

Welding the Fill Passes

The first fill pass is often referred to as the hot pass or first fill layer. The first fill pass should consist of two passes that are placed at either weld toe of the root pass. Do not penetrate through the initial root pass. Refer to Illustration 21 for the location of the first fill pass and subsequent passes. The quantity of subsequent passes will depend on the thickness of the plate.

The flux core arc welding process (FCAW process) is the preferred process for subsequent fill passes. The gas metal arc welding process (GMAW process) and the shielded metal arc welding process (SMAW process) may also be used. Refer to ""Welding Parameters" " at the end of this publication for proper machine settings.

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Illustration 21	g01835073
Placement of welding passes (5) First fill pass (6) Root pass (7) Second fill pass

Note: Slag must be removed after each weld pass. Visually inspect each pass for defects prior to completing the next weld pass.

Note: STT welds in the vertical position are performed in a downhill progression. FCAW, GMAW, and SMAW process welds in the vertical position must be welded in an uphill progression.

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Illustration 22	g01835136
Placement of fill passes over an STT open root pass.

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Illustration 23	g01835137
Completed repair

Illustration 22 and Illustration 23 are pictorial views of an actual repair that shows the first fill layer and the completed joint.

Inspection

Inspect the resulting repair per applicable quality standard.

Grinding to Surface Profile

Grind any excess weld metal to the contour of the surface profile if grinding is required. Do not reduce the thickness of the material less than the adjacent area. Use an abrasive disc with a grit that will result in a smooth texture for final grinding.

Repair Welding A Through Crack With Access To One Side And Using A Permanent Backup Strip

This section assumes that the following steps have been performed.

Cleaning
Preheat
Removal of the defect in the weld

This section also assumes that the evacuation of the through crack has resulted in a root opening that will not permit a good quality open root weld and there is only access to one side of the crack.

Removal of the Weld Defect, Inspection, Verification, and Preparing the Joint

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Illustration 24	g01835155
Crack that has been evacuated (1) Crack

Illustration 24 is a pictorial view of an evacuated crack prior to final grinding of the profile.

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Illustration 25	g01835156
Prepared joint

Illustration 25 is a pictorial view of a prepared joint after grinding the profile. Due to the nature and the path of this particular crack, the root opening varied from 8 to 14 mm (0.32 to 0.55 inch). Therefore, open root welding is not feasible and a permanent backup strip must be used.

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Illustration 26	g01835256
Cross section view of anticipated grinding (A) Section thickness (B) 0.0 to 2 mm (0.0 to 0.08 inch) material thickness at the root (C) 6 mm (0.25 inch) minimum root opening (2) Gouging depth (3) Prepared surface after final grind

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Illustration 27	g01835257
Cross section view of prepared joint (B) 0.0 to 2 mm (0.0 to 0.08 inch) material thickness at the root (C) 6 mm (0.25 inch) minimum root opening (D) 70 Degree included angle (E) 30 Degree (3) Prepared surface after final grind

Refer to Illustration 26 and Illustration 27 for the approximate dimensions of a prepared joint that requires a permanent backup strip.

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Illustration 28	g01834873

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Illustration 29	g01834876

A 152 mm (6 inch) electric grinder with a 0.64 mm (0.025 inch) cutting wheel and a 178 mm (7 inch) pneumatic grinder with a 36 grit sanding pad are the recommended tools in order to prepare a weld joint. Illustration 28 and Illustration 29 are pictorial views of a cutting disk and an electric grinder.

Note: A reciprocating saw with a metal cutting blade may be used on a crack that has branched out at several angles. Some cases will require the use of a reciprocating saw and a cutting wheel.

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Illustration 30	g01834879

Visually verify that the entire crack has been removed. Use magnetic particle inspection (MT) or dye penetrant testing (PT) after the visual test (VT) in order to ensure that the entire crack has been removed. Refer to Illustration 30 for a pictorial view of a portable magnetic yoke that is used in the MT.

Note: MT inspection may be completed while the part is at an elevated temperature. However, PT requires the part to be at room temperature or near room temperature. In order to reduce the rework time, use magnetic particle inspection with dry, visible, magnetic particles with a color that enhances the component for inspections of parts that are in process.

