CSWIP 3.1: Question with Answer and Explanation – Part 12

CSWIP 3.1 QUESTION AND ANSWER SERIES

(145mb) Books & Chapter wise Questions (General Paper + Technical Paper) and Answers. Examination notes on Practical Examination of Plate/Pipe CSWIP 3.1 Learning Presentation

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CSWIP 3.1: Question with Answer and Explanation – Part 1

CSWIP 3.1: Question with Answer and Explanation – Part 2

CSWIP 3.1: Question with Answer and Explanation – Part 3

CSWIP 3.1: Question with Answer and Explanation – Part 4

CSWIP 3.1: Question with Answer and Explanation – Part 5

CSWIP 3.1: Question with Answer and Explanation – Part 6

CSWIP 3.1: Question with Answer and Explanation – Part 7

CSWIP 3.1: Question with Answer and Explanation – Part 8

CSWIP 3.1: Question with Answer and Explanation – Part 9

CSWIP 3.1: Question with Answer and Explanation – Part 10

CSWIP 3.1: Question with Answer and Explanation – Part 11

CSWIP 3.1: Question with Answer and Explanation – Part 12

CSWIP 3.1: Question with Answer and Explanation – Part 13

CSWIP 3.1: Question with Answer and Explanation – Part 14

CSWIP 3.1: Question with Answer and Explanation – Part 15

CSWIP 3.1: Question with Answer and Explanation – Part 16

CSWIP 3.1: Question with Answer and Explanation – Part 17

CSWIP 3.1: Question with Answer and Explanation – Part 18

CSWIP 3.1: Question with Answer and Explanation – Part 19

CSWIP 3.1: Question with Answer and Explanation – Part 20

1) Cast and Helix are terms that refer to:

2) A MMA electrode which is classified as an E7024 (according to AWS) is a:

We use “Exclusion principle”

3) An electrode is classified to BS EN ISO 2560 as E 35 3 B. What does 35 signify?

Pls take note:

• With BS EN ISO 2560: it is classified follow yield strength
• With AWS A5.1 & A5.5: it is classified follow TENSILE STRENGTH

4) A large diameter pipe with a wall thickness of 10mm is to be used for a cross-country pipeline. Which electrode type could be used to combine high welding speed and deep penetration?

Cellulosic Electrode compositions are only available for welding low carbon non-alloyed steels although nickel additions may be made to improve notch toughness. Charpy-V values of around 27J at -20°C are possible in the unalloyed electrodes. The high hydrogen level means that any steel welded with these electrodes should be selected to have a very high resistance to hydrogen induced, cold cracking. They should not be used without giving due consideration to the steel composition, restraint and the need for preheat. The characteristics of deep penetration, high deposition rates and the ability to be used vertically down means that the main use for these electrodes is for cross country pipelining although they are used to a more limited extent for welding storage tanks.

Cellulosic electrodes contain a high proportion of cellulose in the coating and are characterised by a deeply penetrating arc and a rapid burn-off rate giving high welding speeds. Weld deposit can be coarse and with fluid slag, deslagging can be difficult. These electrodes are easy to use in any position and are noted for their use in the ‘stovepipe’ welding technique.

5) Which of the following electrode types would produce the highest levels of hydrogen?

• Cellulosic electrodes: hydrogen content is 80-90 ml/100 g of weld metal.
• Rutile electrodes: hydrogen content is 25-30 ml/100 g of weld metal.
• Basic covering: have the lowest level of hydrogen (less than 5 ml/100 g of weld metal).

6) Which of the following electrode types would produces the lowest levels of hydrogen?

• Cellulosic electrodes: hydrogen content is 80-90 ml/100 g of weld metal.
• Rutile electrodes: hydrogen content is 25-30 ml/100 g of weld metal.
• Basic covering: have the lowest level of hydrogen (less than 5 ml/100 g of weld metal).

7) Basic electrodes are often sold vacuum packed. The reason is:

8) A general terms which of the following would required the highest preheat if all other factors were the same as per ISO BS EN 1011?

• Cellulosic electrodes: hydrogen content is 80-90 ml/100 g of weld metal.
• Rutile electrodes: hydrogen content is 25-30 ml/100 g of weld metal.
• Basic covering: have the lowest level of hydrogen (less than 5 ml/100 g of weld metal).

Cellulosic electrodes have highest Hydrogen content and easy lead to Cold crack. So, it to be required the highest preheat to avoid this cracking type.

Preheat: Preheat, which slows the cooling rate, allows some hydrogen to diffuse away, and generally reduces the hardness, and therefore susceptibility to cracking, of hard, crack-sensitive microstructural regions. The recommended levels of preheat for carbon and carbon manganese steel are detailed in EN 1011-2: 2001 (which incorporates nomograms derived from those in BS 5135: 1984). The preheat level may be as high as 200°C for example, when welding thick section steels with a high carbon equivalent (IIW CE) value.

Alloyed weld metal where preheat levels to avoid HAZ cracking may be insufficient to protect the weld metal. Low hydrogen processes and consumables should be used. Schemes for predicting the preheat requirements to avoid weld metal cracking generally require the weld metal diffusible hydrogen level and the weld metal tensile strength as input.

9) When welding medium carbon steel plates over 90mm in thickness would the basic electrode require any pre-treatment before use?

10) When welding medium carbon steel plates over 100mm in thickness would basic electrodes require any pre-treatment before use?

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