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The correct choice is (d) Wax PATTERN

Best EXPLANATION: In this apparatus of the thermit welding process, the QUESTION MARK here represents the pattern made up of wax. This process is basically carried out in FUSION welding.

The correct option is (b) False

The explanation: It is HOT WELDING that a liquid or a MOLTEN state is used for the joining of two pieces of metal. But in cold welding, there is no USE of a liquid phase, that is, joining is done without using heat.

Correct OPTION is (a) True

Best explanation: Single stage converter is used to reduce the pressure from the cylinder pressure to the welding pressure, which can take place in a single stage. However, it TENDS to freeze in cold weather. This is because an abrupt expansion and resulting drop in initial pressure MAKES rapid cooling of the GAS and may cause ice formation in the presence of MOISTURE.

Correct choice is (c) Sand PLUG

For EXPLANATION I would say: The PART represented by the question mark is the sand plug. Superheated liquid steel is poured, which then effects in forming the weld. This process, HENCE, is a fusion welding process.

Right option is (d) PREVENTING other elements into molten METAL

For EXPLANATION I would say: A coated electrode is a further classification of a consumable electrode. The purpose of the electrode is to maintain the arc, to SHIELD the molten metal from oxygen and nitrogen PRESENT in the air and to provide other alloying elements into the molten metal.

Right CHOICE is (c) 2300°C

For explanation I would say: Water gas is a type of fuel gas that is used for the WELDING of thin SHEETS of steel which have a thickness of up to 8 mm. The flame temperature of water gas is approximately about 2300°C.

The CORRECT choice is (d) Air-acetylene

The explanation: AMONG the FOLLOWING, plasma ARC, electro-slag and submerged arc are few of the TYPES of arc welding. Air-acetylene is one of the forms of gas welding processes.

Right choice is (c) Ultrasonic welding

Easy explanation: For the welding of carbon steel material, ONE may USE the arc welding method. To gas weld carbon steel is also a feasible option and carbon STEELS can be TREATED using forge welding also, but it cannot be welded using ultrasonic welding.

Correct option is (d) 7

Easy EXPLANATION: Just like any other GAS welding equipment, the welding torch gets SUBSTITUTED by a cutting torch in oxygen cutting process. The TOTAL number of openings available in the torch are six, with a large opening at the center, making the count to SEVEN.

The CORRECT choice is (c) Mechanical pressure

Best explanation: In spot WELDING process, the METAL or the alloy parts which are to be welded, are heated in their in their ZONES. To bring these parts in contact with one another, mechanical pressure is applied, causing them to CONNECT.

The correct choice is (a) 675°C

For EXPLANATION I would say: In oxygen cutting process, not all steels can be treated by this METHOD. Only high alloy steels can be treated by this method. These steels need to be preheated before oxygen cutting. The temperature RANGE up to which these steels are preheated is about 650°C to 700°C.

Correct choice is (b) False

Easy explanation: In CARBON arc WELDING, the carbon is PRESENT at the negative electrode, where the electrode TEMPERATURE is at 3200°C. This temperature is lesser than that at the positive electrode. Carbon electrode is KEPT at a lower temperature on the negative electrode, to avoid the mixing of carbon in the weld. If the carbon gets mixed with the weld, the weld might end up becoming brittle.

The CORRECT ANSWER is (d) SLAG basin

Easiest EXPLANATION: NONE.

Right answer is (b) Metal sheets

The BEST explanation: Oxy-acetylene PROCESS is most suited for the JOINING of metal sheets or for joining metal plates which are having a thickness of 2mm to 50mm. While joining, the molten metal flows together to FORM a continuous joint.

The correct answer is (b) False

To explain I WOULD say: In gas welding, a flashback is a condition in which the flame burns inside the gas torch. Flashback is generally caused by improper mixing of GASES, which further INCREASES the rate of flame propagation to high EXTENT that the flame goes back to the mixing chamber. If it is not stopped, the flame may BURN the mixture and may travel back into the cylinder.

Correct OPTION is (a) True

Explanation: Slags used in welding are generally a combination of SILICA materials and some carbonate compounds. In fusion welding, some amount of BEAD CONTROL has to be done, which is done by the slags, for this purpose, to improve its performance, microelements like NITROGEN are added.

Correct option is (C) 57kgf/mm^2

For explanation I WOULD SAY: When there is an addition of some MICROELEMENTS in the slag along with a few nonmetallic inclusions, there is an INCREASE in the strength of the mild steel arc weld. The maximum amount of strength goes up to 57 kgf/mm^2, which is 570 N/mm^2.

The CORRECT ANSWER is (b) 900°C

Explanation: The process of fusion WELDING can be used for JOINING metal to a metal or a metal can be joined to a ceramic. For the joining of this process, a TEMPERATURE of 900°C is provided for the approach.

The CORRECT option is (d) 6-10 kWh

Easy explanation: The amount of electrical energy consumed required per KG for a D.C. welding operation, is 6 kWh to 10 kWh. Direct current PROVIDES the advantage of distribution of the heat NEEDED inside the ARC.

