Hard Questions

Question 1

4. How much total pressure is on the face of a drum that is 36 inches in diameter with a gauge pressure of 125 psi?

Answer 1

Dia X Dia X .7854 X Pressure = Total lbs. Pressure.
36 X 36 X .7854 X 125 = 127,235 lbs. total pressure.

Question 2

5. What are seven heat losses in a boiler?

Answer 2

Moisture in the fuel, moisture in the air, moisture formed in burning hydrogen, excess air, incomplete combustion, unburned carbon in the ash, radiation.

Moisture contained in fuel.
Moisture in air.
Moisture formed in the burning of hydrogen.
Heat carried away in dry flue gasses.
Incomplete combustion of carbon.
Unburned carbon in ash.
Radiation and other unaccountable losses.

Question 3

19. What need to be done to a new boiler before putting into service?

Answer 3

A hydrostatic test, boil out with alkaline solution to remove the oils and have the safeties checked by a licensed person.

You need to perform a hydrostatic test, have the safety valve checked by a licensed person and boil out with a caustic solution to remove oil.

Question 4

24. The gauge on a pump discharge reads 125 PSI. How high is the discharge pipe?

Answer 4

A column of water one foot tall exerts a pressure at its base of .433 PSI so 125/.43=288.68 feet high.

Question 5

27. Why is it important to have good lubrication on centrifugal pumps?

Answer 5

They operate at high speeds and long periods of time.
handle water that is often at high temps.

Question 6

29. How much horsepower would be required to drive a single acting deep well pump delivering 200 gpm against a measured head of 250 foot?

Answer 6

200 gpm x 8.33 = 1666 ppm
250 x 1666 = 416500
416500/33000=12.62 hp

GPM X lbs. / gal Xft. of head X specific gravity / Ft. lbs. / Hp. = Hp.

200 X 8.33 X 250 X1.0 / 33,000 = 12.65 hp
GPM lbs./gal ft. of head specific gravity ft. lbs.
Not considering the losses.

Question 7

30. What things do you consider when selecting a new pump?

Answer 7

Type of liquid, Temperature and conditions of liquid being pumped, capacity, variation of suction, total head requirements, space limitations, pump arrangement, the type of drive, ambient conditions and voltage.

Question 8

33. How are turbine blades made and of what material are they made? How are the blades fastened and held in place?

Answer 8

Turbine blades are dropped forged steel, they are rolled and drawn sections of stainless steel.
Rotating blades are secured by “T” root fastenings with lugs machined on the shank straddling the blade groove, and held against the shoulder in the groove by half round sections, caulked in place at the bottom. Stationary blades are anchored in straight sided grooves by a series of short keys, which fit into auxiliary grooves cut in the blade shank, and in the side of the main groove.

They are drop forgings of steel or alloys, depending on the condition under which they are to operate. They are rolled and drawn sections. Rotating blades are fastened in place by a t-root fastening with lugs. Stationary blades are anchored by a series of short keys.

Question 9

38. How is leaking around the rotor prevented?

Answer 9

With labyrinth packing and water seals.

Question 10

40. How is the viscosity of oil measured?

Answer 10

By a standard say bolt universal (SSU) viscosometer. This test is done by noting the time in seconds it takes 60 ml of oil at standard temps of 70 degrees F, 100 degrees F, 130 degrees F, and 210 degrees F to flow through the orifice.

Question 11

41. Define rupture disk.

Answer 11

A rupture disk is a pre-bulged membrane made of various metals, based on the service for which it is intended. The disk may be used instead of, or with an atmospheric relief valve on the turbine exhaust, in case the condenser looses vacuum.

Question 12

43. How many gallons per hour will a cooling tower evaporate per ton of refrigeration, knowing that 1000 btus are needed to evaporate 1 pound of water in the tower?

Answer 12

1000 btus per lb = tower rating; 8.33 pounds per gallon of water; 288000 btus per ton of refrigeration; 1000 x8.33 =8330; 288000/8330 = 34.69 gallons per ton

1 ton of refrigeration = 288,000 BTU’s in a 24 hour period

BTU’s per ton of refrigeration / (rated BTU’s /lb. X lbs./gal)
288,000 (1,000 8.3 = 8,300)
288,000/8,300 = 34.69 gallons per ton.

Question 13

44. Why is superheated steam used in a turbine?

Answer 13

Superheated steam will do more work, cause less wear, less friction, and less maintenance.
The value of superheated steam in these applications is its ability to release tremendous quantities of internal energy yet remain above the condensation temperature of water vapor; at the pressures at which reaction turbines and reciprocating piston engines operate.
Superheating and pressure reduction through expansion ensures that the steam flow remains as a compressible gas throughout its passage through a turbine or an engine, preventing damage of the internal moving parts.

Question 14

45. What could cause a turbine to be noisy?

Answer 14

Unbalanced rotating parts, misaligned or bent shaft, scale, moisture in the steam, loose bearings, overheating, worn parts, or the sound could be coming from the machine the turbine is operating.

