API 570 Piping Inspector Certification Exam — Questions and Answers

Question 1: What is cavitation in a piping system?

Thermal expansion of liquid in a closed system
Formation and collapse of vapor bubbles due to pressure drop below vapor pressure (Correct answer)
Air trapped in a high point of pipe
Erosion of pipe from abrasive particles

Correct answer: Formation and collapse of vapor bubbles due to pressure drop below vapor pressure

Cavitation occurs when local pressure drops below the fluid's vapor pressure, forming bubbles that collapse violently and damage equipment.

Question 2: What is the difference between a socket weld and a butt weld fitting?

Socket welds use a fillet weld at the outside of the fitting; butt welds use a groove weld joining pipe ends directly (Correct answer)
Socket welds are used only on high-pressure lines; butt welds on low-pressure lines
Socket welds require PWHT; butt welds do not
There is no structural difference between them

Correct answer: Socket welds use a fillet weld at the outside of the fitting; butt welds use a groove weld joining pipe ends directly

Socket weld fittings slip over the pipe end and are sealed with a fillet weld, while butt weld fittings are beveled to match the pipe end for a full-penetration groove weld.

Question 3: What does ASME PCC-2 provide guidance on?

Repair of pressure equipment and piping using various repair methods (Correct answer)
Design of pressure vessels
Certification of piping inspectors
Quality control for pipe manufacturing

Correct answer: Repair of pressure equipment and piping using various repair methods

ASME PCC-2 provides standard repair methods and procedures for pressure equipment and piping, including mechanical clamps, full encirclement sleeves, composite wraps, and welded repairs.

Question 4: Under ASME B31.3, which examination category requires 100% radiographic or ultrasonic examination of welds?

Normal fluid service (Category D)
Severe cyclic conditions
Utility service only
High-pressure service or Category M (highly hazardous) fluid service (Correct answer)

Correct answer: High-pressure service or Category M (highly hazardous) fluid service

High-pressure service and Category M (highly hazardous) fluid service in ASME B31.3 require 100% examination of welds due to the elevated risk associated with failure.

Question 5: Which type of pipe cap is used on a pipe end that may need to be reopened later?

Welded cap
Crimped cap
Compression cap
Threaded cap (Correct answer)

Correct answer: Threaded cap

A threaded cap can be removed and reinstalled without cutting pipe, making it ideal for pipe ends that may need future access.

Question 6: What is the purpose of a 'piping flexibility analysis' required by ASME B31.3?

To determine the required pipe wall schedule
To ensure the piping system has adequate flexibility to prevent overstress from thermal expansion and terminal movements (Correct answer)
To verify that pipe supports can carry the deadweight load
To calculate the maximum allowable flow velocity

Correct answer: To ensure the piping system has adequate flexibility to prevent overstress from thermal expansion and terminal movements

Flexibility analysis verifies that thermal expansion, contraction, and equipment terminal movements do not cause stresses exceeding code-allowable limits or unacceptable nozzle loads.

Question 7: According to API 570, how is the 'long-term corrosion rate' different from the 'short-term corrosion rate'?

There is no distinction — only one corrosion rate is calculated
Long-term applies to external corrosion; short-term to internal corrosion
Long-term rate is for buried pipe; short-term rate is for above-ground pipe
Long-term uses all inspection data back to baseline; short-term uses only the last two inspection readings (Correct answer)

Correct answer: Long-term uses all inspection data back to baseline; short-term uses only the last two inspection readings

API 570 defines long-term rate using all available thickness data back to baseline, while short-term rate uses only recent measurements; inspection intervals are based on the more conservative of the two.

Question 8: Determine the pipe type using schedule No. 40S.

HDPE
Stainless steel (Correct answer)
Carbon Steel
Alloy Steel

Correct answer: Stainless steel

The 'S' suffix in pipe schedule numbers, such as '40S,' specifically indicates that the pipe dimensions conform to ASME B36.19M, which is the standard for stainless steel pipes. While carbon steel pipes use schedules like '40' (without the 'S') and follow ASME B36.10M, the 'S' is a key differentiator for stainless steel. This suffix ensures the pipe's wall thickness corresponds to the standard for stainless steel, which often has different wall thickness requirements for a given nominal pipe size compared to carbon steel.

Question 9: In a risk-based inspection (RBI) program for piping, what are the two factors that determine inspection priority?

Last inspection date and current wall thickness
Operating pressure and temperature
Age of the piping and material grade
Probability of failure (PoF) and consequence of failure (CoF) (Correct answer)

Correct answer: Probability of failure (PoF) and consequence of failure (CoF)

RBI prioritizes inspection resources by combining the probability of failure (based on corrosion mechanisms and rates) with the consequence of failure (safety, environmental, and economic impacts).

Question 10: What does isometric indicates' cloud marking mean?

Change in Piping system
Change occurred in Revision (Correct answer)
Change in material
Change in isometric

Correct answer: Change occurred in Revision

In piping isometric drawings, a 'cloud' or 'revision cloud' drawn around a specific area indicates that a change has been made to that part of the drawing since the previous revision. This visual cue helps engineers and fabricators quickly identify modifications and ensure they are working with the most up-to-date design information. It's a standard practice for revision control and communication in engineering documentation.

