API 510 QUESTIONS & ANSWERS

(CLOSED 1)
Instructions:
Choose only one answer, which you think is most appropriate.
Use the attached answer sheet in answering the following questions.

1.

Post weld heat treatment of vessel welds generally results in:

a.
b.
c.
d.

2.

A pressure vessel fabricated in 1960 was in service. It has been

decided to remove the top head and extend the height and
replace the dish head with a new one. The proposal is:
a.
b.
c.
d.

3.

The proposal can be accepted for review by

authorised inspector
No modification is allowed on this vessel
A pressure vessel engineer
should be
consulted for approval
None of the above

Vessels that are known to have a remaining life of over

__________ years or that are protected against external
corrosion need not have insulation removed for the periodic
external inspection.
a.
b.
c.
d.

4.

Reduction in hardness
Increase of tensile strength
Increase of both strength and ductility
None of the above

10
15
5
20

After an inspection interval is completed and if calculations

indicate that an inaccurate rate of corrosion has been assumed
initially, how do you determine the corrosion rate for the next
inspection period?
a.
b.
c.
d.

eck the original calculations to find out what the

error is in the original assumption.
Unless the corrosion rate is changed by Jurisdiction, the
initial rates shall be used.
The corrosion rate shall be adjusted to agree with the
actual rate found.
Call in a corrosion specialist

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
5.

If a vessel is made up of unknown materials and

computations must be made to determine the MAWP what
can the inspector or the vessel engineer do to establish the
MAWP?
a.

6.

b.

Assume MOC as SA 283 Gr. C and joint efficiency = 0.7

c.

The vessel made of the unknown material must be

removed from service and vessel of known material must be
installed.

d.

The vessel of unknown material shall be subjected to

hydrostatic tests while having strain gages on it to determine
its yield strength and thus allowable stress.

RBI assessment can be used to alter the inspection

strategy provided:
a.
b.
c.
d.

7.

c.
d.

Cooler dry locations.

Very cold locations with year round temperature less
than 25F
Warmer, wet locations
Warmer dry locations

Soil-to-air (S/A) interfaces for partially buried vessels are a

location where localized corrosion may take place. If the buried
part is excavated for inspection, how deep should the excavation
be to determine if there is hidden damage?
a.
b.
c.
d.

9.

The degradation methods are identified and evaluated

The RBI is fully documented.
A third party conducts the RBI
Both A and B above

What climatic area may require a very active program for

corrosion under insulation?
a.
b.

8.

The lowest grade material and highest joint efficiency in

the applicable code may be assumed for calculations.

12 to 18 inches
6 to 12 inches
12 to 24 inches
6 to 18 inches

2 Common way to minimize temper embrittlement is to limit

a.

J factor for weld metal.

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
b.
c.
d.
10.

The minimum hydro test temperature for in-service vessel of 2

thickness is:
a.
b.
c.
d.

11.

1
2
3
All 4

What type of repairs and procedures may the inspector give

prior general authorisation to continue (provided the inspector is
satisfied with the competency of the repair organization)?
a.
b.
c.
d.

14.

Fatigue cracks.
Creep cracks.
Stress corrosion cracks.
Hydrogen induced cracks.

Minimum Design thickness for a vessel shell is 10 mm. Following

four plates were received with actual thickness equal to: 10.2
mm, 9.7mm, 10.3mm, and 9.6 mm. As per ASME Sec. VIII
Div.1, how many plates will you release for vessel fabrication?
a.
b.
c.
d.

13.

MDMT+10F
MDMT+30F
MDMT+ 0C
MDMT+ 0C

Clam shell type crack failure having concentric rings called

beach marks showing waves of crack propagation is typically
the description of
a.
b.
c.
d.

12.

X factor for base metal.

J factor for base & X factor for weld metal.
X factor for base & J factor for weld metal

Major repairs and minor procedures

Limited or routine repairs
Major alterations and re-ratings
Minor re-ratings and alterations

A vessel in service has different zones of corrosion. The next

inspection frequency will be decided by:
a.
b.

Zone with highest rate of corrosion

Zone with lowest remaining life

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
c.
d.
15.

Resistance to sulphidation is generally achieved by

a.
b.
c.
d.

16.

b.
c.
d.

Oxygen
Water (i.e., Wet H2S)
Sulphur
a and c above

The leak tightness of the relief valves is tested on the test block
at a pressure equal to:
a.
b.
c.
d.

20.

Hydrogen blistering near liquid level

Hydrogen blistering on top dished head
Hydrogen blistering near the bottom of vessel
None of above

H2S is in sour crude is more harmful in presence of:

a.
b.
c.
d.

19.

Transgranular, branching and aggravated by increasing

temperature
Intergranular and unidirectional (straight) and aggravated
al low temperature
Independent of chloride content
None of the above

In planning for an internal inspection of a vertical vessel that has

acidic corrodents, what type of corrosion would you expect to
find on the vessel shell from inside?
a.
b.
c.
d.

18.

Upgrading to higher nickel alloys

Upgrading to higher chromium alloys
Upgrading to higher copper based alloys
All of the above.

