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IET/CH/TP/002-R2, Sept. 11

1BAPI 510- PRESSURE VESSEL INSPECTOR COURSE

2BVOLUME-1

3BCONTENTS PROGRAM SCHEDULE

PART I - CERTIFICATION INFORMATION FROM API.

8BPART II - GUIDELINES FOR CLEARING API 510 EXAMINATION

9BPART III - CODE WISE PUNCH POINTS

PART IV- CASE STUDIES,

PART V - WPS/PQR ROAD-MAP AND REVIEW

PART VI - ADDITIONAL INFORMATION

PART VII - DAILY EXAM & POINTS TO RECALL

PART VIII - QUESTION BANK: QUESTIONS ON API 510 CODES

PART IX - QUESTION BANK: QUESTIONS ON ASME CODES

PART X - QUESTION BANK: QUESTIONS ON RECOMMENDED

PRACTICES

IET/CH/TP/002-R2, Sept. 11

4BAPI 510- INSERVICE PRESSURE VESSEL INSPECTOR

5B PREPARATORY COURSE

PART I

CERTIFICATION INFORMATION

FROM API.

API 510- INSERVICE PRESSURE VESSEL INSPECTOR

PREPARATORY COURSE

PART II

GUIDELINES FOR

CLEARING API 510

CERTIFICATION

EXAMINATION SUCCESSFULLY

1 IET/CH/TP/002-R02, Sept.11

API 510 CERTIFICATION FOR IN-SERVICE INSPECTION

GUIDELINES FOR CLEARING API 510 EXAMINATION

SUCCESSFULLY

INTRODUCTION

Pressure Vessels are a major installation in Petroleum Refineries,

Petrochemical plants, Oil terminals and other process plants. They store

variety of fluids, which may be Explosive, Corrosive or Toxic in nature. The

equipments are also subjected to high pressures and moderate to elevated

temperatures. All these factors may cause corrosion and other damages to the

vital equipments.

The corrosion may cause thinning, pitting or cracking of pressure vessel wall.

The internal pressure will tend to bulge the piping at the corroded locations,

releasing the explosive or toxic contents resulting in serious consequences to

the plant, personnel and the people at large. It is therefore essential that

during the planned shutdowns, the degradation and damages inflicted to the

Plant equipment, Pressure Vessels, Piping and Tanks should be monitored

and evaluated so as to arrive at the 3R decisions. i.e. Run-Repair-

Replace decisions.

More specifically, this course describes the essentials of what to inspect, where

to inspect, how much to inspect and what to accept so as to evaluate the safety

and mechanical integrity of in-service Pressure Vessels. The course also covers

methods of repair, alteration, re-rating and replacements of affected Pressure

Vessels.


The API Courses provide the participants the guidelines and methodology of

carrying out inspection of in-service equipments. It also provides techniques

for the assessment of the wear and tear of the equipments as well as to

measure de-gradation and damages caused to the process equipments due to

the process conditions.

If the assessment indicates that the equipment is safe to run, the

participants are further taught how to estimate the safe remaining life and the

methods to extend the useful life of the equipments.

If the decision is that the equipment needs repair, the course teaches the

participants, how to carry out such repairs of the damaged part without

causing damage to the whole equipment. It also covers the methods of re-

rating the equipment by evaluating the mechanical integrity if it is not

possible to restore the equipment to its original design conditions.

COURSE OBJECTIVES This examination preparation course is designed to prepare the participant to

successfully sit for the API-510 exam. Through your concentrated effort, and

the material provided in this course, you should have sufficient information to

pass the examination.

The majority of the classroom study will focus on the Body of Knowledge . The

goal, is to obtain a perfect score. Therefore please take your daily classroom

activity and assigned homework seriously.

The material contained in this manual is to be thoroughly studied and

practiced prior to attending the course. The math examples and practice

problems are based on the types of questions given on the API-510 exam.

Through the use of these examples, you will be exposed to many of the

formulas used during the course.


Remember, this is a very intense course. There will be eight hours of

classroom study each day. The instructor will be available to answer questions

or to assist any participant having difficulty with the homework assignments

or any topic discussed during class. There will be from two to three hours of

homework assignments each day. Daily quizzes are given and one practice

API-510 examination is provided. The pace is fast and focused.

The participant is responsible for making all arrangements for taking the

examination including confirming your eligibility and applying to the

American Petroleum Institute.

No reference material of any kind will be permitted during the closed book

portion; some examining proctors may permit language translation

dictionaries. There will be some common knowledge mathematical questions

on the practical portion of the exam - remember to have your calculator

available for this part of the exam.

During this course, we will attempt to duplicate actual examination conditions

including using a separate answer sheet during the practice examination.

WEIGHTAGE OF MARKS

As per the Effectivity Sheet for API 510 exam, there are total 8 codes

prescribed for examination. However, all of them are not equally important

and do not therefore require equal emphasis. About 50 percent questions are

asked from one code API 510 which is hardly 40 pages, while all other 6 codes

contribute 50% marks which are more than 1,000 pages.

Following distribution scheme will help the participant to decide how much

time he should spend for each document during preparation.

Note: The weightage indicated is approximate and for guidance only.


A . API Publications:

API 510, Pressure Vessel Inspection Code.50 %

API RP 571, Damage Mechanisms..3 %

API RP 572, Inspection of Pressure Vessels..8 %

API RP 576, Inspection of Pressure-Relieving Devices5 %

API RP 577, Welding Inspection and Metallurgy3 %

B. ASME Publications:

Section V, Nondestructive Examination8 %

Section VIII, Division 1, Pressure Vessel Code.20 %

Section IX, Welding and Brazing Qualifications..8 %

API 510: TIPS FOR MAXIMIZING EXAMINATION SCORE

a. From Chapter 1, just note the scope, application and exclusions.

Chap. 2 lists only the reference documents.

b. There are only 12 or 16 important definitions out of total 62 from

Chapter 3 of API 510. Normally 3 to 4 definitions are asked in closed-

book exam.

c. From Chapter 4, usually 2 or 3 questions are asked. Concentrate on

responsibilities clause. Also see App. B for certification

requirements.

d. From Chapter 5, about 15-18 questions are asked. About 10-12 in

closed book and 4-6 in open book.


e. From Chapter 6, about 15-18 questions are asked. Particularly pay

attention to Inspection intervals, which attracts at least 5 to 6

questions and they could be either open book or closed book.

f. From Chapter 7 also 15-18 questions are asked. This is only five page

chapter and almost all paras should be studied thoroughly.

g. From chapter 8 more attention to be provided on all repair

techniques and approval authorization part. There may be 3 or 5

questions on this chapter.

h. There may be 2 or 3 questions on overall API-510 code for the

purpose of assessing the overall under standing of code.

i. Chapter 9 as well as App. E are excluded from examination.


j. As regards ASME Sec. V and IX, the course content is categorized in

10 categories. 8 of them are listed under calculations while 9 and 10

are listed under welding and NDT. You may expect at least one open

book and one closed book question on each of these. Additionally,

under the category internal pressure, you may expect 4 open book

questions one each for thickness calculation for the 4 types of end

closures.


TIME MANAGEMENT DURING EXAM:

Both open and closed book sessions are 4 hours each. This means

about 25 to 28 questions per hour for closed book and 12 to 15 questions

per hour for open book. For proper time management following are useful

suggestions.

a) You may start from Question No. 1 and proceed. If after 1 hour you

feel that you are maintaining the required progress as mentioned

above proceed serially.

b) If, however, you are behind the required rate, start jumping the

questions, i.e., start attempting those questions you can answer,

deleting whose answer you do not know. Proceed like this till the

end. Do not leave any question unanswered whose answer you

know.

c) Then come back to deleted questions and attempt them using

your feel factor. Go on like this till say last 10-15 minutes are

remaining.

d) If there are still some questions where you have no clue at all just

mark the answer at random in last 10-15 minutes. This may give you

few chance marks. Do not leave any question un-attempted.

e) After completion of writing exam, if you have still time (which you

normally have) you may go through your answers just to check

quickly if you have filled a wrong circle.

8

IET/CH/TP/002-R02, Sept.11

API 510- INSERVICE PRESSURE VESSEL INSPECTOR PREPARATORY COURSE

PART III

CODE WISE PUNCH POINTS

SUMMARY OF ALL CODES AND STANDARDS FOR API 510) EXAMINATION

9


API 510 CERTIFICATION PREPARATORY COURSE

API 510 - Pressure Vessel Inspection Code Note: Figures in parenthesis give the reference number of code

paragraphs from where the punch points are drawn up.

A Section 1 : Scope of API 510

1. API 510 covers in-service inspection, repair, alteration and re-

rating activities for pressure vessels and Pressure Relief

Devices protecting the vessel. (1.1.1)

2. API 510 applies to all Refining and chemical process vessels

that have been placed in service.

