1. Q:-What is the ASME code followed for design of piping systems in Process piping (Refineries & Chemical Industries)?
Answer: – B31.5
2. Q:-Which American standard is referred for selection of following piping element?
a. Flanges
b. Butt Welded fittings
c. Gasket
d. Socket and Threaded fittings
e. Valves
f. Pipes.
Answer: –
A. Flanges :-
I. ASME B16.1 : – Cast iron pipes flanges and flanged fittings.
II. ASME B16.5 : – Carbon steel pipes flanges and flanged fittings. (Up to 24")
III. ASME B16.47 : – Large Diameter steel flanges. (Above 24")
B. Butt welded fittings :-
I. ASME B16.9 : – Steel butt welding fittings.
II. ASME B16.28 : – Butt-welded short radius elbows and returns bends.
C. Gasket :-
I. ASME B16.20 / API -601: – Metallic gaskets for pipe flanges- Spiral wound, Octagonal ring Joint and Jacketed flanges.
II. ASME B16.21 : – Non metallic gasket.
D. Socket & Threaded fittings :-
I. ASME B16.11 : – Forged steel socket welding and threaded fittings.
E. Valves :-
I. ASME B16.10 : – Face to face and end to end dimension of valves.
II. ASME B16.34 : – Flanged and butt-welded ends steel valves (Pressure and Temperature ratings) except Ball, Plug and Butter fly Valves.
F. Pipes :-
I. ASME B36.10 : – Welded and Seamless wrought iron pipes.
II. ASME B36.19 : – Stainless steel pipes.
3. Q:-How can flanges be classified based on Pipe Attachment?
Answer: –
Flanges can be classified based on pipe attachment as: –
Slip – on. : – The Slip-on type flanges are attached by welding inside as well asoutside. These flanges are of forged construction.
Socket Weld. : – The Socket Weld flanges are welded on one side only. These are used for small bore lines only.
Screwed. : – The Screwed-on flanges are used on pipe lines where welding cannot be carried out.
Lap Joint. : – The Lap Joint flanges are used with stub ends. The stub ends are welded with pipes & flanges are kept loose over the same.
Welding Neck. : – The Welding neck flanges are attached by butt welding to the pipe. These are used mainly for critical services where the weld joints need radio graphic inspection.
Welding Neck. : – The Welding neck flanges are attached by butt welding to the pipe. These are used mainly for critical services where the weld joints need radio graphic inspection.
4. Q:-How can flanges be classified based on Pressure- temperature ratings?
Answer: –
Flanges are classified based on pressure temperature ratings as: –
A. 150
B. 300
C. 400
D. 600
E. 900
F. 1500
G. 2500
Pressure temperature rating carts in the standard ASME16.5 specify the non-shock working gauge pressure to which the flange can be subjected to at a particular temperature.
5. Q:-How the Gaskets are classified based on the type of construction?
Answer: –
Based on the type of construction, gaskets are classified as: –
A. Full face.
B. Spiral wound metallic.
C. Ring type.
D. Metal jacketed.
E. Inside bolt circle.
6. Q:-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.
7. Q:-From which size on wards NB of pipe is equal to OD of Pipe?
Answer: –
From the size 14" and onwards NB = OD of pipe.
8. Q:-What is the basis of using of short radius & long radius elbow?
Answer: –
1D(Where "D" is the diameter of the pipe.) and 1.5D (Where "D" is the diameter of the pipe)
9. Q:-From which side of pipe will you take a branch connection?
Answer: –
When Fluid is Gas, Air or Steam and Cryogenic Service – Topside. When Fluid is Liquid – Bottom Side.
10. Q:-Why do we provide High Point Vent (HPV) and Low Point Drain (LPD) in piping?
Answer: –
HPV – for removing Air during Hydro-test.
LPD – for draining water after conducting Hydro-test.
11. Q:-What is the function of valves?
Answer: –
A. Isolation.
B. Regulation.
C. Non-Return.
D. Special purpose.
12. Q:-How the valves are classified based on end connection?
Answer: –
Valves are classified based on end connection as: –
A. Screwed ends.
B. Socket ends.
C. Flanged ends.
13. Q:-What should be the radius of long radius elbow?
Answer: –
1.5D (Where "D" is the diameter of the pipe)
14. Q:-What should be the radius of short radius elbow?
Answer: –
1D(Where "D" is the diameter of the pipe.)
15. Q:-Normally where do we use the following?
a. Eccentric reducers.
b. Concentric reducers.
Answer: –
A. Eccentric reducers = Pump suction to avoid Cavitation, To maintain elevation (BOP) in rack.
B. Concentric reducers = Pump discharge, vertical pipeline etc.
16. Q:-What is the minimum distance to be maintained between two welds in a pipe?
Answer: –
The thumb rule is that the minimum distance between adjacent butt welds is 1D. If not, it is Never closer than 1-1/2″. This is supposedly to prevent the overlap of HAZs. Minimum spacing of circumferential welds between centerlines shall not be less than 4 times the pipe wall thickness or 25 mm whichever is greater.
17. Q:-What are the types of check valves?
Answer: –
Check valves are divided into two types based on check mechanism as: –
A. Lift check valve.
B. Swing check valve.
18. Q:-What are the Criteria for Pipe Supporting?
Answer: –
Following are the points, which should be taken into account for proper supporting: –
A. Load of bare pipe + fluid + insulation (if any).
B. Load of bare pipe + water fill.
C. Load of valves and online equipment and instrument.
D. Thermal loads during operation.
E. Steam out condition, if applicable.
F. Wind loads for piping at higher elevation, if required.
G. Forced vibration due to pulsating flow.
H. Bare pipe with size above 12" shall be supported with Pad or Shoe.
19. Q:-What is the purpose of providing Graphite Pads in supports below shoes?
Answer: –
To reduce the friction factor. The co-efficient of friction for Graphite Pads is 0.1
20. Q:-What is the difference between variable spring hanger and constant spring hanger?
Answer: –
Variable spring Hanger: – As the name itself indicates the resistance of the coil to a load changes during compression.
Constant spring Hanger: – Constant spring hanger provides constant support force for pipes and equipment subjected to vertical movement due to thermal expansion.
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by Sopa QCS