Characteristic SCC in Austenitic S.S. generally will be

a.

17.

Average rate of corrosion shall be taken into consideration

Average remaining life of the vessel shall be considered

Same as set pressure

90% of the set pressure
Same as reseat pressure
None of the above

The principal reason for inspecting a pressure relief device is to

determine:

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
a.
b.
c.
d.
21.

Which of the following tests must be conducted on a valve as

soon as it has been received in the shop for inspection?
a.
b.
c.
d.

22.

d.

Valve testing on test benches in shop

Application of rupture discs
Training requirements for mechanics involved in
inspection and repair of pressure relieving devices
All of the above

For vessels which are supported on concrete saddles and working

in an area where the humidity is high which areas on them are
typically susceptible to external corrosion?
a.
b.
c.
d.

24.

Visual inspection
Hydrotesting of valve body
Radiographic testing
Check set-pressure

API 576 does not address:

a.
b.
c.

23.

Condition of pressure relief device and if it is functioning

properly
The remaining life of pressure relief device.
The spring coil diameter.
The body thickness.

At the anchor bolts in the foundation

At the Points of contact of the metal surface with the
concrete
All of the above
None of the above

Inspection records contain the following information for a TML

on a dished head. (Thk. in inches) On the basis of this
information, the long-term corrosion rate for the location is:
Thickness
0.500
0.425
0.400
a.
b.
c.
d.

Year
0
5
10

1 mils per year

5 mils per year
10 mils per year
100 mils per year

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
25.

A certain C. S. vessel which required impact testing was required

to have PWHT initially according to code requirement. After 10
years when repaired by welding PWHT is to be carried out.
Performing PWHT is found to be impracticable. Which of the
following is relevant (as per API-510)?
a.
b.
c.
d.

26.

PWHT may be exempted, if proper NDE is carried out.

Carry out temper-bead welding as alternative to PWHT.
Carry out both hydro-testing and pneumatic testing in
lieu of the PWHT.
Carry out preheating to minimum 200F

A cylindrical shell with thickness = 4.0, ID=96, S=17100 and

E=0.85 and C. A. = 1/8 showed metal loss of 1/4 within the
areas lying 8 on either side of the longitudinal welds. You
analysis of situation is:
a. Recalculate shell thickness tminimum considering E=1.0
b. The thinned area is on or within weld area hence (a) above
can not be adopted
c. Prepare repair procedure and restore the metal loss as per
API -510
d.
b and c above

27.

Materials used for making repair by welding in carbon steel

vessels shall have the following limitations?
a.
b.
c.
d.

28.

They shall meet the requirements stipulated in NACE

Standard.
The carbon content shall not be over 0.35%
Welding repair shall be done by using only the GTAW
process
All of the above

For non-continuous corrosive service with remaining life 25

years, external inspection shall be performed not later than:
a.
b.
c.
d.

10 years
12.5 years
5 years
None of above

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
29.

An ellipsoidal head has an internal diameter of 76 inches and

depth of 21 inches (including a straight face dimension of 2
inches). What should its spherical (crown) radius be?
a.
b.
c.
d.

30.

For carrying out temper bead welding technique in lieu of

PWHT, apart from other requirements, which of the following is
acceptable?
a.
b.

c.
d.
31.

76.9 inches
15.6 inches
68.4 inches
All of the above

The root and final pass of weld shall be radiographed.

Weld metal shall be deposited for second pass while the
first pass below the second pass is still not cooled down
and its cooling rate is retarded due to the heat of second
pass.
After depositing each layers of the weld, the weld
shall be PT checked.
Both b and c

Calculate the remaining life and external insp. interval of a

vessel given the following data:
Actual thickness
= 0.955 inch
Minimum thickness required = 0.759 inch
Thickness at previous inspection 5 years prior to present
inspection
= 1.025 inch
a.
b.
c.
d.

32.

20 years, 10 years
14 years, 5years
28 years, 10 years
None of the above

As per API 510, the organization who carry out PRV repair,
testing has to be:
a.
b.
c.
d.

Needs to be a certified company to perform all repair work

in accordance to ASME.
Needs to have have documented quality control procedure
Needs to have qualified personnel to carry out the job
within scope of repair
Only b and c above

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
33.

A vessel which was inspected six years ago and had shell
thickness = 0.870. As on today the thickness as reported by
filed inspection is 0.786. What was the corrosion rate over last
six years?
a.
b.
c.
d.

34.

If the vessel in above question has minimum permissible

thickness = 0.618 for the present design conditions. What will
be estimated remaining life of the vessel if corrosion rate
remains same?
a.
b.
c.
d.

35.

11 Years, 5 Years
10 Years, 5 Years
5 Years, 5 Years
None of the above

What is the maximum defect permitted on the convex surface of

a welder qualification bend test after bending?
a.
b.
c.
d.

37.

10 years
12 years
14 years
None of above

For a vessel, remaining life is estimated as 22 years from now,

next planned internal and external inspection shall not be later
than:
a.
b.
c.
d.

36.

