API 510 Preparatory Class Radiographic and Radioscopic Examination

API 510 Preparatory Class Radiographic and Radioscopic Examination

https://www.hvacmepcontractors.com       API 510 Preparatory Class Radiographic and Radioscopic Examination, Service Restrictions, Spot Examinations of Weld Joints, Joint Efficiencies, 

Objectives

Understand the service restrictions placed on weld joints

based on service conditions.

Identify weld joints by Categories (location in vessel).

Identify welds by Types. (how made, double welded etc.).

Determine the accept/reject values for weld

imperfections located using radiography.

Define the extent of radiography required by Code for a

desired joint efficiency.

Lesson 1

Objectives

Find weld joint efficiency (E) by using Table UW-12.

Determine weld joint efficiencies based on RT markings.

Determine the E to be used for calculating the required

thickness or allowed pressure for Seamless Shell

sections and Seamless heads.

Understand the rules for using welded pipe and tubing.

Lesson 1

(a) When vessels are to contain lethal footnote 1 substances,

either liquid or gaseous, all butt welded joints shall be

fully radiographed, except under the provisions of

UW-2(a)(2) and UW-2(a)(3) below, and UW-11(a)(4).

When fabricated of carbon or low alloy steel, such vessels

shall be postweld heat treated.

footnote 1 1When a vessel is to contain fluids of such a

nature that a very small amount mixed or unmixed with

air is dangerous to life………..

UW-2 Service Restrictions

Page 114 Section VIII

If determined as lethal, ………….

(1) The joints of various categories (see UW-3) shall be as

follows.

(a) Except under the provisions of (a)(2) or (a)(3) below,

all joints of Category A shall be Type No. (1) of Table

UW-12.

(b) All joints of Categories B and C shall be Type No. (1)

or No. (2) of Table UW-12.

UW-2 Service Restrictions

Type 1

Double Welded butt joint

or equivalent. Backing if

used must be removed.

Type 2

Single welded

butt joint with

backing which

remains in place.

These are the only two types which are

considered acceptable for radiography by Section

VIII Div.1

(a)

.

The term “Category” as used herein defines the location

of a joint in a vessel, but not the type of joint.

(1) Category A. Longitudinal welded joints within the main

shell, communicating chambers, transitions in diameter,

or nozzles; any welded joint within a sphere, within a

formed or flat head, or within the side plates of a flatsided

vessel; circumferential welded joints connecting

hemispherical heads to main shells, to transitions in

diameters, to nozzles, or to communicating chambers.

(2) Category B. Circumferential welded joints within the

main shell, communicating chambers, nozzles, or

transitions in diameter including joints between the

transition and a cylinder at either the large or small end;

circumferential welded joints connecting formed heads

other than hemispherical to main shells, to transitions in

diameter, to nozzles, or to communicating chambers.

UW-3 Welded Joint Category Page 115

(3) Category C. Welded joints connecting flanges, Van

Stone laps, tubesheets, or flat heads to main shell, to

formed heads, to transitions in diameter, to nozzles, or to

communicating chambers any welded joint connecting one

side plate to another side plate of a flat sided vessel.

(4) Category D. Welded joints connecting communicating

chambers or nozzles to main shells, to spheres, to

transitions in diameter, to heads, or to flat-sided vessels,

and those joints connecting nozzles to communicating

chambers (for nozzles at the small end of a transition in

diameter, see Category B).

UW-3 Welded Joint Category

(b) When butt welded joints are required elsewhere in this

Division for Category B, an angle joint connecting a

transition in diameter to a cylinder shall be considered as

meeting this requirement provided the angle a (see Fig.

UW-3) does not exceed 30 deg. All requirements pertaining

to the butt welded joint shall apply to the angle joint.

UW-3 Welded Joint Category

 

One important note:

Hemispherical heads form a Category A joint between

themselves and the other part, shell another hemispherical

head etc.

Hemispherical Heads are Never considered Seamless by

Code rules. The Category A weld made by attaching the

Hemispherical Head to shell is considered part of the Head

for calculation purposes.

