CSWIP Multiple Choice Questions - Practice Paper 3

Hard stamping, as a method of transferring material identification, may not be allowed for high integrity applications because it has the potential to damage the material. This damage can compromise the structural integrity and performance of the material, which is undesirable in applications where safety and reliability are critical. Therefore, alternative methods that do not pose a risk of material damage may be preferred in such cases.

High heat input welding refers to a welding process that generates a significant amount of heat per unit length. In this case, the correct answer of 5KJ/mm indicates a high heat input because it represents 5 kilojoules of heat energy being inputted per millimeter of weld. This level of heat input is considerably higher compared to the other options provided, such as 550J/mm, 55J/mm, and 5.5J/mm, which indicate lower amounts of heat energy being inputted per millimeter of weld.

Preheating a low alloy steel prior to welding helps to reduce the risk of heat-affected zone (HAZ) cracking. When welding, the heat generated can cause rapid cooling and contraction in the surrounding area, leading to high levels of residual stress and potential cracking in the HAZ. Preheating the steel before welding helps to slow down the cooling rate, allowing for more uniform cooling and reducing the risk of HAZ cracking. This is particularly important in low alloy steels, which are more susceptible to cracking due to their composition and properties.

To measure arc voltage accurately, it is recommended to connect the voltmeter across the arc and as close as possible to the arc itself. This is because the voltage across the arc can vary depending on factors such as arc length, electrode type, and welding conditions. By placing the voltmeter near the arc, it can provide a more precise measurement of the voltage at that specific location, giving a more accurate representation of the welding conditions. Connecting the voltmeter anywhere else in the circuit may not provide an accurate measurement of the arc voltage.

A crack running along the centreline of a weld bead could be caused by the weld bead being too deep and very narrow. When the weld bead is too deep and narrow, it creates a high concentration of stress along the centreline, which can lead to cracking. This is because the excessive heat input and rapid cooling from the narrow width of the bead can cause the metal to contract and crack.

The correct answer is pWPS. pWPS stands for preliminary Welding Procedure Specification. It is the initial document prepared before conducting a Weld Procedure Qualification test. This document outlines the proposed welding parameters, materials, and techniques that will be used in the test. It serves as a guideline for the actual WPS (Welding Procedure Specification) that will be developed and qualified based on the results of the test. The pWPS helps ensure that the welding process is planned and executed correctly, leading to a successful qualification test.

Agglomerated submerged arc welding flux is susceptible to moisture pick-up. This is because agglomerated flux is made up of granules that have been bonded together, leaving small spaces between them. These spaces can easily absorb moisture from the surrounding environment, leading to a decrease in the effectiveness of the flux. In contrast, neutral and fused fluxes are less prone to moisture absorption due to their different composition and structure. Therefore, agglomerated flux requires more careful handling and storage to prevent moisture contamination.

Solidification cracking in the weld metal is associated with SAW (Submerged Arc Welding) more often than it is with MMA (Manual Metal Arc) welds. Solidification cracking occurs when the weld metal solidifies and contracts, causing it to crack. SAW is a welding process that uses a flux to protect the weld metal from atmospheric contamination, which reduces the risk of solidification cracking. MMA welds, on the other hand, are more prone to solidification cracking due to the lack of such protective measures. Therefore, solidification cracking is more commonly associated with SAW than MMA welds.

The correct answer is through-thickness ductility of a steel plate (the Z direction). The STR test is specifically designed to measure the ability of a steel plate to deform and stretch in the Z direction, perpendicular to the plane of the plate. This is important because it determines the plate's resistance to cracking or failure under certain conditions. By measuring the through-thickness ductility, engineers can assess the plate's overall structural integrity and suitability for various applications.

Using back-step welding is a technique where the welder welds in short sections, moving backwards from the end of the joint towards the start. This helps to control the heat input and prevents excessive distortion in the thin plate. By welding in short sections and allowing each section to cool before moving on, the accumulated heat is minimized, reducing the risk of distortion. This technique is particularly effective for thin plates where distortion is a common issue.

In MMA welding of a 60mm wall nozzle to a 100mm wall vessel shell, it is important to check the preheat temperatures before welding starts/restarts. This is necessary to ensure that the materials are at the correct temperature for welding, which helps to prevent cracking and improve the quality of the weld. The preheat temperatures should be checked on both the shell and nozzle, as both components are involved in the welding process. Additionally, it is important to check the temperatures at points at least 75mm from the joint edge to ensure that the entire area is adequately preheated. Therefore, the correct answer is "All of the above."

Agglomerated SAW flux is susceptible to breaking down into fine particles during circulation. Agglomerated flux is made up of larger particles that are bonded together. However, when the flux is circulated, the bonding between the particles can weaken, causing them to break down into smaller particles. This can lead to issues such as clogging in the flux delivery system and poor weld quality.

The typical temperature range for normalizing a C-Mn steel plate is 880-920ºC. Normalizing is a heat treatment process that involves heating the steel plate to a temperature above its critical range and then cooling it in still air. This process helps to refine the grain structure of the steel, improve its mechanical properties, and relieve internal stresses. The temperature range of 880-920ºC is commonly used for normalizing C-Mn steel plates to achieve the desired properties and structure.

The SAW (Submerged Arc Welding) process with one pass per side would be expected to produce the least distortion in a 15mm straight butt weld. This is because SAW is a high-deposition welding process that uses a flux to cover the weld, which helps in controlling the heat input and minimizing distortion. Additionally, the single pass per side reduces the number of heat cycles and the overall amount of heat input, further reducing the potential for distortion.