Ensure that the area is free of debris, rough edges, and pockets that will trap magnetic particles in order to eliminate false indications. Follow Step 1 through Step 5 in order to verify that the entire crack has been removed.

Place one leg of the yoke on each side of the excavated crack. Obtain good contact with the steel component.

During the energizing of the yoke, gently apply dry magnetic particles with a bulb type applicator.

Remove the yoke from the area and visually inspect the area for indications of particles.

Apply additional particles to the area as you energize the yoke along the length of the evacuation. Energize the yoke along the length of the excavation in increments that are equal to the distance between the legs of the yoke. Do not wash away the areas that were previously magnetized.

Continue to excavate the crack and grind the profile until the crack has been removed.

Note: The entire crack must be removed. The component may be cooled down and a dye penetrant may be used if there is any question.

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Illustration 31	g01865613
Placement of backup strip (4) TIG electrode (5) Backup strip

The dimensions of the permanent steel backup strip will depend on the configuration of the excavation. Every attempt should be made in order to accommodate a single, continuous strip that runs the full length of the weld joint.

Illustration 31 is a pictorial view of a steel backup strip ASTME A36 that was inserted through the root opening. The backup strip is 6.4 mm (0.25 inch) thick and 38 mm (1.50 inch) wide. The backup strip was then lifted against the back side of the plate. A 2.4 mm (0.094 inch) TIG electrode was welded to the backup strip in order to position the backup strip.

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Illustration 32	g01865593
Placement of backup strip (D) 70 Degree included angle (F) 3 mm (0.12 inch) minimum (5) Backup strip

The thickness of the backup strip should be kept to a minimum in order to assist with the insertion of the backup strip. A thicker backup strip will be more difficult inserting through the gap into an enclosed cavity. A 6.4 mm (0.25 inch) thick backup strip is the minimum thickness that should be used. A 6.4 mm (0.25 inch) thick backup strip is sufficient to prevent a burn through with the specified welding parameters. Select a backup strip that will ensure a 3 mm (0.12 inch) overlap of the backup strip on both sides along the entire length of the joint. Refer to Illustration 32. The inside profile of the plate may not be flat. However, make every attempt to minimize the gap between the backup strip and the back side of the plate. The gap between the backup strip and the back side of the plate should be 0 mm (0 inch) when it is possible.

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Illustration 33	g01835356
Prepared joint with a permanent backup strip

Tack weld the backup strip in place. Remove the rod that was used to lift the backup strip and grind one half of the thickness from the tack welds prior to finish welding. This will ensure a proper fusion between the tack welds and the fill passes. Illustration 33 is a pictorial view of a weld joint with properly ground tack welds.

Welding the Root Passes and Fill Passes

The flux core arc welding process (FCAW process) is the preferred process for the root passes and subsequent fill passes. The gas metal arc welding process (GMAW process) and the shielded metal arc welding process (SMAW process) may also be used. Refer to ""Welding Parameters" " at the end of this publication for proper machine settings.

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Illustration 34	g01835528
Placement of welding passes (6) First fill pass (7) Root pass (8) Second fill pass

The first fill pass is often referred to as the hot pass or first fill layer. The first fill pass should consist of two passes that are placed at either weld toe of the root pass. Do not penetrate through the permanent backup strip. Refer to Illustration 34 for the location of the first fill pass and subsequent passes. The quantity of subsequent passes will depend on the thickness of the plate.

Note: Welding the root pass with the SST process is not recommended.

Note: Slag must be removed after each weld pass. Visually inspect each pass for defects prior to completing the next weld pass.

Note: STT welds in the vertical position are performed in a downhill progression. FCAW, GMAW, and SMAW process welds in the vertical position must be welded in an uphill progression.

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Illustration 35	g01835544

Illustration 35 is a pictorial view of the results from a repair that followed these guidelines.

Inspection

Inspect the resulting repair per applicable quality standard.

Grinding to Surface Profile

Repair Welding A Through Crack With Access To Both Sides Of The Crack

Cleaning
Preheat
Removal of the defect in the weld

This section also assumes that both sides of the crack are accessible.

