Can Anyone help me with this problem? thanks

[crazy legs]

Your team has been hired by an oil drilling company to solve a problem.� They need to weld a copper ring inside a long steel pipe which has been inserted into an oil well.� They are able to reach down the steel pipe with the copper ring but then have no way of welding the copper to the inside of the steel ring.� They have asked you to devise a method of welding the two metals together.� You have decided to cold weld the two metals together.� The copper ring will be machined on the oil rig to your specifications.� You been provided with the following information.



The inside diameter of the steel pipe is (10.000 � 0.002) cm.

The inside diameter of the copper ring must be (8.20 � 0.01) cm.

The copper ring is 5.5 cm long.

The temperature of the inside of the steel pipe varies between 20�C and 120�C.

The copper ring must be welded a distance 25 m below the opening of the steel pipe and it can be lowered at a rate of 25 cm/sec.

You have already estimated that the main heat gain mechanism for the copper ring as it is lowered is via radiation.

The steel pipe is currently at 40�C while the copper is currently at 20�C.

There is a limited amount of liquid nitrogen available.� You estimate that you have 3 litres at present.� The web site below gives the density of liquid nitrogen:

http://antoine.fsu.umd.edu/chem/senese/101/mea surement/faq/density-liquid-air.shtml



Explain how you will proceed and show your calculations which verify that it is possible to cold weld the two metals together given the constraints above.� You need to provide the dimensions of the copper ring which will

[Avatar]

I think access to the internet during exams should be banned

[kermit911]

I didn't know it was allowed.