I85PREP
⌘ K
NCCER Pipeline Ops study materials
NCCER Pipeline Ops study resources

NCCER Pipeline Ops practice questions

One question at a time. Build your NCCER Pipeline Ops understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Pipeline Operations

In pipeline terminology, what does the term 'station' most commonly refer to?

  1. A designated facility where pumps, valves, or metering equipment control flow and pressure Correct answer.
  2. The internal coating applied to reduce friction loss
  3. A short segment of pipe between two weld joints
  4. The depth of cover measured from the top of the pipe to grade

Explanation

A station is a facility location along a pipeline where equipment such as pumps, valves, meters, and controls are installed to manage flow and pressure. Field terms like 'pump station' and 'meter station' follow this usage. The other definitions describe pipe joints, cover depth, and internal coating, which are distinct concepts.

Question 2Pipeline Operations

Which pipeline component is installed to allow isolation of a section for maintenance without shutting down the entire line?

  1. Line break valve or block valve Correct answer.
  2. Pig signaler
  3. Test lead
  4. Scraper trap

Explanation

Block valves, including line break valves, are placed along a pipeline so a segment can be isolated while other sections continue operating. Scraper traps and pig signalers support pigging, and test leads support cathodic protection testing. They do not provide sectional isolation.

Question 3Pipeline Operations

A pipeline operator records a pressure drop that travels through the line faster than the product flows. What phenomenon is being observed?

  1. A cathodic protection current
  2. A steady-state friction gradient
  3. A thermal expansion of the product
  4. A pressure surge, or transient wave Correct answer.

Explanation

A transient, or surge, is a pressure wave that propagates through the fluid at the speed of sound in the product, which is much faster than bulk flow velocity. Steady-state friction gradients change gradually along the line. Thermal expansion and cathodic protection currents are unrelated to fast pressure-wave travel.

Question 4Pipeline Operations

Why do pipeline operators run cleaning pigs through a line on a scheduled basis?

  1. To recharge the cathodic protection system
  2. To verify the wall thickness of the entire pipe
  3. To increase the line's maximum allowable operating pressure
  4. To remove wax, scale, and debris that reduce flow efficiency Correct answer.

Explanation

Cleaning pigs scrape and push accumulated wax, scale, and debris out of the line, restoring flow capacity and reducing corrosion risk. They do not raise MAOP, measure wall thickness throughout, or affect cathodic protection. In-line inspection tools, not cleaning pigs, assess wall thickness.

Question 5Pipeline Operations

What is the primary purpose of cathodic protection on a buried steel pipeline?

  1. To reduce external corrosion by making the pipe the cathode of an electrochemical cell Correct answer.
  2. To detect third-party excavation activity
  3. To prevent internal erosion from abrasive solids
  4. To keep the product above its pour point

Explanation

Cathodic protection supplies current so the pipe surface becomes cathodic, suppressing the anodic corrosion reaction on the external surface. Internal erosion, product temperature, and excavation detection are handled by other systems, such as flow control, heating, and one-call programs.

Question 6Pipeline Operations

A controller notices that discharge pressure at a pump station rises while suction pressure falls. Which condition best explains this?

  1. An increase in suction supply pressure
  2. A decrease in product viscosity
  3. A failed cathodic rectifier
  4. A downstream blockage or valve closure restricting flow Correct answer.

Explanation

When flow is restricted downstream, the pump pushes against higher resistance, raising discharge pressure while suction pressure drops because less product is drawn from upstream. Lower viscosity would reduce pressure, higher suction supply would raise suction pressure, and a rectifier affects corrosion, not hydraulics.

Question 7Pipeline Operations

What does the term 'MAOP' represent in pipeline operations?

  1. Minimum annual operating permit
  2. Measured average outlet pressure
  3. Maximum allowable operating pressure Correct answer.
  4. Mandatory annual overhaul procedure

Explanation

MAOP is the maximum allowable operating pressure, the highest pressure at which a pipeline segment may be operated under design and regulatory limits. The other expansions are invented and do not match standard pipeline terminology.