Removal Of The Weld Defect And Preparing The Joint On The First Side

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Illustration 36	g01864973
Profile of gouge prior to grinding (1) Crack (2) Gouging depth (A) Section thickness (B) 2 to 4 mm (0.08 to 0.16 inch) after gouging

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Illustration 37	g01864975
Cross section view of anticipated grinding (2) Gouging depth (3) Prepared surface after final grind (A) Section thickness (C) 2 to 4 mm (0.08 to 0.16 inch) after final grind (D) 60 degree included angle (E) 30 degree

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Illustration 38	g01865533
Cross section view of prepared joint on the first side (3) Prepared surface after final grind (A) Section thickness (C) 2 to 4 mm (0.08 to 0.16 inch) after final grind (D) 60 degree included angle (E) 30 degree

Refer to Illustration 36, Illustration 37, and Illustration 38 for the approximate dimensions of a prepared joint with access to both sides of the crack. Use these dimensions in order to prepare the joint for repair.

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Illustration 39	g01834873

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Illustration 40	g01834876

A 152 mm (6 inch) electric grinder with a 0.64 mm (0.025 inch) cutting wheel and a 178 mm (7 inch) pneumatic grinder with a 36 grit sanding pad are the recommended tools in order to prepare a weld joint. Illustration 39 and Illustration 40 are pictorial views of a cutting disk and an electric grinder.

Note: A reciprocating saw with a metal cutting blade may be used on a crack that has branched out at several angles. Some cases will require the use of a reciprocating saw and a cutting wheel.

Welding the Root Passes and Fill Passes On The First Side

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Illustration 41	g01864977
Placement of welding passes on the first side (4) First fill pass (5) Root pass (6) Second fill pass

The first fill pass is often referred to as the hot pass or first fill layer. The first fill pass should consist of two passes that are placed at either weld toe of the root pass. Do not penetrate through the initial root pass.Refer to Illustration 41 for the location of the first fill pass and subsequent passes. The quantity of subsequent passes will depend on the thickness of the plate.

Note: Welding the root pass with the SST process is not recommended.

Note: Slag must be removed after each weld pass. Visually inspect each pass for defects prior to completing the next weld pass.

Note: STT welds in the vertical position are performed in a downhill progression. FCAW, GMAW, and SMAW process welds in the vertical position must be welded in an uphill progression.

Removal of the Weld Defect, Inspection, Verification, and Preparing the Joint On The Back Side

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Illustration 42	g01864978
Profile of gouge prior to grinding on the back side (7) Gouge on back side

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Illustration 43	g01864979
Cross section view of anticipated grinding on the back side (8) Final grind prior to welding (F) 30 degree (G) 60 degree included angle

Use air arc gouging in order to evacuate the crack. Make sure that the gouge cuts into the root pass from the first side. Refer to Illustration 42 for a profile of the gouge and the depth of the gouge prior to the final grind. Refer to Illustration 43 for a profile of the final grind.

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Illustration 44	g01834879

Visually verify that the entire crack has been removed. Use magnetic particle inspection (MT) or dye penetrant testing (PT) after the visual test (VT) in order to ensure that the entire crack has been removed. Refer to Illustration 44 for a pictorial view of a portable magnetic yoke that is used in the MT.

Place one leg of the yoke on each side of the excavated crack. Obtain good contact with the steel component.

During the energizing of the yoke, gently apply dry magnetic particles with a bulb type applicator.

Remove the yoke from the area and visually inspect the area for indications of particles.

Apply additional particles to the area as you energize the yoke along the length of the evacuation. Energize the yoke along the length of the excavation in increments that are equal to the distance between the legs of the yoke. Do not wash away the areas that were previously magnetized.

Continue to excavate the crack and grind the profile until the crack has been removed.

Note: The entire crack must be removed. The component may be cooled down and a dye penetrant may be used if there is any question.

Welding the Root Passes and Fill Passes On The Back Side

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Illustration 45	g01864980
Placement of weld passes on the back side (9) Root pass (10) First fill pass (11) Second fill pass

The first fill pass is often referred to as the hot pass or first fill layer. The first fill pass should consist of two passes that are placed at either weld toe of the root pass. Do not penetrate through the initial root pass. Refer to Illustration 45 for the location of the first fill pass and subsequent passes. The quantity of subsequent passes will depend on the depth of the gouge on the back side.

Note: Welding the root pass with the SST process is not recommended.

Note: Slag must be removed after each weld pass. Visually inspect each pass for defects prior to completing the next weld pass.

