MECHANICAL FITTER INTERVIEW QUESTIONS AND ANSWERS

MECHANICAL FITTER INTERVIEW QUESTIONS AND ANSWERS

1.     Define Valve?

               Valve is a Mechanical flow control element in the process.

2.     What are types of valves?

·        Gate Valve

·        Globe Valve

·        Ball valve

·        Butterfly Valve

·        Needle Valve

·        Plug Valve

·        Diaphragm Valve

·        Non-Return Valve

·        Knife Edge Valve

·        Drain Valve

·        Float Valve

·        Flush Bottom Valve

·        Pinch Valve

·        Pen Stack Valve etc.

3.     Explain the valve parts?

A.    Gate Valve – Body, Bonnet, Seat, Gate, Stem, Hand Wheel, Gland Bush, Gland Flange, Gland Bolt and Nuts. Hand Wheel lock nut.

B.     Ball Valve – Body , End Piece , Ball , Stem , Seal , Seal Follower , Seat , Lock Nut , Handle Gland Packing , Gland Flange , Gland Stud and nut.

C.     Globe Valve – Body , Bonnet , Seat , Plug , stem ,  Hand Wheel , Lock Nut ,Gland Packing , Gland Flange , Gland Stud and nut.

D.    Butterfly – Body , Disc , Stem , Seat ring , Seat ring holder , Bush , End cover , Hand Wheel  or Gear Box , Gland Bush , Gland Packing , Gland Flange , Gland Stud and nut.

 

4.     What are the types of Gaskets?

·        CAF – Compressed Asbestos Fiber Filled Gasket

·        Semi Metallic Gasket 

·        Metallic Gasket

·        Rubber Gasket

·        Teflon Gasket

·        Spiral Wound Gasket

·        RTJ – Ring Type Joint

·        Graphite Gasket

·        Impregnated Gasket

·        Graf oil Gasket  

5.     What is Gasket? Where it is used?

·        It is sealing member between two flanges.

Uses:

1.     Water Line, Gas Line, Air Line used CAF Gasket.

2.     RTJ – High Pressure Line.

3.     Chemical Line – Rubber Gasket and Teflon Gasket.

4.     Steam Line – Semi Metallic, Metallic and Graphite.

5.     Impregnated Gasket – Valve Sealing Gasket.

6.     Spiral Wound – Steam Line.

6.     What is flange? Types of Flanges?

Flanges used to connect both lines (Fluid, Gas, Oil, Water….)

                                   Thread Type Flange

            Modified Flange

            Weld Neck Flange

            Slip On Flange

            Goose Neck Flange

            Socket Weld Flange

            Stepped Flange

            Spade Flange

            Spectacle Flange

            Blind Flange

7.     What is Gland packing? Uses of gland packing?

Gland packing is a Sealing member between two moving parts or stationary.

It is used for arrest the leak through shaft various lines.

            1. Teflon Gland packing

            2. Graphite Gland packing

            3. Carbon Gland packing

            4. Virgin PTFE Gland packing

            5. Graf oil Gland packing

8.     What are PRV and PSV?

PRV(Pressure Relief valve) release excessive more than set point, released fluid re circulated.

PSV(Pressure Safety Valve) released pressure more than set point to safe the equipments.

9.     Give the parts name of PSV?

            Body

            Bonnet

            Nozzle

            Disc

            Disc Holder

            Stem

            Blow down ring

            Blow down ring lock screw

            Spring Bottom Plate

            Spring

            Spring Top Plate

            Control Screw

            Lock Nut

            Cap

            Gasket

10.                  What is the use of SPADE, SPECTACLE, and BLIND?

SPADE- Give space between two flanges and give flow through the spade.

SPECTACLE – Combination of SPADE and BLIND and both option done in one flange.

BLIND – Used for close the line.

11.                  What is PPE?

PPE- Personnel Protective Equipment

E.g.) Helmet, Boiler Shout, Safety Goggles, Safety Shoe, Gloves, Dust Mask etc... 

12.                  What is heat exchanger? What are the types of heat exchanger?

It is an Equipment to use for Exchange the heat(Cooling or Heating purpose)

Types:

            Fixed Tube Heat Exchanger

            Floating Tube Heat Exchanger

            U Tube Exchanger

            Plate Type Exchanger

            Fin Fan Cooler Heat Exchanger

            Bridge Lock Exchanger

13.                  Explain the following valves Shell and Seat Testing?

Ball Valve

Gate Valve

Globe Valve

Butterfly valve

Plug valve

Shell Test of above valves:- 

             Testing flange to be fixed on both sides. Pressurized one side under the valve partial open condition as per the standard. Check the leakage through body, Bonnet sealing area, Gland packing area.

Seat Test of above valves:-

            Testing flange to be fix on one side of the valve. Pressurized the valve under fully closed condition as per the standard. Check the leakage through Seat in opposite side. Follow the same procedure while checking the another seat except Globe and Butterfly.

14.                  What are the testing mediums used for testing?

            Water, DM Water, Air, Kerosene, Oil, Soap water.

15.                  What is Steam trap and Gas trap?

Steam trap using for removal of Water from Steam.

Gas trap using for removal of water from gas.

16.                  What is the use of Vacuum Breaker?

It is used to remove Vacuum (Air Bubbles) from Water line.

17.                  What is the use of Ejector?

Ejector is used to create Vacuum for process.

18.                  Define Non Sparking Tools? 

Non Sparking tools used in Gas, Oil and Chemicals.

E.g. Brass hammer, Brass Wedge, Brass Spanner, Copper hammer, Copper rod , Brass rod , Brass chisel  , Rubber hammer , Nylon hammer. 

19.                  What is Strainer?

Strainer is a control element to arrest dust from flowing fluids.

20.                  What is work permit system?

Work Permit is an Authority for doing work in a process plant.

Types:

Cold Work Permit- Without Sparking, Without Heat etc.

Hot Work Permit- With heat (Grinding, Cutting, Welding)

Note: Two times only extend the permit after the normal valid of permit.

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