Question 15

47. If you have a 12” steam line carrying 150 pounds of pressure, what is the total thrust exerted on the fixed anchors?

Answer 15

150 X 12 X 12 X .7854 = 16,964.64 lbs thrust or 8 ½ ton
Psi X Dia X Dia X .7854

Question 16

48. List six ways to test steam traps.

Answer 16

Temp difference in and out, listening device, temp crayons, flow indicator, test valves, and knowledge of equipment

Question 17

49. 28.5” of mercury is equal to what psi?

Answer 17

One inch of mercury is = .491 PSI
.491 X 28.5 = 13.99 PSI

Question 18

59. What is a three phase ‘Y’ connected alternator?

Answer 18

It has three windings, 120 degrees apart in phase relationship, connected in a Y shape. The middle point of the Y is common connection of one end of each winding. The other end of each winding is a line connection. The middle point of the Y may or may not be brought out as another line connection.

Question 19

66. What are phosphates and chelents?

Answer 19

Internal boiler chemicals used to control hardness in boiler water.

Phosphates are an internal boiler water treatment used to precipitate solids as sludge.
An internal boiler water treatment used to hold solids in suspension.

Question 20

70. What is the difference between a volute and a turbine pump?

Answer 20

A volute pump is one in which the impeller rotates in a casing of spiral design. A turbine is one in which the impeller is surrounded by diffusion rings.

The primary difference between turbine and volute pumps is the presence or lack of diffusion vanes. In volute pumps there are no diffusion vanes, but rather the outer casing is a spiral. The form of the outer casing reduces water velocity (and eventual pressure) by creating an equal flow of water as it moves around the spiral toward the nozzle. The spiral is sometimes called a volute, hence the name for this particular type of pump.

Question 21

74. How much horsepower does it take to push 433 lbs of water against a 278 ft head?

Answer 21

433 x 278 x 1 over 33000 = 3.64 hp

Question 22

75. How much horsepower does it take to push 200 gpm against a 250 ft head?

Answer 22

200 x 8.33 x 250 x 1 over 33000 = 12.62 hp

GPM X lbs. / gal Xft. of head X specific gravity / Ft. lbs. / Hp. = Hp.

200 X 8.33 X 250 X1.0 / 33,000 = 12.65 hp
GPM lbs./gal ft. of head specific gravity ft. lbs.
Not considering the losses.

Question 23

80. Name four kinds of categories of stage turbines.

Answer 23

Single, velocity, pressure, and pressure and velocity.

Single, velocity, pressure, pressure and velocity, composite.

In modern turbines, three types of staging are employed, either separately or in combination: (1) pressure (or impulse) staging, (2) reaction staging, and (3) velocity-compound staging.

Question 24

83. What are the temps of oil going to the burner and why should it be near its flash point?

Answer 24

4 = 135 degrees #5= 185 degrees #6= 220 degrees It will ignite easier and stay lit.

Question 25

88. Who can inspect and repair your UST leak detection and overfill protection systems and list six things to log on the report?

Answer 25

A qualified UST inspector/contractor six things on the report are: Identify equipment, release detection, suspect or confirmed releases, spill and overfill protection, corrosion protection and records kept, walk through inspection.

Question 26

91. Referring to metal what is tenacity, ductility, malleability, resilience, elasticity, hardness?

Answer 26

Tenacity is ability to resist pulling stress. Ductility is ability to endure elongation. Malleability is ability to change shape by hammering. Elasticity is ability to resume normal shape. Resilience is capacity for storage and return of work energy while being stressed to its elastic limit. Hardness is ability to resist wear.

Question 27

95. What are amines? Name two classes.

Answer 27

Boiler chemicals that evaporate and go out with the steam to keep condensate PH above acid, Low pressure and high pressure Amines.

Question 28

98 How does a centrifugal pump eliminate balance problems?

Answer 28

Through the use of balancing devices to control and indicate flow in a return line, thrust bearings, double flow impellers. balancing the rotating components they spin at high speeds ? schedule regular inspections for your pump Hydraulically and dynamically

Question 29

104. Centrifugal pump delivers 600 gpm and runs at 1,700 rpm, what would be its capacity at 2,000 rpm?

Answer 29

New rpm - / old- rpm X gpm = new capacity 2,000 / 1,700 X 600 gpm = 705.9 gpm new capacity 600/1700= .353 .353x2000= 705 gpm

Question 30

118. The EPA requires what records are kept regarding underground fuel tanks?

Answer 30

Upon request you must provide to EPA records on installation, monitoring, cathodic protection, release detection equipment calibration, maintenance repairs and closures.

Question 31

127. Describe gland sealing steam.

Answer 31

It is low pressure steam, used in conjunction with labyrinth packing to seal the low pressure end of the condenser.

Question 32

129. The gauge on a pump discharge reads 125 psi, how high is the discharge pipe?

Answer 32

A column of water exerts a pressure at its base of .433 psi, so 125/.433=288.68 feet high.

Question 33

130. What are the advantages and disadvantages of fuel oil versus coal?

Answer 33

Advantages over coal, it is easily stored, less space, safer, less man power needed, cleaner emissions, plant can be kept clean. Disadvantages - cost of oil higher, impurities plugging strainers and burners, cleaning of tanks and disposal of sludge costly, sulfur in oil causes corrosion in equipment and pollution of air.

