For tight leakage joints, following type of thread is best suited
Metric
Buttress
Square
NPT (national pipe threads)
Correct Answer :
D. NPT (national pipe threads)
Related Questions
Spring index is
Ratio of coil diameter to wire diameter
Load required to produce unit deflection
Its capability of storing energy
Indication of quality of spring
According to I.B.R., when the thickness of boiler shell (t) is greater than 8 mm, then the diameter of rivet hole (d) is obtained by
Equating tearing resistance of the plate to the shearing resistance of the rivets
Equating tearing resistance of the plate to the crushing resistance of the rivets
Equating shearing resistance to the crushing resistance of the rivets
None of the above
Split nut is a locking device in which
One smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
A slot is cut partly in middle of nut and then slot reduced by tightening screw
A hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip
Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter pin splitted and bent in reverse direction at the other end
A compound cylinder with inner radius 50 mm and outer radius 70 mm is made by shrinking one cylinder on to the other cylinder, the junction radius is 60 mm and the junction pressure is 1.1 N/mm². The maximum hoop stress developed in the inner cylinder is
3.6 N/mm² compression
3.6 N/mm² tension
7.2 N/mm² compression
7.2 N/mm² tension
In a multiple V-belt drive, when a single belt is damaged, it is preferable to change the complete set in order to
Reduce vibration
Reduce slip
Ensure uniform loading
Ensure proper alignment
A sliding bearing in which although lubricant is present, the working surfaces __________ contact each other at least part of the time, is called boundary lubricated bearing.
Partially
Fully
Either A or B
None of these
Which of the following pipe joints would be suitable for pipes carrying steam?
Flanged
Threaded
Bell and spigot
Expansion
The circumferential and longitudinal strains in a cylindrical boiler under internal steam pressure are εc and εl respectively. The change in volume of the boiler cylinder per unit volume will be
εc + 2εl
2εc + εl
εc + εl²
εc² + εl
The constant factor in case of R10 series of preferred numbers is
1.06
1.12
1.26
1.58
The expansion joint is mostly used for pipes which carry steam at __________ pressures.
Low
High
Medium
None of these
Which one of the following loading is considered for the design of axles?
Bending moment only
Twisting moment only
Combined bending moment and twisting moments
Combined action of bending moment, twisting moment and axial thrust
A shaft is subjected to fluctuating loads for which the normal torque (T) and bending moment (M) are 1000 N-m and 500 N-m respectively. If the combined shock and fatigue factor for bending is 1.5 and combined shock and fatigue factor for torsion is 2, then the equivalent twisting moment for the shaft is
2000 N-m
2050 N-m
2100 N-m
2136 N-m
The centre distance between two meshing involute gears is equal to
(Sum of base circle radii)/cosφ
(Difference of base circle radii)/cosφ
(Sum of pitch circle radii)/cosφ
(Difference of pitch circle radii)/cosφ
Soderberg relation is based on __________ of the material whereas all other failure relation for dynamic loading are based on ultimate strength of the material.
Elastic strength
Yield strength
Shear strength
None of these
The helix angle for single helical gears ranges from
10° to 15°
15° to 20°
20° to 35°
35° to 50°
In hydrodynamic bearings
The oil film pressure is generated only by the rotation of the journal
The oil film is maintained by supplying oil under pressure
Do not require external supply of lubricant
Grease is used for lubrication
When bevel gears having equal teeth and equal pitch angles connect two shafts whose axes intersect at right angle, then they are known as
Angular bevel gears
Crown bevel gears
Internal bevel gears
Mitre gears
The belt slip occurs due to
Heavy load
Loose belt
Driving pulley too small
Any one of the above
Whether any core is required in wire ropes
Yes
No
Sometimes
Rarely
Belt slip may occur due to
Heavy load
Loose belt
Driving pulley too small
All of the above
The ratio of pitch circle diameter in millimetres to the number of teeth, is called
Circular pitch
Diametral pitch
Module
None of these
When two nonintersecting and non-coplanar shafts are connected by gears, the arrangement is known as
Spur gearing
Helical gearing
Bevel gearing
Spiral gearing
The velocity of sliding ________ the distance of the point of contact from the pitch point.
Is directly proportional to
Is inversely proportional to
Is equal to cos φ multiplied by
Does not depend upon
An imaginary circle which by pure rolling action gives the same motion as the actual gear, is called
Addendum circle
Dedendum circle
Pitch circle
Clearance circle
Turn buckle has
Right hand threads on bout ends
Left hand threads on both ends
Left hand threads on one end and right hand threads on other end
No threads
Taper on the cotter and slot is provided
On both the sides
On one side only
On none of the sides
May be provided anywhere
In designing a key, it is assumed that the distribution of forces along the length of key
Varies linearly
Is uniform throughout
Varies exponentially, being more at the torque-input end
Varies exponentially, being less at the torque-input end
The maximum normal stress theory is used for
Plastic materials
Brittle materials
Non-ferrous materials
Ductile materials
The strap end of a connecting rod of steam engine is joined by
Gib of cotter joint
Sleeve and cotter joint
Spigot socket cotter joint
Knuckle joint
For steel, the ultimate strength in shear as compared to ultimate strength in tension is
1/2
1/3
1/4
2/3