Gas Distribution Systems Flashcards

What fusion method creates a joint between two polyethylene pipe sections by heating the pipe ends and pressing them together?

Answer: Butt fusion

Butt fusion heats the squared pipe ends to a molten state and then fuses them together under controlled pressure to create a joint as strong as the pipe.

What is the purpose of a pressure test performed on a new gas distribution main before it is placed in service?

Answer: To verify the integrity of the pipe and joints before gas introduction

Pre-service pressure testing confirms that new piping and all joints are leak-free and structurally sound before gas is introduced.

What does the term 'squeeze-off' mean in the context of polyethylene gas pipe?

Answer: Mechanically flattening a PE pipe to stop gas flow

Squeeze-off is the process of mechanically compressing a polyethylene pipe flat to stop gas flow for maintenance or emergency response.

What instrument is used by gas utility workers to detect the presence of natural gas in air?

Answer: Combustible gas indicator (CGI)

A combustible gas indicator (CGI) measures the concentration of combustible gas in air and alerts workers to potentially dangerous accumulations.

How is natural gas odorized before distribution to customers?

Answer: Mercaptan (ethyl mercaptan or similar) is injected into the gas stream

Mercaptans (thiols) are injected into the gas stream to give odorless natural gas a distinctive rotten-egg smell detectable at low concentrations.

What does a gas distribution operator mean by 'locating and marking' a pipeline?

Answer: Identifying and marking the horizontal position of buried pipeline before excavation

Locating and marking involves using electronic equipment to find buried pipelines and placing surface marks to guide safe excavation by others.