Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ChE Design > MATERIALS & CONSTRUCTION PART A > Flashcards

MATERIALS & CONSTRUCTION PART A Flashcards

1
Q

The overriding
considerations when selecting engineering materials for chemical process plant?

A

High temperature strength
Ability to resist corrosion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Who is responsible for recommending materials
that will be suitable for the process conditions?

A

Process Designer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Who must also consider the requirements of the
mechanical design engineer

A

Process engineer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The material selected by the process engineer must have?

A
  1. Sufficient strength
  2. Easily worked
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What material should be selected?

A

Most economical that satisfies both process and mechanical requirements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The material selected will be a material that gives ?

A

lowest cost over the working life of the plant allowing for maintenance and replacement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are other factors to be considered when selecting a material?

A

Product contamination
Process safety

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The most important characteristics to be considered when selecting a material of construction are? (7)

A

Mechanical Properties
Effect of temperature on mechanical properties
Corrosion Resistance
Any special properties required
Ese of Fabrication
Availability in standard sizes
Cost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Under mechanical properties

A

Strength
Stiffness
Toughness
Hardness
Fatigue
Creep resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Measured through tensile strength

A

strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Measured through elastic modulus (Young’s Modulus)

A

Stiffness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Measured through fracture resistance

A

Toughness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

measured through wear resistance

A

Hardness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Under effect of temperature on mechanical properties particularly the effects of:

A

high temp
low temp
thermal cycling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Under ease of fabrication

A

Forming
Welding
Casting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Under Special properties required

A

Thermal conductivity
Electrical resistance
Magnetic properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Under Availability in Standard sizes

A

Plates
Section
Tubes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What materials are satisfactory in all fabrication operations?

A

Nickel and Monel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Material with the highest annealing temp

A

Nickel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

A measure of the basic strength of a material

A

Tensile Strength/Stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

the maximum stress that the material will withstand, measured by a standard
tensile test

A

Tensile Strength/Stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Older name of Tensile strength/stress

A

Ultimate Tensile Strength (UTS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

the stress to cause a specified permanent extension

A

Proof stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Metals/Alloy that has the highest tensile strength

A

Monel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Percentage of proof stress

A

0.1%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What codes are calculated from Tensile strength/stress

A

ASME Boiler and Pressure Vessel (BPV)
European EN 13445 Pressure vessel code

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Hardest metal/alloy

A

Monel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Ability to resist bending and buckling

A

Stiffness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Function of elastic modulus of the material and the shape of the cross-sectional area of the member (the second moment area)

A

Stiffness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Slope=

A

Stiffness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

The stress beyond which a material becomes plastic

A

Yield point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

An indication the tendency for an element to return to its original form after being subjected to a force

A

Stiffness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Measures how much stress can be applied to an element before it deforms permanently or fractures

A

Strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Measures a material’s resistance to surface deformation

A

Hardness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Associated with tensile strength

A

Toughness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Measure of the material’s resistance to crack propagation

A

Toughness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What ductile materials stop the propagation of crack by local yielding at the crack tip. They have crystal structure

A

Steel
Aluminium
Copper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

The crystal structure of the ductile materials stop the propagation of crack by?

A

Local yielding at the crack tip

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

In this materials, the local yielding does not occur, that’s why they are brittle

A

Cast irons
Glass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

T/F: Brittle Materials are strong in tension but weak in compression

A

F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Under ____ any incipient cracks present are closed up

A

Compression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Technique developed that allowed the use of brittle materials in situations where tensile stress would normally occur

A

Use of pre-stressed concrete and
Glass-fibre-reinforced plastics in Pressure vessel construction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Are induced to counteract external stresses

A

Internal stresses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Curve downward

A

Load deflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Horizontal side to side

A

Tendons stressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Horizontal to center

A

Prestress forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Curve upward to center

A

Prestress deflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Indication of a material’s ability to resist wear

A

Hardness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Hardness is measure using

A

Brinell Madness Test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

An important property if the equipment is being designed to handle abrasive solids, or liquids containing suspended solids that are likely to cause erosion

A

Hadness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Hard to hardest

A

Lead
Pure aluminium
Copper
Soft brass
Hardened aluminium
Mild steel
Annealed chisel steel
White cast iron
Nitrided surface
Glass
Rhenium diboride

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

T/F: The higher the impression diameter the lower the Brinell Number

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Is likely to occur in equipment subject to cyclic loading

A

Fatigue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Examples where fatigue occurs

A

Cracks in bicycle frame
Helical gear
Spring
Steering arm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Gradual extension of a material under a steady tensile stress over a prolonged period of time

A

Creep

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Usually only important at high temperatures like with steams and gas turbine blades

A

Creep

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

For a few materials like ____ the rate of creep is significant at moderate temperatures

