Oklahoma (OK) Process Piping Journeyman Exam
1. What is the primary code governing process piping systems in Oklahoma?
ANSWER : ASME B31.3, the Process Piping Code, is the primary code governing
process piping systems in Oklahoma. It establishes requirements for design,
materials, fabrication, assembly, examination, inspection, and testing of piping used
in petroleum refineries, chemical plants, pharmaceutical plants, textile plants,
paper plants, semiconductor plants, and other related industries.
2. Define 'process piping' as recognized under ASME B31.3.
ANSWER : Process piping refers to piping components used to convey fluids,
including raw, intermediate, or finished chemicals, petroleum products, gas, steam,
air, water, or other fluids in manufacturing, industrial, or institutional facilities. It
includes pipes, fittings, valves, and associated components designed to handle
process conditions, as distinct from building services or utility piping.
3. What does the term 'design pressure' mean in process piping?
ANSWER : Design pressure is the maximum internal or external pressure the
piping system is designed to withstand, including any surge allowances. It is used to
determine wall thickness and component pressure ratings. Per ASME B31.3, design
pressure must not exceed the maximum allowable working pressure (MAWP) of
the weakest component in the system.
4. What is 'design temperature' in the context of process piping?
ANSWER : Design temperature is the temperature at which the maximum
allowable stress value of a piping component is determined. It is the highest or
lowest temperature expected under operating conditions. The design temperature
governs the selection of materials, as elevated temperatures reduce allowable
stress values, while extremely low temperatures require materials with
appropriate impact toughness.
5. Explain the purpose of hydrostatic testing in process piping.
ANSWER : Hydrostatic testing verifies the pressure integrity and leak-tightness of a
completed piping system before commissioning. The system is filled with water and
pressurized to 1.5 times the design pressure, typically held for a minimum of 10
minutes. It reveals weld defects, faulty fittings, or inadequate mechanical joints that
may not be visible by other examination methods.
6. What is a pneumatic leak test and when is it used instead of a hydrostatic test?
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, Oklahoma (OK) Process Piping Journeyman Exam
ANSWER : A pneumatic leak test uses a compressible gas (air, nitrogen, or other
inert gas) instead of water to pressurize the piping. It is conducted at 1.1 times the
design pressure per ASME B31.3 and is used when the piping cannot be filled with
water due to structural limitations, process contamination concerns, or the risk of
water damage to the system. Because compressed gas stores energy and is
hazardous, pneumatic testing requires additional safety precautions.
7. What is the difference between a weld examination and a weld inspection?
ANSWER : Weld examination is performed by the piping manufacturer or
contractor and involves visual, radiographic, ultrasonic, magnetic particle, or liquid
penetrant methods to assess weld quality. Weld inspection is performed by an
authorized inspection authority independent of the fabricator, verifying that
examination results meet code requirements. Examination is a quality control
function, while inspection is a quality assurance oversight function.
8. What is a Schedule 40 pipe and how is wall thickness determined?
ANSWER : Schedule 40 is a standard pipe wall thickness designation used in the
ASME pipe schedule system. Wall thickness is determined based on the design
pressure, design temperature, allowable stress of the pipe material, and a quality
factor. The formula used is: t = PD/(2SE + 2YP), where P is design pressure, D is
outside diameter, S is allowable stress, E is weld quality factor, and Y is a
temperature-dependent coefficient.
9. What materials are commonly used in process piping?
ANSWER : Common materials used in process piping include carbon steel (ASTM
A106), stainless steel (ASTM A312), alloy steel, cast iron, ductile iron, copper,
aluminum, and thermoplastic materials such as PVC and CPVC for lower-pressure
applications. Material selection is based on fluid compatibility, operating
temperature and pressure, corrosion resistance requirements, and cost
considerations.
