Procedures for the Repair of Cracks in Reach Booms{6000, 6501} Caterpillar

Excavator:

330C (S/N: MCA1-UP; JAB1-UP; JCD1-UP; GAG1-UP; BTM1-UP)

330C L (S/N: CYA1-UP)

330C (S/N: HAA1-UP)

330C L (S/N: KDD1-UP; RBH1-UP; JNK1-UP; MKM1-UP; CAP1-UP; GKX1-UP; DKY1-UP)

330C LN (S/N: CGZ1-UP)

330D (S/N: KAB1-UP; EAH1-UP; PCK1-UP; MEY1-UP)

330D L (S/N: RDA1-UP)

330D (S/N: GBC1-UP)

330D L (S/N: NBD1-UP; B6H1-UP; FFK1-UP; THJ1-UP; LRM1-UP; ERN1-UP; JLP1-UP; MWP1-UP; LDR1-UP; HAS1-UP; RAS1-UP; EDX1-UP; T2Y1-UP)

330D LN (S/N: GGE1-UP)

Introduction

This special instruction outlines the recommended basic procedures for the repair of cracks at the boom foot or rear baffle plate of a reach boom. The procedures in this publication are applicable to any of the listed models. Instructions for making the parts that are needed for this procedure are included in this publication.

Do not perform any of the procedures until you have read the information in this publication. Understand and perform all of the safety instructions and information. Safety instructions and information is associated with the removal, handling, repair, and installation of the implements and the components in the front linkage.

Also, refer to the appropriate Parts Manual, Operation and Maintenance Manual, Disassembly and Assembly Manual, and Service Manual.

Required Parts

The required parts are defined in each section of this Special Instruction. Use the designs that are provided in order to fabricate the parts that are needed. All of the plates must be fabricated from ASTM A572 Grade 42 or Grade 50 steel, or the equivalent steel with a minimum yield strength of 290 MPa (42000 psi).

Welding Requirements

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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

Welding quality is critical to the success of the installation procedure. Welds must be smooth and continuous. Neither undercutting nor overlapping is allowed. Grind the ends of the welds to a smooth radius.

Prepare the metal for welding according to ""Preparing the Metal for Welding" ". Refer to the illustrations in this special instruction for welding symbols and specifications.

Stick welding SMAW of the casting for the boom foot is not recommended. The casting has a high carbon content.

Use LB-26 Electrodes (AWS E7016 or AWS E7018) or equivalent electrodes to weld the baffle plate and the reinforcement plates. Basic welding wire ESAB OK tubrod 15.00 with a 1.2 mm (0.05 inch) diameter can also be used. The basic welding wire must be the equivalent to AWS A5.20 E71T-5 with positive polarity. The welding wire must be shielded with CO₂ gas or Argon/CO₂ 80/20 gas.

Welding of the gouged grooves requires LB-52 (AWS E7018), or an equivalent electrode. Basic welding wire ESAB OK tubrod 15.00 with a 1.2 mm (0.05 inch) diameter can also be used.

All electrodes must be completely dried. The electrodes can be dried by heating the electrodes to 300°C (572°F). The electrodes must be dried for at least 30 minutes.

Do not weld in windy conditions. Do not weld when temperatures are below 16°C (60°F).

Penetration characteristics may vary greatly depending on the electrode diameter, shielding gas, welding current, and plate thickness. Geometry of welded joints, surface conditions, and composition of the base metal and electrode also affect the welds.

A root pass should be applied before each weld is finished.

Maintain a 3 mm (0.12 inch) minimum root opening on all cross welds and circle welds.

All of the welds to the boom must be in the direction from the rear of the boom toward the front of the boom unless the direction of the welds are otherwise specified.

All repair welds should be done in a controlled environment. Controlled environments prevent the rapid cooldown after the repair. Controlled environments would be inside of a repair shop.

All welds should be done in the horizontal or the flat position in order to make a smooth surface finish.

Make sure that the root cause of the crack in the boom is determined. Eliminate the root cause before proceeding with the repair.

Make sure that a repair plan is developed in order to prevent losing the alignment of the bores and true position.

If the repair requires an access hole in the boom, make sure that the backup strips are installed correctly with the proper gap. Remove the backup strips that are not installed correctly. Gouge out the welded joint if the backup strips are removed. Repair the welded joint with new backup strips that are properly installed.

Tack welds that were used during fabrication of the boom at the factory can be removed if the welds are contributing to the crack. The tack weld on the back side of a backup strip is an example.

Needle peen all of the repaired weld joints in order to achieve the maximum fatigue life.

When possible, grind the surface smooth on the repaired structure. The smooth finish from the grinder will eliminate stress risers. A smooth transition between the weld and the plate material should be maintained. A radius of 3 mm (0.12 inch) in the weld toe will provide maximum fatigue life.

Illustration 1	g01561364
Grind The Weld Toe. (R) Grind the weld toe smooth.

For more welding information, consult the Caterpillar Service Welding Guide, SEBD0512.

Preparing the Metal for Welding

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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.

All grease, water, paint, rust, dirt and scale must be removed before welding. Any of these materials will discharge gas which will cause porosity in the weld deposit. Water and rust will cause hydrogen embrittlement. Hydrogen embrittlement causes cracks in the weld deposit.

Remove paint, rust, dirt, and scale with a wire brush or by buffing or grinding. Shot blasting all work areas will also remove foreign material.

Remove any oil or grease that is on the boom with a Caterpillar approved solvent.

Before you do any welding on the boom, remove all foreign material and paint a minimum of 50 mm (2.0 inch) beyond the area of the weld.

Cover all finished bores and threads. Finished bores and threads must be protected from all of the following items: foreign material, welding, gouging and paint spatters. Do not remove the covers until the boom is painted.

Weld 25.4 mm (1 inch) square tie bars across the ears for the head end of the stick cylinder. The tie bar will prevent the ears from bending when the boom is positioned for the repairs.

Preparing the Machine for Servicing

1. Move the machine to level ground. The ground must support the machine's weight. Personal injury or death can result if the surface below the machine cannot support the weight of the machine.

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Be sure all personnel are clear of the equipment while the equipment is being lowered. Failure to stay clear of the equipment while the equipment is being lowered may result in personal injury.

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Illustration 2	g00100836
The servicing position of an Excavator is shown in this illustration. The bucket is flat on the ground. The stick is in a vertical position.

2. Put the machine in the servicing position. The bucket must rest flat on the ground after the boom is lowered.

3. With the machine in the servicing position, remove the bucket from the stick. Refer to the Disassembly & Assembly module for machine systems with your machine. Buckets weigh approximately 958 kg (2110 lb) to 1820 kg (4010 lb).

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates.

4. Remove the stick from the boom. Refer to the Disassembly & Assembly module for machine systems with your machine. Sticks weigh approximately1195 kg (2650 lb) to 1348 kg (2975 lb).

5. Position the boom on the ground. Refer to the Disassembly & Assembly module for machine systems with your machine.

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Hydraulic oil pressure can remain in the hydraulic systems after the engine and pump have been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent possible injury, refer to the section, Testing and Adjusting, "Hydraulic System Pressure - Release" before any fitting, hose or component is loosened, tightened, removed or adjusted. When possible, the bucket or attachment must always be lowered to the ground before service is started. When it is necessary for the boom to be in the raised position while tests or adjustments are done, be sure that the boom, stick and bucket or attachment have correct support. The swing lock (if equipped) must be engaged before service is started. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made.

6. Move the control levers for the boom, the stick, the bucket, swing operation, and the left and right travel to the full stroke positions. This movement will release any actuator pressure in the hydraulic lines.

7. Move the hydraulic activation control lever to the UNLOCKED position. This will release any pressure in the pilot system. For further details on this procedure, refer to the machine's Operation and Maintenance Manual.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

8. Slowly loosen the fill/vent plug on the hydraulic tank. This will relieve the pressure in the hydraulic tank.

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Accidental machine starting can cause injury or death to personnel working on the machine. To avoid accidental machine starting, turn the battery disconnect switch to the OFF position and remove the key. If the machine is not equipped with a battery disconnect switch, disconnect the battery cables from the battery and tape the battery clamps. Place a do not operate tag at the battery disconnect switch location to inform personnel that the machine is being worked on.