Question 8Pipeline Operations

Which document typically defines the operating limits, alarm setpoints, and control philosophy for a pipeline system?

  1. The welding procedure specification
  2. The one-call ticket log
  3. The operations and maintenance manual with its control narrative Correct answer.
  4. The material test report for the pipe steel

Explanation

The operations and maintenance manual, supported by the control narrative, documents operating limits, alarm setpoints, and control philosophy. Material test reports, one-call logs, and welding procedures address different concerns such as steel properties, excavation notification, and weld quality.

Question 9Pipeline Operations

During a leak survey along a natural gas pipeline right-of-way, a technician uses a flame ionization detector. What is the technician primarily measuring?

  1. Soil resistivity
  2. Pipeline internal pressure
  3. Combustible gas concentration in the air sample Correct answer.
  4. Pipe wall thickness

Explanation

A flame ionization detector responds to hydrocarbon gas in the sampled air, allowing the technician to locate leaks by detecting elevated combustible gas concentration. It does not measure internal pressure, soil resistivity, or wall thickness, which require pressure gauges, resistivity meters, and inspection tools.

Question 10Pipeline Operations

What is the main function of a pig signaler installed on a pipeline?

  1. To isolate the line during emergencies
  2. To measure product density
  3. To regulate downstream pressure
  4. To indicate when a pig passes a specific location Correct answer.

Explanation

A pig signaler detects the passage of a pig at a specific point, helping operators track pig location and confirm launch or receipt. Pressure regulation, density measurement, and emergency isolation are performed by regulators, densitometers, and block valves.

Question 11Pipeline Operations

A pipeline segment shows a slow, steady loss of pressure that is not explained by changes in flow rate or temperature. Which action is the most appropriate first step?

  1. Recalibrate the pig signaler
  2. Increase cathodic protection current
  3. Increase pump speed to restore pressure
  4. Compare inlet and outlet volumes to check for a mass balance discrepancy Correct answer.

Explanation

An unexplained pressure loss can indicate a leak, and a volume balance between inlet and outlet is a standard method to confirm whether product is being lost. Raising pump speed would mask the symptom, and cathodic protection or pig signaler adjustments do not address line integrity.

Question 12Pipeline Operations

Which factor most directly determines the required wall thickness for a given pipeline design pressure?

  1. Pipe diameter, design pressure, and allowable stress per the design code Correct answer.
  2. The number of pig runs per year
  3. The color of the exterior coating
  4. The length of the right-of-way

Explanation

Wall thickness is calculated from design pressure, pipe diameter, and allowable stress using code formulas, often with allowances for corrosion and temperature. Coating color, pigging frequency, and right-of-way length do not enter the wall thickness calculation.

Question 13Pipeline Operations

A pipeline is being started up after hydrostatic testing. Why is air typically purged from the line before introducing the product?

  1. To lower the pipeline's MAOP
  2. To increase the product's viscosity
  3. To prevent formation of a flammable or explosive mixture and reduce pressure surges Correct answer.
  4. To improve cathodic protection efficiency

Explanation

Trapped air can mix with hydrocarbons to form a flammable atmosphere and can cause pressure surges when compressed. Purging with an inert gas or product displaces the air. Viscosity, cathodic protection, and MAOP are not improved by purging.

Question 14Pipeline Operations

What is the purpose of a surge relief valve on a liquid pipeline?

  1. To measure flow rate
  2. To filter solids from the product
  3. To add odorant to the product
  4. To relieve pressure spikes that could exceed the pipeline's design limits Correct answer.

Explanation

Surge relief valves open when pressure exceeds a setpoint to protect the line and equipment from transient overpressure. Odorization, filtration, and flow measurement are handled by separate devices.

