Control valve interview questions and answers part2


#1

1. What are functions of valves?

Isolation, regulation, non-return and special purposes

2. What are the steps in selection of valve?

What to handle, liquid, gas or powder, fluid nature, function, construction material, disc type, stem type, how to operate, bonnet type, the body ends, delivery time, cost, warranty.

3. What are special valves?

Multi-port, flush bottom, float, foot, pressure relief, a breather.

4. What materials are used for the construction of valves?

Cast iron, bronze, gun metal, carbon steel, stainless steel, alloy carbon steel, polypropylene and other plastics, special alloys.

5. What is trim?

Trim is composed of stem, seat surfaces, back seat bushing and other small internal parts that normally contact the surface fluid.

6. What is wire drawing?

This term is used to indicate the premature erosion of the valve seat caused by excessive velocity between seat and seat disc when the valve is not closed tightly.

7. What are pressure tests carried out on valves?

Shell-hydrostatic, seat-hydrostatic, seat-pneumatic

8. What are available valve operators?

Handlever, handwheel, chain operator, gear operator, powered operator likes electric motor, solenoid, pneumatic and hydraulic operators, Quick acting operators for non-rotary valves (handle lift).

9. What are ball valve body types?

Single piece, double piece, three pieces, the short pattern, long pattern, sandwich and flush bottom design.

10. What are types of check valve?

Lift check valves and swing check valves.

11. What are non-slam check valves?

Swing check valve, conventional check valve, wafer check valve, tilting disc check valve, piston check valve, stop check valve, ball check valve.

12. What are the types of bonnets?

Bolted bonnet, bellow sealed bonnet, screwed on the bonnet, union bonnets, A U-bolt and clamp type bonnet, breechlock bonnet, pressure seal bonnet.

13. Where is WYE body globe valve used?

In line ports with stem emerging at 45 degree, for erosive fluids due to smoother flow pattern.

14. How to install a globe valve?

Full port: More than 85% of bore size,
Reducer port: One size less than the connected pipe

15. What is metal seated lubricated plug valve?

A plug valve with no plastic material, where grease is applied to contacting surfaces for easy operation.

16. What is Teflon sleeved plug valve?

PTFE sleeve between plug and body of the valve, low turning effort, minimum friction, temperature limitation, anti-static design possible.

17. What are uses of four-way valve?

Reversal of pump suction and delivery, By pass of strainer or meter, reversal of flow through filter, heat exchanger or dryer.

18. What are the types of bonnets?

Bolted bonnet, bellow sealed bonnet, screwed on a bonnet, union bonnets, A U-bolt and clamp type bonnet, breechlock bonnet, pressure seal bonnet.

19. What is lantern ring?

It’s a collection point to drain off any hazardous seepages or as a point where lubricant can be injected, it is in the middle of packing rings.

20. What is dimensional standard for plug valve?

API 599.