Question 11: Which type of weld discontinuity is typically caused by incorrect travel speed or arc length during pipe welding?

Undercut (Correct answer)
Slag inclusion
Porosity
Lack of root penetration

Correct answer: Undercut

Undercut is a groove melted into the base metal adjacent to the weld toe, usually caused by excessive current, incorrect angle, or too high travel speed.

Question 12: What is the significance of the Cv value for a control valve?

It represents the flow coefficient measuring flow capacity (Correct answer)
It specifies the valve's temperature limit
It defines the valve body material grade
It indicates the valve's pressure rating

Correct answer: It represents the flow coefficient measuring flow capacity

The Cv (flow coefficient) represents the volume of water in US gallons per minute that flows through a fully open valve at a 1 psi pressure drop.

Question 13: What is 'dead leg' in a piping system and why is it a concern?

An underground section that cannot be inspected
A valve locked in the closed position
A section of pipe with no flow where fluid stagnates, risking contamination or corrosion (Correct answer)
A pipe run with no supports, causing sag

Correct answer: A section of pipe with no flow where fluid stagnates, risking contamination or corrosion

A dead leg is a section of piping where fluid does not flow, creating a zone where bacteria can grow, corrosion can accelerate, or product quality can degrade — a particular concern in pharmaceutical and food processing systems.

Question 14: What is the purpose of the ANSI/ASME pipe schedule number system?

To indicate the pipe wall thickness relative to the outside diameter (Correct answer)
To classify the pipe's pressure-temperature rating class
To specify the pipe end preparation type
To identify the pipe material grade

Correct answer: To indicate the pipe wall thickness relative to the outside diameter

Pipe schedule numbers (Sch 40, Sch 80, etc.) define the wall thickness as a ratio, where higher schedule numbers indicate thicker walls for higher pressure service.

Question 15: Which piping symbol on a P&ID represents a gate valve?

Two triangles pointing away from each other
A filled circle on a line
A circle with an X through it
Two triangles pointing toward each other at their tips (Correct answer)

Correct answer: Two triangles pointing toward each other at their tips

On a P&ID, a gate valve is represented by two triangles with their points meeting at the centerline of the pipe, symbolizing the wedge-shaped gate disc that slides perpendicular to flow.

Question 16: Which gasket material is typically used for flanged connections in high-temperature steam applications?

Spiral-wound stainless steel with graphite filler (Correct answer)
PVC or PTFE sheet
Cork composite
Rubber or neoprene

Correct answer: Spiral-wound stainless steel with graphite filler

Spiral-wound gaskets with stainless steel winding and graphite filler are designed to handle high temperature and pressure in steam service.

Question 17: What type of corrosion mechanism causes damage specifically in the heat-affected zones of welds in sensitized stainless steel?

Erosion corrosion
Intergranular corrosion (weld decay) (Correct answer)
Uniform corrosion
Galvanic corrosion

Correct answer: Intergranular corrosion (weld decay)

Sensitized stainless steel (carbide precipitation at grain boundaries during welding) becomes susceptible to intergranular corrosion in the weld HAZ, known as 'weld decay.'

Question 18: What does 'Schedule 160' indicate compared to 'Schedule 80' for the same nominal pipe size?

Schedule 160 has a thicker wall and higher pressure capability (Correct answer)
Schedule 160 is only for stainless steel pipe
Both schedules have identical wall thickness
Schedule 160 has a thinner wall and lower pressure rating

Correct answer: Schedule 160 has a thicker wall and higher pressure capability

Higher schedule numbers indicate greater wall thickness; Schedule 160 pipe has a significantly thicker wall than Schedule 80, providing higher pressure capacity.

Question 19: Which type of elbow fitting is used when space is limited and a tighter bend radius is required?

Long-radius elbow
Street elbow
Short-radius elbow (Correct answer)
Reducing elbow

Correct answer: Short-radius elbow

A short-radius elbow has a centerline radius equal to the nominal pipe diameter, making it more compact than a long-radius elbow.

Question 20: The maximum support spacing for 6-inch Schedule 40 carbon steel pipe carrying water, as typically provided in support span tables, is approximately:

30 feet
8 feet
17 feet (Correct answer)
4 feet

Correct answer: 17 feet

Standard span tables (e.g., ASME B31.1 Appendix A) indicate approximately 17 feet for 6-inch water-filled carbon steel pipe based on allowable sag and stress.

Question 21: What is the recommended slope for a gravity drain line in a process piping system?

1:50
1:100 (Correct answer)
1:200
1:500

Correct answer: 1:100

A slope of 1:100 (1 mm per 100 mm) is a common minimum for gravity drainage to ensure complete liquid removal.

Question 22: What is a Welding Procedure Specification (WPS)?