3. API is applicable to vessels constructed in accordance with

applicable construction code, or constructed without a

construction code (1.1.2)

4. API 510 shall not be used in conflict with regulatory

requirements. If API 510 code requirements are more stringent

than regulation, then requirements of the code shall govern

(1.1.3)

5. Following are excluded from API 510 (1.2.2)

a. Vessels on movable structures.

b. All exemptions listed in ASME Sec. VIII (Div. 1)

c. Very small vessels with certain limitation of volume and

pressure.

10


B Section 2 : References. 6. Important reference documents which have been referred in

API 510:

a. API 571 : Damage Mechanisms

b. API 572 : Recommended Practice for pr.

vessel inspection

c. API 576 : Inspection of Pr. Relief Devices.

d. RPI RP 577 : Welding inspection & Metallurgy.

e. API RP 578 : Material Verification program

f. API 579 : Fitness for service ( FFS).

g. API 580 : Risk Based Inspection (RBI).

h. API Publ. 2201 : Procedures for welding or Hot

tapping on the equipment in service.

C Section 3 : Definitions. This chapter gives definitions.

7. Alteration : A Physical change in any components affecting the

design (3.2)

8. Authorised inspection agency : Any one of the following (3.6)

a. Inspection organisation of jurisdiction.

b. Inspection organisation of insurance company

c. Inspection organisation of owner - User.

d. Organisation or individual under the contract with owner

user.

9. Examiner : A person who assists the inspector by conducting

specific NDE (3.20)

10. Engineer : One or more persons evaluating mechanical and

material characteristics (like strength calculations, corrosion,

the vessel integrity etc.) (3.19)

11


11. Repair : Work necessary to restore a vessel suitable for safe

operation at design conditions. Any work not specifically

conditions. Any work not specifically considered as alteration is

considered repair.

12. Repair organisation : Any one of following (3.54)

a. Holder of ASME Stamp (e.g., U Stamp)

b. Holder of R Stamp

c. Owner user who repairs his own equipment.

d. Sub-contractor appointed by owner user for repair jobs.

e. Organisation authorised by jurisdiction.

13. Rerating : A change in either design temperature, the MDMT or

MAW rating of vessel. (3.56)

14. Condition Monitering locations are designates areas on vessel

where periodic examinations are conducted (3.9)

D Section 4 : Organisation and Responsibility. 15. Owner / User holds overall responsibility for all activities under

API 510 (4.1).

16. Before implementing API 510, the owner / user organization

should prepare quality assurance manual describing inspection

and control activities (4.2.1).

17. Engineer is responsible to owner user for design, engineering

review, analysis and evaluation of pressure vessels. (4.2.2)

18. Inspector is responsible to owner user to assure that NDE

testing activities meet API 510 requirements. All NDE results

must be evaluated by inspector. (4.2.4)

19. Examiner shall perform NDE in accordance with job

requirement (4.2.5)

12


20. Repair organization is responsible to owner user and shall

provide materials, equipment, quality control and workmanship

as required for repair activities. (4.2.3)

E Section 5 : Inspection Examination and Testing. 21. Before taking up any inspection, an inspection plan shall be

developed by inspector or Engineer (5.1.1).

22. A RBI assessment determines Risk by combining the

probability and the consequence of failure (5.2)

23. RBI assessment shall be preformed in accordance with API

580. The detailed RBI methodology is presented in RBI 581 (5.

2)

24. Before performing any inspection inspector should review the

prior inspection results. (5.3.4)

25. Internal inspection is preformed by inspector. The primary goal

of internal inspection is to find damage that can not be found by

regular monitoring of external CMLS. (5.5.2.1)

26. On-stream inspection may be used as alternative to internal

inspection under certain conditions. It shall be conducted by

either Inspector or examiner. It may include several NDE

techniques to check for various types of damages. (5.5.3)

27. External Inspection is essentially visual inspection conducted

externally to check for leakage, hot spots, vibration distortion

etc. It is normally conducted by inspector but may also be

conducted by other qualified persons. (5.5.4)

28. CUI inspection is required for insulated vessels where moisture

ingress is likely and vessels operate between 100 F to 3500 F

for carbon and alloy steels and 1400 F to 4000 F for Austenitic

Stainless Steels (5.5.6)

13


29. Thickness measurement is usually done by UT techniques.

(5.7.2)

30. Ultrasonic Scanning or profile radiography is preferred where

corrosion is localized (5.7.2)

31. Pressure test is conducted if inspector believes it is necessary

after the repairs. Pressure text is normally required after an

alteration. (5.8.1)

32. Hydrostatic Test Pressure on vessels is as follows (5.8.2)

a. For vessels constructed prior to 1999 = 1.5. X MAWP X stress ratio.

b. For vessels constructed after 199 = 1.3 X MAWP X stress ratio.

33. The pressure test temperature shall be above (5.8.6).

MDMT + 100 F for vessel thickness upto 2" and MDMT + 300 F

for vessels thicker than 2".

F Section 6 : Inspection Frequency. 34. External Inspection frequency shall not exceed lesser of internal

inspection interval or 5 years. (6.4.1)

35. Internal and on-stream inspection frequency shall not exceed

lower of one-half the remaining life or 10 years.

If remaining life is less than 4 years inspection interval may be

full remaining life up to a maximum of two years. (6.5.1)

36. ARBI assessment may be used to establish appropriate

inspection interval for internal on stream and external inspection

and 10 years limit may be exceeded. (6.3.1)

37. If service conditions of a vessel are changed inspection

intervals shall be established for new service condition. (6.2.2)

14


38. If both ownership and location of vessel are changed, Allowable

Service Conditions and inspection interval shall be established.

(6.2.2)

39. On stream - inspection may substituted for internal inspection if

the inspector approves, for following conditions. (6.5.2)

a. General corrosion rate is less than 5 mpy as confirmed for at

least 5 years.

b. vessel remaining life in at least 10 years.

c. vessel is not operating in creep temperature range.

d. vessel is not subject to SCC.

e. vessel does not have non integral lining inside.

40. For Multi zone vessels each zone shall be inspected based on

interval for that zone. (6.5.3)

41. Pressure-Relieving devices shall be tested in accordance with

API 576 (6.6)

42. The repair organization for PRDS shall have a documented

quality control system. (6.6.1)

43. The repair organization shall have documented training

program to ensure that personnel are adequately qualified

required (6.6.1)

44. Testing and inspection interval for PRD s.

a. Five years for typical service.

b. Ten years for clean and non-corrosive service. (6.6.2)

G Section 7 : Inspection data evaluation. 45. Corrosion rate (7.1)

Long term corrosion rate = t initial t actual

years between t initial & t actual.

Short term corrosion rate = t previous t actual

years between t previous & tactual.

46. Out of long-term and short-term corrosion rates the inspector in

consultation with corrosion specialist shall select the rate that

best reflects current conditions (7.1.1.2)

47. For newly installed vessel or for change or service corrosion

rate can be estimated based on : (7.1.2)

a. Data collected on vessels in same or similar service.

b. corrosion rate may be estimated from published data.

c. If there is not data on any of above on-stream determination

after 1000 hours of service shall be made.

48. Remaining life = t actual t required

corrosion rate

(7.2.1)

49. MAWP determination (7.3.1)

The thickness (t) used for MAWP formula is given by

t = tactual - 2 (corrosion rate X Interval)

50. For evaluation of locally thinned are corrosion averaging may

be done over a length (L) not exceeding following (7.4.2.1)

a. For vessel I.D. upto 60", L=lesser of ID or 20"

2

b. For vessel I.D. above 60", L=lesser of ID or 40"

3

51. Pitting Evaluation (7.4.4)

15


16


Widely scattered pits may be ignored if all of the following are

true.

a. Remaining thickness below the pit is greater than one-half or

required thickness.

b. Total pitted area (i.e. deeper than corrosion allowance) does

not exceed 7 sq. in

c. Sum of pit dimension that is deeper than corrosion allowance

along any 8 inch straight live does not faced 2 inches.

52. If a vessel with joint efficiency less than 1 has corroded surface

away from the weld, an independent calculation using weld joint

factor = 1 can be made.

Surface away from weld means surface beyond 1 inch on either

side or twice the required thickness which ever is greater, as

measured from toe of the weld. (7.4.5)

53. To recalculate required thickness for tori-spherical head use

following guideline (7.4.6)

a. For knuckle region use thickness formula in construction

code.

b. For central portion use Hemispherical head formula with

crown radius equal to O.D. of shell.

c. Central portion is defined as center of head with diameter

equal to 0.8 times shell diameter.

54. To recalculate the required thickness for 2:1 ellipsoidal head

use following guide line. (7.4.6)

a. For Knucle region use construction code formula.

b. For central portion use Hemispherical head formula with

crown radius equal to 0.9 times the inside shell diameter.

c. Central portion is defined as center of head with diameter

equal to 0.8 times shell diameter.

17


55. If exact material specification for carbon steel unknown, then

use allowable stress value (s) for S.A 2836 Gr. C material (7.7).

56. If extent or radiography done originally is not known (E is

unknown) then for butt welds use E=0.7 (7.7).