Question 15Pipeline Operations

A control room operator receives a high-high pressure alarm at a mid-line block valve station. What is the most appropriate immediate response?

  1. Increase flow to clear the pressure
  2. Disable the alarm to prevent nuisance trips
  3. Ignore the alarm until the next shift
  4. Follow the emergency response procedure, which may include reducing pump output or isolating the affected segment Correct answer.

Explanation

A high-high pressure alarm indicates a condition that could threaten integrity, so the operator follows established emergency procedures, which may include reducing pump output or isolating the segment. Ignoring, increasing flow, or disabling alarms would escalate risk.

Question 16Pipeline Operations

In a liquid pipeline, what does 'batching' refer to?

  1. Replacing a section of pipe
  2. Calibrating a flow meter
  3. Moving different products sequentially through the same line as distinct slugs Correct answer.
  4. Testing the line with water

Explanation

Batching is the practice of shipping different products, such as grades of fuel, in sequence through a single pipeline, separated by an interface. Pipe replacement, hydrostatic testing, and meter calibration are unrelated operations.

Question 17Pipeline Operations

Why is interface (transmix) management important in a batched products pipeline?

  1. Mixing at product boundaries can cause off-specification product that must be downgraded or reprocessed Correct answer.
  2. It reduces the need for cathodic protection
  3. It increases the line's design pressure
  4. It eliminates the need for block valves

Explanation

Where two batches meet, mixing creates an interface that may not meet either product specification, so operators track and segregate it for downgrade or reprocessing. Interface management does not affect design pressure, valve needs, or cathodic protection.

Question 18Pipeline Operations

What does a SCADA system provide to pipeline operations?

  1. Chemical treatment of the product
  2. Mechanical protection against overpressure
  3. Remote monitoring and control of field equipment from a central location Correct answer.
  4. Physical isolation of pipeline segments

Explanation

SCADA, or supervisory control and data acquisition, collects field data and allows remote control of pumps, valves, and other equipment from a control center. Overpressure protection, chemical treatment, and physical isolation are provided by relief devices, injection systems, and valves.

Question 19Pipeline Operations

A technician must verify the setpoint on a pressure safety valve. Which action respects typical pipeline safety practice?

  1. Adjust the setpoint based on the technician's experience
  2. Follow the written procedure and confirm the setpoint against the design basis before testing Correct answer.
  3. Remove the valve and leave the line unprotected during testing
  4. Test the valve while the line is at full operating pressure

Explanation

Safety-critical devices must be tested and set per written procedures and the design basis, using isolation and proper documentation. Adjusting by feel, testing live without isolation, or leaving the line unprotected would violate safe practice.

Question 20Pipeline Operations

What is the primary reason pipeline rights-of-way are patrolled on a regular schedule?

  1. To increase the pipeline's flow capacity
  2. To measure product density at each mile
  3. To recalibrate the cathodic protection rectifiers
  4. To identify encroachments, leaks, and ground disturbances that could threaten the line Correct answer.

Explanation

Patrols look for third-party encroachment, visible leaks, erosion, and other ground disturbances that could compromise pipeline integrity. Density measurement, rectifier calibration, and flow capacity are handled by instruments and engineering, not patrols.

Question 21Pipeline Operations

A hydrostatic test is performed on a new pipeline segment. What is the main purpose of this test?

  1. To measure cathodic protection current
  2. To confirm the product meets specification
  3. To check the operation of pig signalers
  4. To verify that the segment can withstand pressures above its operating limit without failure Correct answer.

Explanation

Hydrostatic testing pressurizes the segment with water above its operating pressure to prove strength and reveal leaks before service. Product quality, pig signalers, and cathodic protection are verified by other means.

Question 22Pipeline Operations

Why is odorant added to natural gas in distribution pipelines?

