API RP 576 5 Causes of Improper
Performance Exam Questions and
Answers (Latest Update 2026)
5.1 Corrosion -
correct answer ✅5.1.1 General
Corrosion is a basic cause of many of the difficulties encountered
with pressure-relief devices. An understanding of the
process/operating conditions need to include and resulting damage
mechanisms are required in order to establish and maintain an
inspection program of relief valves that yields the highest
probability of preventing their damage. Changes in
process/operating conditions need to include an evaluation of the
corrosion potential of the relief valve. There are several other
sources of industry data that specifically identify typical
degradation mechanisms for various operating units. Specifically
applicable to the refining and petrochemical industry is API 571
covering damage mechanisms.
Corrosion often appears as pitted or broken valve parts, deposits of
corrosive residue that interfere with the operation of the moving
parts, or a general deterioration of the material of the relieving
device.
,API RP 576 5 Causes of Improper
Performance Exam Questions and
Answers (Latest Update 2026)
Valve malfunction may also be due to sticking of the disc to the
nozzle or other disc holder in the guide. This sticking may be caused
by corrosion or galling of the metal or by foreign particles in the
guiding surfaces. Foreign particles in the guiding surfaces tend to
roll metal up, causing severe galling. The use of a bellows can keep
the foreign particles away from the guiding surfaces. Sticking of
valves illustrates a disc holder that is frozen in the guide as a result
of corrosion, e.g. in sour gas services.
Corrosion may be slowed or mitigated by the selection of more
suitable devices or device materials. Proper maintenance is also a
consideration since a leaking valve allows fluids to circulate in the
upper parts of the valve, which can contribute to the corrosion of
its movable parts. Protective coatings may offer protections against
corrosion in some services.
Bellows can protect moving p
5.1.2 Examples of Preventative Actions for Corrosion -
correct answer ✅A rupture disk device installed on the inlet
and/or outlet of a pressure-relief valve can provide added corrosion
protection of the valve internals.
, API RP 576 5 Causes of Improper
Performance Exam Questions and
Answers (Latest Update 2026)
In many instances, valves with differing materials of construction
can impede or altogether mitigate the effects of corrosion. The use
of an O-ring or resilient seat in a pressure-relief valve may stop
leakage past the seating surface and eliminate corrosion in the
valve's working parts. However, O-ring elastometers may have a
limited life under stress due to degradation caused by temperature,
corrosive species, aging, or swelling. Bellows seal can be used to
protect the spring and the bonnet cavity of the valve from the
corrosive loading fluid.
5.2 Damaged Seating Surfaces -
correct answer ✅Imperfections in seating surfaces may contribute
to improper valve action in service. To prevent leakage of the
loading fluid, an optical precision on the order of three light
beads/bands according to manufacturer's specifications should be
maintained in the flatness of seating surfaces on metal-seated
pressure-relief valves (see API 527).
There are many causes of damaged valve seats in refinery or
chemical plant service, including the following.
a) Corrosion.
Performance Exam Questions and
Answers (Latest Update 2026)
5.1 Corrosion -
correct answer ✅5.1.1 General
Corrosion is a basic cause of many of the difficulties encountered
with pressure-relief devices. An understanding of the
process/operating conditions need to include and resulting damage
mechanisms are required in order to establish and maintain an
inspection program of relief valves that yields the highest
probability of preventing their damage. Changes in
process/operating conditions need to include an evaluation of the
corrosion potential of the relief valve. There are several other
sources of industry data that specifically identify typical
degradation mechanisms for various operating units. Specifically
applicable to the refining and petrochemical industry is API 571
covering damage mechanisms.
Corrosion often appears as pitted or broken valve parts, deposits of
corrosive residue that interfere with the operation of the moving
parts, or a general deterioration of the material of the relieving
device.
,API RP 576 5 Causes of Improper
Performance Exam Questions and
Answers (Latest Update 2026)
Valve malfunction may also be due to sticking of the disc to the
nozzle or other disc holder in the guide. This sticking may be caused
by corrosion or galling of the metal or by foreign particles in the
guiding surfaces. Foreign particles in the guiding surfaces tend to
roll metal up, causing severe galling. The use of a bellows can keep
the foreign particles away from the guiding surfaces. Sticking of
valves illustrates a disc holder that is frozen in the guide as a result
of corrosion, e.g. in sour gas services.
Corrosion may be slowed or mitigated by the selection of more
suitable devices or device materials. Proper maintenance is also a
consideration since a leaking valve allows fluids to circulate in the
upper parts of the valve, which can contribute to the corrosion of
its movable parts. Protective coatings may offer protections against
corrosion in some services.
Bellows can protect moving p
5.1.2 Examples of Preventative Actions for Corrosion -
correct answer ✅A rupture disk device installed on the inlet
and/or outlet of a pressure-relief valve can provide added corrosion
protection of the valve internals.
, API RP 576 5 Causes of Improper
Performance Exam Questions and
Answers (Latest Update 2026)
In many instances, valves with differing materials of construction
can impede or altogether mitigate the effects of corrosion. The use
of an O-ring or resilient seat in a pressure-relief valve may stop
leakage past the seating surface and eliminate corrosion in the
valve's working parts. However, O-ring elastometers may have a
limited life under stress due to degradation caused by temperature,
corrosive species, aging, or swelling. Bellows seal can be used to
protect the spring and the bonnet cavity of the valve from the
corrosive loading fluid.
5.2 Damaged Seating Surfaces -
correct answer ✅Imperfections in seating surfaces may contribute
to improper valve action in service. To prevent leakage of the
loading fluid, an optical precision on the order of three light
beads/bands according to manufacturer's specifications should be
maintained in the flatness of seating surfaces on metal-seated
pressure-relief valves (see API 527).
There are many causes of damaged valve seats in refinery or
chemical plant service, including the following.
a) Corrosion.
