30 September 2023

difference between Pipe and Tube | long radius elbow | short radius elbow | Eccentric reducers | Concentric reducers | ERW & Seamless pipes

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difference between Pipe and Tube

1. What is the difference between Pipe and Tube?

Answer: – Pipe is identified by NB and thickness is defined by Schedule whereas Tube is identified by OD & its thickness as BWG (Brimingham wire gauge or 1/100 inch).

2. From which size onwards NB of pipe is equal to OD of Pipe?
Answer: – From the size 14” and onwards NB = OD of pipe.

3. What should be the radius of long radius elbow?
Answer: 1.5D (Where “D” is the diameter of the pipe.)

4. What should be the radius of short radius elbow?
Answer:- 1D(Where “D” is the diameter of the pipe.)

5. What is the basis of using of short radius & long radius elbow?
Answer:- Long radius elbow are used for small pressure drop whereas short radius elbow are used for high pressure drops. For catalyst flows vary long radius elbows are used.

6. Normally where do we use the following?
A. Eccentric reducers.
B. Concentric reducers.
A. Eccentric reducers = Pump suction to avoid Cavitation, To maintain elevation (BOP) in rack.
B. Concentric reducers = Pump discharge, vertical pipeline etc.

7. Concentric reducer is used in pump suction. (Yes / No). Explain.
No. Air pockets may form if concentric reducer is used at pump suction, which results in cavitation and cause damage to Pump. To avoid this problem, Eccentric Reducer with flat side up (FSU) is used in Pump Suction.

8. Where the ERW spiral & longitudinal pipes are used?
Answer: – Use depends upon the availability of pipes. Nothing functional difference.

9. Where the ERW & Seamless pipes are used?
Answer: – Above 18” ERW pipes are used. Below 18” seamless pipes are used. Seamless pipes can sustain higher temperature & pressure.

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