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8. What can you say about the origin of such a term as “kelly
joint”?
9. Why is the kelly considered to be a precision instrument
nowadays? What were the reasons of adding extra hard joints
above and below the kelly?
10. Which consequences of hanging up can you name?

Exercises

Exercise 1. Answer the following question after you have
read the text
1. What are the drill string components?
2. How can you describe the early-day drill collar?
3. At what point in the drill string is there neither tension nor
compression?
4. What are drill collars made of?
5. What variations of drill collar can you name?
6. Which grades of drill pipe cover API specifications? On
which properties are they based? What are their characteristics?
7. Which kinds of upset do you know? What can you tell
about internal-external upset?
8. Are tool joints an integral part of drill pipe?
9. What progress has been made in tool joint design?
10. How do you understand such terms: "excessive wear"
and "abuse"?
11. Which methods of attaching tool joints to drill pipe are
still in use? What are advantages and disadvantages of each type of
connection?
12. What is the main purpose of creation of the FH (full
hole) design?
13. What can you say about the origin of such a term as
"kelly joint"?

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