57. Typical pressure vessel records consist of 4 types of

information.

a. Construction and design information.

b. Inspection History.

c. Repair, Alteration, re-rating information.

d. Fitness for service records.

H Section 8 : Repairs Alteration Re-rating. 58. Approval of repair or alteration procedures: (7.1.2)

For Repairs : Inspector

For Alterations : Inspector and Engineer.

59. Authorization of repair/ alteration work on vessels complying

with

a. ASME Sec. VIII Div. 1 : Repairs by Inspector.

b. ASME Sec. VIII Div. 2 : Both Repairs and Alteration to be

authorized by Inspector and Engineer.

60. The inspector shall approve all repair and alteration work at the

hold points and after completion. (8.1.2)

61. Materials used for welded repairs and alterations shall be of

known weldable quality. Carbon or alloy steels with carbon

content more than 0.35% shall not be welded.

62. Normally temporally repairs are replaced by permanent repair

at next turnaround but may remain for longer period if approved

by engineer and inspector (8.1.5.1).

63. Fillet welded patches may be used for making temporary

repairs. (8.1.5.1.2)

64. New fillet patch on existing fillet patch is not permitted when

installing a fillet welded patch adjacent to existing fillet welded

patch, distance (d) between toes of fillet weld shall not be less

than

d = 4 RT

d = Toe - to - Toe distance

R = Inside radius of vessel

T = Actual thickness of vessel wall

65. Full encirclement lap band are permitted by code under certain

restrictions (8.1.5.1.3)

66. Non-penetrating nozzles (including pipe caps) are permitted as

permanent repairs. (8.1.5.1.4)

67. Insert plates are accepted as permanent repairs if :

a. Full penetration butt welds are used.

b. Welds are radiographed as per construction code.

c. Plates shall have round corner with minimum 1 inch

radius. (8.1.5.2.2)

68. For overlay repairs filter material of lower strength than base

metal is permitted if :

a. Repair thickness does not exceed 50% of required

thickness.

b. Thickness of repair weld is increased by ratio of tensile

strength of base metal to tensile strength of filter.

c. Increased thickness is given 1:3 taper.

d. Repair made with minimum two passes. (8.1.5.3.2)

69. For damaged S.S. cladding with base metal exposed to

Hydrogen migration, before repair degassing should be done.

Additionally, for P-3, P-4 and P-5 materials base metal in repair

18


19


area should be examined by UT at least 24 hours after

completed repair. (8.1.5.4.3)

70. For on-stream welds refer API 2201 for guidance (8.1.6)

71. Welders and procedures used for repairs shall be qualified as

per ASME Sec. IX

72. Local PWHT is permitted instead of 3600 banding with certain

precautions (8.1.6.4.1).

73. Pre-heat method may be used as alternative to PWHT for P No.

1 and same P No. 3 and P. No. 5 materials, if impact test was

required (8.1.6.4.2)

74. NDE of welds. (8.1.7)

For weld overlay and Fillet welds - PT or MT

For butt - welds - Radiography as per the construction code.

75. Re-rating calculations shall be performed by engineer. Re-

rating of old vessel (built prior to 1999) can be done as per

latest code under certain conditions. Re-rated pressure and

temperature shall be shown by additional name plate or

stamping on existing name plate. (8.2)

20


ASME Sec. VIII Div. 1

(Figures in parenthesis give reference paragraph of ASME Sec. VIII.

Div. 1, from where punch points are)

A. INTRODUCTION : 1. A pressure vessel is a container for the purpose of holding the

pressure, either internal or External (U-1 a2)

2. ASME Sec. VIII. Div. 1 contains requirements and guidance for

pressure vessel materials, design, fabrication, inspection and

testing (u-1 A 3).

3. Following are excluded from scope of ASME Sec. VIII. Div. 1

(u- 1c).

a. All piping systems.

b. All fired vessels (i.e. Boilers)

c. Vessels with operating pressure less than or equal to 15

psig.

d. Vessels with inside diameter less than or equal to 6

inches.

B. Weld Category, types, joint Efficiency : 4. "Weld joint category" defines the location of a joint in a vessel

but not the type of joint. They are indicated by letters A, B, C, D

(UW-3)

5. There are 4 categories of joints (UW-3)

Category A : All longitudinal welds in shell and nozzles.

: All welds in Heads.

: Circumferential weld joining Hemispherical

head to shell.

Category B : All circumferential welds in shell and

nozzles.

21


: Circumferential welds joining shell to any

formed head (other than Hemispherical

head)

Category C : All Flange Welds.

Category D : All welds joining nozzle to the vessel shell or

head.

6. Longitudinal welds are normally full stress welds, while

circumferential welds are half stress welds.

7. Welds type are indicated by numbers (UW-12)

Type 1 : Typically double welded giving full

penetration.

Type 2 : Full penetration weld with backing strip in

place.

Type 3 : Joints welded from one side only (May or

may not be full penetration weld).

8. Table UW-12 gives weld joint efficiency to be used in thickness

formulas depending on full, spot or Nil radiography.

9. Extent of radiography is indicated, on name plate (UG-116).

RT 1 : Full Radiography (with all butt welds fully

radio graphed)

RT 2 : Full Radiography (Category a welds full

length and category B spot radio graphed).

RT 3 : Spot Radiography (For both category A & B)

RT 4 : No radiography.

10. Joint Efficiency for reamers for dished heads depends on

radiography of shell to head weld (UW-12d).

11. Joint Efficiency for welded pipes and tubes is always taken as 1

(UW-12e).

C. Thickness of vessel components : 12. Various thick nesses for vessel are defined as below

(Mandatory Appendix 3)

a. Required Thickness : Thickness required for holding

pressure.

b. Design thickness : Required thickness plus

corrosion allowance.

c. Nominal thickness : Commercially available thickness

as used for vessel fabrication.

13. Required thickness of cylindrical shell having internal design

pressure (P), Internal radius (R) Allowable stress (S), Joint

efficiency (E) is given by (UW-27).

Required thickness = PR

SE - 0.6 P

MAWP for cylindrical shell = SE t

R +0.6t.

14. Head thickness and depths (UW - 32)

a. 2:1 Ellip head : depth = D, Thk = nearly same as shell.

b. Hemispherical head : depth = D, Thk = nearly half of

shell.

c. Torispherical head thickness= 1.77 times shell thk approx.

D. MAWP Analysis : 15. Water causes a static head pressure given by

1 ft water column = 0.433 psi.

16. Total pressure is given by = vessel MAWP plus static head.

17. Total at any point can not exceed vessel part MAWP for that

location.

22


18. Vessel MAWP is measured at top of the vessel. It is least value

of all part MAWPS after deducting the static head on that part

(UG-98a)

E. External Pressure : 19. Allowable external pressure on cylindrical shell is given by (UG-

28).

Pa = 4B (Use this formula if B is given)

3 (Do/t)

Pa = 2AE (Use this formula if A is given)

3 (Do/t)

F. Pressure Testing : 20. ASME code prefers Hydrostatic pressure test as standard test.

Pneumatic Test may be used only if Hydrostatic Test can not be

performed due to Design reasons or process reasons. (UG-99,

UG-100)

21. Standard Hydrostatic Test (UG-99)

a. The test is applied after all fabrication inspection is

completed.

b. Hydrostatic test pressure = 1.3 X MAWP X stress at test pr.

stress at Design pr.

c. Inspection pressure shall be not less than test pressure

divided by 1.3

d. Test temperature = MDMT + 300 F

e. Relief value Pressure = 1.1/3 times test pr.

22. Pneumatic Test (UG-100)

a. Performed only if Hydro test is not possible due to design or

process reason

b. Prior to test PT or MT examination of nozzle welds is

mandatory to identify cracks if any as per UW-50.

c. Pneumatic test pr = 1.1 X MAWP X Stress test temp.

Stress at Design temp.

23


24


d. Test Temperature = MDMT + 300 F (shall)

e. Pressurization in 6 steps. first step 50% of test pr

subsequent steps 10% of test pr.

f. Inspection pressure shall be at test pressure divided by 1.1.

23. Test gage range (UG-102) Ideal range 0 to twice the test pr.

Min. range 0 to 1.5 times test pr.

Max. range 0 to 4 times test pr.

G. Impact Testing : 24. For carbon and low ally steel vessels operating at low

temperature, impact testing requirements of materials is

decided by figure UCS-66. (UCS-66)

25. Steps in deciding impact test requirements. (UCS-66)

a. First decide curve for given material.

b. Go to Fig. UCS-66, If MDMT-Thickness combination point

is on or above the curve from (a), Impact testing not

required if below, Impact test is required.

c. If the point is close to curve, Table UCS-66 is helpful in

deciding exactly whether the point is above, on, or below

the curve.

d. All base metals above 6 inch thickness and all welds

above 4 inch thickness always require impact tests.

26. If impact tests are required as per above steps, there are further

exemptions possible if thickness for curve 'A' materials is less

than or equal to 0.5" and for curve B, C, D thickness is less than

or equal to 1 inch [UG-20(f)]

27. For carbon steels (P No. 1) further reduction of 300 F from

temperature on UCS - 66 curve can be given if PWHT was

performed when it was not mandatory by code.