10. What is cathodic protection and why is it used in underground process piping?
ANSWER : Cathodic protection is an electrochemical technique used to prevent
corrosion of metallic piping buried underground or submerged in water. It works
by making the pipe the cathode of an electrochemical cell, either through the use of
sacrificial anodes (galvanic method) or impressed current systems. In Oklahoma,
underground process piping handling hydrocarbons or hazardous fluids typically
requires cathodic protection to comply with EPA and state environmental
regulations.
11. What is the purpose of pipe supports and what types are used in process piping?
ANSWER : Pipe supports carry the weight of the pipe, its contents, insulation, and
attached equipment, while controlling movement caused by thermal expansion,
vibration, or dynamic loads. Types used in process piping include rigid supports
(pipe hangers, clamps, cradles), variable spring hangers, constant effort supports,
guide supports that allow axial movement but restrict lateral movement, and
anchors that prevent movement in all directions.
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, Oklahoma (OK) Process Piping Journeyman Exam
12. What is thermal expansion and how is it addressed in process piping?
ANSWER : Thermal expansion is the increase in pipe length resulting from
temperature increases during operation. If not properly managed, it can cause
excessive stress, distortion, or failure of pipes and connected equipment. It is
addressed through the use of expansion loops, expansion joints (bellows-type or
slip-type), offsets in piping layouts, and flexible piping arrangements that allow
controlled movement without overstressing the system.
13. Define the term 'fluid service' as used in ASME B31.3.
ANSWER : Fluid service refers to the application of a piping system, classified by
the nature and properties of the fluid being conveyed. ASME B31.3 classifies fluid
services as Category D (non-flammable, non-toxic, not damaging to human tissue,
design pressure below 150 psi), Category M (highly toxic fluids), high-pressure
services, and normal fluid service, which covers all other applications. The
classification determines the required examination, testing, and design
requirements.
14. What is a butt weld joint and when is it preferred in process piping?
ANSWER : A butt weld joint is made by welding two pipe ends placed end-to-end
with their axes aligned. The joint requires beveling of the pipe ends before welding
to ensure full penetration. Butt welds are preferred in high-pressure, high-
temperature, or critical service applications because they provide full-strength,
smooth-bore connections with minimal flow restriction and are suitable for
radiographic examination.
15. What is a socket weld fitting and what are its limitations?
ANSWER : A socket weld fitting is a type of fitting into which the pipe end is
inserted before being fillet-welded around the outside of the socket. Socket welds
are used on smaller pipe sizes (typically 2 inches and below) where high-pressure
service is required but full radiographic examination may not be practical.
Limitations include a small crevice at the bottom of the socket that can trap fluid
and cause crevice corrosion, making them unsuitable for crevice-sensitive fluids or
high-purity services.
16. What is a flange and what are the common types used in process piping?
ANSWER : A flange is a projecting rim or collar at the end of a pipe or fitting used
to make a bolted connection with another flange. Common types used in process
piping include weld neck flanges (connected by butt weld, highest integrity), slip-on
flanges (slide over pipe and are fillet welded), blind flanges (used to close a pipe
end), threaded flanges, lap joint flanges, and socket weld flanges. Weld neck flanges
are preferred for high-pressure and high-temperature service.
17. What is ASME Class 150, 300, 600 as applied to flanges?
ANSWER : ASME flange pressure classes (150, 300, 600, 900, 1500, 2500) are
pressure-temperature rating designations for flanged fittings and flanges per ASME
B16.5. A higher class number indicates a higher pressure rating. For example, a
Class 150 flange in carbon steel at 100°F has a MAWP of approximately 285 psi,
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, Oklahoma (OK) Process Piping Journeyman Exam
while a Class 300 flange has a MAWP of approximately 740 psi under the same
conditions. The actual pressure-temperature rating depends on the material and
service temperature.
18. What is the purpose of a gasket in a flanged connection?
ANSWER : A gasket is a deformable material placed between two mating flange
faces to create a pressure-tight seal when the bolts are tightened. It accommodates
minor surface imperfections in the flange faces and provides a flexible sealing
element. Gasket materials are selected based on fluid compatibility, temperature,
and pressure. Common types include spiral wound, ring type joint (RTJ), full face,
and raised face gaskets.
