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WorksheetsUnit 3.1 – Pipe Sizing and Selection PART 2
Total questions: 46
Worksheet time: 23mins
Pipe racks are arranged to:
Minimize welding time
Allow easy equipment access
Lower schedule numbers
Increase thermal expansion
Which of the following is NOT a standard fitting?
Tee
Bend
Nozzle plate
Flange
Flanged joints are often selected when:
High vibration is expected
Frequent disassembly for maintenance is required
Temperature is below freezing
Corrosion allowance is high
Screwed joints are typically limited to:
High-pressure steam lines
Small-diameter pipes
Large chemical reactors
Long pipe racks
In economic diameter selection, increasing pipe diameter generally:
Raises pumping cost
Raises capital cost but lowers pumping cost
Lowers both costs
Has no cost effect
The optimum diameter is found where:
Pumping cost equals capital cost
Schedule number is minimum
Wall thickness equals corrosion allowance
Sonic velocity equals actual velocity
The empirical formula dopt=0.664G0.3ρ−0.14 is used for:
Stainless steel 304, 25–200 mm
A106 carbon steel, 25–200 mm
Stainless steel 250–600 mm
Schedule 80 pipes
For 304 stainless steel, 25–200 mm, the empirical constant is:
0.465
0.550
0.534
0.664
The Towler & Sinnott formulas are:
Mandatory ASME code
Empirical cost-based estimates
Derived from B31.3 directly
Used only for gas compressibility
Which of the following is not part of the ASME code but is useful for economic sizing?
Temperature factor γ
Towler & Sinnott diameter formulas
Casting quality factor E
Pressure design thickness formula
A 150 mm carbon-steel line carries a liquid with available free head. No pump is planned. The best pipe size is chosen primarily to:
Minimize total annualized cost
Minimize diameter while meeting flow
Match schedule 80
Reduce vibration
If a steam line is designed with internal diameter 0.25 m, what is the recommended design velocity?
0.05 m/s
0.2 × 0.25 ≈ 0.05 m/s
0.4 m/s
0.1 m/s
Given safe working pressure 120 psi and safe working stress 12 000 psi, the schedule number is approximately:
(120 × 1000)/12 000 ≈ 10
40
80
160
When might flanged joints be preferred even if welding is feasible?
Pipe rarely opened
Frequent equipment maintenance
Low temperature only
When schedule number is high
Which statement best explains why thermal expansion must be considered?
It determines sonic velocity
It can impose unacceptable stresses on connected equipment
It affects casting quality
It changes the schedule number
The primary purpose of specifying a pipe schedule is to indicate its:
Outside diameter
Wall thickness for a given nominal size
Flow capacity
Surface roughness
Which component carries the combined weight of process and service pipes between buildings?
Pipe saddles only
Pipe racks
Expansion bellows
Anchor bolts
Pipe hangers and supports are mainly designed to:
Increase pressure rating
Prevent excessive deflection and stress
Lower sonic velocity
Increase schedule number
A piping system automatically gains flexibility from:
Smooth internal finish
Layout bends and natural routing
Higher schedule number
Increased wall thickness
Expansion loops are used chiefly to:
Reduce pump head
Absorb thermal expansion
Increase erosion resistance
Lower fluid density
Dead-weight loads on a pipe include all of these EXCEPT:
Pipe material weight
Fluid weight
Insulation weight
Ambient air pressure
The reaction load from fluid pressure drop is generally:
The dominant stress source
Negligible in design
Larger than thermal expansion
Equal to dead weight
The ASME B31.3 formula for required wall thickness treats most process pipes as:
Thin cylinders
Spheres
Thick cylinders
Vacuum vessels
High-pressure steam lines are an exception and must be treated as:
Thin cylinders
Thick cylinders
Spheres
Flat plates
The corrosion allowance is included in the formula as part of:
Temperature factor γ
Allowance “c”
Casting quality factor E
Diameter d
The casting quality factor E represents:
Thermal conductivity
Strength of welds or cast pipe quality
Sonic velocity margin
Pipe roughness
Temperature factor γ accounts for:
Thermal expansion loops
Material strength reduction at service temperature
Friction loss
Vibration effects
Standard pipe sizes for stainless steel are specified in:
ASME B36.19
ASME B36.10M
API 650
ASTM A105
Standard pipe sizes for wrought steel and wrought iron are in:
ASME B36.10M
ASME B36.19
API 1104
ASTM D2000
For gases and vapors, the design velocity must remain below:
100 % of sonic velocity
30 % of sonic velocity
75 % of sonic velocity
10 % of sonic velocity
When motive power is free, pipe diameter is normally chosen to:
Minimize pumping energy
Maximize schedule number
Increase pressure drop
Match pump suction velocity
Design velocity for pump discharge can be estimated as:
0.06 d + 0.4 m/s
0.02 d + 0.1 m/s
0.2 d m/s
0.6 d m/s
Design velocity for pump suction is approximately:
0.02 d + 0.1 m/s
0.06 d + 0.4 m/s
0.2 d m/s
0.4 d m/s
Design velocity for steam or vapor is estimated as:
0.2 d m/s
0.02 d + 0.1 m/s
0.06 d + 0.4 m/s
0.1 d m/s
Economic pipe diameter balances:
Only pipe capital cost
Capital cost and pumping cost together
Only maintenance cost
Schedule number and velocity
Increasing pipe diameter generally:
Decreases capital cost and pumping cost
Increases capital cost but decreases pumping cost
Increases both
Has no economic effect
The empirical optimum-diameter formula for 25–200 mm A106 carbon steel uses coefficient:
0.664
0.534
0.550
0.465
For 250–600 mm A106 carbon steel, the coefficient is:
0.664
0.534
0.550
0.465
For 25–200 mm 304 stainless steel, the coefficient is:
0.550
0.465
0.664
0.534
For 250–600 mm 304 stainless steel, the coefficient is:
0.465
0.550
0.664
0.534
The Towler & Sinnott equations for economic diameter are:
Mandatory ASME standards
Empirical cost-based estimates
Outdated and unused
Pressure-drop correlations
Economic diameter formulas consider:
Flow rate (G) and fluid density (ρ)
Only pipe schedule
Casting quality factor
Thermal expansion loops
Which joint type is preferred for final connection to valves and equipment for easy disassembly?
Welded
Flanged
Screwed
Brazed
Which factor is most critical to prevent erosion in liquid service?
Limiting fluid velocity
Increasing schedule number
Using expansion loops
Selecting thicker insulation
Why are standard fittings catalogues important for design?
They ensure compatibility with national standards
They eliminate corrosion allowance
They reduce economic diameter
They control sonic velocity
In the schedule number formula Schedule=Pw×1000σw, Pw is:
Pump pressure
Safe working pressure
Pressure drop
Gauge vacuum pressure