25


H. Nozzle welds and Re-inforcements: 28. The nozzle welds shall be checked for code conformance by

comparing with suitable diagrams given in code (UW-16)

29. Throat of filled weld = 0.707 X leg of weld.

30. Nozzle shall be adequately reinforced by providing the

reinforcement pad if required (UG 36 C 3)

31. Reinforcement area must be within limits of reinforcements

given by : (UG - 37)

a. Limit along vessel wall = 2 d

b. Limit perpendicular to wall = 2.5 tn.

c. Diameter of finished opening.

d. tn = nozzle thickness.

32. Reinforcement Area required = d X tr

(tr = Required thickness of shell).

33. Extra available in vessel wall = d (t - tr.)

(t = vessel shell thickness as provided.)

34. Extra available in nozzle = 5 tn (tn - trn.)

(trn = Required thickness of nozzle.)

35. Reinforcement pad is not required if :

a. nozzle opening is less than or equal to 23/8 inch. for shell

thickness above 3/8 inch.

b. For nozzle opening up to 3.5 inch. for shell thickness 3/8

inch. or less. (UG - 36 C 3).

26


J. Misc. Requirements : 36. Weld misalignment and weld reinforcements must be within

code requirements (UW-33 and UW - 35).

37. Ovality tolerance shall not exceed one percent of Nominal

diameter. (UG-80)

38. Maximum under tolerance on plates is lesser of 6% ordered

thickness or 0.01 inch i.e. 0.25 mm (UG-16 C).

39. For welding unequal thickness, a taper transition of 1:3 must be

provided i.e. taper length = 3 times plate offset (UW -9).

40. PWHT requirement depends on P No. of material and

thickness. The minimum holding temperature and holding time

shall be as per tables UCS-56 for various P. Nos. (UCS-56).

27


ASME - Sec. IX - welding Qualification Code

Note : Figures in parenthesis give reference cause in the code.

1. ASME Sec. IX gives requirement for Qualifying Procedures and

welders (QW 100).

2. For Procedure Qualifications a test coupon is welded and then

tested for strength (tension tests) and ductility (Bend tests) to

ensure that the weld has required properties (QW- 141).

3. In performance qualification we determine welder's ability to

produce sound welds by conducting either Bend tests or

Radiography. (QW 141, 142)

4. Tension test is passed if either of the following is satisfied.

a. If break is in weld metal is must be at strength above the

specified minimum tensile strength of Base metal.

b. If break is in base metal it must meet at least 95% of

minimum tensile strength of Base metal. (QW 153).

5. Bend test (It may be Face bend, root bend or side bend) is

passed if test specimen does not show open discontinuity more

than 1/8 inch. (3 mm.) (QW 163).

6. Radiography for welder qualification shall meet acceptance

criteria of ASME Sec. IX (QW 191.2).

7. A PQR is a record of welding data used to weld test coupon. It

also contains test results on backside it can not be revised.

(QW 202.2)

8. A WPS is used to provide direction for making production

welds. It shall be within ranges qualified by P & R (QW 200.1)

28


9. A P & R support WPS as long as essential variables on both

are same.

10. For P & R test to pass it shall pars 2 tension tests and 4 bend

tests (QW 202).

11. Bend tests are 2 face Bend and 2 Root bends for coupon

thickness less than 3/4" (19 mm) and 4 side bend tests if

thickness is equal to greater than 3/4" (QW 451)

12. P Q R should also list P. No. (for parent metal) F.No. (for filler

metal) and A-No. (for weld metal) [QW-422, QW-432, QW-442].

13. For procedure qualification test coupon may be a plate or pipe.

plate qualities for pipe and vice versa (QW 211)

14. A procedure qualification in any position qualities the procedure

in all positions. (QW-203)

15. For welder qualification 2 bend tests or Radiography can be

used (Except for GMAW - 5 process) [QW - 452] and QW 304

16. for welder qualification position is important (QW - 461.9)

Qualification Test Position Qualified 1 G (flat) 1 G

2 G (Horizontal) 1G, 2 G

3 G (Vertical) 1 G, 3 G

4 G (Overhead) 1 G, 4 G

5 G (Pipe fixed) 1 G, 3 G, 4 G, 5 G

6 G (Pipe at 450) All.

2 G and 5 G All.

17. For pipe positions 5 G and 6 G qualification 4 bend tests are

required and all must pass. (QW-452).

18. If a welder passes procedure qualification test, be is also

qualified for performance in that position. (QW -301.2)

29


19. When welder is qualified by radiography for plate test

coupon, at least 6" length shall be examined by radiography

and for pipe, entire weld circumference shall be examined. (QW

- 302.2)

20. Performance qualification of a welder is affected if he does not

weld with a process for 6 months or more. If there is specific

reason to question his ability to make acceptable welds his

qualification for the welding he is doing shall be revoked. (QW-

322)

30


ASME Sec. V - Non destructive Examinations.

A. General : 1. ASME Sec. V. gives methods and requirements for conducting

NDT. It becomes applicable only if referred by the other

referencing codes.

2. The user of Sec. V. Code is responsible for following.

a. Getting NDT personnel properly certified.

b. All NDT examinations require written procedures.

c. All NDT equipments shall be as per Sec. V.

d. Equipments shall be calibrated as required by Sec.V.

e. Records retention.

B. RT Examination : 3. For RT Examination, either hole type or wire type IQI shall be

used.

4. A radiograph is considered satisfactory, if it is within the density

limits and has required IQI image. For hole type 2 T hole and

for wire type the designated wire image shall be seen.

5. Density limitation :

2 to 4 for Gamma Rays.

18 to 4 for X rays.

Density variation permitted = +30% to - 15%

6. Selection of IQI is based on weld thickness plus the weld

reinforcement. Thickness of backing strip is excluded.

7. IQI is normally placed on Source side unless inaccessibility

prevents it. They IQI may be placed on Film side and a Lead

letter F shall be put adjacent to it.

31


8. Hole IQI may be placed on or near the weld. Wire IQI is placed

on the weld with wires perpendicular to the weld axis.

9. Double wall double image technique is suitable for pipes up to

3.5" OD.

10. Back scatter shall be avoided. If light image of Lead Letter - B is

seen on dark background then the backscatter is excessive and

radiograph shall be rejected.

C. PT Examination. 11. For conducting PT on certain materials, the contaminants shall

be controlled as follows.

a. For Nickel and its alloy : Sulpher content not to exceed

1% of residue.

b. For Austenitic S.S. Duplex S.S. and Titanium content of

chlorine plus Florien shall not exceed 1% of residue.

12. Two type of penetrates (visible and Fluorescent) can be used.

For excess penetrate removal 3 methods are used for visible

and fluorescent.

- Water washable

- Post Emulsifying.

- Solvent Removable.

This results in total 6 techniques.

13. PT is normally conducted between temperatures 500 to 1250 F

(100 to 520 C). For below or above this range special penitents

shall be used and the dwell time should be worked at using

quenched Aluminum blocks.

14. After applying the developer, interpretation shall be done within

10 to 60 minutes.

15. Intermixing of penetrate material from different families (i.e.

visible & fluorescent) or penetrate materials from different

manufacturers are not permitted.

D. MT Examination : 16. The Magnetic Particle Examination can be performed on

Ferromagnetic materials for finding surface and near surface

defects.

Drug or wet Iron powder and visible, or fluorescent powder is

used.

17. Prod Technique used Direct current. The distance between

prods shall be 3 inches to 8 inches. This is suitable for finding

surface and near surface defects.

18. Yoke technique is suitable for surface defects only and can use

A.C., D.C. or permanent magnet.

19. Ammeter on instrument shall be calibrated annually by

comparing 3 current readings with a standard Ammeter, and

permitted tolerance is + 10% of full scale.

20. For yoke, the electromagnetic yokes shall be calibrated

annually by checking lifting power.

A.C. yoke shall lift 10 pounds (4.5 kg.)

D.C. yoke shall lift 40 pounds (18 kg.)

21. Lifting power of permanent magnet yoke shall be checked daily

prior to use by lifting 40 pounds (18 kg) weight.

22. Examination is performed in two perpendicular directions.

32


33


E. UT Examination :

23. Pulse - Echo contact method is used for finding thickness and

laminations.

24 In Direct contact (single element) method is not suitable for

smaller thickness hence delay line method is used which uses a

delay block to delay the echo.

25. In delay line, end of delay is made to coincide with Zero

thickness on CRT.

26. Dual Search units are also used using two crystals one for

sending pulse and other for receiving echo. On smaller

thickness this method results in vee-error which needs

correction.

27. For thick section measurement use of multiple echo technique

is made. The calibration block chosen is smaller thickness

which will permit standardizing the full-sweep distance to

adequate accuracy on CRT.

28. For measurement at high temperatures thickness correction is

needed. A positive error of 1% per 1000 F increase in results.