19. Describe the correct procedure for tightening flange bolts.
ANSWER : Flange bolts must be tightened in a cross-pattern (diametrically
opposite bolt sequence) to ensure even loading of the gasket. The tightening is
done in multiple passes, incrementally increasing torque to the specified value. The
torque value is based on the bolt size, material, and gasket type. Proper lubrication
of bolt threads and nut faces is required to achieve accurate torque-to-tension
conversion. Final torque values should be verified using a calibrated torque
wrench.
20. What is a check valve and where is it used in process piping?
ANSWER : A check valve is a one-directional valve that allows fluid to flow in only
one direction and automatically prevents backflow when the flow reverses. It is
used to protect pumps, compressors, and other equipment from reverse flow
damage, to prevent siphoning, and to maintain pressure in portions of a system
during shutdowns. Common types include swing check, lift check, dual plate (wafer
check), and ball check valves.
21. What is a pressure relief valve and why is it required in process systems?
ANSWER : A pressure relief valve (PRV) is a safety device that automatically opens
to release fluid when system pressure exceeds the set point, protecting equipment
from overpressure damage or catastrophic failure. Under ASME and Oklahoma
regulations, pressure relief protection is required on pressure vessels, heat
exchangers, and piping systems that could be exposed to overpressure from
process upsets, blocked-in conditions, fire exposure, or thermal expansion of
trapped liquid.
22. What is the difference between a pressure relief valve and a safety valve?
ANSWER : A pressure relief valve (PRV) is designed primarily for liquid service and
opens proportionally as pressure increases above the set point. A safety valve is
designed for gas or steam service and pops open quickly to a fully open position
when the set pressure is reached. The term 'safety relief valve' applies to devices
suitable for both liquid and gas service. All three are code-required overpressure
protection devices, but they are selected based on the service fluid.
23. What is a globe valve and what are its typical applications?
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1. What is the primary code governing process piping systems in Oklahoma?
ANSWER : ASME B31.3, the Process Piping Code, is the primary code governing
process piping systems in Oklahoma. It establishes requirements for design,
materials, fabrication, assembly, examination, inspection, and testing of piping used
in petroleum refineries, chemical plants, pharmaceutical plants, textile plants,
paper plants, semiconductor plants, and other related industries.
2. Define 'process piping' as recognized under ASME B31.3.
ANSWER : Process piping refers to piping components used to convey fluids,
including raw, intermediate, or finished chemicals, petroleum products, gas, steam,
air, water, or other fluids in manufacturing, industrial, or institutional facilities. It
includes pipes, fittings, valves, and associated components designed to handle
process conditions, as distinct from building services or utility piping.
3. What does the term 'design pressure' mean in process piping?
ANSWER : Design pressure is the maximum internal or external pressure the
piping system is designed to withstand, including any surge allowances. It is used to
determine wall thickness and component pressure ratings. Per ASME B31.3, design
pressure must not exceed the maximum allowable working pressure (MAWP) of
the weakest component in the system.
4. What is 'design temperature' in the context of process piping?
ANSWER : Design temperature is the temperature at which the maximum
allowable stress value of a piping component is determined. It is the highest or
lowest temperature expected under operating conditions. The design temperature
governs the selection of materials, as elevated temperatures reduce allowable
stress values, while extremely low temperatures require materials with
appropriate impact toughness.
5. Explain the purpose of hydrostatic testing in process piping.
ANSWER : Hydrostatic testing verifies the pressure integrity and leak-tightness of a
completed piping system before commissioning. The system is filled with water and
pressurized to 1.5 times the design pressure, typically held for a minimum of 10
minutes. It reveals weld defects, faulty fittings, or inadequate mechanical joints that
may not be visible by other examination methods.