9. Remove the key which starts the machine. Secure the cab.

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NOTICE
Before carrying out arc welding on the machine or on any equipment attached to the machine, disconnect all power and ground leads from the batteries in order to avoid possible damage to electronic components.

10. Disconnect all power and ground leads from the batteries in order to avoid possible damage to the electronic components.

11. Disconnect the boom cylinders from the boom. Refer to the Disassembly & Assembly module for machine systems with your machine.

12. Remove the boom from the machine. Refer to the Disassembly & Assembly module for machine systems with your machine. Booms weigh approximately 3401 kg (7500 lb) to 4309 kg (9500 lb).

Crack Identification

The recommendation for repair or replacement of the boom will depend on the location and the magnitude of the damage. The following six examples are the locations of the most common cracks. Refer to Illustration 3. Refer to Illustration 4 through Illustration 9 for the details of the six most common cracks. Also, there are examples of the Type A and the Type F cracks that extend into the top, the bottom, and the side plates. Refer to Illustration 10 and Illustration 11.

Illustration 3	g01623705
Typical Boom (A) Vertical crack on the center section of the side plate at the rear of the baffle plate (B) Crack on the side plate and the top or bottom plate at the rear of the baffle plate (C) Vertical crack at the joint for the boom foot (D) Crack at the joint for the boom foot that extends into the top or bottom plate (E) Vertical crack at the boom foot that extends into the casting and/or the side plate (F) Crack at the boom foot that extends into the casting and the top plate or the bottom plate

Illustration 4	g01524583
Location Of Type A Crack

Illustration 5	g01524584
Location Of Type B Crack

Illustration 6	g01524585
Location Of Type C Crack

Illustration 7	g01524586
Location Of Type D Crack

Illustration 8	g01524587
Location Of Type E Crack

Illustration 9	g01524590
Location Of Type F Crack

Illustration 10	g01623706
Extended Type A Crack Into Boom

Illustration 11	g01527641
Extended Type F Crack Into Boom

Contact your Excavator Product Support Group for additional information or with any questions about other types of cracks.

Machine Profile Information

The machine configuration, the working conditions, and the severity of the application is important information in order to determine the correct repair for the damage. Use the following form for a machine profile in order to collect the information. Use the form in order to determine the severity of the damage and the possible root cause. Send the completed form to the Product Support Group. The information will be used in order to develop the proper recommendations for service. Including attachments of digital photographs is helpful.

Illustration 12	g01525067
Form For A Machine Profile

Send the prognostic data that has been downloaded from the ADEM by the ET for 330C and 330D Excavators.

Addition of Reinforcement Plates

Repaired booms may not be as durable as originally fabricated because of the damage from cracks and the effects of the heat that is generated during the repair. Caterpillar Engineering recommends the use of reinforcement plates for the maximum durability and fatigue life. The dealer and the customer will consider any concerns of the observed appearance of the repair. The dealer and the customer will determine if the reinforcement plates are added. Certain applications will require the addition of reinforcement plates. If the damage from the crack is severe and the repair is extensive, the addition of reinforcement plates may be required. The addition of the appropriate reinforcement plate can be discussed with the service group. Use the following procedure if the decision of adding reinforcement plates is made.

Procedure for the Addition of Reinforcement Plates

The following procedure describes the details for the addition of reinforcement plates on the rear baffle plate and the boom foot. Make sure that the cracks in these areas have been repaired before completing the following procedure.

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Illustration 13	g01623718
Left Hand Reinforcement Plate (1) For The Baffle Plate In The Boom (A) 13.5 mm (0.53 inch) (B) 15 mm (0.6 inch) (C) 378 mm (14.9 inch) (D) Radius 80 mm (3.1 inch) (E) 150 mm (5.9 inch) (F) 535 mm (21.1 inch) (G) 12 mm (0.5 inch) (H) 118.1 mm (4.65 inch) Reference dimension (J) 243 mm (9.6 inch) (K) Radius 160 mm (6.3 inch)

1. Fabricate the reinforcement plate (1) that is shown in Illustration 13. Use the steel that is specified in the ""Required Parts" " section of this document. The plate is used on the left side of the boom. Fabricate a reinforcement plate for the right side of the machine. The plate is a mirror image of Illustration 13.

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Illustration 14	g01623774
Reinforcement Plate (3) For The Boom Foot (G) 12 mm (0.5 inch) (M) 20 mm (0.8 inch) (N) 100 mm (3.9 inch) (P) Radius 300 mm (11.8 inch) in 2 places (R) 712 mm (28.0 inch) (S) 600 mm (23.6 inch) (T) Radius 250 mm (9.8 inch) in 2 places (U) 559 mm (22.0 inch)

2. Fabricate the reinforcement plate (3) that is shown in Illustration 14. Use the steel that is specified in the ""Required Parts" " section of this document. Plate (3) can be used on both sides of the boom.

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Illustration 15	g01623826
Grind Existing Welds Smooth. (1) Fabricated reinforcement plate (3) Fabricated reinforcement plate (AC) Existing weld (AD) Existing weld

3. Make sure that the existing welds (AC) and (AD) are ground smooth and flush before tack welding the plates.

4. Tack weld plate (1) and plate (3) with a maximum gap of 1 mm (0.04 inch) between the reinforcement plates and the base plates.

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Illustration 16	g01624125
Weld Plates On The Boom (N) 15 mm (0.6 inch) (P) 30 mm (1.2 inch) Reference dimension (R) 20 mm (0.8 inch) (S) Grind the toe smooth. (T) 35 mm (1.4 inch) Reference dimension

5. Weld the reinforcement plates for the rear baffle plate and the boom foot. Weld (W1) length A-D, B-C, F-G, and E-H. Weld (W2) length A-B, E-F, and G-H. Weld (W3) C-D. Refer to Illustration 16. Refer to Table 1 for the weld specifications.
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   Table 1

   Welding Specifications
   Item	Description
   W1	12 mm (0.5 inch) butt weld
   W2	10 mm (0.4 inch) fillet weld
   W3	12 mm (0.5 inch) butt weld 35 mm (1.4 inch) wide. Grind the weld smooth.

6. Grind the finished surface of the welds. Make sure that the radius of the weld toe is controlled to a minimum of 3 mm (0.12 inch) in order to maximize the fatigue life. Make sure that there are no notches or abrupt transitions. Use a brush or an air gun and remove any water, oil, dust, or any weld splatter.

7. Apply primer paint for corrosion control. Apply touch-up paint on the area with the repaired welds.

Stress Relief Of The Boom

Booms from the factory have been stress relieved in order to extend the life of the structure. The effects of the heat from cutting and welding eliminate the benefit of the stress relief. After a boom is repaired, consider stress relief of the structure because of the known benefits.

Maintain the Alignment of the Bores

Illustration 17	g01526251
Verification Of The Alignment Of The Bores (A) 110.043 ± 0.043 mm (4.3324 ± 0.0017 inch) Diameter for 2 holes (C) 1122 mm (44.2 inch) (D) 2610 mm (102.8 inch) (E) 50.9 mm (2.00 inch) nominal dimension and 47.9 mm (1.89 inch) minimum (F) 6500 mm (255.9 inch) (G) 140 ± 0.032 mm (5.512 ± 0.001 inch) Diameter for 2 holes

Heat from welding and cutting causes distortion that can change critical dimensional relationships. The measurement of the axis for the bore at the boom foot (PT1) relative to the axis for the bore at the pivot boss (PT2) should be performed after the repair. Refer to Illustration 17. Make sure that the pin for the boom foot will enter the bore. Maintain the parallel position of the bores. Maintain the distance between the axis of each bore. Dimensional conformance is critical for the assembly of the pins and the boom cylinders.

Remove the bearings, if necessary. Weld bore (PT1). Machine the bore to the correct diameter. Install new bearings. Confirm that the dimensional conformance between the bores has been maintained.

Repair Procedure by Type of Crack

Use the appropriate procedure in order to repair the damage from the crack on the boom. Specific procedures for the type of the crack and location of the crack will follow.

Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate

This procedure describes the repair for cracks on the right side plate or the left side plate at the rear baffle plate.

The crack is most frequently located on the weld toe on the front side of the baffle plate. Step 1 through Step 13 describes the repair that is performed by accessing the front side of the baffle plate. Step 14 through Step 24 describes the repair that is performed by accessing the rear side of the baffle plate.

