API576

Question 1

The use of an O-ring or resilient seat in a pressure-relief valve may stop

Answer 1

lakage past the seating surface and eliminate corrosion in the valve’s working parts.

Question 2

Bellows seal can be used to protect the spring and the bonnet cavity of the valve from the

Answer 2

corrosive loading fluid.

Question 3

O-ring elastomers may have a limited life under stress

Answer 3

due to degradation caused by temperature, corrosive species, aging, or swelling.

Question 4

springs may weaken and fail due to the use of improper materials in high-temperature service, failed
springs are almost always caused by

Answer 4

corrosion. Surface corrosion and stress corrosion cracking are the most prevalent of this type of failure in refineries.

Question 5

Hydrogen sulfide (H2S) frequently causes

Answer 5

SCC of springs

Question 6

Valve testing - Special attention is needed if the relief

valve is placed in

Answer 6

superheated steam service to compensate for temperature.

Question 7

To ensure that the valve is opening, some overpressure should be carefully applied because an

Answer 7

audible leak could otherwise be misinterpreted as the result of reaching the set pressure.

Question 8

Incorrect calibration of pressure gauges is a frequent cause of

Answer 8

improper valve setting.

Question 9

gauges should be calibrated frequently on a calibrated

Answer 9

dead weight tester.

Question 10

Snubbers on pressure gauges are not generally recommended since they tend to

Answer 10

clog and produce pressure lag.

Question 11

Many direct-acting spring-loaded pressure-relief valves have one or more internal rings that can be adjusted. The pressure-relief valve adjusting ring or rings will control the

Answer 11

1. valve blowdown—the difference between the

set pressure and the reseating pressure—and valve simmer, depending on the design of the valve being tested.

Question 12

To functionally test the pressure-relief valve and measure the blowdown

Answer 12

, similar media properties of the service fluid and adequate flow capacities to fully cycle the valve are needed.

Question 13

All valve parts, particularly guiding surfaces and bellows, should be checked thoroughly

Answer 13

for any type of fouling.

Question 14

galling

Answer 14

A condition whereby excessive friction between high spots results in localized welding with subsequent splitting and a further roughening of rubbing surfaces of one or both of two mating parts

Question 15

galling happens (3)

Answer 15

1. corrosion or foreign particles,
2. valve chatter or flutter caused by improper piping at the valve inlet or outlet or by severe oversizing of the valve.
3. system operates too close to the set pressure resulting in frequent relieving.

Question 16

Improper handling can occur during

Answer 16

shipment, maintenance, or installation.

Question 17

Lifting lever wiring is only used for

Answer 17

transport and needs to be removed before installation

Question 18

in making this determination,

four types of inspections can be used.

Answer 18

They are “shop as-received pop test,”
“shop inspection/overhauls,”
“field internal inlet and outlet piping inspections,” and “visual on-stream inspections.

Question 19

Only an _________ should isolate a relief device by closing any adjacent block valves upstream or downstream

Answer 19

authorized person

Question 20

Block valves used with relief devices should be verified to have sufficient flow area (e.g. full port) to prevent

Answer 20

low restriction and excessive pressure drop.

Question 21

Some precautions to follow when inspecting valves exposed to hazardous materials include the following. (2)

Answer 21

1. a) Evaluate the potential for the valve to contain pyrophoric [e.g. iron sulfide (FeS)] or reactive materials, and determine the appropriate precautions for the material involve
   2.Valves in acid or caustic service should be handled very carefully adhering to rigorous handling procedures prior to pre-pop testing of the “as-removed” pressure-relief valve. After pre-popping,
   pressure-relief valves should be immediately neutralized.

Question 22

where block valves are closed to enable removal of relief devices from equipment during operation, it is usually impossible to directly inspect this piping. In potential fouling services, __________ should be considered for piping upstream or downstream of pressure-relief valves looking for locations where potential fouling deposits may collect that could restrict flow or cause corrosion under deposits.

Answer 22

profile radiography

Question 23

Pressure-relief valves that do not pop at inlet pressures of 150 % of CDTP should be considered as

Answer 23

stuck shut,

Question 24

If the valve initially opens at the cold differential test pressure (CDTP),

Answer 24

no further testing to determine the “as-received” pop pressure is needed.

Question 25

If the initial pop is at a pressure higher than the CDTP, the valve should be

Answer 25

tested a second time.

Question 26

If the initial pop is at a pressure lower than the CDTP, the spring may have become weakened, the valve may (3)

Answer 26

1. have been set improperly at its last testing,
2. the seat may have been damaged
3. or the setting changed during operation.

Question 27

It is the first test that is recorded as the “as-received” pop pressure. This “as-received” pop pressure is used in determining

Answer 27

the inspection interval.

Question 28

The ___________ should define the criteria that constitute an “as-received” pop test failure

Answer 28

owner-user

Question 29

as-received pop testing should be conducted ____ to cleaning in order to yield accurate
as-received pop testing results

Answer 29

prior

Question 30

the results of the “as-received” test show that the valve tests properly, then disassembly of the
valve for further inspection ___(is or is not required)_____ unless restoration of the valve to the “as new” condition is
required

Answer 30

may not be required,

Question 31

After the valve has been adjusted/cleaned, it should be actuated at least once to prove the accuracy of the setting. Some manufacturers recommend a valve be actuated (popped) ______

Answer 31

at least three times,

Question 32

ASME BPVC Section VIII valves, the deviation of the as-found set pressure from the nameplate set
pressure should not exceed ___for pressures less than or equal to 70 psi (500 kPa) or _____for
pressures greater than 70 psi (500 kPa)

Answer 32

±2 psi (±15 kPa) / ±3 %

Question 33

ASME BPVC Section VIII, Division 1, deviation shall not be less than ____ or greater than______

Answer 33

0 % / +10 %.

Question 34

Once the valve is set to pop at its CDTP, it should be checked for

Answer 34

leakage.

Question 35

it can be tested for seat tightness by increasing the pressure on the valve up to the manufacturer’s specified simmer pressure
(oftentimes this is 90 % of the CDTP) and observing the discharge side of the valve for evidence of leakage.

Question 36

a relief valve that does not pop at _____ of the set

pressure is considered a failure to open.

Answer 36

130 %

Question 37

accumulation

Answer 37

The pressure increase over the maximum allowable working pressure (MAWP) of the vessel or piping system,

Question 38

backpressure

Answer 38

The pressure that exists at the outlet of a pressure-relief device as a result of the pressure in the discharge system. Backpressure is the sum of the superimposed and built-up backpressures.

Question 39

blowdown

Answer 39

The difference between the set pressure and the closing pressure of a pressure-relief valve,

Question 40

cold differential test pressure

CDTP

Answer 40

The pressure at which a pressure-relief valve is adjusted to open on the test stand. The cold differential test pressure includes corrections for the service conditions of superimposed backpressure or temperature or both.

Question 41

simmer

Answer 41

The audible or visible escape of compressible fluid between the seat and disc,

Question 42

as-received pop testing results that will help establish the appropriate .

Answer 42

inspection and servicing interval

Question 43

if fouling is noticed when RV is removed , what should be done?

Answer 43

reduce inspection cycle

Question 44

oversizing the valve can?

Answer 44

open/close valve repeatedly

Question 45

To prevent leakage of the loading fluid, an optical precision on the order of ____________
specifications should be maintained in the flatness of seating surfaces on metal-seated pressure-relief valves

Answer 45

three light beads