Explore topic-wise InterviewSolutions in .

Right answer is (a) less than 16t in case of tension JOINT, where t is thickness of thinner plate

Explanation: The clear spacing between EFFECTIVE LENGTHS of intermittent WELDS should not be less than 16 times and 12 times the thickness of thinner plate jointed in case of tension joint and compression joint respectively, and should never be more than 200MM.

The correct CHOICE is (a) 795.36 N/mm

Easy explanation: Minimum size of WELD = 3mm

Maximum size of weld = 10-1.5 = 8.5mm

Assume weld size = 6mm

Effective throat THICKNESS, te = 0.7 X 6 = 4.2mm

Strength of weld = te [fu/(√3 x 1.25)] = 410 x 4.2 /(√3 x 1.25) = 795.36 N/mm.

Right choice is (B) Unsafe

Best EXPLANATION: Lw = 150mm, Throat thickness, te = 5×12/8 = 7.5 mm

Strength of weld = Lwtefy/1.25 = 150×7.5x250x10^-3/1.25 = 225kN < 400kN. Therefore JOINT is unsafe and INADEQUATE.

The correct answer is (d) √(fa^2+3q^2)

The EXPLANATION: When fillet welds are SUBJECTED to combination of normal and shear stress, the equivalent stress is given by fe = √(fa2+3q^2), where fa = normal STRESSES, compression or tension, due to axial force or bending MOMENT, q = shear stress due to shear force or tension.

Correct choice is (a) P/ttlw

The explanation: When welds are subjected to compressive or TENSILE or shear force ALONE, the stress in weld is given by q = P/ttlw , where q=shear stress in N/MM^2, P = force transmitted, tt = effective throat thickness of weld in mm, LW = effective length of weld in mm.

The CORRECT CHOICE is (c) FU/√3

Easy explanation: Design nominal STRENGTH of FILLET weld = fu/√3, where fu is smaller of ultimate stress of weld or parent metal.

Correct choice is (a) should not be less than 4 times the THICKNESS of thinner part

For EXPLANATION I would say: The LENGTH of overlap of PLATES to be fillet welded in lap joint should not be less than 4 times the thickness of thinner part.

Right option is (c) 0.7

To EXPLAIN: The value of K VARIES with ANGLE between fusion FACES. Values of K for different ANGLES between fusion faces are :

Angle between fusion faces

60˚-90˚

91˚-100˚

101˚-106˚

107˚-113˚

114˚-120˚

K

0.7

0.65

0.6

0.55

0.5

Correct ANSWER is (a) equal to twice the size of weld

The BEST I can explain: END returns are made equal to twice the size of weld to relieve the weld lengths from high stress CONCENTRATIONS at the ends.

Correct choice is (c) EQUAL to overall length minus twice the WELD size

The best I can EXPLAIN: EFFECTIVE length of fillet weld is taken equal to overall length minus twice the weld size. The deduction is made to allow for craters to be FORMED at the ends of welded length.

The correct option is (b) four TIMES the size of weld

For explanation: As per IS CODE, the actual LENGTH of FILLET weld should not be less than four times the size of weld. If this requirement is not met, the size of weld should be one fourth of the effective length.

The CORRECT answer is (d) PLATES joined at straight angles

The explanation: T-joints are used to fabricate built up sections such as T-shapes, I-shapes, plate girders, BRACKETS and stiffeners where TWO plates are joined at RIGHT angles.

The correct option is (a) not be less than 3mm

Explanation: The MINIMUM size of fillet WELD should not be less than 3mm and not more than THICKNESS of thinner part JOINED.

Correct ANSWER is (c) only stresses due to INTERNAL forces are considered

To explain I would SAY: The following are the assumptions made in analysis of welded joints: (i) welds connecting various joints are HOMOGENOUS, isotropic and elastic elements, (ii) parts connected by weld are rigid and their deformations are neglected, (iii) only stresses due to external forces are considered. Effects of residual stresses, STRESS concentration and shape of welds are neglected.