  1. To provide a detectable warning smell so leaks can be noticed Correct answer.
  2. To increase the heating value of the gas
  3. To reduce pipeline corrosion
  4. To lower the gas pressure

Explanation

Natural gas is naturally odorless, so an odorant such as mercaptan is added to give a recognizable smell that helps people detect leaks. Odorant does not raise heating value, reduce corrosion, or lower pressure.

Question 23Pipeline Operations

An operator wants to confirm that a newly installed flow meter is accurate. Which method is most appropriate?

  1. Estimate flow from pump speed alone
  2. Assume accuracy if the meter is new
  3. Compare its readings with a calibrated reference meter or prover Correct answer.
  4. Rely on the manufacturer's catalog value

Explanation

Meter accuracy is confirmed by comparison with a calibrated reference, such as a prover or master meter, following a documented calibration procedure. Catalog values, pump speed estimates, and the assumption of newness do not verify accuracy.

Question 24Pipeline Operations

A pipeline experiences a sudden pressure drop followed by a rapid rise at a pump station. Which combination of causes is most likely?

  1. A cathodic protection rectifier failure
  2. A slow change in product viscosity
  3. A gradual temperature increase
  4. A rapid valve closure causing a surge wave Correct answer.

Explanation

Rapid valve closure or a sudden flow change creates a surge, seen as a sharp pressure drop followed by a rebound as the wave reflects. Temperature, viscosity, and rectifier issues change conditions gradually and do not produce this signature.

Question 25Pipeline Operations

A section of pipeline must be taken out of service for repair. Which sequence best reflects safe isolation practice?

  1. Reduce pump speed and proceed without valve isolation
  2. Rely on SCADA indication alone before opening the line
  3. Identify and confirm the isolation points, close and lock block valves, relieve and verify zero energy, then begin work Correct answer.
  4. Close the nearest valve and start work immediately

Explanation

Safe isolation requires identifying boundaries, closing and locking valves, relieving trapped pressure, and verifying zero energy before work begins. Closing only the nearest valve, skipping isolation, or trusting SCADA alone leaves stored energy and product that could injure workers.

Question 26Pipeline Operations

In pipeline terminology, what does the abbreviation MAOP stand for?

  1. Minimum Allowable Outlet Pressure
  2. Minimum Acceptable Operating Parameter
  3. Maximum Allowable Operating Pressure Correct answer.
  4. Maximum Applied Overpressure Protection

Explanation

MAOP is the highest pressure at which a pipeline may be operated under the design and regulatory limits established for that segment. It is a fixed operating ceiling, not a variable parameter or a minimum threshold.

Question 27Pipeline Operations

A controller notices that discharge pressure at a pump station rises while suction pressure falls. Which condition best explains this pattern?

  1. A downstream block valve has opened wider
  2. The pump is being operated at a lower speed
  3. A restriction has developed downstream of the pump Correct answer.
  4. Suction supply tank level has increased

Explanation

A downstream restriction reduces flow, causing discharge pressure to climb while suction pressure drops as the pump starves. Opening a valve or lowering speed would reduce discharge pressure rather than raise it.

Question 28Pipeline Operations

During a leak survey along a natural gas pipeline right-of-way, a technician uses a flame ionization detector. What is the instrument primarily detecting?

  1. Ionized combustion products of hydrocarbon gas in a hydrogen flame Correct answer.
  2. Ultrasonic noise from escaping high-pressure gas
  3. Combustible gas concentration by catalytic combustion
  4. Temperature rise caused by gas expansion

Explanation

A flame ionization detector burns the sample in a hydrogen flame and measures the ions produced, giving a sensitive response to hydrocarbon gases. It does not rely on catalytic beads, ultrasound, or thermal effects.

Question 29Pipeline Operations

A pipeline segment shows a slow, steady loss of pressure that is not explained by changes in flow rate or temperature. Which condition is most consistent with this observation?

  1. A normal thermal contraction of the product
  2. A temporary change in product batch density
  3. A correctly functioning pressure relief valve
  4. A small leak or developing pipeline integrity defect Correct answer.