10 mpy
12 mpy
14 mpy
none of above

inch
1/8 inch
1/16 inch
3/16 inch

Certification of contaminants shall be obtained for all PT

materials used on:
a.
b.
c.
d.

Carbon steels
Ferritic stainless steels
Austenitic stainless steels
None of the above

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
38.

The scope of the ASME Boiler and Pressure Vessel, Code, Section
V includes:
a.
b.
c.
d.

39.

For Ammeter calibration

allowable tolerance is:
a.
b.
c.
d.

40.

NDE acceptance criteria

How to perform NDE to achieve a desired result
Where to do NDE (i.e. what welds to examine)
All of above.
for

magnetizing

equipment,

the

+5%
+10%
+15%
+20%

Which of the following are commonly preferred to know the

process side degradation of pressure vessels?
a.
b.
b.
c.

On stream inspection.
Internal inspection
External inspection as alternative to internal inspection
Any of above is OK

41. For MT examination by Prod technique the magnetizing current

required depends on:
a.
b.
c.
d.
42.

Prod Spacing
Thickness of item under Inspection
a & b above
None of above

While deciding the governing thickness for crown portion for

corroded 2:1 ellipsoidal head, API 510 stipulates that & crown
thickness shall be calculated:
a.
b.
c.
d.

According to relevant ellipsoidal dished head

formula
According to code formula for spherical heads with head
radius equal to 0.9 D, where D is shell dia meter.
Thickness of crown shall be same as knuckle thickness.
None of the above

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
43.

For a vertical column, Int. dia. = 48'' and height (T-T) = 80ft,
The vessel MAWP is 60 psi. Minimum vessel part MAWP for
bottom dished head (2:1 Ellip type) shall be:
a.
b.
c.
d.

44.

How is hammer testing utilized?

a.
b.
c.
d.

45.

As a preliminary survey for thinned areas

As a independent test method for which ASNT Certification
in NDT is available
As a important tool in the hands of the Authorized
inspection only
To carry out Carpy impact test

Which of the following represent grouping of weld-metals

in ASME IX?
a.
b.
c.
d.

46.

94.6 psi
82.8 psi
95.5 psi
None of above

P Nos.
F Nos.
S Nos.
A Nos.

Which is/are advantage of magnetic particle testing over

penetrant testing?
a. It can detect surface discontinuities with foreign material
imbedded in them.
b. It is faster on individual parts.
c. It can detect near-surface discontinuities.
d. All of the above

47.

Double wall Double image technique is used for the radiography

of:
a.
b.
c.
d.

Plate welds
Tubular products with outer diameter less than 3.5 inch
Large pipes with outer diameter 200 mm and
above
Heavy castings

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
48.

As per ASME Sec. VIII Div. 1, if permanent deformation is

observed due to over pressure during hydrotesting:
a.
b.
c.
d.

49.

The size of a properly deposited equal fillet weld is shown as 10

mm. The throat dimension for this weld will be approximately:
a.
b.
c.
d.

50.

b.
c.
d.

Conduct RT after 48 hours of observing the defective

condition
Nozzles and adjacent shell areas should be inspected
for distortion and cracking
Use acoustic emission monitoring
All of the above

Identify the correct statement (s)

a.
b.
c.
d.

52.

10 mm
8 mm
7 mm
9 mm

If any setting is noticed on a vessel, which of the following

should be done:
a.

51.

The inspector should ask for re-test using proper test

pressure and new pressure gauges.
Follow-up the hydro-testing by a pneumatic test at proper
pressure, taking suitable precautions as given in code
The inspector may ask for providing additional stiffening
rings around vessel and carry out re-hydro test at proper
test pressure.
The inspector may reject the vessel.

SSC is aggravated due to wet H2S

Hydrogen blistering may occur on I.D, O.D, or any where
within wall thickness of the pressure vessel.
High hardness & High strength steels are more likely to
undergo damage due to SCC compared to low strength/
low hardness steels
All of the above are correct statements

Cracks and laminations look similar from surface however,

generally:
a. Cracks run normal to vessels surfaces
b. Lamination runs slant or parallel to surface
c. a and b above

API 510 QUESTIONS & ANSWERS

(CLOSED 1)
d. None of above
53.
typically
a.
b.
c.
d.
54.

High temperature hydrogen attack

due to
Methane gas formation
Wet H2S formation
Temper embrittlement
Presence of molybdenum in alloy steels.

The nonmetallic coating disbonding in a vessel can be

better detected by:
a.
b.
c.
d.

55.

Eddy current testing

Holiday detection
Ultrasonic testing
Acoustic emission testing
External inspection of a pressure vessel starts with:

a.
b.
c.
d.
56.

is

Ladder, stairs, walkway and platforms of the vessel

Insulation, skirt and foundation
The external surfaces, of vessel
Dimensional check of the vessel

Before carrying out an inter service inspection on a

vessel put in-service for quite some time what the inspector
should do first?
a.
b.

Check the material in which it is constructed.

Check the permanent file of the
vessel.

c.
d.

Check the progressive history file of the vessel.

Check the original thickness
report.