Explain how a magnetic field can be used to test the soundness of a weld.
What will be an ideal response?
A magnetic field is induced in a part by passing an electric current through or around it. The magnetic field is always at right angles to the direction of current flow. Ferromagnetic powder registers an abrupt change in the resistance in the path of the magnetic field, such as would be caused by a crack lying at an angle to the direction of the magnetic poles at the crack. Finely divided ferromagnetic particles applied to the area will be attracted and outline the crack.
The flow or discontinuity interrupting the magnetic field in a test part can be either longitudinal or circumferential. A different type of magnetization is used to detect defects that run down the axis, as opposed to those occurring around the girth of a part. For some applications you may need to test in both directions.
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Explain how salinity is measured
What will be an ideal response?
Good watering practices will reduce plant damage caused by low humidity
Indicate whether the statement is true or false
?What are some types of materials that can be cut using one of the related cutting processes?
A. ?glass and plastic B. ?printed circuit boards C. ?cloth and fiberglass insulation D. ?All of the above
PROBLEM 3.31
PROBLEM 3.31 While an oil well is being drilled at a depth of 2500m, it is observed that the top of the 200-mm-diameter steel drill pipe (G = 77.2 GPa) rotates through 2.5 revolutions before the drilling bit starts to operate. Determine the maximum shearing stress caused in the pipe by torsion.