Dart Sub

Question 0

How many pieces make up the Dart Sub?

Answer 0

Two - the upper and lower bodies which contain inner bushings

Question 1

What is the purpose of the Dart Sub?

Answer 1

It is used as a backup if the ROV panel fails to set and test the RLSA. It redirects pressure from the drill string through the ROV panel and to the RLST.

Question 2

Can any upper and lower subs be made up together?

Answer 2

Not likely. The upper and lower subs are machined and threaded as a set and are not torqued.

Question 3

What is the purpose of the anti-rotation keys?

Answer 3

The upper and lower bodies are not torqued together. They are held in place by the anti-rotation keys.

Question 4

What are the shear pin ratings on the dart sub bushings?

Answer 4

Upper - 4 shear pins - 1,000 psi

Lower - 6 shear pins - 1,500 psi

Question 5

List and describe the location and purpose of all the seals associated with the Dart Sub.

Answer 5

• Upper and lower Darts - each has 3 O-Rings to seal between dart and bushing
• Upper and lower Bushings - each has 4 O-Rings to seal between Bushing and body
• Upper Body - has 2 S-Seals at acme threads to seal where bodies thread together
• Upper Body - has an O-Ring at base of acme threads used as a trash seal

Question 6

How can you tell if the Bushings are in re-set position and ready to run?

Answer 6

You have communication between the compensation and the set/test ports and the shear pin holes line up with the shear pin grooves in the bushings.

Question 7

Why must the compensation ports be left open when running subsea?

Answer 7

The compensation ports allow the hoses to fill with water preventing them from being crushed from the hydrostatic pressure subsea

Question 8

What are the ID’s of the Bushings and OD’s of the Darts?

Answer 8

Upper Bushing - 2.4”
Lower Bushing - 2.2”
Upper Dart - 2.505”
Lower Dart - 2.305”

Question 9

What are the threads on the connections of the Dart Sub?

Answer 9

6 5/8” REG box/pin