34


API RP 572 - Inspection of Pressure Vessels.

1. API 572 covers guide lines for conducting detailed inspection of

pressure vessels.

2. Basic reasons for inspection are to determine the physical

condition of the vessel and to determine type rate, and causes

of degradation and damage. A good timely inspection results is

safety, continuity and reliability of the plants equipments.

3. Creep damage depends on time, temperature & applied

stress.

4. Graphitization may take please due to long exposure in

range of 825o f to 1400o f ( 440oC to 760o f in which

carbide decomposes to produce ferrite ( pure iron ) and

Graphite noodles ( pure carton ). This causes loss of

strength steel . In-situ metallography is useful in detecting

Graphitization .

5. De alloying is selective leaching or loss of one or more alloy

components example. Dezincification of copper-zinc (brass)

alloy.

6. Hydriding of titanium alloys is that Titanium alloys may become

brittle (lose ductility) due to absorption of Hydrogen.

7. External inspection starts with platform and ladders, which is

mostly visual and supplemented by hammer test.

8. Anchor bolts may be checked by sideway blow with hammer.

9. Grounding connection should be checked for good electrical

contracts and the resistance. Recommended resistance is 5

ohms or less but shall not exceed 25 ohms in any case.

35


10. Vibrations of auxiliary equipments (pressure gauges, right glass

etc.) should be arrested by adding support or vibration analysis

should be done to make sure that fatigue failure will not occur.

11. External distortion may be measured by taking measurements

from a parallel line (typically a stretched wire) to vessel wall.

12. During internal inspection cracks are likely to be found in weld

and HAZ particularly at nozzle welds if following factors are

present (more factors present means more susceptibility.)

a. Heavy wall vessel.

b. Hydrogen or Hydrocarbon service.

c. Wet H2S service,

d. Caustic or Amine service.

e. material with coarse grain structure.

f. High strength materials.

g. Low-chrome materials.

Best method to check internal cracks is WEMT.

13. Areas directly above and below the liquid level in vessels

containing acidic corrodants are subject to Hydrogen Blistering.

14. Laminations appear similar to cracks. Laminations run slant to

surface while cracks run at right angles.

15. Corrosion of Metallic lining can be monitored using corrosion

tabs made from lining material and welded at right angles.

16. Where a lining leaks, whether corrosion has taken place behind

it can be determined by taking VT thickness measurement from

outside.

17. Non metallic lining are typically inspected visually or by High

voltage spark testing also known as Holiday detection.

36


API RP 576 - Inspection of Pressure Relieving devices

1. API 576 describes inspection and repair practices for Pressure

Relieving Devices (PRDs). It does not cover training

requirements for mechanics involved in inspection & repair of

PRDs.

2. Difference between Release Pressure and set pressure is

known as Overpressure and difference between set pressure

and closing pressure is called Blow down.

3. Cold differential test pressure (CDTP) is the test bench set

pressure. It includes correction for back pressure &

temperature.

4. Safety valves are used on compressible fluids (Gases, Vapors)

and Relief valves are used an incompressible fluids (liquids).

5. Safety Relief valve works as Safety valve if installed on gases

and vapors. I works as Relief valve if installed on liquids.

6. Conventional Safety Relief valve operation is directly affected

by changes in back pressure.

7. Balanced Safety Relief valve incorporates a bellow or other

devices to minimize effect of back pressure on operation. This

valve is suitable when the discharge from valves must be piped

to remote location.

8. Pilot operated valves are PRDs in which the main valve is

combined with and controlled by a auxiliary valve (pilot).

9. Rupture discs are used to protect the PRD against corrosion or

plugging due to system fluid.

10. Conventional Rupture Disk is designed to burst when it is

overpressured on concave side. It provides satisfactory service

for operating conditions withe 70% or less of the rated burst

pressure.

11. Reverse acting rupture disc is designed to burst when it is

overpressure on convex side. They use bursting device like

knife blade or shear rings. They can be used for operating

conditions up to 90% of rated burst pressure.

12. Transportation of pressure Relief valves (PRV) should be in

upright position.

13. The PRV should be installed directly on the vessel and it should

not be connected by lengthy piping to avoid chattering of valve.

14. As soon as the valve is received in shop and mounted on test

block "as received" pop pressure shall be noted.

15. After "as received" pop test valve is visually inspected, decision

on dismantling the valve is taken. If pop test and visual are ok,

normally there is no need to dismantle the valve.

16. After re-assembly the valve pop pressure is checked. The

deviation of pop pressure from set pressure shall not exceed.

a + 2 psi for pressures up to 70 psi.

b. + 3% for pressures above 70 psi.

17. Valve is also tested for leak tightness at a pressure equal to

90% of CDTP, by bubble test method.

18. The Maximum inspection and testing interval is 10 years.

19. Visual on-stream inspection which is like a survey (to check that

correct valve is at correct location, correct tag is at correct

valve, valve is not leaking, valve operation is not obstructed

etc). This survey shall be conducted at a interval not more than

5 years.

37


38


API RP 571 - Damage Mechanisms.

1. Temper embrittlement is reduction in toughness in low alloy

chromium steels due to long exposure in high temperature

range (6500 F to 11000 F).

2. Common way to minimize temper embrittlement is to limit "J"

factor for base metal and "X" factor for weld metal.

3. Brittle fracture is sudden fracture under stress due to loss of

ductility at low temperature, cracks are typically, sharp straight,

non-branching.

4. Some reduction in possibility of brittle fracture may be achieved

by performing PWHT.

5. Fatigue is typically caused due to surface notch and cyclic

stresses. If cyclic stress are due to mechanical reasons

(rotating shaft, rapid change of pressure) it is Mechanical

Fatigue. If cyclic stresses are due to changes of temperature, it

is thermal fatigue. If surface notch is due to corrosion and cyclic

stresses are present it is corrosion Fatigue.

6. Thermal Fatigue cracks are dagger shaped and oxide filled.

7. Thermal fatigue is prevented by preventing stress concentration

and controlling thermal cycling.

8. Mechanical fatigue failure typically shows "Beach-mark" or

"clam shell" type concentric rings. Mechanical fatigue can be

prevented by avoiding stress concentration at surface.

9. Corrosion Fatigue can be prevented by using coatings or

inhibitors or by using more corrosion resistant materials.

39


10. Erosion-corrosion is damage that occurs when corrosion

contributes to erosion by removing protective scale due to the

combined action.

11. Erosion Corrosion increases with velocity, turbulence,

concentration of impacting medium size and hardness of

impacting particles.

12. Some methods to reduce Erosion-corrosion are increasing pipe

diameter to reduce velocity, using large radius bends,

increasing surface hardness, using corrosion-resistant

materials.

13. Atmospheric corrosion increases with high humidity (marine

environment) and atmospheric pollution (industrial environment)

and is best prevented by providing coating / painting.

14. CUJ is caused due to water trapped under insulation, for carbon

steel it may show scale formation and for S.S. it may show

pitting and cracking due to chloride stress corrosion cracking.

15. CVI may be prevented by providing protective painting and

maintaining insulation is good condition to prevent the moisture

entry.

16. Cooling water corrosion is caused by dissolved salts, gases

(typically oxygen) or microbes (which may be present in

stagnant or low velocity water).

17. Cooling water corrosion can be prevented by chemical

treatment, maintaining flow velocity and monitoring oxygen

contact in water.

18. Boiler water corrosion is result of dissolved gases namely

oxygen and carbon di oxide.

40


19. Best method to reduce Boiler water corrosion is to use de-

aerator for Boiler feed water, monitoring presence of oxygen

and using oxygen scavangers like Hydrazine.

20. Chloride stress cracking corrosion is typically takes place on

Austenitic Stainless steel between 1500 to 4000 F in chloride

environment.

21. Austenitic S.S. (300 Series) are most suceptible duplex

stainless steels are somewhat resistant and Nickel Alloys (more

than 40% Nickel) and almost immune.

22. For Hydro-testing of Austenitic S.S. Vessels and pipes use

water with low or free of chlorides (typically less than 50 ppm,)

23. Caustic Stress corrosion cracking typically takes place on

carbon steel adjacent to welds which are not stress relieved.

24. Higher temperature and higher caustic concentration increases

suceptibility.

25. Best method to prevent caustic stress corrosion cracking is

conducting PWHT of completed weld or use of Nickel alloys

should be considered.

26. Sulphidation of carbon and alloy steels typically takes place

above 5000 F and increases with and sulpher concentration

increasing temperature.

27. Best method to prevent sulphidation is upgrading to higher

chromium alloys.

28. High temperature Hydrogen attack (HTHA) takes place at

temperature above 4000 F due to migration of atomic Hydrogen

which combines with carbide in carbon steels forming methane

gas, which can not diffuse out, collects at grain boundaries and

causes cracking.

41


29. Best method to avoid use of HTMA is select materials using API

RP 941 curves (Nelson curves). HTHA can be detected by

metallography.