Explanation

An unexplained, gradual pressure decline points to product loss through a small leak or a developing defect. Normal thermal and batch effects would track with measured temperature or density changes.

Question 30Pipeline Operations

A control room operator receives a high-high pressure alarm at a mid-line block valve station. What is the most appropriate first response?

  1. Increase pump speed to push product through the station
  2. Ignore the alarm until it clears on its own
  3. Verify the reading and reduce pressure by adjusting upstream controls Correct answer.
  4. Dispatch a crew to the site before taking any control action

Explanation

The operator should confirm the alarm is real and act to reduce pressure using available controls before dispatching personnel. Increasing pump speed would worsen the condition, and ignoring the alarm risks a failure.

Question 31Pipeline Operations

In a liquid pipeline, what does batching refer to?

  1. Repairing a section of pipe with a clamp
  2. Running an inspection pig through the line
  3. Moving different products or grades through the line in sequence Correct answer.
  4. Testing the line at elevated pressure

Explanation

Batching is the sequential movement of distinct products or grades through the same pipeline, separated by an interface. It is not a pressure test, pig run, or repair activity.

Question 32Pipeline Operations

A pipeline experiences a sudden pressure drop followed by a rapid rise at a pump station. Which combination of causes is most consistent with this event?

  1. A gradual increase in product temperature
  2. A rapid valve closure creating a surge wave Correct answer.
  3. A slow buildup of paraffin in the line
  4. A steady decrease in downstream demand

Explanation

A rapid valve closure stops flow abruptly, causing a pressure drop followed by a surge wave as momentum reverses. Thermal changes, paraffin buildup, and demand shifts develop gradually and do not produce this signature.

Question 33Pipeline Operations

A pipeline controller must calculate the volume of product delivered over a shift using meter readings and corrections. Which correction is most important when product temperature differs from the reference condition?

  1. Correcting for temperature to a standard volume basis Correct answer.
  2. Correcting for the age of the meter
  3. Correcting for the number of valve operations
  4. Correcting for the color of the product

Explanation

Liquid volume changes with temperature, so readings are corrected to a standard temperature basis for accurate custody transfer. Color, valve operations, and meter age do not provide the physical correction needed.

Question 34Pipeline Operations

An in-line inspection tool reports a cluster of corrosion features in a pipeline segment. Which action best represents a risk-based response?

  1. Reduce operating pressure only after a failure occurs
  2. Ignore the findings until the next scheduled inspection
  3. Assess feature severity against criteria and schedule remediation by priority Correct answer.
  4. Immediately replace the entire pipeline system

Explanation

Risk-based integrity management evaluates the severity of each feature against defined criteria and prioritizes repairs accordingly. Wholesale replacement, inaction, or waiting for failure are not proportionate responses.

Question 35Pipeline Operations

A pump station shows normal discharge pressure but declining throughput over several days, with no change in product properties. Which diagnosis deserves first investigation?

  1. A failure of the odorization system
  2. An increase in the number of right-of-way patrols
  3. A partial blockage or fouling in the downstream line Correct answer.
  4. A change in the pipeline's design pressure rating

Explanation

Normal discharge pressure with falling throughput suggests increasing resistance downstream, such as a partial blockage or fouling. Odorization, design rating, and patrol frequency do not explain reduced hydraulic capacity.

Question 36Pipeline Operations

During a batch transition, a controller must decide when to divert the interface volume. Which information is most critical to that decision?

  1. The length of the right-of-way patrol route
  2. The predicted interface volume and the product specifications Correct answer.
  3. The number of operators on shift
  4. The color of the pipeline coating

Explanation

Diverting the interface depends on knowing its predicted size and the specification limits of the adjacent products. Coating color, staffing, and patrol route length do not inform the cut point.

Question 37Pipeline Operations

A pressure surge is predicted when a downstream block valve closes rapidly. Which mitigation is most effective at reducing the surge magnitude?