Note: STT welds in the vertical position are performed in a downhill progression. FCAW, GMAW, and SMAW process welds in the vertical position must be welded in an uphill progression.

Inspection

Inspect the resulting repair per applicable quality standard.

Grinding to Surface Profile

Repair Welding A Crack That Is Not A Through Crack

This section assumes that the following steps have been performed.

Cleaning
Preheat
Removal of the defect in the weld

This section also assumes that the crack has been removed and the evacuation of the crack has resulted in a root opening that does not extend through the thickness of the plate.

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Illustration 46	g01835553
Profile of gouge prior to grinding (A) Section thickness (1) Profile of gouged surface

The evacuation should appear similar to the one that is shown in Illustration 46. However, the depth of the crack may vary.

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Illustration 47	g01835560
Cross section view of anticipated grinding (A) Section thickness (1) Profile of gouged surface (2) Prepared surface after final grind

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Illustration 48	g01835561
Cross section view of prepared joint (A) Section thickness (B) 70 Degree (C) 35 Degree (4) Slight radius

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Illustration 49	g01835562
Longitudinal view of the prepared joint (A) Section thickness (D) 45 Degree

Finish grind the gouged area to a 70 degree included angle. Leave a slight radius at the root. Refer to Illustration 47, Illustration 48, and Illustration 49.

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Illustration 50	g01835653
Prepared weld joint

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Illustration 51	g01835655
Close up view of a properly prepared weld joint

Illustration 50 and Illustration 51 are pictorial views of a properly prepared crack that was not a through crack.

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Illustration 52	g01834873

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Illustration 53	g01834876

A 152 mm (6 inch) electric grinder with a 0.64 mm (0.025 inch) cutting wheel and a 178 mm (7 inch) pneumatic grinder with a 36 grit sanding pad are the recommended tools in order to prepare a weld joint. Illustration 52 and Illustration 53 are pictorial views of a cutting disk and an electric grinder.

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Illustration 54	g01834879

Visually verify that the entire crack has been removed. Use magnetic particle inspection (MT) or dye penetrant testing (PT) after the visual test (VT) in order to ensure that the entire crack has been removed. Refer to Illustration 54 for a pictorial view of a portable magnetic yoke that is used in the MT.

Place one leg of the yoke on each side of the excavated crack. Obtain good contact with the steel component.

During the energizing of the yoke, gently apply dry magnetic particles with a bulb type applicator.

Remove the yoke from the area and visually inspect the area for indications of particles.

Apply additional particles to the area as you energize the yoke along the length of the evacuation. Energize the yoke along the length of the excavation in increments that are equal to the distance between the legs of the yoke. Do not wash away the areas that were previously magnetized.

Continue to excavate the crack and grind the profile until the crack has been removed.

Note: The entire crack must be removed. The component may be cooled down and a dye penetrant may be used if there is any question.

Welding the Root Passes and Fill Passes

The flux core arc welding process (FCAW process) is the preferred process for all weld passes. The gas metal arc welding process (GMAW process) and the shielded metal arc welding process (SMAW process) may also be used. Refer to ""Welding Parameters" " at the end of this publication for proper machine settings.

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Illustration 55	g01835679
Placement of welding passes

Refer to Illustration 55 for the location of the weld passes. The quantity of weld passes will depend on the thickness of the plate.

Note: Slag must be removed after each weld pass. Visually inspect each pass for defects prior to completing the next weld pass.

Note: STT welds in the vertical position are performed in a downhill progression. FCAW, GMAW, and SMAW process welds in the vertical position must be welded in an uphill progression.

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Illustration 56	g01835695
(5) Welding in progress (6) Completed weld

Illustration 56 is a pictorial view of the results from a repair that followed these guidelines.

Inspection

Inspect the resulting repair per applicable quality standard.

Grinding to Surface Profile

Welding Parameters

FCAW Process In All Positions

The flux core arc welding process (FCAW process) may be used if out of position welding is required. Use the shielding gas that is specified by the manufacturers with a E71T (AWS A5.20) welding electrode. The weld that is deposited by these electrodes will have the following mechanical properties. Refer to Table 3.

Note: Only use flux cored electrodes that have been properly stored in packages that are resistant to moisture. The electrodes must be undamaged or the electrodes must have been in a drying oven that is maintained at 120° C (250° F).