1. Position the boom on the side on repair stands. Booms weigh approximately 3401 kg (7500 lb) to 4309 kg (9500 lb).

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Illustration 18	g01624346
Dimensions For The Removal Of A Section Of The Bottom Plate (A) Cut bottom plate (B) 4.4 mm (0.17 inch) (C) 450 mm (17.7 inch) (D) 4.5 mm (0.18 inch) (G) Original seam for the top plate and the bottom plate

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Illustration 19	g01561175
Removal Of The Bottom Plate

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Illustration 20	g01561173
Removal Of The Bottom Plate

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Illustration 21	g01561174
Removal Of The Bottom Plate

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Illustration 22	g01539354
Cuts For An Access Hole (J) 450 mm (17.7 inch) (K) 450 mm (17.7 inch) (L) Welds on the body in the center section of the bottom plate (M) Cross welds in the center section of the bottom plate

2. Cut the weld joint between the side plate and the bottom plate (L). Cut both sides of the boom. Make sure that the center sections of the side plates are not damaged by the cut. The cut section of the bottom plate will be destroyed during the process. Position the boom with the bottom side of the boom up. Refer to Illustration 20. Cut a section from the center of the bottom plate (M). Refer to Illustration 18 for the dimensions. Refer to Illustration 30 for the dimensions of the new plate.

   Note: Use a magnet or a suitable lifting device in order to prevent the cut plates from falling freely on an operator or on a bystander.

3. After the access hole has been cut from the center section, examine the welds on the front side of the baffle plate. Make sure that the crack in the side plate and in the welds is examined. Make sure that the root cause of the cracks has been determined. Make sure that the root cause has been eliminated before proceeding with the repair.

   Use the procedure that follows in order to remove the cracks in the welds and for the repair weld of the rear baffle plate. Refer to Illustration 23.

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   Illustration 23	g01561252
   (a) Step 3.a (b) Step 3.b (c) Step 3.c (d) Step 3.d (e) Step 3.e (f) Step 3.f (g) Step 3.g

   1. Gouge out the fillet weld for the rear baffle plate and the side plate that is closest to the boom nose.

   2. Grind the surfaces for the weld that was removed. Clean the surfaces for the weld that was removed.

   3. Gouge out the crack in the side plate inside the boom for a V-groove weld. Gouge out the crack to a depth of 10 mm (0.4 inch). Gouge out 50 mm (2 inch) beyond the visible end of the crack.

   4. Weld a root pass. Weld two passes in order to finish the weld. Grind the weld smooth.

   5. Weld a 12 mm (0.5 inch) fillet weld.

   6. Gouge out the crack in the side plate on the outside of the boom for a V-groove weld. Gouge out the crack to a depth of 10 mm (0.4 inch).

   7. Weld a root pass. Weld two passes in order to finish the weld. Grind the weld smooth.

Note: Gouges should extend 50 mm (2.0 inch) beyond the full length of the crack. Perform all repair welds in the horizontal position.

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Illustration 24	g01561363
Grind The Weld Toe.

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Illustration 25	g01561364
Grind The Weld Toe. (R) Grind the weld toe smooth.

4. The angle of the weld toe should be less than 45 degrees. Grind the weld toe smooth if the surface of the weld is rough. Apply needle peening at the weld toe in order to eliminate stress risers.

   Note: Surfaces that have been ground must be smooth without deep marks or undercuts that could initiate future cracks.

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Illustration 26	g01561365
Bevel On The Bottom Plate (S) 25 degree bevel

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Illustration 27	g01561367
Grind A Bevel On The Bottom Plate.

5. Clean the edges at the opening in the bottom plate (M) in the center section. Add a 25 degree bevel that is 15 mm (0.6 inch) on both edges.

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Illustration 28	g01534495
Backup Strip (X) 429 mm (16.9 inch) (Y) 25 mm (1.0 inch) (Z) 10 mm (0.4 inch)

6. Fabricate 2 backup strips.

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Illustration 29	g01536793
Alignment Of The Backup Strip

7. Use clamps in order to make sure that the backup strips are flush with the side plate. Make sure that there is less than a 0.5 mm (0.02 inch) gap between the backup strip and the parent material of the side plate in the center section. Misalignment of the backup strip will severely reduce the life of the structure. Refer to Illustration 29.

   Note: Tack weld the backup strips with three 3 mm (0.12 inch) fillet welds that are 20 mm (0.8 inch) long on the V-groove side of the backup strip. Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip.

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Illustration 30	g01623869
Replacement Plate For The Cut Section (AA) 452.3 mm (17.81 inch) Reference dimension (AB) 3328 mm (131.0 inch) Reference dimension (AC) The radius of 3314 mm (130.5 inch) is a reference dimension. (AD) 500 mm (19.7 inch) (AE) 8.2 degrees reference dimension (AF) 31 mm (1.2 inch) (AG) 452 mm (17.8 inch) (AH) 14 mm (0.6 inch) (AL) 2 mm (0.1 inch) Maximum (AM) 25 Degrees

8. Use the dimensions and shape of the plate that was removed in Step 2 as a guide. Fabricate the replacement plate for the cut section. Refer to Illustration 30. Grind a smooth 25 degree bevel on the ends of the plate. Refer to Table 2 for the dimensional tolerances for any fabricated plate.
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   Table 2

   Tolerances For The Fabrication Of The Plates (1)
   Dimensional Range		Tolerance
   0 mm (0 inch) up to 315 mm (12.4 inch)		± 1.5 mm (± 0.06 inch)
   316 mm (12.4 inch) up to 1000 mm (39.4 inch)		± 1.8 mm (±0.07 inch)
   1001 mm (39.4 inch) up to 2000 mm (78.7 inch)		± 2.5 mm (± 0.01 inch)
   2001 mm (78.7 inch) up to 4000 mm (157.5 inch)		± 3.5 mm (± 0.14 inch)

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   ( 1 )

   All corners have a maximum radius of 6 mm (0.2 inch).

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Illustration 31	g01539276
Bevel On The Side Plate (AS) 45 degree bevel on the side plate

9. Grind a 45 degree bevel that is 13 mm (0.5 inch) deep on the side plates in the center section. Leave a flat on the bevels that is approximately 3 mm (0.1 inch). Refer to Illustration 31.

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Illustration 32	g01562553
(1) Weld the backup strip. (2) Build up the side plates with weld passes before welding the bottom plate. (3) Grind the edges smooth and straight.

10. The final preparation for the installation of the new bottom plate is inspection and repair of the weld joints. Inspect all edges and surfaces. Make any necessary repairs. Build up of the edge with weld beads in order to produce a flush weld joint, if necessary. Grind the weld smooth. Make sure that there are no gaps in the weld joints for the new bottom plate and the side plates.

    Note: Make sure that the weld joint is flush between the center section of the side plates and the fabricated bottom plate. Build up the side plates with weld beads. Grind the weld smooth in order to create a weld joint that is flush if the side plates were damaged during the removal of the bottom plate. Use a backup strip, if necessary. Refer to Illustration 32.

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Illustration 33	g01539293
Tack Welds Of The Bottom Plate In The Center Section (AR) Locations of the tack welds

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Illustration 34	g01562693
Weld The New Bottom Plate.

11. Use clamps in order to make sure that the weld joint between the replacement bottom plate and the side plates is flush. Tack weld the fabricated bottom plate in the position that is shown in Illustration 33. Use a steel runoff plate in order to create a weld dam at the edge of the weld. In order to minimize weld distortion, make sure that the tack weld between the side plates and the bottom plate does not affect the future installation of the cross welds. Refer to Illustration 22 for the location of the cross welds.

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Illustration 35	g01625388
Welds On The Body Of The Boom

12. Weld the cross welds for the center section of the bottom plate in the horizontal position. Grind the welds smooth. Turn the boom so that the right side is horizontal. Weld the 16 mm (0.6 inch) fillet weld between the side plate and the bottom plate. Weld in the horizontal position. Grind the tie-ins for the welds. Refer to Table 3 for the weld specification.
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    Table 3

    Weld Specifications
    Item	Description
    W4	12 mm (0.5 inch) bevel weld over a 12 mm (0.5 inch) fillet weld

13. Grind the cross welds flush. The joints for the cross welds should not be visible.

Perform Step 14 through Step 24 if the crack extends through the side plate at the side of the rear baffle plate that faces the boom foot.