A

Lead

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

_____ Will creep under its own weight at room temperature and ___ must be supported at frequent intervals

A

Lead
Lead linings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Reported as the stress to rupture in 100,000 hours at the test temperature

A

Creep strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

____ and ____ of metals decrease with increasing temperature

A

Tensile strength and elastic modulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

____ and ____ of metals decrease with increasing temperature

A

Tensile strength and elastic modulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Tensile strength and elastic modulus of metals ____ with increasing temperature

A

Decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Tensile strength of mild steel (low carbon, C<0.25%) is 450 Pa at 25°C falling to ___ @500°C

A

210 Pa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Young’s Modulus of Mild steel is 200,000 Pa at 25°C and falls to _____ at 500°C

A

150,000 Pa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

SA-285 Plain Carbon Steel plate cannot be used to construct a pressure vessel with design temperature

A

> 900°F or 482°C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

If any pressure vessel designed to for use above 900°F, what must be used

A

Killed steel or Alloy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Maximum allowable stress used in design is always based on the?

A

Design temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Are superior in sufficient strength at the design temperature that gives an economic and mechanically feasible wall thickness

A

Stainless steel than carbon steels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Will be important if the material is subjected to high stresses at elevated temperatures

A

Creep resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Special alloys that are used for high temperature equipment such as furnace tubes in environments that do not contain silphur

A

Inconel or incoloy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

A these temperatures, metals that are normally ductile can fail in a brittle manner

A

Less than 10°C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

Serious disasters have occurred through the failure of this at low temperatures

A

Welded carbon steel vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

The phenomenon of _____ is associated with the crystalline structure of the metals

A

Brittle failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Are more liable to brittle failure

A

BCC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

For this low temperature equipment, austenitic steel (FCC) or aluminium (Hex) should be specified

A

Cryogenic plant
Liquefied - gas storage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Austenitic steel has

A

FCC

75
Q

Aluminium alloys has ____ structure

A

Hexagonal lattice

76
Q

Example of V-notch impact tests

A

Charpy test

77
Q

Are used to test the susceptibility of materials to brittle failure

A

Charpy test

78
Q

Is a complex phenomenon and is dependent on plate thickness and residual stress present after fabrication as well as the operating temperature

A

Brittle fracture of welded structure

79
Q

General wastage of material

A

Uniform corrosion

80
Q

Dissimilar metals in contact

A

Galvanic corrosion

81
Q

Localized attack

A

Pitting

82
Q

An electrochemical process

A

Metallic corrosion

83
Q

Four components necessary to set up an electrochemical cell

A

Anode
Cathode
Conducting medium
Completion of the electrical circuit

84
Q

Corroding electrode

A

Anode

85
Q

Passive, non-corroding electrode

A

Cathode

86
Q

Corroding fluid

A

Electrolyte

87
Q

Cathodic areas can arise in many ways

A

Dissimilar metals
Corrosion products
Inclusions in the metals such as slag
Less well - aerated areas
Areas of differential concentration
Differential strained areas

88
Q

The more or less uniform wastage of material by corrosion, with no pitting or other forms of local attack

A

Uniform corrosion

89
Q

If the corrosion of a material can be considered to be Uniform, the life of the material in service can be predicted from experimentally determined?

A

Corrosion rates

90
Q

Expressed as penetration rate in inches per year or mils per year

A

Corrosion rates

91
Q

1 mill = inches?

A

10^-3

92
Q

Can be expressed as weight loss in milligrammes per square decimeter per day

A

Corrosion rates

93
Q

In here, the corrosion rate is measured by the reduction in weight of a specimen of known area over a fixed period of time

A

Corrosion testing

94
Q

Of judging corrosion rate in mdd, it must be remembered that the penetration rate depends on ?

A

Density of the material

95
Q

Corrosion rate of ferrous metals

A

100 mdd = 0.02 ipy

96
Q

1 ipy = mm per year

A

25

97
Q

What can be considered as an acceptable rate of attack will depend on the __ of the material, the ____ particularly as regards to safety and the ____ of the plant

A

Cost
Duty
Economic life

98
Q

If the corrosion rate of inexpensive metals like carbon and low alloy steels less than 0.01 ipy, the more expensive alloy’s like brasses and aluminium will be

A

0.01/2

99
Q

If the corrosion rate indicates only short exposures then the design engineer should

A

Allow for frequent inspection of the plant and periodic replacement of the affected equipment

100
Q

Uniform corrosion affects in two ways

A

Reduces the on-stream factor
Increase the maintenance cost

101
Q

Number of days of production per year

A

On-stream factor

102
Q

T/F: usually the impact of the frequent shutdown and replacement is so negative that the use of more expensive alloys
With better corrosion resistance can be justified