6. What is a pneumatic leak test and when is it used instead of a hydrostatic test?
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, Oklahoma (OK) Process Piping Journeyman Exam
ANSWER : A pneumatic leak test uses a compressible gas (air, nitrogen, or other
inert gas) instead of water to pressurize the piping. It is conducted at 1.1 times the
design pressure per ASME B31.3 and is used when the piping cannot be filled with
water due to structural limitations, process contamination concerns, or the risk of
water damage to the system. Because compressed gas stores energy and is
hazardous, pneumatic testing requires additional safety precautions.
7. What is the difference between a weld examination and a weld inspection?
ANSWER : Weld examination is performed by the piping manufacturer or
contractor and involves visual, radiographic, ultrasonic, magnetic particle, or liquid
penetrant methods to assess weld quality. Weld inspection is performed by an
authorized inspection authority independent of the fabricator, verifying that
examination results meet code requirements. Examination is a quality control
function, while inspection is a quality assurance oversight function.
8. What is a Schedule 40 pipe and how is wall thickness determined?
ANSWER : Schedule 40 is a standard pipe wall thickness designation used in the
ASME pipe schedule system. Wall thickness is determined based on the design
pressure, design temperature, allowable stress of the pipe material, and a quality
factor. The formula used is: t = PD/(2SE + 2YP), where P is design pressure, D is
outside diameter, S is allowable stress, E is weld quality factor, and Y is a
temperature-dependent coefficient.
9. What materials are commonly used in process piping?
ANSWER : Common materials used in process piping include carbon steel (ASTM
A106), stainless steel (ASTM A312), alloy steel, cast iron, ductile iron, copper,
aluminum, and thermoplastic materials such as PVC and CPVC for lower-pressure
applications. Material selection is based on fluid compatibility, operating
temperature and pressure, corrosion resistance requirements, and cost
considerations.
10. What is cathodic protection and why is it used in underground process piping?
ANSWER : Cathodic protection is an electrochemical technique used to prevent
corrosion of metallic piping buried underground or submerged in water. It works
by making the pipe the cathode of an electrochemical cell, either through the use of
sacrificial anodes (galvanic method) or impressed current systems. In Oklahoma,
underground process piping handling hydrocarbons or hazardous fluids typically
requires cathodic protection to comply with EPA and state environmental
regulations.
11. What is the purpose of pipe supports and what types are used in process piping?
ANSWER : Pipe supports carry the weight of the pipe, its contents, insulation, and
attached equipment, while controlling movement caused by thermal expansion,
vibration, or dynamic loads. Types used in process piping include rigid supports
(pipe hangers, clamps, cradles), variable spring hangers, constant effort supports,
guide supports that allow axial movement but restrict lateral movement, and
anchors that prevent movement in all directions.
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, Oklahoma (OK) Process Piping Journeyman Exam
12. What is thermal expansion and how is it addressed in process piping?
ANSWER : Thermal expansion is the increase in pipe length resulting from
temperature increases during operation. If not properly managed, it can cause
excessive stress, distortion, or failure of pipes and connected equipment. It is
addressed through the use of expansion loops, expansion joints (bellows-type or
slip-type), offsets in piping layouts, and flexible piping arrangements that allow
controlled movement without overstressing the system.
13. Define the term 'fluid service' as used in ASME B31.3.
ANSWER : Fluid service refers to the application of a piping system, classified by
the nature and properties of the fluid being conveyed. ASME B31.3 classifies fluid
services as Category D (non-flammable, non-toxic, not damaging to human tissue,
design pressure below 150 psi), Category M (highly toxic fluids), high-pressure
services, and normal fluid service, which covers all other applications. The
classification determines the required examination, testing, and design
requirements.
14. What is a butt weld joint and when is it preferred in process piping?
ANSWER : A butt weld joint is made by welding two pipe ends placed end-to-end
with their axes aligned. The joint requires beveling of the pipe ends before welding
to ensure full penetration. Butt welds are preferred in high-pressure, high-
temperature, or critical service applications because they provide full-strength,
smooth-bore connections with minimal flow restriction and are suitable for
radiographic examination.
