Page 140 - CITS - Welder - Trade Theory

WELDER - CITS

20 Mechanical testing for welder performance qualification will be normally - Bend test (root bend & face bend or
side bend and number of bends, depending on applicable codes / standard requirements.)

21 The order, location / position of mechanical test specimen cutting and removal shall be as per applicable
specification, code or governing standard.
22 Bend testing shall be performed with required radius of bend (normally bend radius - 2 times the specimen
thickness.)
23 Some standards require only NDT (normally visual and radiography testing) for welder performance
qualification. Some specification requires only mechanical testing (bend test). Some customer require both
NDT and mechanical testing.
6G position arrangement

Welders performing the 6G qualification testing, will weld in all positions including horizontal, vertical and overhead.
Hence, if a welder pass 6G test, he will automatically qualifies for welding in all position. (Fig 3)

Fig 3

Importance of pre-heating, post- heating and

maintenance of inter pass temperature, use of
temperature indicating crayons

Objectives : At the end of this lesson you shall be able to
• describe the important of pre-heating and post heating.
• explain the inter pass temperature.
• explain the indicating CRAYONS.

Different methods of heat treatment: Direct preheating, indirect preheating, local preheating
Preheating and its purpose: Preheating means heating a joint to be welded before or during welding to a certain
temperature as shown in tables 1 and 2.

TABLE 1
Preheating of various Metals

Metal Temperature °C
Nickel alloys (wrought) Warm it below 16°
Nickel alloys (cast) 90° - 200°
Copper and copper alloys 200° maximum
Silicon bronze 90°
Brass low zinc 200° - 260°
Brass high zinc 260° - 370°
Phosphor bronze 150° - 200°

127

CITS : C G & M - Welder - Lesson 33 - 43