A

T

103
Q

What must be added to the minimum vessel wall thickness to comply with PV codes

A

Allowances for expected corrosion over the plant life

104
Q

T/F: the corrosion allowance can be economically or mechanically prohibitive if the corrosion rate is high

A

T

105
Q

T/F: the corrosion allowance should be atleast equal to the expected corrosion loss during the desired life of of the vessel

A

T

106
Q

Corrosion depends on

A

Temperature
Concentration of corrosion fluid

107
Q

Increase in temperature usually (not always) ____ the rate of corrosion

A

Increases

108
Q

Corrosion rate will depend on other factors that are affected by temperature like

A

Oxygen solubility

109
Q

As an example, the corrosion of mild steel in sulphuric acid, where the rate has unacceptably high in dilute acid and at concentrations above 70%, but is acceptable at intermediate concentration

A

Complex effects

110
Q
  • If dissimilar metals are placed in contact in an electrolyte, the
    corrosion rate of the anodic metal will be ______, as the metal
    ______ in the electrochemical series will readily act as a _____
A

increased
lower
cathode

111
Q

What is an example of metal that at certain conditions form natural protective film in oxidizing environments?

A

Stainless steel

112
Q

The state of forming a natural protective film is called

A

Passive

113
Q

” indicates the absence of the protective film

A

Active

114
Q

Minor shifts in position in the series can be expected in other
electrolytes, but the series for _______ is a good indication of the
combinations of metals to be avoided.

A

sea water

115
Q
  • If metals that are widely separated in the galvanic series have to be
    used together, they should be electrically _______ from each other,
    breaking the conducting circuit
A

insulated

116
Q

Alternatively, if _____ of the anodic material can be accepted,
the _______ of this material can be ________to allow for the
increased rate of corrosion.

A

sacrificial loss
thickness
increased

117
Q

will depend on the relative areas of the anodic and
cathodic metals.

A

Corrosion rate

118
Q

T/F: A high cathode to anode area should be avoided

A

T

119
Q

are used to protect underground steel pipes.

A

Sacrificial anodes

120
Q

highly localized corrosion that forms pits in the metal surface

A

Pitting

121
Q

T/F: If a material is liable to pitting, penetration can occur prematurely and
corrosion rate data are not a reliable guide to the equipment life.

A

T

122
Q

Causes of Pitting

A

Not uniform composition of metals
Impingement of bubbles
Aerated medium

123
Q

Example of not uniform composition of metals

A

Presence of slag in welds

124
Q

occurs during cavitation in pumps, which is an
example of erosion-corrosion

A

Impingement of bubbles

125
Q

the oxygen concentration will be lower at the bottom of a
pit, and the bottom will be anodic to the surrounding metal, causing
increased corrosion and deepening of the pit

A

Aerated medium

126
Q

When attack is caused by aerated medium, how can pitting be reduced?

A

Good surface finish

127
Q

the preferential corrosion of material at the grain (crystal) boundaries

A

Intergranular Corrosion

128
Q

In this corrosion, though the loss of material will be small, it can cause the catastrophic
failure of equipment

A

Intergranular corrosion

129
Q

a common form of attack on alloys but occurs rarely with pure metals

A

Intergranular corrosion

130
Q
  • The attack is usually caused by a differential couple being set up between
    impurities existing at the grain boundary.
  • Impurities will tend to accumulate at the grain boundaries after heat treatment.
A

Intergranular Corrosion

131
Q

Classic example of intergranular corrosion

A

Weld decay of unstabilized stainless steel

132
Q

caused by the precipitation of chromium carbides at the grain
boundaries in a zone adjacent to the weld, where the temperature has
been between 500–800°C during welding

A

Weld dacay of unstabilized stainless steel

133
Q

can be avoided by annealing after welding

A

Weld decay

134
Q

can be avoided by annealing after welding
By using low carbon grades
grades stabilized by the addition of tatnium or niobium

A

weld decay

135
Q
A
136
Q

Corrosion rate and form of attack can be changed if the material is under ?

A

Stress

137
Q

Generally, the ____ will not change significantly within normal design stress values

A

Rate of attack

138
Q

Stress corrosion cracking can occur with some combination of ____,____ and ___

A

Metal
Corrosive media
Temperature

139
Q

The general name given to a form of attack in which cracks are produced that grow rapidly, and can cause premature, brittle failure of the metal

A

Stress corrosion cracking

140
Q

Conditions necessary for Stress corrosion cracking to occur

A

Simultaneous stress cracking and corrosion
Specific corrosive substance particularly the presence of Cl-, OH- NO3- and NH4+ ions

141
Q

Can cause cracking

A

Mild stress

142
Q

Examples of mild stress

A

Residual stresses from fabrication and welding

143
Q

Examples of corrosion cracking

A

Season cracking of brass cartridge cases
Caustic embrittlement of steel boilers
Stress corrosion cracking of stainless steels in the presence of chloride ions

144
Q

How can stress corrosion cracking be avoided?