15. What is a socket weld fitting and what are its limitations?
ANSWER : A socket weld fitting is a type of fitting into which the pipe end is
inserted before being fillet-welded around the outside of the socket. Socket welds
are used on smaller pipe sizes (typically 2 inches and below) where high-pressure
service is required but full radiographic examination may not be practical.
Limitations include a small crevice at the bottom of the socket that can trap fluid
and cause crevice corrosion, making them unsuitable for crevice-sensitive fluids or
high-purity services.
16. What is a flange and what are the common types used in process piping?
ANSWER : A flange is a projecting rim or collar at the end of a pipe or fitting used
to make a bolted connection with another flange. Common types used in process
piping include weld neck flanges (connected by butt weld, highest integrity), slip-on
flanges (slide over pipe and are fillet welded), blind flanges (used to close a pipe
end), threaded flanges, lap joint flanges, and socket weld flanges. Weld neck flanges
are preferred for high-pressure and high-temperature service.
17. What is ASME Class 150, 300, 600 as applied to flanges?
ANSWER : ASME flange pressure classes (150, 300, 600, 900, 1500, 2500) are
pressure-temperature rating designations for flanged fittings and flanges per ASME
B16.5. A higher class number indicates a higher pressure rating. For example, a
Class 150 flange in carbon steel at 100°F has a MAWP of approximately 285 psi,
Page 3 of 43
, Oklahoma (OK) Process Piping Journeyman Exam
while a Class 300 flange has a MAWP of approximately 740 psi under the same
conditions. The actual pressure-temperature rating depends on the material and
service temperature.
18. What is the purpose of a gasket in a flanged connection?
ANSWER : A gasket is a deformable material placed between two mating flange
faces to create a pressure-tight seal when the bolts are tightened. It accommodates
minor surface imperfections in the flange faces and provides a flexible sealing
element. Gasket materials are selected based on fluid compatibility, temperature,
and pressure. Common types include spiral wound, ring type joint (RTJ), full face,
and raised face gaskets.
19. Describe the correct procedure for tightening flange bolts.
ANSWER : Flange bolts must be tightened in a cross-pattern (diametrically
opposite bolt sequence) to ensure even loading of the gasket. The tightening is
done in multiple passes, incrementally increasing torque to the specified value. The
torque value is based on the bolt size, material, and gasket type. Proper lubrication
of bolt threads and nut faces is required to achieve accurate torque-to-tension
conversion. Final torque values should be verified using a calibrated torque
wrench.
20. What is a check valve and where is it used in process piping?
ANSWER : A check valve is a one-directional valve that allows fluid to flow in only
one direction and automatically prevents backflow when the flow reverses. It is
used to protect pumps, compressors, and other equipment from reverse flow
damage, to prevent siphoning, and to maintain pressure in portions of a system
during shutdowns. Common types include swing check, lift check, dual plate (wafer
check), and ball check valves.
21. What is a pressure relief valve and why is it required in process systems?
ANSWER : A pressure relief valve (PRV) is a safety device that automatically opens
to release fluid when system pressure exceeds the set point, protecting equipment
from overpressure damage or catastrophic failure. Under ASME and Oklahoma
regulations, pressure relief protection is required on pressure vessels, heat
exchangers, and piping systems that could be exposed to overpressure from
process upsets, blocked-in conditions, fire exposure, or thermal expansion of
trapped liquid.
22. What is the difference between a pressure relief valve and a safety valve?
ANSWER : A pressure relief valve (PRV) is designed primarily for liquid service and
opens proportionally as pressure increases above the set point. A safety valve is
designed for gas or steam service and pops open quickly to a fully open position
when the set pressure is reached. The term 'safety relief valve' applies to devices
suitable for both liquid and gas service. All three are code-required overpressure
protection devices, but they are selected based on the service fluid.
23. What is a globe valve and what are its typical applications?
Page 4 of 43