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Illustration 36	g01562873
Remove The Bottom Plate At The Boom Foot.

14. Remove the bottom plate at the boom foot. Refer to Illustration 36. Make sure that the edges of the side plates are not damaged by the cuts. The section of the bottom plate will be destroyed during the process.

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Illustration 37	g01546835
Cut The Weld For The Side Plate.

15. Cut the remaining welds from the bottom plate on the right side of the boom. Refer to Illustration 37. Position the boom so that the left side is up. Cut the remaining welds from the bottom plate on the left side of the boom. Make sure that the edges of the side plates are not damaged by the cuts.

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Illustration 38	g01562902
Cut The Bottom Plate From The Casting For The Boom Foot.

16. Position the boom so that the bottom plate is up. Cut the cross weld at the weld joint for the center section of the bottom plate. A backup strip is located under this weld joint. Cut the weld at the weld joint between the bottom plate and the casting for the boom foot. Make sure that the casting is not damaged by the cuts. Refer to Illustration 38. Instructions for the fabrication of a new bottom plate will be described later in this procedure.

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Illustration 39	g01542075
Access For The Baffle Plate From The Boom Foot (AU) Crack locations

17. Inspect and repair the welds on the rear side of the baffle plate. Refer to Illustration 39. Repeat Step 3.a through Step 3.g if any weld is cracked or if the baffle plate is loose. Refer to Illustration 23.

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Illustration 40	g01565055
Grind The Bevel On The Side Plate.

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Illustration 41	g01542077
Bevel On The Bottom Plate And On The Side Plate (AV) 25 degree bevel (AW) 45 degree bevel

18. Prepare the exposed plate and the edges of the casting for the receipt of a new bottom plate. Grind 45 degree bevels that are 12 mm (0.5 inch) deep on the rear section of the side plate. Refer to Illustration 40. Position the boom so that the bottom side is up. Grind the edges of the center section on the bottom plate. Grind a 25 degree bevel that is 12 mm (0.5 inch) deep. Grind a flat on the bevels that is approximately 3 mm (0.1 inch). Refer to Illustration 41.

    Note: Make sure that the weld joint is flush between the center section of the side plates and the fabricated bottom plate. Build up the side plates with weld beads in order to remove any gaps. Grind the weld smooth in order to create a weld joint that is flush if the side plates were damaged during the removal of the bottom plate.

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Illustration 42	g01542256
Repair Of The Casting For The Boom Foot

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Illustration 43	g01565073
Grind The Repair Weld Smooth.

19. Position the boom so that the bottom plate is up. Weld the casting for the boom foot in order to fill any holes, gouges, or gaps. Grind the welds on the casting flush for an improved weld joint with the bottom plate. Refer to Illustration 42 and Illustration 43.

20. Fabricate a backup strip. Refer to Illustration 28.

21. Use clamps in order to make sure that the backup strips are flush with the bottom plate. Make sure that there is less than a 0.5 mm (0.02 inch) gap between the backup strip and the parent material of the bottom plate in the center section. Misalignment of the backup strip will severely reduce the fatigue life.

    Note: Tack weld the backup strips with three 3 mm (0.12 inch) fillet welds that are 20 mm (0.8 inch) long on the V-groove side of the backup strip. Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip.

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Illustration 44	g01542273
Fabricated Bottom Plate (BA) 850 mm (33.5 inch) (BC) 20 mm (0.7 inch) Radius (BD) 1000 mm (39.4 inch) Radius (BE) 500 mm (19.7 inch) (BF) 2 mm (0.1 inch) Maximum (BG) 25 degrees + 5 degrees − 2 degrees (BH) 14 mm (0.6 inch) (BK) 119.6 mm (4.71 inch) (BL) 1528 mm (60.2 inch) (BM) 179.6 mm (7.07 inch)

22. Fabricate the bottom plate that is shown in Illustration 44.

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Illustration 45	g01565335
(BR) Tack weld

23. Use a magnet or a suitable lifting device and position the new bottom plate on the boom. Make sure that the root opening is a minimum of 3 mm (0.1 inch) and a maximum of 10 mm (0.4 inch). Make sure that there are no gaps between the backup strip and the bottom plate. Tack weld the plate securely in the seam of the root opening with high quality welds. Refer to Illustration 45.

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Illustration 46	g01542716
Vertical Clamp For The Bottom Plate At The Boom Foot

24. Clamp the bottom plate vertically along the boom in order to eliminate gaps between the new bottom plate and the side plates. Clamp from the middle of the boom toward the boom nose. Refer to Illustration 46.

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Illustration 47	g01542722
Tack Welds (BR) Tack weld

25. Tack weld the new bottom plate with both side plates. Begin at the weld joint for the center section and make the tack welds toward the boom foot. Remove the clamps. Refer to Illustration 47.

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Illustration 48	g01542695
Bottom Plate At The Boom Foot (BR) Tack weld (BS) Root opening

26. Reposition the boom with the weld joint between the new bottom plate and the casting for the boom foot in the horizontal position. Clamp the new bottom plate with the casting for the boom foot in order to eliminate any gaps. Tack weld the new bottom plate with the casting for the boom foot. Tack weld the plate with 3 mm (0.12 inch) fillet welds that are 20 mm (0.8 inch) long. Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip.

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Illustration 49	g01565473
Weld The Bottom Plate At The Boom Foot.

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Illustration 50	g01542723
Weld For The Bottom Plate At The Boom Foot

27. Finish weld the joint between the bottom plate and the casting for the boom foot. Finish the surfaces with a smooth grind. Needle peening on the weld toe is recommended for the maximum life of the structure.
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    Table 4

    Weld Specifications
    Item	Description
    W5	16 mm (0.6 inch) fillet weld

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Illustration 51	g01565493
Weld The Bottom Plate At The Center Section Of The Boom.

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Illustration 52	g01542724
Weld For The Bottom Plate At The Center Section Of The Boom. (BW) 3 mm (0.1 inch) Minimum

28. Finish weld the cross weld at the center section of the boom. Allow the welded area to cool between passes. The weld in the root is continuous over the tack welds. No stops are allowed. Make sure that the tie-in welds for both of the top plates and the bottom plates are good. Grind the weld toe smooth.
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    Table 5

    Weld Specifications
    Item	Description
    W6	15 mm (0.6 inch) V-groove weld

    Note: Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip. Do not exceed the 20 mm (0.8 inch) length.

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Illustration 53	g01565654

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Illustration 54	g01572273
Weld The Bottom Plate And The Side Plate.

29. Position the boom so that the right side is horizontal. Make a root pass and finish weld the joint between the side plate and the bottom plate. Refer to Illustration 54. Refer to Table 3 for the weld specifications. Weld (W4) length CA-BX and CB-BY. Allow the welded area to cool between passes. Make all welds in the horizontal position. Raise the boom nose in order to keep the weld horizontal. Grind the toe of the weld smooth. Needle peening is recommended for the maximum life of the structure.

30. Position the boom so that the left side is horizontal. Repeat the instructions from Step 29.

31. Grind the cross welds flush when the repair welds are completed. The weld joints for the cross welds should not be noticeable.

Procedure for the Repair of a Type B Cracks in the Side Plate and Top or Bottom Plate at the Rear Baffle Plate

This procedure describes the repair procedure for cracks on the side plate and on the top or the bottom plate at the rear baffle plate. Use the information from the section ""Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate" " in this document. The cracks should be repaired by the same procedure.

Gouge out the crack on the top plate or the bottom plate from the inside of the boom. Refer to Step 3 from the section ""Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate" " in this document. Weld the crack in the boom. Repeat the procedure for the outside of the boom.

If a severe crack in the side plate extends into the top plate or the bottom plate, contact the Product Support Group. Provide the information from the machine profile that is shown in Illustration 12. The examples that follow describe a severe crack:

• The crack extends through half of the width for the top plate or the bottom plate.

• The crack has opened and the two plates have separated.

Illustration 55	g01546634

Illustration 56	g01546635

Refer to Illustration 55 and Illustration 56 for examples of booms with severe cracks.