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Table 3
Mechanical Properties for a E71T (AWS A5.20) Welding Electrode
Tensile Strength	480 MPa (70000 psi)
Yield Strength	400 MPa (58000 psi)
Elongation	22%
Impact Toughness	27 N·m (20 lb ft) at −18° C (0° F)

The manufacturer and the welding position may cause the welding parameters to vary. Refer to Table 4 for the welding parameters for a 1.1 mm (0.045 inch) diameter electrode.

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Table 4
Welding Parameters for a 1.1 mm (0.045 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
4445 mm (175 inch) per minute (minimum)	22 - 24	130
8890 mm (350 inch) per minute (mid range)	26 - 28	210
10795 mm (425 inch) per minute (maximum)	29 - 31	275

The manufacturer and the welding position may cause the welding parameters to vary. Refer to Table 5 for the welding parameters for a 1.3 mm (0.052 inch) diameter electrode.

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Table 5
Welding Parameters for a 1.3 mm (0.052 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
5080 mm (200 inch) per minute (minimum)	22 - 24	185
7620 mm (300 inch) per minute (mid range)	26 - 28	210
10795 mm (425 inch) per minute (maximum)	29 - 31	275

The manufacturer and the welding position may cause the welding parameters to vary. Refer to Table 6 for the welding parameters for a 1.6 mm (1/16 inch) diameter electrode.

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Table 6
Welding Parameters for a 1.6 mm (1/16 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
3175 mm (125 inch) per minute (minimum)	22 - 24	170
6350 mm (250 inch) per minute (mid range)	26 - 28	275
9525 mm (375 inch) per minute (maximum)	29 - 31	365

Use the direct current electrode positive (DC reverse polarity) and remove the slag after every pass.

FCAW Process For Flat and Horizontal Positions

The flux core arc welding process (FCAW process) may be used for the flat welding position (1F) and the horizontal welding position (2G). Use the shielding gas that is specified by the manufacturers with a E70T-1 (AWS A5.20) welding electrode. The weld that is deposited by these electrodes will have the following mechanical properties. Refer to Table 7.

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Table 7
Mechanical Properties for a E70T-1 (AWS A5.20) Welding Electrode
Tensile Strength	480 MPa (70000 psi)
Yield Strength	400 MPa (58000 psi)
Elongation	22%
Impact Toughness	27 N·m (20 lb ft) at −18° C (0° F)

The manufacturer and the welding position may cause the welding parameters to vary. Refer to Table 8 for the welding parameters for a 1.6 mm (1/16 inch) diameter electrode.

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Table 8
Welding Parameters for a 1.6 mm (1/16 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
3175 mm (125 inch) per minute (minimum)	23 - 25	170
6350 mm (250 inch) per minute (mid range)	25 - 28	275
9525 mm (375 inch) per minute (maximum)	29 - 31	365

The manufacturer and the welding position may cause the welding parameters to vary. Refer to Table 9 for the welding parameters for a 2.0 mm (5/64 inch) diameter electrode.

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Table 9
Welding Parameters for a 2.0 mm (5/64 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
4445 mm (175 inch) per minute (minimum)	26 - 28	350
6350 mm (250 inch) per minute (mid range)	29 - 31	400
8255 mm (325 inch) per minute (mid range)	31 - 33	470

The manufacturer and the welding position may cause the welding parameters to vary. Refer to Table 10 for the welding parameters for a 2.4 mm (3/32 inch) diameter electrode.

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Table 10
Welding Parameters for a 2.4 mm (3/32 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
3175 mm (125 inch) per minute (minimum)	24 - 27	335
6350 mm (250 inch) per minute (mid range)	30 - 32	530
8255 mm (325 inch) per minute (mid range)	33 - 35	615

Use the direct current electrode positive (DC reverse polarity) and remove the slag after every pass.

GMAW Process In All Positions

The gas metal arc welding (GMAW process) may be used for all welding positions. Use the shielding gas that is specified by the manufacturers with a ER70S-3 (AWS A5.18) welding electrode. The weld that is deposited by these electrodes will have the following mechanical properties. Refer to Table 11.