30. Wet H2S exposure causes 4 types of damages namely

Hydrogen blistering, Hydrogen induced cracking (HIC), Stress

Oriented Hydrogen induced cracking (SOHIC) and sulphide

stress corrosion cracking (SSC).

31. Hydrogen blistering takes place due to migration of atomic

hydrogen in steel and combining to term hydrogen molecules

which typically collect at voids, slags, porosity causing

Hydrogen pressure to build up and producing Hydrogen Blister.

32. The Hydrogen blisters formed within steel at different levels will

grow and combine to form Hydrogen induced cracking which

typically has stepwise appearance.

33. The HIC cracks formed within HAZ will propagate rapidly in

perpendicular to surface due to loss of ductility to HAZ and due

to stress this is called SOHIC.

34. The Sulphide formed during the wet H2S exposure (Fe+ H2S -

FeS 2H) causes cracking under combined action of Sulphide

and stress (which is caused due to internal pressure in vessel)

leading to SSC.

35. Best method to prevent wet H2S damage is use of controlled

Hardness Steel (typically less than 22 HRC) and steel with low

percentage of Sulpher and Phosphorous impurities (which

reduces voids and porosity in steel).

36. SOHIC and SSC can also be reduced by performing stress

relieving of welds.

42


API RP 577 - Welding Inspection and Metallurgy.

1. Recordable indications means the indications recorded on data

sheet which need not exceed the rejection criteria.

2. Reportable indications means the indications which exceed the

rejection criteria. They should be recorded on data sheet and

also reported to appropriate authorities to get them rectified.

3. Any electrodes or fluxes that have become wet should be

discarded.

4. For visual examination the personnel are required to

demonstrate jagger J-1 eye test annually.

5. Direct Visual examination requires access to bring the eye

within 6" to 24" from the surface at an angle not less than 300.

6- Radiographic Film density is quantitative measure of film

blackening. Clear film has zero density. Exposed film that

allows 10% of light to pass has density =1. A

film density of 2, 3, 4 allows 1%, 0.1 % and 0.01% of light to

pars through the film respectively.

7. Straight beam techniques are used for thickness evaluation or

to check laminations. Shear wave (Angle beam) techniques are

employed for finding discontinuities in welds.

8. In UT, A-scan typically given pulse-echo display. B-scan shows

a cross-sectional view of the object and C-scan shows plan

view of object.

9. The HAZ is that portion of the base metal (adjacent to the weld)

that has not been melted but whose mechanical properties or

microstructure is altered due to heat of welding. For carbon

steels HAZ includes the regions heated to greater than 13500 F

(7000 C).

10. The hardness values in HAZ for steels in Refinery service is

given in Table 11 (For Carbon steels it is 200 BHN) Hardness in

11. "Weldability" is defined as capacity of the metal to be welded

under under the fabrication conditions imposed.

12. Weldability is measured by Carbon Equivalent (CE) formula.

CE= C + Mn + Cr + Mo + V + Si + Ni + Cu

6 5 15

13. Typically steels with CE less than 0.35% requires no

preheating. CE will CE of 0.35% to 0.55% requires preheating

and CE greater than 0.55% require both pre-heating and

PWHT.

14. Simplest welability tests are the strength and ductility test of

weld.

15. For qualifying welder on "GMAW - S" process bend tests shall

be used instead of Radiography.

43



PART IV

CASE STUDIES

NUMERICAL EXAMPLES FOR UNDERSTANDING APPLICATION OF CODE RULES


API 510 PREPARATORY COURSE

CASE STUDY 1 (Thickness Calculations) ASME Sec VIII Div. 1

Design Data for Pressure Vessel:

Design Pressure = 100 psi

Inside diameter = 96 inches

Corrosion Allowance = 0.125 inch

Shell Joint efficiency = 0.85 (spot examination)

Head joint efficiency = 1.0

Allowable stress of material = 17500 psi

1. Calculate minimum required thickness for cylindrical shell.

2. Calculate the design thickness of shell above question.

3. What Nominal thickness for the shell will you select, if plates are available in

steps of 1/16 inch increment?

4. Calculate shell MAWP for above cylindrical shell.

5. Calculate required thickness for a Hemispherical Head.

6. Calculate design thickness for Hemispherical Head.

7. Calculate the minimum required thickness for 2 :1 Ellipsoidal head.

8. Calculate the design thickness for 2:1 Ellipsoidal head.

9. If dished head thickness in Question: 8 is rounded to next 1/16 inch, what

will be the nominal thickness of formed head?

10. Calculate Head MAWP for above ellipsoidal head.

11. Calculate the minimum required thickness for a std. Torispherical head using

following data: Design Pr = 100 psi, Allowable stress = 17500 psi.

Head Joint efficiency = 1, Corr. Allow = 0.125, Head Crown radius = 96 inch.

12. Calculate design thickness for the Torispherical head in above question.

13. If a horizontal Vessel was made using the above cylindrical shell & the

ellipsoidal heads what will be Vessel MAWP for this vessel? (the static head

due to contents can be ignored for horizontal vessel).


SOLUTION: CASE STUDY 1

DATA: P = 100 psi, R = 48.125 inch, S = 17500 psi, S = 17500 psi, E = 0.85

1. t = PR

SE 0.6 P

t = 100 x 48.125

17500 x 0.85 (0.6 x 100)

= 0.325 required thickness = 0.325 inch

2. Design thickness = required thickness + corrosion allowance

= 0.325 + 0.125 = 0. 450 inch

3. Select next higher step of 1

16

Nominal Thickness = 0.5 inch

4. Shell MAWP = S E t

R + 0.6 t

Here, t = Nominal Thickness corrosion allowance

= 0.5 0.125 = 0.375 inch.

Shell MAWP = 17500 x 0.85 x 0.375 = 115.37 psi

48.125 + (0.6 x 0.375)


5. Hemispherical head thickness

t = PL

2SE 0.2 P

t = 100 x 48.125

2 x 17500 x 1 (0.2 x 100)

= 0.138 Required thickness = 0.138 inch

6. Design thickness = 0.138 + 0.125 = 0.263 inch

7. For Ellipsoidal head

t = PD

2SE 0.2 P

t = 100 x 96.25

2 x 17500 x 1 0.2 x 100

= 0.275 Required thickness = 0.275 inch

8. Design thickness = 0.275 + 0.125 = 0.400

9. Use nominal thickness of dished head after forming.

Use 7/16 inch thickness = 0.4375 inch

10.

MAWP = 2 SET = 2 x 17500 x 1 x 0.3125

D + 0.2 t 96.25 + 0.2 x 0.3125

Here t = nominal thickness C.A. = 0.4375 0.125

= 0.3125 inch


11. For torispherical head t = 0.885 PL

SE 0.1 P

t = 0.885 x 100 x 96.125

17500 x 1 (0.1 x 100)

= 0.486 inch

12. Design Thickness = 0.486 + 0.125 = 0.611 inch

13. Vessel part MAWP for shell = 115.37 psi

Vessel part MAWP for heads = 113.563.psi

Vessel MAWP will be lowest value of vessel part MAWP,

Hence, vessel MAWP = 113.563.psi


CASE STUDY 2 (MAWP Calculations)

Q.1 A vessel is using service fluid with specific gravity = 1. What is the static

head at a location 30 feet from Top of Vessel?

Q. 2 If Vessel in Q. 1 is stamped as Vessel MAWP = 120 psi. What is Total

Pressure at location (a) 30 feet from top of vessel? (b) 50 feet from top of

vessel (sp. qr. of fluid = 1)

Q. 3 After 20 years of service for above vessel, due to corrosion and thickness

reduction, it was found that vessel part MAWP at location 30 ft from top

became 125 psi and the vessel part MAWP at location 50 ft from top became

130 psi. What will be the safe vessel MAWP now?


SOLUTION :CASE STUDY- 2 (MAWP Calculation)

1) Static head = 0.433 x liquid column in feet

0.433 x 30 = 12.99 psi

2) Total Pressure = Vessel MAWP + Static head

(a) For location 50 ft from top

Total pressure = 120 + 12.99

= 132.99 psi

(b) For location 50 ft from top

Total pressure = 120 + 0.433 x 50

= 120 + 21.65

= 141.65 psi.

3) Vessel MAWP = Part MAWP Static head

a) For location 30 ft from top

Vessel MAWP = 125 0.433 x 30

= 125 12.99

= 112.01

b) For location 50 ft from top,

Vessel MAWP = 130 0.433 x 50

= 130 21.65

= 108.35

Out of a) & b) above lower value will give safe Vessel MAWP = 108.35 psi.


CASE STUDY 3 (Pressure Testing)

Following information is taken from vessel data sheet for a new vessel.

Design Pr = 130 psi. Vessel MAWP = 150 psi.

Safe stress at design temperature = 18000 psi

Safe stress at test temperature = 19800 psi

Vessel MDMT = 10o F

Calculate the following Q.1 Hydrostatic Test Pressure

Q. 2 Hydrostatic Test temperature

Q.3 Relief valve set Pressure

Q.4 Pneumatic Test Pressure

Q.5 Pneumatic Test temperature

Q.6 Inspection pressure at which leak check shall be performed for Pneumatic

Test

Q.7 First stage pressure for Pneumatic Test

Q.8 What will be total pressure at the end of fourth step of Pneumatic test?

