What is seam welding?

Seam welding is a welding technique in which two similar or dissimilar metals are connected by electric current and a nugget formation is formed in the process.Mostly,these nuggets are formed in the form of butt or the overlapping welding components.Seam welding is one of the types of resistance welding.

DN1050 large diameter custom bend with seam welding and girth welding

Types of seam welding:

Seam welding can be divided in two main categories namely:continuous motion seam welding and intermittent motion seam welding.

Continuous motion seam welding:

In the continuous motion method of seam welding the electrodes are rotated at a predetermined constant speed and the current impulses timed to get an overlapping weld. Alternatively the work pieces may be moved at constant speed with the electrodes idling under the welding pressure.

Intermittent motion seam welding:

In the intermittent method the work pieces move till the weld position stop for the welding to take place automatically move to the next weld position, stop again for welding and so on. This method is suitable for seam welding in thicker sheets which are too thick to be properly welded by the continuous motion method.

Ultrasonic nondestructive testing for large diameter 90 degree elbow welds

Types of seam welding joint:

The common types of seam welding joint are:lap seam weld(common type weld) and butt seam weld.

Lap seam weld:

The type of weld in which the two workpieces slightly overlap along the edges is called as lap seam weld.The overlapping metal is mashed and welded at the same time.

Butt seam weld:

The type of welding in which the edges of sheets are joined and welded to form a butt joint is called as butt seam welding. This technique is mainly used for manufacturing of welded pipes. An electric current is used to heat the metal in the weld zone.

Weld for large diameter elbow

Advantages of seam welding:

• This welding is a quicker process than spot welding.
• It is a continuous welding technique suitable for gas & liquid tight containers.
• Energy is utilized efficiently in this technique.
• This technique is ideal for making gas or liquid tight vessels.
• It doesn’t need the use of filler material.
• No pollutions like fumes of gases because filler material is not utilized.
• This technique can produce liquid tight & gas-tight joints.
• Since the joint is forged due to heat & pressure, a durable weld is formed in seam welding.
• This welding is easy to operate.
• Seam welding gives sturdy design & excellent performance.

Disadvantages of seam welding:

• Requires complex control system to regulate the ravel speed of electrodes as well as the sequence of current to provide satisfactory overlapping welds. The welding speed, spots per inch and timing schedule are all dependent on each other
• Difficult to weld metals having thickness greater than 3mm
• Relatively higher current is thus required for seam welding than for spot welding.
• The work pieces to be welded are over lapped sufficiently to prevent metal flowing out from the edges of the pieces during welding under pressure.

Large-diameter automatic welding elbows finished in Haihao Group

Applications of seam welding:

1. Used to fabricate liquid or gas tight sheet metal vessels such as gasoline tanks, automobile mufflers and heat exchangers.

2. The production of seam welded pipes and tubing (butt seam weld).

Haihao Group manufacture steel pipes,butt welding pipe fittings,forged pipe fittings and flanges more than 30 years,recently our company do nondestructive testing of welds,the methods contain ultrasonic testing,magnetic particle testing,penetrant testing and radiographic testing.If you want to know more about our products,please email us:sales@haihaogroup.com