Procedure for the Repair of a Type C Crack in the Vertical Seam at the Side Plates at the Boom Foot

The following information describes the repair procedure for cracks on the side plate in front of the casting for the boom foot. The procedure describes the steps for a crack on the right side of the boom. Use the mirror image of this procedure in order to repair a similar crack on the left side of the boom.

1. Position the boom with the right side horizontal on suitable repair stands. The approximate weight of a boom is 3401 kg (7500 lb) to 4309 kg (9500 lb).

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Illustration 57	g01562873
Remove The Bottom Plate From The Boom Foot.

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Illustration 58	g01546835
Cut The Weld For The Side Plate.

2. Remove the bottom plate from the boom foot. Cut the weld on the side plate. Refer to Illustration 57. Make sure that the side plates are not damaged by the cut. Refer to Illustration 58. The bottom plate may be destroyed from the process. Refer to Illustration 44 for the dimensions in order to fabricate a new bottom plate.

   Note: Make sure that the crack does not extend into the ear of the casting for the boom foot.

3. Cut the remaining welds from the bottom plate on the right side of the boom. Refer to Illustration 58. Position the boom so that the left side is up. Cut the remaining welds from the bottom plate on the left side of the boom. Make sure that the side plates for the boom are not damaged during this process.

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Illustration 59	g01562902
Cut The Bottom Plate From The Casting For The Boom Foot.

4. Position the boom so that the bottom plate is up. Cut the cross weld at the weld joint for the center section of the bottom plate. A backup strip is located under this weld joint. Cut the weld at the weld joint between the bottom plate and the casting for the boom foot. Refer to Illustration 59.

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Illustration 60	g01542075
Access For The Baffle Plate From The Boom Foot (AU) Crack locations

5. Inspect and repair the welds on the rear side of the baffle plate. Refer to Illustration 60. Repeat Step 3.a through Step 3.g if any weld is cracked or if the baffle plate is loose. Refer to Illustration 23.

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Illustration 61	g01566393

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Illustration 62	g01546893
V-Groove On The Side Plate Inside The Boom

6. Position the boom with the inside of the left side plate in the horizontal position. Remove the backup strip on the cracked boom foot. Gouge out the crack on the plate that is located on the inside of the boom. Gouge out approximately 10 mm (0.4 inch) of the plate thickness. Weld the V-groove and grind the weld smooth. Needle peening is recommended in order to stress relieve the weld joint.

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Illustration 63	g01566397

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Illustration 64	g01571243
Gouge Out The Weld On The Side Plate Of The Boom.

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Illustration 65	g01546894
V-Groove On The Side Plate Outside The Boom

7. Reposition the boom with the outside of the left side plate horizontally for the gouging and the welding. Gouge out the entire vertical weld. Refer to Illustration 64. Gouge out 50 mm (2.0 inch) beyond the end of the crack. Use the marks from the heat as a guide for the weld on the inside of the boom. Refer to Illustration 65. Cut a 25 degree bevel on the casting and on the side plate.

8. For repairs of the cracks in the opposite side plate, use the mirror image procedure.

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Illustration 66	g01548657
Weld On The Side Plate At The Boom Foot

9. Lift the boom nose in order to make sure that the welding is done in the horizontal position. Refer to Illustration 66. Weld the V-groove and grind the weld smooth. Needle peening is recommended in order to stress relieve the weld joint.

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Illustration 67	g01565055
Grind The Bevel On The Side Plate.

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Illustration 68	g01542077
Bevel On The Bottom Plate And On The Side Plate (AV) 25 degree bevel (AW) 45 degree bevel

10. Prepare the exposed plate and the edges of the casting for the receipt of a new bottom plate. Grind 45 degree bevels that are 13 mm (0.5 inch) deep on the rear section of the side plate. Refer to Illustration 67. Position the boom so that the bottom side is up. Grind the edges of the center section on the bottom plate. Grind a 25 degree bevel that is 15 mm (0.6 inch) deep. Grind a flat on the bevels that is approximately 3 mm (0.1 inch). Refer to Illustration 68.

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Illustration 69	g01542256
Repair Of The Casting For The Boom Foot

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Illustration 70	g01565073
Grind The Repair Weld Smooth.

11. Position the boom so that the bottom plate is up. Weld the casting for the boom foot in order to fill any holes, gouges, or gaps. Grind the welds on the casting flush for an improved weld joint with the bottom plate. Refer to Illustration 69 and Illustration 70.

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Illustration 71	g01562553
(1) Weld the backup strip. (2) Build up the side plates with weld passes before welding the bottom plate. (3) Grind the edges smooth and straight.

12. The final preparation for the installation of the new bottom plate is inspection and repair of the weld joints. Inspect all edges and surfaces. Make any necessary repairs. Build up of the edge with weld beads in order to produce a flush weld joint, if necessary. Grind the weld smooth. Make sure that there are no gaps in the weld joints for the new bottom plate and the side plates.

    Note: Make sure that the weld joint is flush between the center section of the side plates and the fabricated bottom plate. Build up the side plates with weld beads. Grind the weld smooth in order to create a weld joint that is flush if the side plates were damaged during the removal of the bottom plate. Use a backup strip, if necessary. Refer to Illustration 71.

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Illustration 72	g01542273
Fabricated Bottom Plate (BA) 850 mm (33.5 inch) (BC) 20 mm (0.7 inch) Radius (BD) 1000 mm (39.4 inch) Radius (BE) 500 mm (19.7 inch) (BF) 2 mm (0.1 inch) Maximum (BG) 25 degrees + 5 degrees − 2 degrees (BH) 14 mm (0.6 inch) (BK) 119.6 mm (4.71 inch) (BL) 1528 mm (60.2 inch) (BM) 179.6 mm (7.07 inch)

13. Fabricate the bottom plate that is shown in Illustration 72.

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Illustration 73	g01534495
Backup Strip (X) 429 mm (16.9 inch) (Y) 25 mm (1.0 inch) (Z) 10 mm (0.4 inch)

14. Fabricate the backup strip that is shown in Illustration 73.

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Illustration 74	g01536793
Alignment Of The Backup Strip

15. Use clamps in order to make sure that the backup strips are flush with the side plate. Make sure that there is less than a 0.5 mm (0.02 inch) gap between the backup strip and the parent material of the side plate in the center section. Misalignment of the backup strip will severely reduce the life of the structure. Refer to Illustration 74.

    Note: Tack weld the backup strips with three 3 mm (0.12 inch) fillet welds that are 20 mm (0.8 inch) long on the V-groove side of the backup strip. Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip.

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Illustration 75	g01565335
(BR) Tack weld

16. Use a magnet or a suitable lifting device and position the new bottom plate on the boom. Make sure that the root opening is a minimum of 3 mm (0.1 inch) and a maximum of 10 mm (0.4 inch). Make sure that there are no gaps between the backup strip and the bottom plate. Tack weld the plate securely in the seam of the root opening with high quality welds. Refer to Illustration 75.

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Illustration 76	g01542716
Vertical Clamp For The Bottom Plate At The Boom Foot

17. Clamp the bottom plate vertically along the boom in order to eliminate gaps between the new bottom plate and the side plates. Clamp from the middle of the boom toward the boom nose. Refer to Illustration 76.

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Illustration 77	g01542722
Tack Welds (BR) Tack weld

18. Tack weld the new bottom plate with both side plates. Begin at the weld joint for the center section and make the tack welds toward the boom foot. Remove the clamps. Refer to Illustration 77.

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Illustration 78	g01542695
Bottom Plate At The Boom Foot (BR) Tack weld (BS) Root opening

19. Reposition the boom with the weld joint between the new bottom plate and the casting for the boom foot in the horizontal position. Clamp the new bottom plate with the casting for the boom foot in order to eliminate any gaps. Tack weld the new bottom plate with the casting for the boom foot. Tack weld the plate with 3 mm (0.12 inch) fillet welds that are 20 mm (0.8 inch) long. Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip.

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Illustration 79	g01565473
Weld The Bottom Plate At The Boom Foot.

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Illustration 80	g01542723
Weld For The Bottom Plate At The Boom Foot

20. Finish weld the joint between the bottom plate and the casting for the boom foot. Finish the surfaces with a smooth grind. Needle peening on the weld toe is recommended for the maximum life of the structure.
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    Table 6

    Weld Specifications
    Item	Description
    W5	16 mm (0.6 inch) fillet weld

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Illustration 81	g01565493
Weld The Bottom Plate At The Center Section Of The Boom.