  1. Reducing the pipe wall thickness
  2. Increasing the closure time of the valve Correct answer.
  3. Increasing the pump discharge pressure
  4. Removing the surge relief valve

Explanation

Slowing the valve closure spreads the flow change over a longer period, reducing the surge wave magnitude. Raising pressure, removing relief, or thinning the wall would worsen the transient or weaken the line.

Question 38Pipeline Operations

A pipeline segment is being returned to service after repairs. Which combination of checks best confirms readiness before product is introduced?

  1. A visual inspection of paint and signage
  2. A review of past patrol reports only
  3. Strength test results, isolation removal, and purge verification Correct answer.
  4. Confirmation that the repair crew has left the site

Explanation

Return to service requires confirmation that strength testing passed, isolations are removed in the correct order, and the line has been purged of air. Cosmetic checks, old patrol reports, and crew departure do not establish mechanical readiness.

Question 39Pipeline Operations

In liquid pipeline operations, what does the term "line fill" refer to?

  1. The maximum volume a tank farm can hold before overfill protection activates
  2. The volume of product physically contained in the pipe between two points at any given time Correct answer.
  3. The amount of product lost to evaporation at each block valve station
  4. The quantity of product scheduled for delivery during a single shift

Explanation

Line fill is the inventory of liquid that must remain in the pipeline to keep it packed and moving; it is not deliverable volume. Controllers track line fill because it changes whenever a segment is drained, filled, or isolated, and it affects batch arrival calculations.

Question 40Pipeline Operations

Which unit is conventionally used to express the gravity of a liquid petroleum product in pipeline quality tracking?

  1. Viscosity index
  2. Reid vapor pressure
  3. Specific heat
  4. API gravity Correct answer.

Explanation

API gravity is the standard petroleum-industry scale derived from specific gravity and is reported on every batch ticket. It shifts with product type and temperature, so it is corrected to a reference temperature before custody transfer calculations.

Question 41Pipeline Operations

A pipeline controller observes a slow, steady decline in suction pressure at a booster pump while discharge pressure stays constant. Which condition is most consistent with this pattern?

  1. Increasing blockage upstream of the pump, such as a partially closed valve or wax restriction Correct answer.
  2. A ruptured downstream mainline releasing product to the environment
  3. A sudden increase in product temperature at the suction header
  4. Failure of the pump discharge check valve to seat

Explanation

Falling suction with steady discharge means the pump is pulling harder against a restriction on its supply side. An upstream obstruction raises the pressure drop across the suction path, lowering available NPSH. Downstream events would instead show up on the discharge side.

Question 42Pipeline Operations

What is the primary function of a scraper (pig) trap on a pipeline?

  1. To meter the volume of product crossing a custody transfer point
  2. To regulate downstream pressure through a throttling orifice
  3. To launch and receive in-line tools and scrapers without depressurizing the mainline Correct answer.
  4. To separate water from crude oil before it enters the pump station

Explanation

A trap is a valved side assembly that lets crews insert or remove a pig while the line stays in service. Proper trap operation requires correct valve lineup, depressurization of the trap barrel, and confirmation that the pig has fully arrived before opening the closure.

Question 43Pipeline Operations

Before opening a pig trap closure for tool retrieval, which step is essential?

  1. Increasing mainline flow to push the pig harder against the stop
  2. Venting and confirming the trap barrel is at atmospheric pressure with the pig fully seated Correct answer.
  3. Opening the kicker valve to pressurize the barrel
  4. Closing the mainline block valve downstream of the trap only

Explanation

The trap barrel must be isolated, drained, and vented to zero gauge before the closure is touched; residual pressure is the leading cause of trap fatalities. Crews also verify the pig has arrived so it does not travel at personnel. Pressurizing or increasing flow at this moment is exactly backwards.