The burn-off rate of the wire in GMAW (Gas Metal Arc Welding) is directly related to the wire feed speed. The wire feed speed determines the rate at which the filler wire is fed into the weld pool. A higher wire feed speed will result in a faster burn-off rate of the wire, providing more filler material for the weld. Conversely, a lower wire feed speed will result in a slower burn-off rate. Therefore, the wire feed speed plays a crucial role in controlling the deposition rate and the quality of the weld.

A large grain size in the Heat Affected Zone (HAZ) of a C-Mn Steel weld joint may result in low toughness. This is because larger grains tend to have less grain boundary area, which can act as barriers to crack propagation. With fewer boundaries to hinder crack growth, the material becomes more susceptible to brittle fracture, leading to lower toughness.

The coefficient of thermal expansion is the property of a material that determines how much it expands or contracts when subjected to temperature changes. In welding, the heat generated can cause significant temperature variations in the material, leading to thermal expansion and contraction. This expansion and contraction can result in distortion and warping of the welded components. Therefore, the coefficient of thermal expansion has the greatest influence on welding distortion.

The presence of iron sulphides in a weld bead can cause solidification cracking. Solidification cracking, also known as hot cracking or hot tearing, occurs when the weld metal solidifies and contracts, but is restrained by the surrounding material. The presence of iron sulphides can promote the formation of low-melting point eutectic phases, which can lead to the formation of cracks during solidification. These cracks can weaken the weld and compromise its integrity.

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The use of low carbon austenitic stainless steels and stabilizer stainless steels helps minimize the risk of weld decay. Weld decay is a form of corrosion that occurs in the heat-affected zone (HAZ) of stainless steel welds. It is caused by sensitization, which happens when carbon combines with chromium in the steel, depleting the chromium content and reducing its corrosion resistance. By using low carbon austenitic stainless steels and stabilizer stainless steels, the carbon content is reduced, preventing sensitization and minimizing the risk of weld decay.

Increasing the Carbon Equivalent Value (CEV) of a steel will result in an increase in the maximum hardness in the Heat Affected Zone (HAZ). CEV is a measure of the steel's composition and indicates its hardenability. Higher CEV means a higher carbon content or the presence of other alloying elements that increase hardness. When the CEV is increased, the steel becomes more susceptible to hardening during the welding process, leading to higher hardness in the HAZ. Therefore, increasing the CEV will result in an increase in the maximum hardness in the HAZ.

According to the given specification, the limit for excess weld metal (h) on a butt weld is h

A macrosection is particularly good for showing overlap in a weld. A macrosection is a cross-sectional view of a weld that allows for a detailed examination of the weld's structure and characteristics. In the case of overlap, it refers to the area where two weld beads overlap each other. By examining the macrosection, one can determine the quality and integrity of the overlap, ensuring that it meets the required standards and specifications. This can be crucial in industries where weld integrity is critical, such as structural engineering or pipeline construction.

The suitable gas/gas mixture for GMAW (Gas Metal Arc Welding) for aluminum is 100% Argon. Argon is commonly used as a shielding gas in aluminum welding because it provides excellent arc stability and prevents oxidation of the weld. It also helps to produce a smooth and clean weld bead. CO2 and 02 gases are not suitable for aluminum welding as they can cause porosity and other defects in the weld.

The initiation of a TIG arc using high frequency spark can potentially damage electronic equipment. High frequency sparks generate electromagnetic interference (EMI) which can disrupt the functioning of sensitive electronic devices. This interference can cause malfunctions, data loss, or even permanent damage to the equipment. Therefore, it is important to avoid using high frequency spark for TIG arc initiation to prevent any potential harm to electronic equipment.

Argon + 20% CO2 is a suitable shielding gas for FCAW of stainless steels because it provides good arc stability and weld penetration. The addition of CO2 helps to improve the weld bead shape and reduce spatter. This gas mixture also provides good protection against atmospheric contamination, ensuring a high-quality weld.

To improve resistance to service failure caused by cyclic loading, it is important to ensure that there are no features that give high stress concentration. High stress concentration can lead to the formation of stress risers, which are points of high stress concentration that can initiate cracks and ultimately lead to failure. By eliminating or minimizing features that create stress concentration, such as sharp corners, notches, or abrupt changes in geometry, the structure becomes more resistant to cyclic loading and less prone to failure. This can be achieved through design modifications or by using techniques such as fillet welding or blending the transitions between different components.

Lamellar tearing is a type of cracking that occurs in steel due to the presence of non-metallic inclusions. It is typically not detectable by conventional inspection methods such as X-ray examination, liquid penetrant examination, or ultrasonic examination. This is because lamellar tearing is a subsurface defect that is not easily visible or detectable using these techniques. Therefore, it is not possible to find lamellar tearing before the weld is made using any inspection method.

The risk of hydrogen cracking is greater when MMA welding low alloy steels for elevated temperature service. This is because low alloy steels have a higher susceptibility to hydrogen cracking, especially when they are exposed to high temperatures. The combination of hydrogen, high temperatures, and the specific composition of low alloy steels can lead to the formation of cracks in the weld, which can compromise the integrity and strength of the welded joint. Therefore, extra precautions and control measures need to be taken when MMA welding low alloy steels for elevated temperature service to minimize the risk of hydrogen cracking.

When welding a C-Mn steel using MMA, if the electrode run-out lengths are much shorter than specified by the WPS, it can result in lower values of HAZ (Heat Affected Zone) toughness. The HAZ is the area surrounding the weld joint that experiences high temperatures during the welding process. Insufficient electrode run-out lengths can lead to inadequate heat input, causing the HAZ to cool too quickly, resulting in reduced toughness. This means that the HAZ will be more prone to cracking or failure under stress.