Q.9 Total 5 pressure gauges with the following ranges are available in the store

0-400 psi, 0-600 psi, 0-800 psi, 0-1000 psi

We need 2 pressure gauges for Pressure test

Which of the two gauges you will choose for Hydrostatic test ?

Q.10 For Pneumatic testing which of the two gauges from the given five gauges you find suitable ?


SOLUTION : CASE STUDY- 3 (Pressure Testing)

1) Hydrostatic Test Pr = 1.3 x MAWP x 19800/18000

= 1.3 x 150 x 1.1

= 214.5 psi

2) Hydrostatic Test temp = MDMT + 30 0 F (Recommended)

= 10 + 30

= 40 0 F

3) Relief Value set Pr = 1 X Test Pr

= 1.333 x 214.5

= 286.0 psi

4) Pneumatic Test Pr = 1.1 x MAWP x 19800/18000

= 1.1 x 150 x 1.1

= 181.5 psi

5) Pneumatic Test Temp (Mandatory) = MDMT + 30 0 F

= 10 +30

= 40 0 F

6) Inspection Pressure = Pneumatic Test Pr

1.1

= 181.5

1.1

= 165 psi

7) First stage Pressure (Pneumatic) = 50% of Test Pr

= 50% of 181.5

= 90.75 psi


8) Pressure at end of fourth stage = 50% + 3 times10% .

= 80% of 181.5

= 145.2 psi

9) For Hydrotest the two gauges are to be selected

Lower limit of range = 1.5 x 214.5 = 321.75 psi

Upper limit of range = 4 x 214.5 = 858 psi

Preferred limit of range = 2 x 214.5 = 429 psi

We can use 3 gauges, 0-400psi, 0-600 psi and 0-800 psi

But Choose the two gauges which are nearest to preferred range

Choose 0-400 psi and 0- 500 psi

10) For Pneumatic testing the two gauges from the given five

Lower limit = 1.5 x 181.5 = 272.25 psi

Upper limit = 4 x 181.5 = 726 psi

Preferred limit of range = 2 x 181.5 = 363 psi

We can use 3 gauges, 0-300 psi, 0-400psi and 0-600 psi But Choose the two gauges which are nearest to preferred range

Choose 0-300 psi and 0-400 psi


CASE STUDY 4 (Assessment for Impact test)

Q.1 A vessel is to be constructed using 1.50 inch thick plates SA 516 Gr 70 Not

normalized. Minimum design metal temperature (MDMT) is 0 0 F. Will you

require impact testing as per Fig. UCS 66 of ASME Sec VIII Div 1?

Q. 2 If the plates in Q. 1 above were normalized. Will impact testing be required

if MDMT is 0 0 F?

Q. 3 If normalized SA 516 Gr 70 plates are used having thickness = 2.5 inch.

MDMT is still 0 0 F. Will you require impact test?

Q.4 A vessel is to be constructed wing 1 inch thick SA 515 Gr. 70 plate material.

MDMT = 60 0 F. Will you specify impact test?

Q. 5 A vessel is made from 1 inch thick plates SA 285 grade C. MDMT = 67 0 F.

Will impact Test be required?

Q.6 A vessel is made from 1 inch thick SA 515 Gr 60 (PN. 1) plates MDMT = 10 0 F. The vessel did not require PWHT as per Code but due to service

requirement, PWHT is to be performed. Is impact testing required?

Q.7 A material having minimum specified yield strength, as 42000 psi was

requiring impact test. Nominal thickness of material is 1 inch during impact

Test impact values reported were

Specimen 1 : 18 ft 1b




Is impact test acceptable?

SOLUTION: CASE STUDY 4 (Assessment for Impact test)

1) In this example Curve B will apply. Referring to Fig UCS 66, the point is

below

the curve, hence Impact Testing is required.

2) New Curve D will apply.

Point lies above curve (thickness = 1.5 & MDMT = 0o F)

Impact test not required.

3) With Thickness = 2.5 inch, MDMT = 0o F & Curve is D

Point lies below curve

Impact test required.

4) Curve A applies

With Thickness = 1 & MDMT = 60o F

Point is below curve.

Impact test required.

5) Curve A applies.

Thickness = 1 MDMT = 67 0 F

The point is close to Curve decision is difficult go to table UCS - 66

For 1 thickness & Curve A, temperature on Curve is 68 0 F. Our MDMT is

less

than 68 0 F impact test required.

6) Curve B applies.

Thickness = 1

Temperature on Curve is 31 0 F (transition temperature)

Due to PWHT (UCS 68 C) a reduction of 30 0 F can be given


Transition temperature now is 31 30 = 1 0 F

Our MDMT = 10 0 F

MDMT is higher than transition temperature.

No impact testing is required.

7) Referring Fig. UG 84.1 & Note b.

Required Average for 3 specimen = 15 ft 1b

Actual average obtained = 18 + 17 + 13 = 48 = 16 ft 1b 3 3

Average obtained, 16 ftlb > 15 ft lb . OK

Minimum for one specimen must be > of Average required = 10 ft/b

Actual minimum for one specimen = 13 ft/b

13 > 10 ft/b -----------------OK

Both criteria of Average & minimum are satisfied Test is accepted.


CASE STUDY 5

(Nozzle Reinforcement Calculation)

A vessel is provided nozzle on the cylindrical shell. Various dimension are as follows (with usual notation) Diameter of finished opening (d) = 4.2 inch, t = 0.8, tr = 0.6, tn = 0.7, tnr = 0.2. Answer questions below : 1) What is Reinforcement limit along vessel wall?

2) What is Reinforcement limit normal to vessel wall?

3) What is total reinforcement area required?

4) What is area available in shell?

5) What is area available in nozzle?


6) Is the nozzle adequately reinforced or will it require additional reinforcing

pad?

SOLUTION: CASE STUDY 5 (Nozzle reinforcement Calculations)

1) Reinforcement limit along the vessel wall = 2d = 2 x 4.2 = 8.4 2) Reinforcement limit normal to vessel wall= 2.5 tn = 2.5 x 0.7 = 1.75 3) Total Reinforcement Area required = dtr = 4.2 x 0.6

= 2.52 sq. inch.

4) Area available in shell = d (t - tr) = 4.2 (0.8 0.6)

= 4.2 x 0.2

= 0.84 sq. inch

5) Area available in nozzle = 5tn (tn- tnr) = 5 x 0.7 x (0.7 0.2)

= 5 x 0.7 x 0.5

= 1.75 sq. inch

6) Total area available in shell & nozzle

0.84 + 1.75

= 2.59 inch

Since Area available (2.59 sq.in.) is greater than area required (2.52 sq.in.)

Nozzle is adequately reinforced.


It does not require separate reinforcement pad.

CASE STUDY 6

(A) External Pressure (UG 28) 1) What will be allowable external pressure for the following?

Is it safe for full Vacuum (15 psi)?

Vessel OD = 96

Vessel thickness = 5/8 (0.625)

Value of Factor A = 0.00022

Value of Factor B = 3000

Corrosion allowance = 1/8

2) For a cylindrical shell having OD = 48,

Shell thickness = 0.5 inch

Corrosion allowance = Nil.

Value of factor A = 0.00015

And value of modules of elasticity = 29 x 106 psi

What is allowable external pressure?

(B) Weld size for openings (UW 16) 1) What will be minimum fillet weld leg dimension for reinforcement

pad to shell weld in sketch a-1 in Fig. UW 16.1 of ASME Code?

Thickness of pad = 0.8 inch. Thickness of shell = 1.

2) What will be the size of fillet weld joining reinforcement pad to

nozzle neck in sketch (h) of Fig. UW 16.1?

The nozzle thickness = 0.5 inch

& reinforcement pad thickness = 0.6 inch.

3) What is throat dimension (tc) required for the fillet weld joining nozzle neck

to shell if shell thickness = 1.2 inch?

Nozzle neck thickness = 1.0


Refer sketch d of UW 16.1

SOLUTION :CASE STUDY- 6

(Miscellaneous Calculations)

(A) Allowable external Pressure is given by 1) Pa = 4B

3 ( Do/ t )

Here Do = 96 inch

t = Net thickness = 5 1 = 1 = 0.5 8 8 2 B = 3000

Pa = 4 x 3000 3 (96/0.5) = 20.8 psi

20.8 > 15 Psi .. safe for full vacuum

2) Here value of B is not available. Allowable external pressure is given

by

Pa = 2AE = 2 x 0.00015 x 29 x 106

3 (Do/t) 3 (48/0.5)

Allowable external pressure= 30.2 psi

(Here t = 0.5, A = 0.00015, E = 29 x 106, Do = 48)


B) 1) Refer Fig. A 1 of UW 16.1 Fillet weld throat dimension = 1 t min 2 t min = Minimum of shell thk, pad thickness & = Minimum of 1, 0.8, 0.75

t min = 0.75 Throat = 1 t min = 1 x0.75 = 0.375 2 2 But throat = 0.707 x leg

leg = Throat = 0.375 = 0.53 0.707 0.707

Minimum leg size = 0.53 2) Refer Fig. h of UW 16.1

throat dimension = 0.7 t min t min = Minimum of 0.5, 0.6, 0.75 t min = 0.5 Throat = 0.7 x 0.5 = 0.35 leg size = Throat = 0.35 = 0.495 0.707 0.707

Minimum leg size = 0.495

3) Refer sketch d of UW 16.1

min t c = smaller of or 0.7 t min but t min = Minimum of 1.2 , 1, 0.75 smaller of or 0.7 x 0.75

= smaller of 0.25 or 0.525 Minimum throat dimension = 0.25


CASE STUDY 7 Numerical in API 510 Code

(A) Following information is available from vessel data sheet & inspection records for a vessel in service. The service in unchanged from 2002 & will continue. Initial thickness = 1.2 inch (1992 May)

First shutdown inspection thickness = 1.1 inch (1997 May)

Second shutdown inspection thickness = 1.05 inch (2002 May)

Current inspection thickness = 0.9 inch (2007 May)

Required thickness = 0.75 inch

Calculate following :

1. Long term corrosion rate

2. Short term corrosion rate

3. What corrosion rate is to be considered of for Remaining life calculation?

4. Calculate Remaining Life.

5. What are next maximum internal & external inspection intervals?

(B) A fillet patch is to be installed on a vessel with vessel ID = 48 inch & vessel

thickness where the patch is to be welded is 3/8. What should be minimum Toe to

toe distance from a similarly welded existing patch?

(C) Calculate corrosion averaging long the for locally corroded areas of

considerable size for following vessels. There is no wind load & there is no

nozzle in corroded area.

Vessel 1, I.D = 32

Vessel 2, I.D = 48

Vessel 3, I.D = 60

Vessel 4, I.D = 90

Vessel 5, I.D = 126


(D) A vessel was constructed with 4 thick SA 516 Gr 70 material (70000 psi

min. tensile strength) there was corroded area having depth = 1.8 inches.

The repair was performed by weld overlay having tensile strength = 60000

psi. What shall be min. build up thickness?

(E) Estimate the maximum permitted next internal & external inspection intervals

for following 4 vessels. All vessels will be in continuous service. No RBI is

performed.

Vessel A, Remaining life = 24 years

Vessel B, Remaining life = 16 years

Vessel C, Remaining life = 8 years

Vessel D, Remaining life = 3 years

(G) A vessel was inspected for thickness measurement. Actual thickness was

found to be 0.86 inch. Next thickness inspection interval is 5 years. Corrosion

rate = 10 mpy. What value of thickness should be used in MAWP calculation ?

(H) Following information is taken from vessel data sheet

Design Pr = 100 psi.

Vessel MAWP = 120 psi.



Vessel MDMT = 10o F.

Vessel thickness = 2 inch.

1. If the above vessel was constructed in 1992, what will be Hydrostatic test

pressure if pressure test was required on it, after major repairs?

2. If the above vessel was constructed in 2002, what will be Hydrostatic test

pressure if pressure test was required on it, after major repairs?

3. What will be the minimum temperature maintained during the Hydrotest ?


SOLUTION : CASE STUDY- 7

(Numericals in API 510 Code) (A) t initial = 1.2 inch (May 1992) t previous = 1.05 inch (May 2002) t actual = 0.9 inch (May 2007) t required = 0.75 inch

1) Corrosion rate (L.T.) = t initial t actual No. of years between t initial & t actual

= 1.2 0.9

15

= 0.020/year = 20 mpy

2) Corrosion rate (S.T.) = t previous t actual No. of years betn t previous & t actual = 1.05 0.9 5 = 0.030/year = 30 mpy 3) S.T. rate reflects current process used S.T. Corrosion rate (30 mpy) for

remaining life calculation.

4) Remaining life = t actual t required/ Corrosion rate = 0.9-0.75 0.030 = 5 years


(5) Next internal inspection = Lower of (1/2 x5) or 10 year

= Lower of 2.5 years or 10 years

= 2.5 years

External inspection = Lower of internal or 5 years

= Lower of 2.5 years or 5years

= 2.5 years

(B) Spacing (d) = 4 RT = 4 48/2 x 3/8

d = 49 = 12 inches.

(C) Vessel 1, L = Lower of ID or 20 (for I. D 60) 2

= Lower of 32 or 20 use 16 inch. 2 Vessel 2, L = Lower of ID or 20 2 = Lower of 48 or 20 use 20 inch. 2 Vessel 3, L = Lower of ID or 20 2 =Lower of 60 or 20. use 20 inch. 2 Vessel 4, L = Lower of ID or 40 (for ID > 60) 3 =Lower of 90 or 40 use 30 inch. 3 Vessel 5, L =Lower of ID or 40 3 =Lower of 126 or 40. use 40 inch. 3


(D) Build up thickness = Repair depth x strength of Base metal

strength of weld metal

= 1.8 x 70000 60000 = 2.1 inch.

(E) Vessel A, Internal = Lower of (Remaining life) or 10 years

= Lower of x 24 or 10

= 10 years.

External = Lower of internal or 5 years

= Lower of 10 years or 5 years

= 5 years.

Similarly for other vessels calculation can be done

Vessel B: Internal = 8 years, External = 5 years

Vessel C: Internal = 4 years, External = 4 years

Vessel D: Internal can be any interval maximum up to 2 years &

external same as internal.

(remaining life is less than 4 years).

F) Thickness (t) = tactual 2 (C.R x Interval)

= 0.86 2 (0.010 x 5)

= 0.86 0.1 = 0.76 inch

G) (1). For Vessel with year of construction 1992,

Hydrostatic test Pr = 1.5 x MAWP x Sat test temp

Sat design temp


= 1.5 x 120 x 19800 = 198 psi 18000

2. For vessel with year of construction 2002,

Hydrostatic test Pr = 1.3 x MAWP x Sat test temp

Sat design temp = 1.3 x 120 x 19800 = 171.6 psi 18000

3) Test temperature = MDMT + 10 deg.F

= 10 + 10 = 20 deg. F




PART V

WPS/POR ROAD-MAP AND REVIEW

No

Start

Is the WPS supported by PQR. Does WPS show

reference No. of the supporting PQR

Has PQR been revised

Is PQR signed and dated

Accept for detailed review

Yes

Yes

No

RR

EE

JJ

EE

CC

TT

Start at Front side of PQR.

For tensile test are qty of specimen, area and unit stress calculation right

Is location of failure stated

Is unit stress > SMTS of base metal

Place WPS & PQR side by side

Yes

No

Is bend test Qty, type stated and correct

Was break in weld metal

Is unit stress > 95% of SMTS of base metal

No

No

No

No

No

Yes

Yes

Is the result stated & OK

No

No Yes

Are results for toughness test (if any) OK

No Yes

Go to tables as follows SMAW - QW 253 SAW QW 254

Check WPS/PQR for QW 402 to QW 410 for the following

WPS: EV, NEV, PQR: EV, Are the documents OK?

Review of WPS/PQR (Road Map)

Do the P, F & A Nos. match with mtl. Spec No & filler AWS No.

Yes

Yes

Yes

No

(QW 451.1)

(QW 153)

(QW 153)

(QW 451.1)

No

Go to back side of PQR.Are the results for tensile, and bend tests stated.

No

Yes

Accept

No

(QW 140)

(QW 163)

(QW 172)

Yes

If the welder is to be qualified on the basis of PQR. Is his Identifying code.

Position of welding recorded on PQR.?

Yes

70 IET/CH/TP/002-R2, Sept. 11


Mistakes in WPS/PQR Documentation.

PQR REVIEW:

A. PQR/2007/011 (Front side):

1. Check P,F and A Nos.P No. 1 is OK, F No. should be 4 instead of 2, A

No. OK

B. PQR (Back Side)

1. No. of Tensile Test Specimen=2 OK. But result of first tensile

specimen(W.M.fracture)is not accepted. Second specimen is OK

2. Bend tests specimen Nos. = 4OK, Test results also OK, but specimen

tested are wrong. They must be 4 side bends for Test coupon

thickness=o.75 inch.

WPS REVIEW:

C. WPS/ 2007/24(Front side)

Check P.No , F No, A No. Change F No. to agree with PQR ( change F no. to

4)

Base metal thickness range shall be= 3/16 inch to 1 inch.

Weld metal thickness range shall be = 0 to 1 inch.

D. WPS (Back side)

Min. Preheat shall be 120 deg.F

PWHT shall be Nil.since PQR is without PWHT.


PART VI

ADDITIONAL INFORMATION

REFERANCE DIAGRAMS & TABLES


TYPICAL IMPACT TESTING APPARATUS


API 510 PREPARATORY COURSE

api 510 prep material.pdf

Documents

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internal pressure

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introduction pressure

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