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Table 11
Mechanical Properties for a ER70S-3 (AWS A5.18) Welding Electrode
Tensile Strength	480 MPa (70000 psi)
Yield Strength	400 MPa (58000 psi)
Elongation	22%
Impact Toughness	27 N·m (20 lb ft) at −18° C (0° F)

The manufacturer and the welding position may cause the welding parameters to vary. Refer to 12 for the welding parameters for a 0.9 mm (0.035 inch) diameter electrode.

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Table 12
Welding Parameters for a 0.9 mm (0.035 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
9525 mm (375 inch) per minute (minimum)	23	195
12700 mm (500 inch) per minute (mid range)	29	230
15240 mm (600 inch) per minute (maximum)	30	275

The manufacturer and the welding position may cause the welding parameters to vary. Refer to Table 13 for the welding parameters for a 1.1 mm (0.045 inch) diameter electrode.

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Table 13
Welding Parameters for a 1.1 mm (0.045 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
8890 mm (350 inch) per minute (minimum)	27	285
12065 mm (475 inch) per minute (mid range)	30	335
12700 mm (500 inch) per minute (mid range)	30	340

The manufacturer and the welding position may cause the welding parameters to vary. Refer to Table 14 for the welding parameters for a 1.3 mm (0.052 inch) diameter electrode.

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Table 14
Welding Parameters for a 1.3 mm (0.052 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
7620 mm (300 inch) per minute (minimum)	30	300
8128 mm (320 inch) per minute (mid range)	30	320
12319 mm (485 inch) per minute (maximum)	32	430

The manufacturer and the welding position may cause the welding parameters to vary. Refer to Table 15 for the welding parameters for a 1.6 mm (1/16 inch) diameter electrode.

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Table 15
Welding Parameters for a 1.6 mm (1/16 inch) Diameter Electrode
Wire Feed Speed	Voltage	Approximate Amperage
5334 mm (210 inch) per minute (minimum)	25	325
5969 mm (235 inch) per minute (mid range)	27	350
7366 mm (290 inch) per minute (maximum)	28	430

Use the direct current electrode positive (DC reverse polarity) and clean the area as cleaning is necessary.

SMAW Process In All Positions

The shielded metal arc welding (SMAW process) may be used with a E7018 (AWS A5.1) welding electrode. The weld that is deposited by these electrodes will have the following mechanical properties. Refer to Table 16.

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Table 16
Mechanical Properties for a E7018 (AWS A5.1) Welding Electrode
Tensile Strength	480 MPa (70000 psi)
Yield Strength	400 MPa (58000 psi)
Elongation	22%
Impact Toughness	27 N·m (20 lb ft) at −18° C (0° F)

Note: The E7018 (AWS A5.1) electrodes are low hydrogen electrodes. These electrodes must be stored in an electrode oven that is maintained at 120° C (250° F) when the electrodes are not used.

Refer to Table 17 for electrode diameter and the approximate current setting.

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Table 17
Diameter	Amperage
3.2 mm (1/8 inch)	70 - 140
4.0 mm (5/32 inch)	110 - 180
4.8 mm (3/16 inch)	190 - 270

Use the direct current electrode positive (DC reverse polarity) and remove the slag after every pass. The width of the weave shall not exceed two times the diameter of the electrode.

Post Weld Treatment

GTAW "TIG" of Fillet Welds for Improved Fatigue Life

Note: The fatigue performance is controlled by the profile of the weld toe. This fatigue performance applies to fabricated structures that have fillet welded attachments to highly stressed members. The fatigue performance can be improved by altering the original welded toe profile. Altering the fatigue performance can be achieved by using several post weld treatment options. This procedure describes a method of using an electric arc to reduce adverse profiles and stress risers. This method creates a seamless transition from one component to the next component.

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Table 18
Required Equipment
Tool	Description
GTAW (TIG) Power supply and a torch.	The power supply must produce 200 amps (min. 60% duty cycle) with a hand control or a foot control.
Shielding Gas	100% Argon and flow meter
Electrode	Lanthanated or Ceriated or Thoriated Tungsten 2.4 mm (0.09 inch diameter) If needed: ER70S-2 filler metal 1.5 mm (0.06 inch diameter)
Grinder	Pneumatic or electric with carbon steel wire wheel attachment
Grinding Wheel	Aluminum Oxide
Radius gauges

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Illustration 57	g01989379
2.4 mm (0.09 inch) Tungsten Electrode Preparation (M) Grinding Marks

Cleanliness and tungsten electrode preparation are the first steps in order to ensure that a proper TIG dressing is achieved. Remove all contaminants from the fillet weld and the surrounding base metal. All rust, dirt, oil, scale, and silicate islands must be removed. This removal can be accomplished quickly via a grinder with a carbon steel wire attachment.