A document prescribing the variables to be used when making a production weld (Correct answer)
A document listing the welder's qualifications
A material certification for filler metal
A record of production weld repairs

Correct answer: A document prescribing the variables to be used when making a production weld

A WPS specifies the welding variables (process, filler metal, preheat, interpass temperature, etc.) required to produce a weld meeting code requirements.

Question 23: What is the 'remaining life' calculation used in piping inspection programs?

The number of pressure cycles remaining before fatigue failure
Time until next scheduled maintenance shutdown
Estimated time until the pipe wall reaches minimum required thickness based on measured corrosion rate (Correct answer)
Calendar time since the pipe was last replaced

Correct answer: Estimated time until the pipe wall reaches minimum required thickness based on measured corrosion rate

Remaining life = (actual thickness - minimum required thickness) divided by the corrosion rate, providing an estimate of how much service life remains before mandatory retirement.

Question 24: What type of fitting is used to connect plastic pipe to metal pipe in residential plumbing?

A dielectric union or transition fitting (Correct answer)
A standard slip coupling
A street elbow
A reducing bushing

Correct answer: A dielectric union or transition fitting

A dielectric union or transition fitting prevents galvanic corrosion between dissimilar metals (or metal and plastic) at the connection point.

Question 25: What does ASME B16.11 standardize?

Flanged fittings for Class 150
Cast iron fittings for drainage
Large-diameter fabricated fittings
Forged fittings including socket weld and threaded fittings (Correct answer)

Correct answer: Forged fittings including socket weld and threaded fittings

ASME B16.11 covers forged steel fittings including socket welding and threaded configurations, specifying dimensions, ratings, and testing requirements.

Question 26: What nondestructive method is best suited for detecting stress corrosion cracking (SCC) in stainless steel piping?

Eddy Current Testing (ET) or Phased Array Ultrasonic Testing (PAUT) (Correct answer)
Hydrostatic testing
Radiographic Testing (RT)
Magnetic Particle Testing (MT)

Correct answer: Eddy Current Testing (ET) or Phased Array Ultrasonic Testing (PAUT)

Eddy current and PAUT are effective for detecting SCC cracks in stainless steel; MT cannot be used on non-ferromagnetic austenitic stainless steel.

Question 27: What is the purpose of ASME B16.9?

To specify dimensions and tolerances for factory-made wrought butt-welding fittings (Correct answer)
To provide standards for pipe support design
To govern threaded pipe fittings dimensions
To define pressure-temperature ratings for flanged joints

Correct answer: To specify dimensions and tolerances for factory-made wrought butt-welding fittings

ASME B16.9 covers factory-made wrought steel butt-welding fittings (elbows, tees, reducers, caps) including their dimensions, tolerances, and marking requirements.

Question 28: What is 'erosion corrosion' in piping, and where does it most commonly occur?

Chemical corrosion in alkaline environments, most common in straight pipe sections
High-temperature oxidation, most common near furnaces
Corrosion caused by electrical grounding current, most common near electrical equipment
Accelerated metal loss caused by the combined effect of corrosive fluid and mechanical erosion from flow, most common at bends, tees, and reducers (Correct answer)

Correct answer: Accelerated metal loss caused by the combined effect of corrosive fluid and mechanical erosion from flow, most common at bends, tees, and reducers

Erosion corrosion occurs where turbulent or high-velocity flow removes protective corrosion films and physically erodes the pipe wall, especially at directional changes.

Question 29: What is the primary purpose of a pipe stress analysis in piping engineering?

To evaluate forces and moments on piping systems under load (Correct answer)
To select pipe material grade
To determine pipe wall thickness
To calculate fluid flow velocity

Correct answer: To evaluate forces and moments on piping systems under load

Pipe stress analysis evaluates forces, moments, and displacements in piping systems caused by pressure, temperature, weight, and other loads.

Question 30: Which type of pipe end preparation is used for socket weld connections?

The pipe is inserted into a female fitting socket and fillet welded (Correct answer)
The pipe end is threaded using NPT threads
The pipe end is beveled at 37.5 degrees
The pipe end is flanged and bolted

Correct answer: The pipe is inserted into a female fitting socket and fillet welded

Socket weld fittings have a female socket that accepts the pipe end, which is then secured with a fillet weld on the outside of the fitting hub.

Question 31: What is 'injection point corrosion' in process piping?

Internal corrosion in fire water injection lines
Localized and often severe corrosion at or near a point where chemicals are injected into a pipe (Correct answer)
Corrosion due to cathodic protection current injection
Corrosion caused by oxygen injection into steam systems

Correct answer: Localized and often severe corrosion at or near a point where chemicals are injected into a pipe

Injection points are high-risk areas for localized corrosion because injected chemicals may not be fully mixed with the process stream, creating concentrated corrosive conditions near the injection nozzle.

API 570 Piping Inspector Certification Exam

The API 570 certification validates that piping inspectors have the knowledge to perform in-service inspection, rating, repair, and alteration of metallic piping systems per API 570, ASME B31.3, and related codes. The exam tests competency across calculations, inspection practices, materials, NDE, and welding qualification.

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35 min

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70%

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