Question 44Pipeline Operations

In natural gas pipeline operations, what does the term "packing" the line mean?

  1. Compressing gas into cylinders for transport by truck
  2. Raising line pressure by holding gas in the segment until demand requires it Correct answer.
  3. Injecting odorant at a city gate station
  4. Coating the internal pipe wall with corrosion inhibitor

Explanation

Packing uses the pipeline itself as storage by increasing pressure and gas inventory during low demand. The stored gas is later withdrawn to meet peak demand, which is why line pack is tracked closely by gas controllers.

Question 45Pipeline Operations

A gas controller sees line pack falling faster than the scheduled delivery rate would explain. Which action is most appropriate first?

  1. Increase compressor discharge pressure to the maximum allowable operating pressure immediately
  2. Reduce odorant injection at the city gate
  3. Compare measured receipts and deliveries against nominations and check for an unaccounted withdrawal Correct answer.
  4. Close all block valves on the affected segment

Explanation

An unexplained pack loss can indicate a leak, meter error, or unauthorized offtake, so the first step is reconciliation of measured versus nominated volumes. Raising pressure or closing valves without diagnosis could worsen the situation or disrupt customers.

Question 46Pipeline Operations

Which document typically authorizes a specific pipeline maintenance task and defines the isolation, hazards, and controls required?

  1. A nomination schedule
  2. A material safety data sheet alone
  3. A work permit with an attached isolation or lockout plan Correct answer.
  4. A bill of lading

Explanation

A work permit ties the job to its hazards and required controls, including energy isolation and gas testing. It documents authorization and is signed off before work begins and at completion.

Question 47Pipeline Operations

A crew must hot-tap a live crude line to install a new branch connection. Which precaution is most important to control the hazard?

  1. Shutting down all upstream pump stations for the duration
  2. Draining the entire line to atmospheric pressure before tapping
  3. Verifying wall thickness and completing the tap with the line under controlled flow and pressure Correct answer.
  4. Removing the section's cathodic protection during the tap

Explanation

Hot tapping is performed on an in-service line, so the fitting and valve must be rated for the pressure and the wall must be thick enough to cut safely. Flow is maintained to avoid stagnation, and the procedure is done under a permit with fire watch where hydrocarbons are present.

Question 48Pipeline Operations

What is the purpose of cathodic protection on a buried steel pipeline?

  1. To detect third-party excavation activity
  2. To suppress electrochemical corrosion by making the pipe surface the cathode of a corrosion cell Correct answer.
  3. To increase the pipe's internal pressure rating
  4. To reduce friction losses along the line

Explanation

Cathodic protection supplies current that shifts the pipe potential so the steel no longer acts as an anode, halting corrosion. It is used together with a coating that provides the primary barrier.

Question 49Pipeline Operations

A close-interval survey shows a section of coated pipe where the pipe-to-soil potential has fallen below the protection criterion. Which interpretation is most reasonable?

  1. The survey instrument must be recalibrated because readings cannot vary along a line
  2. The coating may be damaged or the impressed current system may be underperforming in that area Correct answer.
  3. The pipe has become electrically isolated and needs no further attention
  4. The soil resistivity has dropped, guaranteeing full protection

Explanation

A localized drop in potential suggests coating holidays, shielding, or insufficient current from the rectifier or anode bed. The next step is investigation of the cause, not assuming protection is adequate. Potentials normally vary along a pipeline.

Question 50Pipeline Operations

Which practice best reduces the risk of third-party damage to a buried pipeline?

  1. Increasing MAOP to shorten pump run times
  2. Reducing the frequency of aerial patrols to save cost
  3. Installing additional odorization equipment
  4. Participation in the one-call notification system combined with right-of-way patrols and public awareness Correct answer.

Explanation

Third-party excavation is a leading cause of pipeline incidents, and one-call participation plus patrols and awareness programs are the standard defenses. These measures ensure locates are performed and encroachments are spotted early.