Energy and Utilities Natural Gas Systems 2 — Questions and Answers
Question 1: What is 'peak shaving' in natural gas utility operations?
- Removing impurities from gas during peak season
- Using stored gas during high-demand periods to supplement pipeline supply (Correct answer)
- Reducing pipeline pressure in summer
- Cutting gas to industrial customers first
Correct answer: Using stored gas during high-demand periods to supplement pipeline supply
Peak shaving uses stored LNG or propane-air systems to supplement pipeline gas supply during periods of extremely high demand.
Question 2: What is the primary safety concern when excavating near underground natural gas distribution lines?
- Electrical interference
- Pipeline rupture causing gas release and fire/explosion risk (Correct answer)
- Water contamination
- Signal loss to SCADA systems
Correct answer: Pipeline rupture causing gas release and fire/explosion risk
Striking a gas line during excavation can cause a rupture leading to gas release, fire, or explosion, making 811 call-before-you-dig mandatory.
Question 3: Which material is commonly used for modern natural gas distribution piping in residential service lines?
- Cast iron
- Copper
- Polyethylene (PE) plastic (Correct answer)
- Galvanized steel
Correct answer: Polyethylene (PE) plastic
Polyethylene pipe is widely used for gas distribution because it resists corrosion, is flexible, and is easy to fuse-join.
Question 4: What does a pressure regulator do in a natural gas distribution system?
- Adds odorant to the gas
- Reduces high transmission pressure to safe delivery pressure for customers (Correct answer)
- Monitors gas quality
- Shuts off gas during earthquakes
Correct answer: Reduces high transmission pressure to safe delivery pressure for customers
Pressure regulators step down gas from high transmission pressure to the lower pressures safe for distribution mains and service lines.
Question 5: What is 'cathodic protection' used for in the natural gas industry?
- Protecting workers from gas exposure
- Preventing corrosion of metallic underground pipelines (Correct answer)
- Purifying natural gas
- Measuring gas flow
Correct answer: Preventing corrosion of metallic underground pipelines
Cathodic protection uses electrical current to prevent electrochemical corrosion of buried metallic pipe, extending pipeline life.
Question 6: What does 'therm' measure in natural gas billing?
- Gas pressure at the meter
- 100,000 Btu of energy (Correct answer)
- Volume of gas in cubic feet
- Temperature of the gas
Correct answer: 100,000 Btu of energy
One therm equals 100,000 British Thermal Units (Btu), the unit most residential gas utilities use for billing purposes.
Energy and Utilities Natural Gas Systems 2
What is 'peak shaving' in natural gas utility operations?