MEDICAPS INSTITUTE OF TECHNOLOGY & MANAGEMENT

DEPARTMENT OF MECHANICAL ENGINEERING

PREPARED BY:

SUMIT SHRIVASTAVA SHUBHAM JAWARA RAJPAL SINGH YADAV RAKESH TOMAR SHUBHAM MISHRA

ME-B (BATCH 2013)

OUTLINE

Introduction to Submerged arc welding [SAW]

Process of SAW

Types of SAW

Advantages of SAW

Limitations of SAW

Applications of SAW

INTRODUCTION Submerged arc welding (SAW) is a method in which the heat required to fuse the metal is generated by an arc formed by an electric current passing between the electrode and the workpiece.

There is no visible arc and no sparks, spatter or fume. The electrode may be a solid or cored wire or a strip.

SAW is normally a mechanised process.

PROCESS OF SAW The submerged arc welding flux feeds through the hopper tube and continuously distributes itself over the seam a short distance ahead of the welding zone. The wire feed mechanism begins to feed the welding into the joint at a controlled rate. An electric arc is established as the current flows between the electrode and the work. The carriage is started(manually or automatically) to travel along the seam.

GENERAL SCOPE

Current: the total welding current can range between 100 and 3600 amps.

Wires in one molten pool: from 1 to 6.

Voltage: 20-50 volts.

Speed: 30-350 cm/min.

Deposition rate: 2-100 kg/hr.

TYPES OF SAW

SAW can be employed in five ways

Single Wire

• Single wire welding is the most widely used SAW method.• DC power source is used.• The solid or cored wires of diameter 2.0-4.0 mm are used.• A small diameter produces a higher deposition at the same rate.

TYPES OF SAW

SAW can be employed in five ways

Twin Wire

• For twin wire welding, two wires are connected to the same power source.• DC power source is used• It offers up to 30% higher deposition rates and can be used at higher currents and speeds.• Very high welding speeds can be achieved in fillet welding.

TYPES OF SAW

SAW can be employed in five ways

Tandem

•In tandem sub-arc welding each of the two wires is connected to its own power source and fed simultaneously by its own feed unit.• Both AC and DC source can be used.• The wires are normally large diameter (3.0-5.0 mm) and deposition rates are about twice that of single-wire welding.

TYPES OF SAW

SAW can be employed in five ways

Tandem Twin

•The ESAB tandem-twin process involves two twin wire heads placed in sequence.•Both AC and DC source can be used.•With the use of 4x2.5 mm diameter, wires deposition rates of up to 38 kg/h can be achieved.

TYPES OF SAW

SAW can be employed in five ways

Multi wire

•Up to six wires can be used together, each with their own power source.• The lead wire is usually DC+ polarity with the trailing wires being AC.• Speeds of up to 2.5 m/min can be achieved giving a maximum deposition rate of 90 kg/h.• This technique is particularly suitable for longitudinal pipe welding.

ADVANTAGES OF SAW High quality

Little risk of undercut and porosity

No spatter

Very little risk of lack of fusion due to deep and safe penetration

High deposition rate

High thermal efficiency

No radiation

High welding speeds are possible

LIMITATIONS OF SAW

Precise joint preparation required

No observation of arc and process during welding is possible

High operational effort

It can not be used for plates less than 5mm thickness

Flux is subjected to contamination and adsorbtion of moisture.

Solidification cracking.

Irregular wire feed.

APPLICATIONS OF SAW

This welding method can be used for:-

Fabrication of Boiler Pressure Vessel.

Railroad tank cars.

Structural shapes and cylinders.

Circular welds.

Beam Production.

Ship Building.

Circumferential welding in wind tower fabrication.

Longitudinal pipe welding.

THANKYOU