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Illustration 82	g01542724
Weld For The Bottom Plate At The Center Section Of The Boom. (BW) 3 mm (0.1 inch) Minimum

21. Finish weld the cross weld at the center section of the boom. Allow the welded area to cool between passes. The weld in the root is continuous over the tack welds. No stops are allowed. Make sure that the tie-in welds for both of the top plates and the bottom plates are good. Grind the weld toe smooth.
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    Table 7

    Weld Specifications
    Item	Description
    W6	15 mm (0.6 inch) V-groove weld

    Note: Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip. Do not exceed the 20 mm (0.8 inch) length.

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Illustration 83	g01565654

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Illustration 84	g01572273
Weld The Bottom Plate And The Side Plate.

22. Position the boom so that the right side is horizontal. Make a root pass and finish weld the joint between the side plate and the bottom plate. Refer to Illustration 84. Refer to Table 3 for the weld specifications. Weld (W4) length CA-BX and CB-BY. Allow the welded area to cool between passes. Make all welds in the horizontal position. Raise the boom nose in order to keep the weld horizontal. Grind the toe of the weld smooth. Needle peening is recommended for the maximum life of the structure.

23. Position the boom so that the left side is horizontal. Repeat the instructions from Step 22.

24. Grind the cross welds flush when the repair welds are completed. The weld joints for the cross welds should not be noticeable.

Procedure for the Repair of a Type D Crack in the Vertical Seam at the Side Plates at the Boom Foot Extending into the Top or Bottom Plates

This procedure describes the repair procedure of a crack at the boom foot that extends into the bottom plate. Use the procedure from the section ""Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate" " in this document. The cracks should be repaired by the same procedure.

The replacement of the top plate will be necessary if the crack extends into the top plate. Use the procedure from the section ""Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate" " in this document. The cracks should be repaired by the same procedure except for the fabrication of a new top plate. Refer to Illustration 85.

If a severe crack in the side plate extends into the top plate or the bottom plate, contact the Product Support Group. Provide the information from the machine profile that is shown in Illustration 12. The examples that follow describe a severe crack:

• The crack extends through half of the width for the top plate or the bottom plate.

• The crack has opened and the two plates have separated.

If the top plate and the bottom plate are cracked, the replacement of both plates is not recommended. The replacement of both plates increases the risk of distortion in the structure. The preferred procedure is for the replacement of the plate with the most severe crack and the repair of the remaining plate.

Use the following procedure for the replacement of the top plate.

1. Remove the top plate. Use the same procedure that was described for the removal of the bottom plate in the section ""Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate" " in this document. Use the same procedure that was described in Step 2 through Step 15.

2. Repair the crack on the side plate and the bottom plate. Use the same procedure that was described in Step 16 through Step 9 in the section ""Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate" " of this document.

3. Grind the bevel on the area that was cut on the boom. Use the same procedure that was described in Step 20 through Step 21 in the section ""Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate" " of this document.

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Illustration 85	g01571914
Fabricated Top Plate (BA) 850 mm (33.5 inch) (BC) 20 mm (0.7 inch) Radius (BD) 1000 mm (39.4 inch) Radius (BE) 500 mm (19.7 inch) (BF) 2 mm (0.1 inch) Maximum (BG) 25 degrees + 5 degrees − 2 degrees (BH) 14 mm (0.6 inch) (BK) 119.6 mm (4.71 inch) (BL) 1528 mm (60.2 inch) (BM) 179.6 mm (7.07 inch)

4. Fabricate a new top plate. Refer to Illustration 85.

5. Fabricate a new backup strip. Refer to Illustration 73.

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Illustration 86	g01625643
Weld The New Top Plate On The Boom. (B) 3 mm (0.1 inch) Minimum

6. Install the new top plate. Use the same procedure that was described in Step 22 through Step 23 in the section ""Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate" " of this document. Weld the new plate. Refer to Illustration 126. Weld (W4) length F-L and J-M in two places. Refer to Table 8 for the weld specification.
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   Table 8

   Weld Specification
   Item	Description
   W4	13 mm (0.5 inch) bevel weld over a 16 mm (0.6 inch) fillet weld (2 places)
   W7	18 mm (0.7 inch) V-groove weld

Procedure for the Repair of a Type E Crack in the Vertical Seam at the Side Plate and the Casting at the Boom Foot

The following information describes the repair procedure for cracks that extend from the side plate into the casting for the boom foot. The repair procedure is for cracks that extend a maximum of 38 mm (1.5 inch) into the casting. The procedure describes the steps for a crack on the right side of the boom. Use the same procedure in order to repair a similar crack on the left side of the boom.

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Illustration 87	g01549353
Maximum Crack In The Casting (A) 38 mm (1.5 inch) Maximum

1. Position the boom with the right side horizontal on suitable repair stands. The approximate weight of a boom is 3401 kg (7500 lb) to 4309 kg (9500 lb). Position the boom with the surface for repair as level as possible.

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Illustration 88	g01549395
Vertical Welds (B) Weld between the side plate and the casting (C) Weld between the side plate and plate for the center section

2. Gouge out vertical weld (B) and vertical weld (C) between the top plate and the bottom plate. Refer to Illustration 88. Make sure that the top plate and the bottom plate are not gouged out.

3. Gouge out the weld between the top plate and the side plate. Gouge out the weld between the bottom plate and the side plate. Make sure that the top plate and the bottom plate are not gouged out. Remove the side plate.

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Illustration 89	g01556933
Section Of The Casting For The Boom Foot (A) 30 mm (1.2 inch) Maximum (E) 18 mm (0.7 inch) (F) 7 mm (0.3 inch) (G) 25 degrees + 5 degrees − 2 degrees (H) 275 ± 0.5 mm (10.8 ± 0.02 inch) (J) 120.05 mm (4.726 inch)

4. Inspect the crack on the inside surface of the casting. Cut the crack from the casting. Make sure that the crack does not extend beyond the maximum of 38 mm (1.5 inch) into the casting. Cut a 25 degree bevel on the casting. Refer to Illustration 89.

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Illustration 90	g01557293
Measurement Of The Opening (L) Width (M) Length

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Illustration 91	g01624451
Fabricated Side Plate (R) 1324.9 mm (52.16 inch) Nominal dimension (S) 650.7 mm (25.62 inch) (U) Bend (V) 50 mm (2 inch) Radius (AA) 20 mm (0.8 inch) (CC) 25 degrees + 5 degrees − 2 degrees (FF) 2 mm (0.1 inch) Maximum (HH) 1350 mm (53.1 inch) Nominal dimension (JJ) 1085.7 mm (42.74 inch) Nominal dimension (KK) 8.2 degrees reference dimension (LL) 155.8 mm (6.13 inch) Nominal dimension (NN) Length that was removed from the casting (PP) 315.1 mm (12.41 inch) after forming

Note: The length (NN) of the material that was removed from the casting is added on the length of the new plate. Cut the new plate longer than measurement (R). Grind the new plate to the final length for the best fit of the weld joint.

5. Fabricate a new side plate. Measure the dimensions for the new side plate. Refer to Illustration 90 and Illustration 91. Add the amount of the casting that was removed to the length of the new side plate. Make sure that the root opening is a minimum of 3 mm (0.1 inch). Make sure that the root opening is a maximum of 10 mm (0.4 inch). Refer to Table 2 for the dimensional tolerances for the plate. Refer to Table 9 for the calculated data of the bend.

   Note: Make sure that the measurement (L) and measurement (M) are confirmed before fabricating a new side plate. Refer to Illustration 90. Make sure that the measurements allow a gap in the root of the weld.

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   Table 9

   Calculated Data For The Bend
   Description	Item	Dimension
   Development length	X-Z	1324.9 mm (52.16 inch)
   Straight length	XY	224.6 mm (8.84 inch)
   Angle	Y	8.2 degrees
   Length of the arc	Y	8.1 mm (0.32 inch)
   Straight length	Y-Z	1092.2 mm (43.0 inch)

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Illustration 92	g01559755
Backup Strip (SS) 10 mm (0.4 inch) (TT) 25.0 mm (1 inch) (UU) 3.2 mm (0.13 inch) (WW) 652.4 mm (25.69 inch)

6. Fabricate a new backup strip. The backup strip is used in the weld joint between the plate for the center section and the new side plate. Refer to Illustration 92.

