Diseño Tuberías

PIPING DESIGN QUESTIONAIRE
Authors: Kumar Rudra, Rakesh Patil and Joshua Thinakaran
Oil and Gas Special Projects - L&T, Mumbai - India

Simple 
1. What is the ASME code followed for design of piping systems in Process pipings (Refineries & Chemical Industries)?

(i) B31.1
(ii) B31.3
(iii) B31.5
(iv) B31.9
Answer (III)

2. What do you mean by following items?
 i.) ISLB-400ii) ISMB-600
iii) ISHB-350
iv) ISMC-300
v) ISJB-150
vi) ISLB-200
vii) ISMB-450
viii) ISWB-400
ix) ISJC-200
x) ISLC-350
xii) ISMC-250
Answer:
i. Indian STD light weight beam, Web size – 400 
ii. Indian STD medium weight beam, Web size – 600 
iii. Indian STD ‘H’ beam, Web size – 350 
iv. Indian STD medium weight channel, Web size –300 
v. Indian STD juniorbeam, Web size – 150 
vi. Indian STD light weight beam, Web size – 200 
vii. Indian STD medium weight beam, Web size – 450 
viii. Indian STD wide flange beam, Web size – 400 
ix. Indian STD junior channel, Web size – 200 
x. Indian STD light weight channel, Web size – 350 
xi. Indian STD medium weight channel, Web size – 250

3. What is this item?
 i.ISA-100X100X12
ii)ISA-80X50X10
iii)ISLT-100X100

Answer:
 i.Equal angle size 100x12 THK 
ii.Unequal angle size 80x50x10 THK 
iii.Indian STD light weight tee bar size 100x100

4. What is the difference between stub in and stub on branches? Describe with sketch.

 
Which one is preferred?
For branching of one size lesser of run pipe, Stub On is preferred. For other branchingless than one size of run pipestub in is preferred. The Design is based on ANSI B 31.3

5. 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.

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

7. Write down the outside diameter of following pipe?
 i. 3inch ii) 6 inch iii) 10 inch iv) 14 inch
Answer:
 i. 3 inch=88.9mm ii)6 inch=168.28mm iii) 10 inch=273.06mm iv) 14 inch = 355 mm(OD= Size X 25.4)

8. What is the difference between machine bolt and stud bolt? Answer:
Machine bolt has a head on one side and nut on other side but stud bolt have nuts on both sides.

9. What is soluble dam?
Answer:
Soluble dam is a water-soluble materialused for restricting the purging gas within the pipe.

10. While welding of pipe trunion to pipe/reinforcement pad you have to put a hole or leave some portion of welding why?
Answer:

For venting of hot gas which may get generated due to welding

11. What do you mean by following type of welding?
 i. SMAW ii)TIG

Answer:
 i. SMAW = SHIELDED METAL ARC WELDING
ii. TIG = TUNGSTEN INTERGAS WELDING

12. Find out the elevation of marked point ‘A’
Answer:

Elevation of marked point ‘A’ is 100.050

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

14. Normally where do we use the following?
 i. Eccentric reducers ii)Concentric reducers

Answer:
i. Eccentric reducers= Pump suction to avoid Cavitations, Tomaintain elevation (BOP) in rack.
ii. Concentric reducers= Pump discharge, vertical pipeline etc.
15. Concentric reducer is used in pump suction. (Yes/No). Explain.
Answer:

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.16. What do you mean by Cavitation in Pump?

A pump is designed to handle liquid, not vapour. Vapour forms if the pressure in the pump falls below the liquid’s vapour pressure. The vapour pressure occurs right at the impeller inlet where a sharp pressure drop occurs. The impeller rapidly builds up the pressure which collapses vapour bubbles causing cavitation and damage. This is avoided by...