Objective Piping Interview Questions - Part 04

Question No. 76
Which standard specifies trim numbers for valve?
Answer: API 600.

Question No. 77
What are wetted parts of valve?
Answer: All parts that come in contact with surface fluid are called wetted parts.

Question No. 78
What is wire drawing?
Answer: This term is used to indicate the premature erosion of the valve seat caused by excessive velocity between seat and seat disc, when valve is not closed tightly.

Question No. 79
What is straight through valve?
Answer: Valve in which the closing operation of valve is achieved by 90 degrees turn of the closing element.

Question No. 80
What pressure tests are carried out on valves?
Answer: Shell-hydrostatic, seat-hydrostatic, seat-pneumatic

Question No. 81
What are available valve operators?
Answer: 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).

Question No. 82
What are ball valve body types?
Answer: Single piece, double piece, three piece, the short pattern, long pattern, sandwich and flush bottom design.

Question No. 83
What are two types of ball valve?
Answer: Full port design and regular port design, according to type of seat, soft seat and metal seat.

Question No. 84
Why ball valves are normally flanged?
Answer: Because of soft seat PTFE which can damage during welding.

Question No. 85
What are butterfly valve types?
Answer: Double flange type, wafer lug type and wafer type.

Question No. 86
What are types of check valve?
Answer: Lift check valves and swing check valves.

Question No. 87
What are non-slam check valves?
Answer: Swing check valve, conventional check valve, wafer check valve, tilting disc check valve, piston check valve, stop check valve, ball check valve.

Question No. 88
Where stop check valve is used?
Answer: In stem generation by multiple boilers, where a valve is inserted between each boiler and the main steam header. It can be optionally closed automatically or normally.

Question No. 89
Where diaphragm valves are used?
Answer: Used for low pressure corrosive services as shut off valves.

Question No. 90
What is Barstock Valve?
Answer: Any valve having a body machined from solid metal (barstock).
Usually needle or globe type.

Question No. 91
What is BIBB Valve?
Answer: A small valve with turned down end, like a faucet.

Question No. 92
What is Bleed Valve?
Answer: Small valve provided for drawing off liquid.

Question No. 93
What is BlowDown Valve?
Answer: Refers to a plug type disc globe valve used for removing sludge and sedimentary matter from the bottom of boiler drums, vessels, driplegs etc.

Question No. 94
What is Breather Valve?
Answer: A special self acting valve installed on storage tanks etc. to release vapour or gas on slight increase of internal pressure (in the region of ½ to 3 ounces per square inch).

Question No. 95
What is Drip Valve?
Answer: A drain valve fitted to the bottom of a droplet to permit blowdown.

Question No. 96
What is Flap Valve?
Answer: A non return valve having a hinged disc or rubber or leather flap used for low pressure lines.

Question No. 97
What is Hose Valve?
Answer: A gate or globe valve having one of its ends externally threaded to one of the hose thread standards in use in the USA. These valves are used for vehicular and firewater connections.

Question No. 98
What is Paper-Stock Valve?
Answer: A single disc single seat gate valve (Slide gate) with knife edged or notched disc used to regulate flow of paper slurry or other fibrous slurry.

Question No. 99
What is Root Valve?
Answer: A valve used to isolate a pressure element or instrument from a line or vessel, or a valve placed at the beginning of a branch form the header.

Question No. 100
What is Slurry valve?
Answer: A knife edge valve used to control flow of non-abrasive slurries.
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