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FORGE BONDING: A PROCESS

SAFER THAN HOT WORK

Prepared By : SAGAR PATELGuide : Dr. NITIN V. BHATE

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INTRODUCTION Forge welding is a solid-state welding process that joins two

pieces of metal by heating them to a high temperature and then joins by means of applying pressure in form of hammering or any other means.

This technique is actually a FRICTION WELDING or FRICTION STIR WELDING.

Friction stir welding (FSW) produces welds by using a rotating, non consumable welding tool to locally soften a work piece, through heat produced by friction and plastic work, thereby allowing the tool to “stir” the joint surfaces.

Lohwasser D. , Chen z. ‘Friction stir welding From basics to applications’

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A BRIEF HISTORY In late 1991 this welding method was conceived at TWI (The Welding

Institute).

The process was duly named friction stir welding (FSW), and TWI filed for world-wide patent protection in December of that year.

TWI is a world famous institute in the UK that specializes in materials joining technology.

Compared to conventional friction welding, FSW uses a rotating tool to generate the necessary heat for the process.

FSW is a process that can be automated. It is also a cleaner and more efficient process compared to conventional techniques.

Lohwasser D. , Chen z. ‘Friction stir welding From basics to applications’

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CURRENT WELDING PRACTICES IN INDUSTRIES In chemical industries like petrochemical industries, refineries, spark or

source of ignition is strictly prohibited. There are so many examples of fire caused during HOT WORK carried out in industries.

WHAT IS HOT WORK ? Hot work is an operation that can produce a spark or flame or other

source of ignition having sufficient energy to cause ignition. Also during leaks from pipelines, valves method used to rectify it is

ONLINE SEALING or CLAMPING. WHAT IS ONLINE SEALING ? The injecting online leak sealing is a technique to prevent leakage of

materials, while installing special clamps at the leaking parts & by inject sealant to the cavity and full the entire space, finally become a new structure to plug the leak paths.

Safe Welding, Cutting, and Other Hot Work Practices in Refineries, Gas Plants, and Petrochemical Plants API PUBLICATION 2009, SIXTH EDITION, SEPTEMBER 1995

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HAZARDS OF HOT WORK Potential hazards while drilling Weak or poorly threaded joint Uncontrolled process releases Temporary reusable Platform Exposures to metal fumes and to ultraviolet (UV) radiation Electric shock Fire and explosions Injuries from insufficient PPE Risk of skin cancer Wrong type of work permit used Wrong information about work required on the work permit Failure to recognise the hazards where work is carried out (e.g. flammable substances) Introduction of ignition source in controlled flameproof area (e.g. welding, non spark-proof tools,

non-intrinsically safe equipment used in intrinsically safe zones) Terms of work permit not adhered to (e.g. failure to isolate plant and/or drain lines of hazardous

substances) Failure to hand-over plant in safe condition on completion of work/cancelling of work permit Unauthorised staff performing work permit functions Poor management of the work permit system Insufficient monitoring of the work permit system Permit to Work Systems, HEALTH AND SAFETY EXECUTIVE

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EXAMPLES OF HOT WORK

Worker busy in welding of pipe Online sealing clamp to prevent

leak

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WORKING PRINCIPLE

Insertion of a non consumable rotating tool with a specially designed pin and shoulder between two plates which we want to weld

Rotation of pin tool

Running of pin tool along the weld joint

Bonding and joining of two metals

Mishra R.S., Ma Z.Y. ‘Friction stir welding and processing’

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ADVANTAGES OF FORGE BONDING Eliminates current drilling hazards Reliably strong, 100% forged joint No added leak points Enhanced corrosion properties Permanent reusable platform The relatively low temperature at which the weld is formed

means that the process can be adapted for applications such as welding on live pipelines and in explosive environments.

The absence of an electric arc and a liquid phase in the metal avoids some of the potential problems encountered with arc welding such as contamination of the weld with hydrogen, nitrogen and oxygen.

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SCHEMATIC DIAGRAM OF LEAK ATTENDING BY APPLICATION OF STUD AND PLATE

‘Valve, pipe and pipe component repair ’, forge tech inc., US 20140216566, 2014

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LEAK ATTENDING PROCEDURE IN VALVES

Drill & Tap Injection Port

Friction Forge Injection Port

Friction Forged Injection Port

Friction Forged Stud

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TESTING METHODS OF FORGE BONDING VISUAL INSPECTION

In this type of testing a person or group of people will examine the quality of weld on the basis of its look and their experience.

RADIOGRAPHY

In this type of testing weld can be examined to verify its internal structure and integrity. Industrial radiography can be performed utilizing either X-rays or gamma rays.

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CASE STUDY-1 National Cooperative Refinery Association (NCRA) - McPherson, Kansas They have leak on roof of storage tank containing gasoline

Prepare the site

Affixing studs

Install 3/16” thick deck plate

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CASE STUDY-2 HARBISON-FISCHER, Crowley, Texas is which specializes in sub-

surface oil field rod pumping processes, had an issue with an integral pump part that was taking too long to create and costing too much to produce.

The part was component of the oil pump that used two dissimilar metals

They had been mechanically joining the assembly by threading and soldering a solid Monel rod on the end of mild steel tubes. Both parts required an independent threading operation (one male external on the Monel and one female internal on the steel tube). After cutting the threads on each of the two separate parts they were then threaded together and brazed to further lock the pieces in place and seal the joint.

The proposed friction welding process would require only a “saw cut” end on each of the two pieces prior to joining and could provide a stronger, leak resistant joint.

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CONCLUSION

Forge Bonding or Friction Stir Welding process is safer than conventional metal joining procedure, which eliminates chances of health and environmental hazards cause due to conventional process and also it is beneficial in metallurgical point of view.

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