The CORRECT CHOICE is (a) CONNECTION using lap joint requires large number of erection bolts

Best explanation: Lap joints offer ease of fitting and ease of jointing. It can accommodate minor errors in FABRICATION or minor ADJUSTMENT in length. They are well suited for shop as well as field welding. Connection using lap joint requires a small number of erection bolts. The main drawback of lap joint is that it introduces some eccentricity of loads, unless a double lap joint is used.

The correct option is (c) thickness equal to smaller part, the slope not being steeper than one in FIVE

Easiest explanation: When plates of two different thicknesses and/or widths are joined, the wider or thicker part should be reduced at the butt joint to make thickness equal to smaller part, the slope not being steeper than one in five. When reduction is not possible, the weld metal SHALL be built up at the junction with thicker part to dimensions at least 25% greater than those of thinner part, or ALTERNATIVELY to the dimensions of thicker MEMBER.

The correct option is (a) It is EXTRA weld metal that makes throat DIMENSIONS greater than the thickness of the welded material

To explain I would say: Face REINFORCEMENT is extra weld metal that makes the throat dimensions greater than the thickness of the welded material. The provision of reinforcement INCREASES the efficiency of joint and ensures that depth of weld is at LEAST equal to thickness of the plate.

Correct answer is (b) BUTT joints minimizes the SIZE of connection

Easy explanation: Butt joints eliminates eccentricity developed using lap joints. Butt joints minimizes the size of connection and are aesthetically pleasing over lap joints. Butt joint obtained from FULL PENETRATION groove weld has 100% efficiency.

The correct OPTION is (d) size of weld

To explain I WOULD say: The types of welded joints depends on (i) size and shape of members connected at JOINT, (ii) type of loading, (iii) area available for welding at the joint, (iv) relative cost of VARIOUS types of weld.

The correct answer is (b) by use of low hydrogen electrode

Easiest explanation: Cold cracks occur under room TEMPERATURE run PARALLEL to but under the weld in base metal. Use of low hydrogen electrodes along with PROPER pre-heating and post-heating MAY REDUCE possibility of cold cracks.

The correct option is (c) It can be CORRECTED by depositing additional weld material

For explanation I would SAY: UNDERCUTTING is due to local decrease of thickness of PARENT metal at weld toe. This results in groove in base metal adjacent to toe of weld and LEFT unfilled by weld metal during welding process. Undercutting may result in loss of gross section and will act as stress riser. This defect may be due to excessive current or longer arc length. It can be easily detected visually and can be corrected by depositing additional weld material.

The correct option is (a) Porosity is caused due to insufficient CURRENT

Easy explanation: Porosity is formed when gas pockets or voids are draped during cooling process. It MAY be due to excessively high current or longer arc length or due to poor WELDING procedure. Porosity results in stress CONCENTRATION and REDUCED ductility of metal.

The CORRECT option is (d) use of large electrode

To elaborate: Incomplete fusion MAY result if surfaces to be jointed have not been cleaned properly and are coated with oxides and other foreign materials. Insufficient CURRENT SUPPLIED by WELDING equipment and high rate of welding will result in incomplete fusion.

The correct CHOICE is (b) it is due to use of large size of electrodes

To explain: Incomplete penetration is due to failure of weld metal to penetrate the complete depth of joint where full penetration has been specified. This DEFECT is found in groove welds SUE to UNSUITABLE groove design for selected welding process, use of large size of electrodes, INSUFFICIENT welding current, excessive welding rates.

Correct option is (a) Pre-heating does not HELP to reduce HEAT affected zone cracks

The explanation: Pre-heating of joints help to reduce heat affected zone cracks but increases the COST of welding. It is done to remove SURFACE MOISTURE in highly humid conditions, to disperse hydrogen away from weld pool and heat affected zone, to bring steel to ambient temperature in cold climates.

Correct ANSWER is (C) It has higher yield to ultimate RATIO

Explanation: Weld metal is a mixture of parent metal and steel melted from electrode. The SOLIDIFIED weld metal has properties characteristic of cast steel. It has higher yield to ultimate ratio but lower ductility compared to structural steel.