Question 34

133. What is a polisher?

Answer 34

A polisher is an ion exchange process which is used to remove trace contaminants both dissolved and suspended from high purity water.

Question 35

134. What is a demineralizer?

Answer 35

A demineralizer removes practically all dissolved solids in water. 352. What is demineralization? An ion exchange process using strong acids and bases, in the regeneration used for high-pressure boilers.

Question 36

141. What is a water seal used for?

Answer 36

It is used around the turbine shaft at the high pressure end of the turbine. A water seal consist of a centrifugal pump runner attached to the turbine shaft. The runner rotates in a chamber, in the gland casing. Water is supplied to the chamber at 3 to 8 psi and is thrown out against the sides by the runner, forming a seal. They are used on the low pressure end of a condensing turbine.

Question 37

A safety valve with a 3” seat is on a boiler operating at 100 psi, what is the total pressure acting on the valve?

Answer 37

Total Force = A X P TF = 0.7854 X D sq. X P 0.7854 X 3 X 3 X 100 psi = 706.86 lbs. Total Pressure

Question 38

What is the pressure stage, velocity staging and what is the difference?

Answer 38

Pressure stage allows only a limited pressure drop in one set of nozzles. Velocity staging is applying velocity energy in the steam coming from the nozzles to two or more sets of moving blades, with the pressure drop occurring in the stationary blades. The difference is where the pressure drops occur.

Question 39

What is the difference between an impulse and a reaction turbine, name four types?

Answer 39

The impulse turbine is designed so the expansion of the steam occurs almost entirely in its stationary blades, and there is almost no pressure difference of the steam entering and leaving the stages. Types of Impulse: Re-entry flow, rotor, vertical, horizontal, de Laval Wilkinson, Zoelly, Pelton. The reaction turbine is designed so there is considerable expansion in the rotating blades and there is a pressure difference of the steam entering and leaving the stages. Types of Reaction: Tamden, Cross compound, single flow, double flow, Parsons, Allis chambers, Ingersal Rand.

Question 40

What should the temperature of water be leaving the DA?

Answer 40

Under design conditions the temperature of the outlet water approaches the saturation temperature of the supply steam.

Question 41

Cathodic rectifier tested how often? What does the test consist of? What happens if the test fails?

Answer 41

Periodic testing is required for each type of system as follows: · Sacrificial anode: Every three years · Impressed current: Every year In addition to annual testing, the rectifier of an impressed current CP system must be checked every two months to ensure that current is being delivered to the system. Document this in writing by recording the date, the voltage and amperage displayed on the gauges, and the initials of the person reading the gauges. If the rectifier has an hour meter, record the hours as well. Rectifier readings of impressed current CP systems may be taken by the owner or another person. Advance notification to the MPCA of CP testing is not required. The CP tester must evaluate the CP system according to NACE RP0285, “Corrosion Control of Underground Storage Tank Systems by Cathodic Protection.” At least three test points per tank and per piping run must be utilized. Of the three test points, one must be a local test point, and one must be a remote test point. The third test point can be either local or remote. In order to pass, a sacrificial anode CP system must show structure-to-soil potentials of at least -850 mV for all metal system components. For an impressed current CP system to pass, all components must meet the -850 mV (Instant Off) criteria. In the alternative, the difference between the depolarization voltage and the Instant Off voltage must be at least 100 mV. If one or more components do not show this level of structure-to-soil potential, the system fails and must be repaired or replaced. Structure continuity testing must also be performed. For sacrificial anode CP systems, the continuity tests must demonstrate each protected structures (tank or pipe) are electrically isolated from other protected structures and non-protected structures (electrical conduits, risers, vent lines). For impressed current systems, continuity tests must demonstrate all protected structures are electrically continuous with each other. One common repair is to add new anodes or replace old ones. Repairs must be completed within 60 days after a failing test or as otherwise required by an MPCA enforcement action. Sacrificial anode or impressed current systems may be repaired by a CP tester who is qualified to repair CP systems according to industry standards, or by a corrosion expert. The system must be re-tested within six months after any repairs. Cathodic protection test results must be submitted to the MPCA within 30 days of testing https://www.pca.state.mn.us/sites/default/files/t-u3-27.pdf

Question 42

188. What is the lowest flash point for oil used in a turbine?

Answer 42

325ºF

Question 43

What type of oil is used in turbine?

Answer 43

A very high grade mineral oil which seaparates readily from water, flash point which is not below 325 F. * Shed water that allows solid particles to settle where they can be removed through drains or filtration systems during operations * High operating temperature * Ability to release water and hydrolytic stability * Antifoaming when in contact with air * Wear protection of gearbox, shaft

Question 44

43. What is a 3 phase alternator?

Answer 44

A three phase alternator is an AC electrical generator with 3 sets of windings in the stator. These windings overlap each other in a phase angle, or timing relationship, by 120 degrees with respect to each other. The rotor (field or excitation) current is DC, and adjusted to regulate the output power.

Question 45

140. What is meant by boiler encrustation?

Answer 45

Scaling of the heating surfaces.