Prepare a 2.4 mm (0.09 inch) tungsten electrode. Refer to the dimensions that are shown in Illustration 57. The grinding marks should run parallel to each other.

Adjust the shielding gas flow rate to 15 CFH. Adjust the current control to approximately 200 amps. If a ramp down control is present on the power source, utilize the ramp down control to ensure that proper crater fill control is achieved.

A number of different techniques exist for TIG dressing. These different techniques are due to the variation of the contour of the fillet weld toe. The contour of the fillet weld toe must be reshaped. Use a stringer or weave manipulation of the torch in order to achieve a smooth radius of the weld. A minimum radius of 5.0 mm (0.20 inch) must exist between the base material and the weld metal.

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Illustration 58	g01989420
Stringer Technique

Note: Use a 10 to 15 degree push angle for the stringer technique.

Illustration 58 represents the stringer technique of welding. The center of the arc needs to be 0.0 - 2.0 mm (0.0 - 0.08 inch) from the weld toe into the base material.

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Illustration 59	g01989494
Weave Technique

Note: Use a 10 to 15 degree push angle for the weave technique.

Illustration 59 represents the weave technique of welding.

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Illustration 60	g01989613
Cross section of the proper TIG Dressing

Illustration 60 represents a cross section view of a proper TIG Dressed fillet weld.

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Illustration 61	g01990055
View of a proper TIG Dressing

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Illustration 62	g01990056
View of the proper TIG Dressing

Illustration 61 and Illustration 62 demonstrate the expected results.

Once TIG dressing is completed, the area needs to be cleaned and painted in order to prevent pitting due to corrosion.
Note: Poorly shaped fillet welds with 70 degree to 90 degree transition angles will require several overlapping TIG dressing runs. Overlapping of the TIG dressing runs is required in order to stabilize the weld toe transition area.
Note: TIG dressing can be conducted in the vertical position as long as the TIG dressing is performed in a downhill progression.
Note: Some undercuts will require the addition of filler metal. Adding filler metal can be accomplished by hand feeding ER70S-2 1.5 mm (0.06 inch diameter) into the weld pool. You then repeat the TIG dressing in order to achieve the desired toe radius and the desired profile.

Burr Grinding of Fillet Welds for Improved Fatigue Life

Note: The profile or geometry of the weld toe controls the fatigue performance of fabricated structures. These fabricated structures have attachments that are fillet welded to highly stressed members. Fatigue performance improvement can be achieved through alteration of the original toe profile by several post weld treatment options. This procedure describes a method of using a mechanical means in order to remove adverse profiles and adverse stress risers. This method creates a smooth transition from one component to the next component.

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Table 19
Required Equipment
Tool	Description
Hand Held Grinder	High speed, pneumatic, rotary, pencil grinder - 20,000 rpm
Compressed Air	621 kPa (90 psi) minimum
Tungsten Carbide Burr	The burr is conical shaped with an end diameter of approximately 10.0 mm (0.39 inch).
Leather Welding Jacket
Leather Gloves
Safety Glasses
Face Shield
Radius Gauge
Bridge Cam Gauge

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Illustration 63	g02001292
Pneumatic Rotary Pencil Grinder with Burr

The arrow points to the preferred burr shape.

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Illustration 64	g02001298
Burr grinding the weld

The burr tip should be located over the weld toe. The axis of the tool should be maintained at approximately 45 degrees to the parent plate. The axis of the tool should be inclined at approximately 45 degrees to the direction of travel. Grinding should extend to a depth of 0.5 mm (0.02 inch) below the last visible traces of the weld toe resulting in minimum depth of 0.8 mm (0.03 inch) and maximum depth of 1.0 mm (0.04 inch). The resulting ground surface should be smooth with no visible marks from grinding that are parallel to the weld, but 90 degrees to the weld. All traces of the original weld toe should not be visible via the use of a lower powered magnifying glass.