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Illustration 93	g01559773
Backup Strip (SS) 10 mm (0.4 inch) (TT) 25.0 mm (1 inch) (XX) 3.2 mm (0.13 inch) (YY) 315.7 mm (12.43 inch)

7. Fabricate a new backup strip. The backup strip is used in the weld joint between the casting for the boom foot and the new side plate. Refer to Illustration 93.

   Note: Cut the backup strips longer than measurement (WW) or (YY). Grind the backup strips to the final length for the best fit of the weld joint. The dimensions that are shown in Illustration 92 and Illustration 93 are for reference. Actual measurements of the weld joints will provide the most accurate dimensions for the length and the width.

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Illustration 94	g01536793
Alignment Of The Backup Strip

8. Use clamps in order to make sure that the backup strips are flush with the side plate. Make sure that there is less than a 0.5 mm (0.02 inch) gap between the backup strip and the parent material of the side plate in the center section. Misalignment of the backup strip will severely reduce the life of the structure. Refer to Illustration 94.

   Note: Tack weld the backup strips with three 3 mm (0.12 inch) fillet welds that are 20 mm (0.8 inch) long on the V-groove side of the backup strip. Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip.

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Illustration 95	g01577193
Tack Weld The New Side Plate. (B) Weld between the side plate and the casting (C) Weld between the side plate and plate for the center section (ZZ) Tie-in welds for the top plate and the bottom plate (AAA) No tack weld

9. Use a magnet or a suitable lifting device and position the new side plate on the boom. Position the new plate with a 3 mm (0.1 inch) root opening at weld joint (B) and weld joint (C). Use high quality welds and tack weld the new side plate at the root of weld joint (B) and weld joint (C). Clamp vertically along the boom in order to make sure that there are no gaps between the new side plate, the top plate, and the bottom plate. Tack weld the weld joint between the new side plate and the top plate. Do not tack weld the weld joint between the new side plate and the bottom plate. Weld the tie-in welds for weld joint (B) and weld joint (C) into the top plate and into the bottom plate. Refer to Illustration 95.

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Illustration 96	g01577273
Weld Joint Between The Casting And The New Side Plate (BBB) 3 mm (0.1 inch) Minimum

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Illustration 97	g01577293
Weld Joint Between The Plate In The Center Section And The New Side Plate (BBB) 3 mm (0.1 inch) Minimum

10. Finish weld root passes in weld joint (B) and weld joint (C). Allow the welded area to cool between passes. The weld in the root is continuous over the tack welds. No stops are allowed. Make sure that the tie-in welds for both of the top plates and the bottom plates are good. Refer to Illustration 96 and Illustration 97. Refer to Table 10 for weld specifications.
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    Table 10

    Weld Specifications
    Item	Description
    W8	20 mm (0.8 inch) V-groove weld
    W9	16 mm (0.6 inch) V-groove weld

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Illustration 98	g01578553
Grind A Transition. (B) Weld between the side plate and the casting (C) Weld between the side plate and plate for the center section (CCC) Grind the transition flush. (DDD) No weld and no grind for a transition

11. Grind a 30 mm (1.2 inch) transition for weld (B) and weld (C) tie into the top plate.

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Illustration 99	g01578614
Weld Passes

12. Finish welding the weld joint between the new side plate and the top plate. Refer to the data for the weld passes in Illustration 99. Do not weld the weld joint between the new side plate and the bottom plate. Allow the welded area to cool between passes. Grind the toe of the weld in order to smooth the surface. Needle peening is recommended for maximum service life.

13. Grind the toe of weld (B) and weld (C) in order to smooth the surface.

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Illustration 100	g01546835
Cut The Weld For The Side Plate.

14. Remove the bottom plate in order to achieve a weld with full penetration at the casting for the boom foot. Cut the remaining welds from the bottom plate on the right side of the boom. Refer to Illustration 100. Position the boom so that the left side is up. Cut the remaining welds from the bottom plate on the left side of the boom. Make sure that the side plates for the boom are not damaged during this process.

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Illustration 101	g01562902
Cut The Bottom Plate From The Casting For The Boom Foot.

15. Position the boom so that the bottom plate is up. Cut the cross weld at the weld joint for the center section of the bottom plate. A backup strip is located under this weld joint. Cut the weld at the weld joint between the bottom plate and the casting for the boom foot. Refer to Illustration 101.

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Illustration 102	g01542075
Access For The Baffle Plate From The Boom Foot (AU) Crack locations

16. Inspect and repair the welds on the rear side of the baffle plate. Refer to Illustration 102. Repeat Step 3.a through Step 3.g if any weld is cracked or if the baffle plate is loose. Refer to Illustration 23.

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Illustration 103	g01566393
Remove The Backup Strip.

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Illustration 104	g01578895
Gouge A 30 Degree Bevel.

17. Position the boom in order to remove the new backup strip between the side plate and the casting for the boom foot. Gouge out weld (B) from the plate that is located on the inside of the boom. Gouge out approximately 10 mm (0.4 inch) of the plate thickness. Gouge out a V-groove that has a 30 degree bevel on the sides. Weld the V-groove weld and grind the weld smooth. Refer to Illustration 103 and Illustration 104.

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Illustration 105	g01542273
Fabricated Bottom Plate (BA) 850 mm (33.5 inch) (BC) 20 mm (0.7 inch) Radius (BD) 1000 mm (39.4 inch) Radius (BE) 500 mm (19.7 inch) (BF) 2 mm (0.1 inch) Maximum (BG) 25 degrees + 5 degrees − 2 degrees (BH) 14 mm (0.6 inch) (BK) 119.6 mm (4.71 inch) (BL) 1528 mm (60.2 inch) (BM) 179.6 mm (7.07 inch)

18. Fabricate the bottom plate that is shown in Illustration 105.

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Illustration 106	g01534495
Backup Strip (X) 424 mm (16.7 inch) (Y) 25 mm (1.0 inch) (Z) 10 mm (0.4 inch)

19. Fabricate the backup strip that is shown in Illustration 106.

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Illustration 107	g01565055
Grind The Bevel On The Side Plate.

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Illustration 108	g01542077
Bevel On The Bottom Plate And On The Side Plate (AV) 25 degree bevel (AW) 45 degree bevel

20. Prepare the exposed plate and the edges of the casting for the receipt of a new bottom plate. Grind 45 degree bevels that are 13 mm (0.5 inch) deep on the rear section of the side plate. Refer to Illustration 107. Position the boom so that the bottom side is up. Grind the edges of the center section on the bottom plate. Grind a 25 degree bevel that is 15 mm (0.6 inch) deep. Grind a flat on the bevels that is approximately 3 mm (0.1 inch). Refer to Illustration 108.

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Illustration 109	g01542256
Repair Of The Casting For The Boom Foot

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Illustration 110	g01565073
Grind The Repair Weld Smooth.

21. Position the boom so that the bottom plate is up. Weld the casting for the boom foot in order to fill any holes, gouges, or gaps. Grind the welds on the casting flush for an improved weld joint with the bottom plate. Refer to Illustration 109 and Illustration 110.

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Illustration 111	g01562553
(1) Weld the backup strip. (2) Build up the side plates with weld passes before welding the bottom plate. (3) Grind the edges smooth and straight.

22. The final preparation for the installation of the new bottom plate is inspection and repair of the weld joints. Inspect all edges and surfaces. Make any necessary repairs. Build up of the edge with weld beads in order to produce a flush weld joint, if necessary. Grind the weld smooth. Make sure that there are no gaps in the weld joints for the new bottom plate and the side plates.

    Note: Make sure that the weld joint is flush between the center section of the side plates and the fabricated bottom plate. Build up the side plates with weld beads. Grind the weld smooth in order to create a weld joint that is flush if the side plates were damaged during the removal of the bottom plate. Use a backup strip, if necessary. Refer to Illustration 111.

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Illustration 112	g01536793
Alignment Of The Backup Strip

23. Use clamps in order to make sure that the backup strips are flush with the side plate. Make sure that there is less than a 0.5 mm (0.02 inch) gap between the backup strip and the parent material of the side plate in the center section. Misalignment of the backup strip will severely reduce the life of the structure. Refer to Illustration 112.

