General service railcars (see photo below) are the most familiar railcar we see

Question

General service railcars (see photo below) are the most familiar railcar we see when a train goes by. Typically, they carry liquids, about 30.000 gallons, and some transport gases. They are usually made of carbon steel that must be at least 0.5 inches thick. Like any container, they are subject to implosion (collapsing inward) under the right conditions. Sometimes this happens when railcars are sent for cleaning. A steam lance and/or a steam hose is attached to one of the car's valves, and steam at high temperature is injected into the car. The steam loosens up gunky deposits and causes them to liquefy and flow to the belly of the car and out a belly valve drain into a cache basin. The worker will let the car steam out for a certain amount of time, then close the belly valve, disconnect the steam hose from top valve, and if they are not thinking, will automatically close the top valve. Now the car is full of steam and all air that had been in the car has been displaced. The worker goes home to supper and when he comes back the next day he sees the imploded railcar. Explain why the railcar imploded. Consider the railcar to be a carbon steel cylinder. If atmospheric pressure is 14.7 psi and the pressure inside the railcar before the implosion was 2 psi calculate the total pressure on the railcar that caused it to collapse using the data below. Show your calculations or you get a zero for this part of the problem. Railcar dimensions: 51 ft long. 10 ft in diameter Area of a cylinder is: A =2TT r h + 2pi r^2 Where r = radius, h = height

Explanation / Answer

ANS 1.The tanker implodes because of pressure. In this case, it is air pressure from the surrounding atmosphere. Normally, the pressure inside and outside the tank are approximately the same—about 105 Newtons per square meter.

But if worker removed all the air from the inside of the tank then he would have atmospheric pressure pushing in on the tank, but nothing pushing out. It would be up to the structural integrity of the tank walls to prevent it from collapsing.

Ans 2. diameter = 10ft therefore radius =5 ft height =51fts

   area of railcar cylinder = 2x22/7x5(5+51)= 1758.4 fts

net force OUTSIDE = Pressure outside x area = 14.7x 1758.4=25848.48

now force that caused Implosion = Pressure inside x area = 2x 1758.4= 3516.8

net force= 25848.48-3516.8= 22331.68

therefore net pressure for collapse = Net force / area=22331.68/1758.4= 12.7psi.. (answer)

Related Questions

Navigate

• Browse (All)
• Browse G
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.