A

Selecting materials that are not susceptible in the specific corrosion environment

Relieving stress by post-weld heat treatment

145
Q

The premature failure of materials in corrosive environments caused by cyclic stresses

A

Corrosion fatigue

146
Q

T/F: even mildly corrosive conditions can markedly reduce the fatigue life of a component

A

T

147
Q

Can occur in any corrosive environments and does not depend on the specific combination of corrosive Substance and metal

A

Corrosion fatigue

148
Q

T/F: Materials with high resistance to corrosion must be specified for critical components subjected to cyclic process

A

T

149
Q

The increased rate of attack caused by a combination of erosion and corrosion

A

Erosion Corrosion

150
Q

If a fluid stream contains suspended particles or where there is high____ and ____, erosion will tend to remove the products of corrosion and any ____ and the rate of attack will be markedly _____

A

Velocity
Turbulence protective film
Increased

151
Q

Can be used to prevent erosion Corrosion at the inlet to heat exchanger tubes

A

Plastic inserts

152
Q

Corrosion is normally associated with

A

Aqueous solutions

153
Q

Oxidation can occur in

A

Dry conditions

154
Q

They will oxidize rapidly at high temperatures and their use is limited to temperatures below ___

A

Carbon and low alloy steels
480°C

155
Q

Is the most effective alloying element to give resistance to oxidation, forming a tenacious oxide film

A

Chromium

156
Q

____ is formed by Chromium to give resistance to oxidation

A

Tenacious oxide film

157
Q

Should be specified to temperatures above 480°C in oxidizing atmospheres

A

Chromium alloys

158
Q

Can be used up to 650°C

A

Type 304L stainless steel (18% Cr)

159
Q

Is stabilized by niubiom and can be used up to 850°C

A

Type 347 Stainless steel

160
Q

Can be used as along as sulphur is not present

A

High nickel alloys

161
Q

A very common corrosive contaminant in gas processing, oil refining and energy conversion

A

Sulphur

162
Q

Present in reducing environment as H2S

A

Sulphur

163
Q

Causes sulphidation of metals

A

Sulphur

164
Q

An example of material that must withstand sulphiding and oxidizing at high temperatures

A

Furnace tube

165
Q

Can attack chromium oxide scale that protects the alloy

A

Sulphur

166
Q

Causes breakaway corrosion particularly for high nickel alloys

A

Sulphur

167
Q

Loss of ductility caused by the absorption of hydrogen in metal

A

Hydrogen embrittlement

168
Q

Important when specifying steels for use in hydrogen reforming plant

A

Hydrogen embrittlement

169
Q

Have a great resistance to hydrogen embrittlement than plain carbon steels

A

Alloy steel

170
Q

A chart showing the suitability of various alloys steels for use in hydrogen atmosphere as a function of hydrogen partial pressure and temperature is given in?

A

National Association of Corrosion Engineers

171
Q

Below ___ plain carbon can be used

A

500°C

172
Q

To select the correct material of construction what must be clearly defined

A

Process environment to which the material will be exposed

173
Q

In addition to .ain corrosive chemicals present, consider the following

A

Temperature
Pressure
pH
Trace impurities present
Aeration amount
Stream velocity & agitation
Heat transfer rates

174
Q

Affects corrosion rates and mechanical properties

A

Temperature

175
Q

Causes stress corrosion

A

Trace impurities present

176
Q

Forms differential oxidation cells

A

Aeration amount

177
Q

Causes erodion-corrosion

A

Stream velocity & agitation

178
Q

Related to differential temperature

A

Heat transfer rates

179
Q

Other sources of corrosion data

A

Rabald 1968
NACE 1974
Hamner 1974
Green and Perry 2007
Lai 1990
Schweitzer (2004,1989,2006)
DECHEMA Corrosion Handbook 2005
The ASM Handbook of Corrosion Data

180
Q

Can be used for preliminary screening of materials likely to be suitable

A

Corrosion guides

181
Q

T/F: If the published data indicate that a material is satisfactory, it is guaranteed that it will be suitable for the process environment being considered

A

F

182
Q

T/F: Slight changes in process conditions or presence of unsuspected trace of jmpurities cannot change the rate of attack or nature of corrosion

A

F

183
Q

Guides show clearly those materials that are manifestly ___

A

Unsuitable

184
Q

If actual plant experience Is not available ___ and ___ under simulated plant conditions will help in the selection of sustaible materials

A

Pilot plant tests and laboratory corrosion tests

185
Q

Perform preliminary tests like

A

Inserting coupons of different materials into an apparatus that resists corrosion before testing plant components

186
Q

Reduce the likelihood of component failure and possible release of chemicals during testing

A

Preliminary tests

ChE Design (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions