CSWIP 3.1 Multiple Choice Questions Set

Using MMA electrodes with the flux covering removed as filler rods for TIG welding should not be allowed because the weld metal composition may be wrong. MMA electrodes have a specific composition designed for shielded metal arc welding, and removing the flux covering exposes the metal core, which may not be suitable for TIG welding. The composition of the metal core may not provide the desired mechanical properties or meet the requirements of the TIG welding process. Therefore, using such electrodes can result in poor quality welds and compromised weld integrity.

The correct answer is Basic, cellulosic and rutile. These are the three main types of MMA (Manual Metal Arc) electrodes used for welding C (carbon) and C-Mn (carbon-manganese) steels. Basic electrodes are used for welding high-strength steels and have excellent mechanical properties. Cellulosic electrodes are used for all-position welding and provide deep penetration. Rutile electrodes are versatile and can be used for a wide range of applications.

A Hydrogen controlled MMA electrode can always be recognized by the EN code letter (or AWS code number) because these codes indicate the specific characteristics and properties of the electrode. The code letter or number provides information about the type of coating, the welding position, the current type, and other important factors that determine the suitability of the electrode for specific applications. The electrode length, trade name, and color of the covering may vary and are not reliable indicators of whether the electrode is hydrogen controlled or not.

Arc blow refers to the deflection of the welding arc caused by magnetic forces, which can make it difficult to control the welding process. This phenomenon occurs when the magnetic field generated by the welding current interacts with the magnetic field of the workpiece or surrounding objects. The deflection of the arc can lead to weld defects, such as uneven penetration or misalignment. Therefore, arc blow is a common challenge that welders face and must be managed to ensure proper welding quality.

During TIG welding, the pipe bores of certain materials need to be purged with argon to prevent oxidation of the root bead. Oxidation can occur when the hot metal reacts with oxygen in the air, leading to the formation of oxides on the surface of the weld. This can weaken the weld joint and reduce its integrity. By purging the pipe bores with argon, the oxygen is displaced and a protective atmosphere is created, preventing oxidation and ensuring a high-quality weld.

Low hydrogen electrodes have a basic covering. This type of covering is designed to minimize the amount of hydrogen that is produced during the welding process. The basic covering helps to prevent hydrogen-induced cracking in the weld, which can be a common issue when using other types of electrodes. By using a low hydrogen electrode with a basic covering, welders can achieve strong, high-quality welds without the risk of hydrogen-related defects.

The number 141 refers to the welding process when it is written next to the tail when using symbols.

The correct answer is 300-350ºC. This temperature range is suitable for baking basic coated electrodes. Baking is a process used to remove moisture from the electrodes and improve their performance. Baking at a higher temperature range ensures that the moisture is completely removed, resulting in better weld quality. Baking at lower temperatures may not effectively remove the moisture, while baking at higher temperatures may cause damage to the electrodes. Therefore, a temperature range of 300-350ºC is considered ideal for baking basic coated electrodes.

When the welding travel speed is doubled but the current and voltage remain the same, the heat input will be reduced by 50%. This is because heat input is directly proportional to the welding travel speed. By doubling the speed, the time for which the heat is applied is reduced by half, resulting in a 50% reduction in heat input.

Cellulosic electrodes are used for stovepipe welding in overland pipeline construction. These electrodes have a high cellulose content which creates a thick and easily removable slag. This slag acts as a protective layer over the weld, preventing oxidation and contamination. Cellulosic electrodes also have a deep penetration and produce a strong and ductile weld, making them suitable for pipeline construction where strength and durability are important.

A qualified Welding Procedure Specification serves multiple purposes. Firstly, it gives instructions to the welder, providing them with clear guidelines on how to perform the welding process. Secondly, it provides information to the welder, such as the materials to be used, welding techniques, and any special considerations. Lastly, it gives confidence that the welds will have the specified properties, ensuring that the final product meets the required standards. Therefore, the correct answer is "All of the above."

18% Cr, 8% Ni steel is considered non-magnetic because it contains a high amount of nickel, which has a strong influence on the magnetic properties of the steel. Nickel is a non-magnetic material, and when it is alloyed with steel in significant amounts, it can result in a non-magnetic steel. Therefore, the 18% Cr, 8% Ni steel is the correct answer as it has a composition that makes it non-magnetic.

Excessive current during MMA welding can cause weld spatter. When the current is too high, it can lead to an excessive amount of molten metal being expelled from the weld pool, resulting in spatter. This can occur when the welding machine is set at a higher current than necessary for the specific welding application. Properly adjusting the current to the appropriate level can help reduce spatter and improve the quality of the weld.

A current slope-out device in TIG welding helps to reduce the risk of crater cracking. Crater cracking refers to the formation of cracks at the end of a weld. This device gradually reduces the welding current at the end of the weld, allowing the molten metal to solidify more smoothly and reducing the stress on the weld. By minimizing the risk of crater cracking, the current slope-out device helps to ensure a stronger and more reliable weld.

The correct answer is current because the amount of current flowing through the welding circuit directly affects the heat generated during the welding process. Higher currents result in increased heat, which leads to deeper penetration into the base material. Therefore, controlling the current allows for the desired level of penetration in MMA welding.

The unit KJ/mm is used to express heat input. KJ stands for kilojoules, which is a unit of energy, and mm stands for millimeters, which is a unit of length. Heat input is the amount of energy transferred as heat into a system per unit length, and the KJ/mm unit effectively represents this quantity.

Molybdenum is added to steel to give resistance to creep at elevated service temperatures. Creep is the gradual deformation of a material under constant stress at high temperatures. Molybdenum improves the high-temperature strength and creep resistance of steel by forming strong carbides that help to retain the material's shape and prevent excessive deformation.

An arc strike on a steel component can cause hard spots and cracking. Hard spots are areas of localized hardness in the steel, which can reduce its strength and impact resistance. Cracking refers to the formation of cracks in the steel, which can compromise its structural integrity. Therefore, both hard spots and cracking are considered unacceptable and undesirable in steel components, according to some codes.

Exceeding the maximum width for individual weld beads in a WPS when welding C-Mn steels can lead to a reduction in heat-affected zone (HAZ) toughness. The HAZ refers to the area surrounding the weld where the base metal experiences heat from the welding process. If the width of the weld bead is too large, it can result in excessive heat input to the HAZ, causing it to become brittle and lose its toughness. This can compromise the overall strength and integrity of the welded joint.

Silicon is added to steel and the covering of MMA electrodes in order to provide deoxidation. When steel is being produced, it is important to remove any oxygen present in order to prevent the formation of oxides, which can weaken the material. Silicon has a strong affinity for oxygen and readily reacts with it, forming silicon oxide. This helps to remove the oxygen from the steel, ensuring that it remains strong and free from any detrimental oxides. Therefore, the addition of silicon aids in the deoxidation process, improving the quality and properties of the steel.

Constant current is normally used for manual welding because it provides a stable and consistent current output regardless of changes in the arc length or voltage. This characteristic is ideal for welding applications as it allows for better control of the heat input and penetration, resulting in more precise and reliable welds. Constant voltage, on the other hand, is typically used for automated or semi-automated welding processes where a more consistent voltage output is required. Flat characteristic and motor generator are not commonly used for manual welding.

In a transverse tensile test, brittleness would be indicated if the fracture surface is flat and featureless but has a rough surface. This is because brittleness is characterized by a lack of plastic deformation before fracture, resulting in a clean break without any significant deformation features. The rough surface indicates that the material has fractured in a brittle manner, without any significant plastic deformation.

The electrode type E 38 3 R is classified to BS EN 499.

A fusible insert for TIG welding helps in giving controlled root penetration. This means that it allows the welder to have precise control over the depth and penetration of the weld at the root, ensuring that it is neither too shallow nor too deep. This is important as it ensures the integrity and strength of the weld joint. By using a fusible insert, the welder can achieve consistent and controlled root penetration, resulting in a high-quality weld with minimal defects.

The Nick break and fillet fracture tests are used to assess the weld quality. These tests evaluate the integrity and strength of the weld by examining the presence of any defects or imperfections such as cracks or fractures. By performing these tests, one can determine if the weld meets the required standards and specifications, ensuring a high-quality weld joint.

DC negative is the current/polarity used for TIG welding of all materials except aluminium and magnesium. In TIG welding, the electrode is connected to the negative terminal of the power source, and the workpiece is connected to the positive terminal. This setup allows for better control over the heat input and penetration of the weld. The DC negative polarity provides a stable arc, deep penetration, and good control over the weld pool, making it suitable for welding materials such as steel, stainless steel, and copper alloys.

A fatigue crack occurs due to repeated cyclic loading, causing the material to gradually weaken and eventually crack. As the crack propagates, the material around it undergoes plastic deformation, resulting in the formation of shear lips. However, as the crack continues to propagate, the surfaces on either side of the crack come into contact and rub against each other, causing them to smoothen out. Therefore, the surface of a fatigue crack is expected to be smooth.

The chemical composition of the weld metal deposited by a C-Mn steel MMA electrode is usually controlled by the additions in the flux coating. The flux coating contains various elements and compounds that are added to the electrode to influence the composition of the weld metal. These additions can include alloying elements, deoxidizers, and other substances that help improve the weld quality and properties. By controlling the composition of the flux coating, manufacturers can ensure that the resulting weld metal meets the desired specifications and performance requirements.

In AWS 2.4, a weld symbol for the other side is placed above the solid line. This indicates that the weld is to be performed on the side opposite to the one indicated by the main weld symbol. Placing it above the solid line helps to clearly distinguish it from the main weld symbol and ensures that it is not confused with any other symbols or annotations on the drawing.

According to BS EN 22553, a weld symbol for the other side is placed below the solid line.