03 Pipes That Break and Leak Natural Gas

Question 1

Most people can smell odorized NG at less than:

Answer 1

1ppm

Question 2

Numbers for the LEL

Answer 2

10% or 5,000ppm

Question 3

Key components of residential gas distribution:

Answer 3

1. Curb Box (one quarter turn valve)
2. Service Line (buried pipe connecting gas distribution main to customers riser, usually 3/4” to 1”)
3. Riser
4. Pressure regulator

Question 4

Piping outside the house must be …

Answer 4

Galvanized

Question 5

Pressure regulator converts street pressure to:

Answer 5

0.25psi for home use.

Question 6

Half Foot dial

Answer 6

(on the meter) will be moving if gas is being used in the building.

Question 7

Inside diameter of corrugated stainless steel tubing (CSST)

Answer 7

3/4”

Question 8

Issue with CSST:

Answer 8

Must be grounded effectively to prevent damage from direct or nearby lightning strikes.

Question 9

When responding to lightning strikes check:

Answer 9

for NG leaks (ask neighbors as well)

Question 10

School or Commercial Gas Meter:

Answer 10

Gas flows: Service valve (50 - 70 psi) > Regulator (25-30 psi) > Metering Valve > Meter > Metering Valve > Second Regulator (< 5psi) > Out for distribution to building.

Question 11

Which valve is most important to close if we are ordered to shut off the gas to the building?

Answer 11

Service Valve

Question 12

Bypass Valve

Answer 12

Usually closed and locked. It is opened in order to service or replace the meter itself. (Close meter valve and open bypass valve)

Question 13

Gas distribution systems operate at pressures ranging from 0.25 to 99 psi and consist of:

Answer 13

mains, services, valves and meters
constructed of: steel, cast iron, ductile iron, wrought iron, or plastic (depends on age and type of service)

Question 14

Utility companies are responsible for …

Answer 14

Entire distribution system and usually the gas meter

Question 15

Low pressure distribution systems are around:

Answer 15

0.5 psi
No pressure regulator needed

Question 16

Medium pressures vary from __________.

Answer 16

25-33 psi
Pressure regulator needed

Question 17

High pressure systems are in the ________.

Answer 17

99 psi range.
Use only steel pipe and select plastic pipe

Question 18

A Valve

Answer 18

Mechanical device used to control the flow of gas
1. Manual operation
2. Remote operation
3. Automatic operation

Question 19

Grades of Leaks: Grade 1

Answer 19

Existing or probable hazard. to persons or property requiring immediate repair or continuous action until the conditions are no longer hazardous.

Question 20

Grades of Leaks: Grade 2

Answer 20

A leak that is recognized as being nonhazardous at the time of detection but justifies scheduled repair based on probable future hazard.

Question 21

Grade of Leaks: Grade 3

Answer 21

A leak that is nonhazardous at the time of detection and can be reasonably expected to remain nonhazardous.

Question 22

Gate Stations:

Answer 22

1. Reduce pressure in the line from transmission level (200 - 1500 psi) to distribution levels (0.25 - 200psi)
2. Odorant is added
3. Measures the flow of the gas to determine the amount being received by the utility.

Question 23

From the gate station, the NG moves into distribution lines or “mains” that range from 2” to 24” in diameter.

Question 24

Gas Processing Plants

Answer 24

Remove contaminates to provide a consistent quality NG to consumers.

Question 25

Wellhead and Gas Fields

Answer 25

Gas pushes through the earth under pressures up to 5,000 psi.