In riveted boiler joints, all stresses, shearing, bearing and tensile are based on the

The pull required to tear off the plate per pitch length is (where p = Pitch of rivets, t = Thickness of plates and $${\sigma _{\text{t}}},\,\tau $$ and $${\sigma _{\text{c}}}$$ = Permissible tensile, shearing and crushing stresses respectively)

A

$$\left( {{\text{p}} - 2{\text{d}}} \right){\text{t}} \times {\sigma _{\text{c}}}$$

B

$$\left( {{\text{p}} - {\text{d}}} \right){\text{t}} \times \tau $$

C

$$\left( {{\text{p}} - {\text{d}}} \right){\text{t}} \times {\sigma _{\text{t}}}$$

D

$$\left( {2{\text{p}} - {\text{d}}} \right){\text{t}} \times {\sigma _{\text{t}}}$$

The hoop stress in a riveted cylindrical shell of diameter (d), thickness (t) and subjected to an internal pressure (p) is (where $$\eta $$ = Efficiency of the riveted joint)

A

$$\frac{{{\text{pd}}}}{{{\text{t}}\eta }}$$

B

$$\frac{{{\text{pd}}}}{{2{\text{t}}\eta }}$$

C

$$\frac{{{\text{pd}}}}{{4{\text{t}}\eta }}$$

D

$$\frac{{{\text{pd}}}}{{8{\text{t}}\eta }}$$

In calculating the strength of a riveted joint in tearing, shearing and crushing, the

A

Actual diameter of rivet is used

B

Actual diameter of hole drilled for rivet is used

C

Mean diameter of hole drilled and rivet is used

D

Smaller of the rivet diameter and hole diameter is used

The type of bearing plate used in all joints and on curves to give better bearing area to the rails is

A

flat mild steel bearing plate

B

mild steel canted bearing plate

C

cast iron anti creep bearing plate

D

none of the above

A _________ in a boiler is used to put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit.

A

Blow off cock

B

Fusible plug

C

Stop valve

D

Safety valve

Which of the following types of riveted joint is free from bending stresses?

A

Lap joint

B

Butt joint with single cover plate

C

Butt joint with double cover plates

D

None of the above

A triple riveted butt joint with double straps of unequal width is to be designed for a boiler shell. The pitch of the rivets in the outer row is double the pitch in the inner row and zigzag riveting is proposed. Which of the following statement is correct?

A

There are four rivets per pitch length, all in double shear

B

There are four rivets per pitch length, out of which two are in single shear and two are in double shear

C

There are five rivets per pitch length, all in double shear

D

There are five rivets per pitch length, out of which four are in double shear and one is in single shear

Vertical construction joints are provided where the shearing forces are minimum in the case of

A

Slabs

B

Beams

C

Girders

D

All of these

The shearing stresses in the inner face as compared to outer face of the wire in a heavy close coiled spring is

A

Larger

B

Smaller

C

Equal

D

Larger/smaller depending on diameter of spring coil

If shearing stress in nut is half the tensile stress in a bolt, then nut length should be equal to

A

Diameter of bolt

B

0.75 × diameter of bolt

C

1.25 × diameter of bolt

D

1.5 × diameter of bolt

In riveted boiler joints, all stresses, shearing, bearing and tensile are based on the

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