RMGA Corrosion Control and Cathodic Protection 2

Question 1

In a sacrificial anode cathodic protection system, what happens to the anode over time?

Accepted Answer

It gradually dissolves and must be periodically replaced

Answer

It gains mass as it absorbs corrosion products from the protected pipe

Answer

It converts AC power to DC power to maintain the protection circuit

Answer

Its electrical resistance increases until it must be electronically reset

Question 2

Which instrument setup is used to measure pipe-to-soil potential in cathodic protection surveys?

Accepted Answer

A voltmeter connected between the pipe lead and a reference electrode placed on the soil surface

Answer

A manometer connected between two buried test wires

Answer

An ammeter placed in series with the pipeline test wire

Answer

A megohmmeter connected across an isolation fitting

Question 3

What is stray current corrosion in the context of buried gas pipelines?

Accepted Answer

Corrosion resulting from electrical currents from external sources flowing through the buried pipeline

Answer

Corrosion caused by high-velocity gas flow eroding the interior pipe wall

Answer

Corrosion caused by oxygen dissolved in groundwater contacting the pipe exterior

Answer

Corrosion from microbes living in low-oxygen soil around the pipe

Question 4

Per 49 CFR Part 192, how frequently must cathodic protection levels on gas distribution systems be monitored?

Accepted Answer

At least once each calendar year, not exceeding 15-month intervals

Answer

Monthly

Answer

Every 6 months

Answer

Every 5 years as part of a comprehensive integrity review

Question 5

What is the primary function of a rectifier in an impressed current cathodic protection system?

Accepted Answer

To convert alternating current (AC) from a utility power source to direct current (DC) for the cathodic protection circuit

Answer

To continuously measure pipe-to-soil potential and trigger protection alarms

Answer

To detect coating holidays using electromagnetic induction

Answer

To isolate pipeline sections into individual cathodic protection zones

Question 6

What is the primary purpose of applying external coating to buried gas pipelines?

Accepted Answer

To electrically isolate the pipe exterior from the soil, reducing the area that cathodic protection must defend

Answer

To improve gas flow efficiency by reducing interior friction

Answer

To increase the pipe's rated maximum allowable operating pressure

Answer

To prevent internal condensation and water slug accumulation in the pipeline

Question 7

What does the term 'IR drop' (or IR error) refer to in cathodic protection potential measurements?

Accepted Answer

A voltage error caused by current flowing through soil resistance that makes the measured potential appear more negative than the true pipe potential

Answer

The internal resistance value of the copper-copper sulfate reference electrode

Answer

The dissolution rate of the sacrificial anode expressed in milliamps per year

Answer

The insulation resistance of a holiday detector probe tip