Page 184 - CITS - Welder - Trade Practical

WELDER - CITS

EXERCISE 46 : Pipe joints

Objectives
At the end of this exercise you shall be able to
• explain the advantages of welded pipes
• state different methods of pipes welding
• explain the types of pipe joint and pipe welding positions
• describe the methods of welding pipes in ‘1G’ position.

Job Sequence

Specification of Pipes

• In a pipe its size is measured by nominal diameter (or) nominal outside diameter (OD).
• It is also mentioned as nominal pipe size (NPS).
• Pipe is normally used to transport gases or liquids in a process.
• Tube is normally used for standard purpose and it is mentioned as outside diameter and its wall thickness as
tube.
• As per Indian standard 1161-1998, it is specified as steel tubes of nominal force, and thickness having outside
diameter in mm under light, medium and heavy class. Refer Table 1 as per IS 1161:1998.

Welded pipe joints
• Pipes of all types and sizes are used in great deal today in transporting oil, gas, water etc. They are also used
extensively for piping systems in building, refineries and industrial plants.

Advantages of welded pipe
Pipes are mostly made of ferrous and non-ferrous metals and their alloys. They possess the following advantages.
– Improved overall strength.
– Ultimate saving in cost including maintenance.

– Improved flow characteristics.
– Reduction in weight due to its compactness.
– Good appearance.
Method of pipes welding
The following are the methods of pipe welding by arc.
– Metallic arc welding

– Gas metal arc welding
– Tungsten inert gas welding
– Submerged arc welding
– Carbon arc welding

All these methods, except carbon arc welding are commonly used and the choice of welding depends upon the
size of the pipe and its application.
Types of pipe joints

1 Butt joint
2 ‘T’ joint

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