Correct ANSWER is (b) They are assumed to fail in shear

Explanation: Slot and plug welds are not extensively used in steel construction. They are used to FILL up holes in connections. They are assumed to fail in shear. The inspection of these welds is DIFFICULT. They are useful in preventing overlapping PARTS from buckling.

The correct choice is (a) same

The explanation is: GROOVE WELDS will TRANSMIT FULL load of the members they join, so they should have the same strength as the members they join.

Right choice is (C) They are assumed to fail in tension

To explain I would say: Fillet welds require less precision in FITTING up TWO sections. They are adopted in field as WELL as shop WELDING. They are assumed to fail in shear and are cheaper than groove welds.

Correct choice is (c) TYPE of metal plate

Best explanation: For groove weld, the root opening or gap is provided for the electrode to access the base of the joint. The SIZE of root gap and root face depends on the following : (i) type of welding process, (II) welding position, (III) volume of deposited material, (iv)cost of preparing edges, (v)access for ARC and electrode, (vi)shrinkage and distortion.

The correct option is (d) It introduces a crevice into the weld geometry

The best I can explain: Back-up strip is provided at the bottom of single-V/bevel/J or U grooves. It is commonly provided when WELDING is done from ONE SIDE or when the ROOT opening is excessive. It introduces a crevice into the weld geometry and prevents the problem of burn-through.

Correct option is (b) SLOT and plug weld, groove weld, fillet weld

The explanation: Fillet welds are used extensively (about 80%) followed by groove welds (15%). Slot and plug welds are RARELY used (less than 5%) in structural ENGINEERING APPLICATIONS.

Correct OPTION is (a) Fillet weld

Explanation: Fillet welds are SUITABLE for lap and T-joints and GROOVE welds are suitable for butt, corner, and EDGE joints.

Right CHOICE is (a) SHIELDED metal ARC welding

For explanation: Flux core arc welding, gas-shielded metal arc welding, ELECTRO slag welding have high deposition rates.

The correct option is (c) multiple electrodes may not be used

The EXPLANATION: The following are some ADVANTAGES of electro slag welding: (i) high DEPOSITION rates, (ii) multiple electrodes may be used, (iii)low DISTORTION. Some disadvantages are: (i) welds FLAT or vertical joints only, (ii) complicated set-up, (iii)cooling water is needed.

Correct option is (c) slag removal required

Easy explanation: The following are some ADVANTAGES of flux core arc welding: (i)HIGH deposition rates, (ii)can be used to groove angles as narrow as 30˚, (iii)welds in all positions can be made, (iv)has EXCELLENT WELD pool control. Some disadvantages are: (i) slag removal required, (ii) generates large volume of FUMES and smoke.

The correct answer is (d) high deposition rate

Explanation: GAS-shielded metal arc welding is ALSO called metal-active gas welding. The following are some advantages of gas-shielded metal arc welding : (i) suitable for metals as thin as 0.58mm, (ii)all welding positions can be used, (III) no need to stop welding to change the consumed electrode, (iv)high deposition rates. Some disadvantages are : (i)welding equipment is expensive and COMPLICATED, (ii)cannot be performed outdoors in greater than 8km/hr BREEZE.

The correct ANSWER is (d) affects the weld

The EXPLANATION is: HYDROGEN causes weld to CRACK. Hence most of the welding PROCESSES are low hydrogen welding process.

The correct option is (c) cannot be used for metal SHEETS under 1.5mm thickness

For explanation: The following are some advantages of shielded metal arc welding : (i)LOW equipment cost, (ii)welds many different metals, (iii)welds can be performed in any POSITION, (iv)process less affected by wind, (V)can be performed under most weather conditions. SomeThe disadvantages are : (i)not suitable for metal sheets under 1.5mm thickness,(ii) entire electrode cannot be used, about 25-50mm electrode is wasted.

Correct option is (b) short set-up time

For explanation I WOULD say: The following are some ADVANTAGES of submerged arc welding: (i) high deposition rate, (II)high QUALITY welds with good ductility, high impact strength, good corrosion resistance, (iii)good for welding long joints(in excess of 1m), (iv)no eye protection required. Some disadvantages are : (i) long set-up time, (ii)slag removal NEEDED, (iii)used for flat or horizontal fillets only.