The correct option is (C) 946 kg/m^3

Explanation: The plastic which is used in the PROCESS of speed tip WELDING is polypropylene or POLYPROPENE. It is classified under thermoplastics materials. The density of polypropylene is 946 kg/m^3 and it starts melting at 130°C.

Correct choice is (a) True

To ELABORATE: Materials that have a MEDIUM MELTING point are CONSIDERED to be welded easily and those materials which have their thermal conductivity very HIGH are the toughest to be melted.

The correct option is (C) Electro-slag

The best EXPLANATION: Among the FOLLOWING, seam, projection and spot are few of the types of resistance WELDING. Electro-slag is one of the forms of gas welding processes.

Correct OPTION is (a) True

To explain: Carbon steels which contain carbon in a very low amount are not COMPULSORILY required to be preheated before undergoing welding if the LARGE RUNS are made. This is because, in low carbon steels, unlike HIGH carbon steels, there is no cracking seen on welding.

Right option is (b) OXYGEN

Best explanation: In oxygen cutting method, under considerable amount of pressure, when a JET of oxygen GAS is MADE to blow on the particles of molten iron oxide, the oxygen layer present on the molten iron gets removed.

The correct CHOICE is (a) Low static pressure

To elaborate: In ultrasonic welding method, the parts which are to be JOINED, are KEPT clamping to one ANOTHER in between of supporting member and the welding tip. This clamping is done at a low static pressure.

Correct option is (d) Copper and aluminium

To ELABORATE: The electrodes that are employed in the spot welding are REQUIRED to possess a high AMOUNT of electrical and THERMAL conductivity. Hence, they are primarily made up of copper or copper and tungsten or copper and chromium.

The correct CHOICE is (c) Runner

Easy explanation: In this figure, the QUESTION MARK is represented by the runner. This PROCESS is carried out at FUSION welding.

Right OPTION is (d) 6000°C – 7000°C

Explanation: An electric arc FURNACE generates a LOT of heat when the WORKING metal comes in contact with the electrode. The heat that is generated in this joining process is of the order 6000°C to 7000°C.

Correct CHOICE is (c) Gas SOLUBILITY

The explanation: The AMOUNT of solubility of gas in liquid or solid WELDED metals is considered to be an essential criteria for the control of porosity of the weld. The gas reactions which occur, then regulate porosity.

Correct option is (C) Aluminium

To ELABORATE: The reaction that takes place in between compounds and elements is KNOWN welding with solid reactants. These reaction are exothermic, that is give out heat as a product. Thermit reaction is a COMMON example for this, which is mixture of aluminium and rust.

Correct choice is (a) 3 atm

The explanation: In oxygen CUTTING process, not all STEELS can be treated by this METHOD. Only high alloy steels can be treated by this method. The PRESSURE supply of oxygen should not be low, as it may lead to the formation of slag on the bottom of the cut. The minimum oxygen pressure that can be applied to steels is 3 atmospheres or 300 kN/m^2.

Right choice is (C) 0.38 mm

For explanation I WOULD SAY: None.

Right ANSWER is (b) False

For explanation: The SUPERHEATED melt is heated from the crucible gets poured around the METAL parts. As the welding TEMPERATURE is achieved, there is an application of MECHANICAL pressure to the weld.

Correct choice is (a) ELECTRIC resistance

Best explanation: In the making of an upset butt welding, there are jaws made of COPPER, into which the PART to be WELDED is put, and hence a solid CONTACT is made. At this point of contact, while the current flows, it gets transformed into heat because of electric resistance.

Correct answer is (B) Arc length

To explain: The distance from the center of the arc to the tip of the electrode, right till the BOTTOM of the crater is defined to be the arc length. The arc length is considered to be one of the most ESSENTIAL variable in welding process.

The correct answer is (b) Carbon monoxide

Explanation: In carbon ARC welding, there has to be a protection to be PROVIDED to the molten weld. This protection is provided in the FORM of an envelope by USING a long arc GIVING carbon monoxide gas.

Correct option is (a) 100 to 200A

For explanation I would say: A light MANUAL welding machine has ONE of the LOWEST capacity AMONG all types of welding machines. Its capacity ranges in between 100 to 200A. This machine is portable and is best SUITED for light welding processes.

The correct answer is (a) True

Explanation: In gas WELDING, the hoses are mainly USED for making connections between the gas torch and the REGULATORS, which should be MADE strong, light and flexible enough to make torch movements smooth. In general, welding hose can be of two types that are TWIN welding hose and double welding hose.

Right answer is (a) 43 kgf/mm^2

The best explanation: When there is an addition of some MICROELEMENTS in the slag ALONG with a few materials being present which are not metals, there is an increase in the strength of the mild STEEL ARC weld. The minimum amount of strength goes up to 43 kgf/mm^2, which is 430 N/mm^2.

The correct ANSWER is (a) True

To explain: There are various TYPES of WELDING processes, one of them is a newer welding PROCESS. Under this, there are two types, one is electron-beam and another is the use of LASER.