    Note: Tack weld the backup strips with three 3 mm (0.12 inch) fillet welds that are 20 mm (0.8 inch) long on the V-groove side of the backup strip. Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip.

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Illustration 113	g01565335
(BR) Tack weld

24. Use a magnet or a suitable lifting device and position the new bottom plate on the boom. Make sure that the root opening is a minimum of 3 mm (0.1 inch) and a maximum of 10 mm (0.4 inch). Make sure that there are no gaps between the backup strip and the bottom plate. Tack weld the plate securely in the seam of the root opening with high quality welds. Refer to Illustration 113.

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Illustration 114	g01542716
Vertical Clamp For The Bottom Plate At The Boom Foot

25. Clamp the bottom plate vertically along the boom in order to eliminate gaps between the new bottom plate and the side plates. Clamp from the middle of the boom toward the boom nose. Refer to Illustration 114.

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Illustration 115	g01542722
Tack Welds (BR) Tack weld

26. Tack weld the new bottom plate with both side plates. Begin at the weld joint for the center section and make the tack welds toward the boom foot. Remove the clamps. Refer to Illustration 115.

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Illustration 116	g01542695
Bottom Plate At The Boom Foot (BR) Tack weld (BS) Root opening

27. Reposition the boom with the weld joint between the new bottom plate and the casting for the boom foot in the horizontal position. Clamp the new bottom plate with the casting for the boom foot in order to eliminate any gaps. Tack weld the new bottom plate with the casting for the boom foot. Tack weld the plate with 3 mm (0.12 inch) fillet welds that are 20 mm (0.8 inch) long. Do not tack weld 50 mm (2.0 inch) from the ends of the backup strip.

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Illustration 117	g01565473
Weld The Bottom Plate At The Boom Foot.

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Illustration 118	g01542723
Weld For The Bottom Plate At The Boom Foot

28. Finish weld the joint between the bottom plate and the casting for the boom foot. Finish the surfaces with a smooth grind. Needle peening on the weld toe is recommended for the maximum life of the structure.
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    Table 11

    Weld Specifications
    Item	Description
    W5	16 mm (0.6 inch) fillet weld

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Illustration 119	g01565493
Weld The Bottom Plate At The Center Section Of The Boom.

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Illustration 120	g01542724
Weld For The Bottom Plate At The Center Section Of The Boom. (BW) 3 mm (0.1 inch) Minimum

29. Finish weld the cross weld at the center section of the boom. Allow the welded area to cool between passes. The weld in the root is continuous over the tack welds. No stops are allowed. Make sure that the tie-in welds for both of the top plates and the bottom plates are good. Grind the weld toe smooth. Needle peening is recommended for maximum service life.
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    Table 12

    Weld Specifications
    Item	Description
    W6	15 mm (0.6 inch) V-groove weld

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Illustration 121	g01579083
Grind The Transition Flush. (B) Weld between the side plate and the casting (C) Weld between the side plate and plate for the center section (CCC) Grind the transition flush.

30. Position the boom with the left side horizontal. Grind the start and the stop of weld (B) and weld (C). Grind a 30 mm (1.2 inch) transition for each tie-in weld. The uniform transition provides improved appearance. Needle peening is recommended for maximum service life.

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Illustration 122	g01565654

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Illustration 123	g01625692

31. Weld the root passes for the weld joint between the new side plate and the new bottom plate. Refer to Illustration 122 and Illustration 123. Allow the welded area to cool between passes. Grind the toe of the weld in order to smooth the surface. Needle peening is recommended for maximum service life.
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    Table 13

    Weld Specification
    Item	Description
    W4	13 mm (0.5 inch) bevel weld over a 16 mm (0.6 inch) fillet weld (2 places)

32. Position the boom with the right side horizontal. Grind a 30 mm (1.2 inch) transition for each tie-in weld. Weld the root passes for the weld joint between the new side plate and the new bottom plate. Refer to Illustration 122 and Illustration 123. Allow the welded area to cool between passes. Grind the toe of the weld in order to smooth the surface. Needle peening is recommended for maximum service life.

    The following activities should be considered after the repair procedures are complete:

    • The installation of reinforcement plates should be seriously considered. Especially consider the side of the boom that had part of the casting for the boom foot removed. Reinforcement plates should be installed if the machine returns to a severe application.

    • The locations of the bores should be remachined. During repair, the boom experiences large amounts of heat. Distortion occurs from the heat. The dimensions should be verified.

    • Stress relief should be considered. Needle peening provides a measure of stress relief. Needle peening is localized for the weld area. The entire boom would benefit greatly from stress relief in a furnace.

    • Consider shot blasting and painting the boom. Make sure that the bores and the machined surfaces are properly protected.

Procedure for the Repair of a Type F Crack in the Vertical Seam at the Side Plate and the Casting at the Boom Foot and Extending into the Top or Bottom Plate

This procedure describes the repair procedure for cracks that extend into both the casting for the boom foot and on the top or the bottom plate. Use the information from the section ""Procedure for the Repair of a Type E Crack in the Vertical Seam at the Side Plate and the Casting at the Boom Foot" " in this document. The cracks should be repaired by the same procedure.

If a severe crack in the casting for the boom foot extends into the top plate or the bottom plate, contact the Product Support Group. Provide the information from the machine profile that is shown in Illustration 12. The examples that follow describe a severe crack:

• The crack extends through half of the width for the top plate or the bottom plate.

• The crack has opened and the two plates have separated.

Replace the top plate if the severe crack extends into the casting for the boom foot and into the top plate. Do not replace the bottom plate. Use the same procedure that was described for the removal and the replacement of the top plate in the section ""Procedure for the Repair of a Type E Crack in the Vertical Seam at the Side Plate and the Casting at the Boom Foot" " of this document. Additional information is listed in the procedure that follows. Do not replace both the top and the bottom plate at the same time. There is a great risk of distortion in the structure. Distortion will cause the loss of the dimensional relationships. Repair the smaller crack first. Gouge out the smaller crack from the plate on the outside of the boom. Weld the gouged out area. Grind the weld smooth. Gouge out the crack from the inside. Weld the gouged out area after an access hole has been cut. Complete the weld and grind the welds flush for the maximum life of the structure.

1. Repair the casting for the boom foot. Install a new side plate. Refer to Step 1 through Step 10 in the section ""Procedure for the Repair of a Type E Crack in the Vertical Seam at the Side Plate and the Casting at the Boom Foot" " of this document.

2. Remove the top plate. Refer to the section ""Procedure for the Repair of a Type E Crack in the Vertical Seam at the Side Plate and the Casting at the Boom Foot" " of this document.

3. If the bottom plate is cracked, refer to Step 3 and Step 4 in the section ""Procedure for the Repair of a Type A Vertical Crack in the Side Plate of the Center Section at the Rear Baffle Plate" " of this document.

4. Clean the side plates at the boom foot. Grind a bevel on the side plates at the boom foot. Refer to Step 20 through Step 22 in the section ""Procedure for the Repair of a Type E Crack in the Vertical Seam at the Side Plate and the Casting at the Boom Foot" " of this document.

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Illustration 124	g01542273
Fabricated Bottom Plate (BA) 850 mm (33.5 inch) (BC) 20 mm (0.7 inch) Radius (BD) 1000 mm (39.4 inch) Radius (BE) 500 mm (19.7 inch) (BF) 2 mm (0.1 inch) Maximum (BG) 25 degrees + 5 degrees − 2 degrees (BH) 14 mm (0.6 inch) (BK) 119.6 mm (4.71 inch) (BL) 1528 mm (60.2 inch) (BM) 179.6 mm (7.07 inch)

5. Fabricate a new top plate. Refer to Illustration 124.

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Illustration 125	g01534495
Backup Strip (X) 429 mm (16.9 inch) (Y) 25 mm (1.0 inch) (Z) 10 mm (0.4 inch)

6. Fabricate a new backup strip. Refer to Illustration 125.

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Illustration 126	g01625643
Weld The New Top Plate On The Boom. (B) 3 mm (0.1 inch) Minimum

7. Install the new top plate. Refer to Step 20 through Step 32 in the section ""Procedure for the Repair of a Type E Crack in the Vertical Seam at the Side Plate and the Casting at the Boom Foot" " of this document.