Later on in this lesson we begin our discussion of formed

Seamless Heads. The formed heads on the exam that are

considered seamless are Torispherical and Ellipsoidal,

Hemispherical is not seamless by Code.

UW-3 Welded Joint Category

UW-2 Service Restrictions

1. Which of the following types of welds are required if a

vessel is determined to be in lethal service?

a. Category A and B welds shall be of Type 1.

b. Category A and B welds must be of Type 1 or 2.

c. Category A shall be of Type 1 only, B and C can be of

Type 1or Type 2.

2. Label these welds by Type.

__________ __________

Class Quiz

UW-2 Service Restrictions

1. Which of the following types of welds are required if a

vessel is determined to be in lethal service?

c. Category A shall be of Type 1 only, B and C can be of

Type 1or Type 2.

2. Label these welds by Type.

Type 1 Type 2

Class Quiz

UW -3 Welded Joint Category

1. The category of a joint depends on:

a. What kind of weld was made, fillet or butt.

b. The process used to make the weld.

c. Whether it is vertical or horizontal in the

vessel

d. None of the above.

2. A circumferential weld to attach a flange is what

Category?

a. D

b. C

c. E

d. A

Class Quiz

UW -3 Welded Joint Category

1. The category of a joint depends on:

d. None of the above.

2. A circumferential weld to attach a flange is what

Category?

b. C

Class Quiz

UW -3 Welded Joint Category

3. A circumferential weld used to attach a seamless head

is of what Category?

a. B

b. C

c. E

d. A

4. The circumferential weld to attach a Hemispherical head

to a shell is a Category ____.

Class Quiz

UW -3 Welded Joint Category

3. A circumferential weld used to attach a seamless head

is of what Category?

a. B

4. The circumferential weld to attach a Hemispherical head

to a shell is a Category A .

Class Quiz

5. Label these weld joints by Category

A,B, C or D

5. Label these weld joints by Category

(a) All welded joints to be radiographed shall be examined in

accordance with Article 2 of Section V except as specified

below.

(1) A complete set of radiographs and records, ……shall be

retained by the Manufacturer until the Manufacturer’s Data

Report has been signed by the Inspector.

(2) The Manufacturer shall certify that personnel have

been qualified and certified in accordance with their

employer’s written practice…… SNT-TC-1A shall be used as a

guideline.

UW-51 Radiographic and Radioscopic Examination

of Weld Joints Page 152

…Alternatively, the ASNT Central Certification Program

(ACCP), or CP-189 may be used to fulfill the examination

and demonstration requirements of SNT-TC-1A and the

employer’s written practice.

(3) A written radiographic examination procedure is not

required. Demonstration of density and penetrameter

image requirements on production or technique

radiographs shall be considered satisfactory evidence of

compliance…..

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

(4) The requirements of T-285 of Article 2 ….used only a

guide. Final acceptance of radiographs shall be based on

the ability to see the prescribed penetrameter image and the

specified hole or the designated wire of a wire penetrameter.

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

(b) Indications shown on the radiographs of welds and

characterized as imperfections are unacceptable under the

followingconditions and shall be repaired as provided in

UW-38, and the repair radiographed to UW-51 or, at the

option of the Manufacturer, ultrasonically examined in

accordance with the method described in Appendix 12….

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

(1) any indication characterized as a crack or zone of

incomplete fusion or penetration ;

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

(1) any indication characterized as a crack or zone of

incomplete fusion or penetration ;

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

(1) any indication characterized as a crack or zone of

incomplete fusion or penetration ;

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

(2) any other elongated indication on the radiograph which

has length greater than:

(a) 1/4 in. for t up to 3/4 in.

(b)1/3t for t from 3/4 in. to 2-1/4 in.

(c) 3/4 in. for t over 2-1/4 in.

Where;

t = the thickness of the weld excluding any allowable

reinforcement.

UW-51 Radiographic and Radioscopic Examination

For a butt weld joining two members having different

thicknesses at the weld, t is the thinner of these two

thicknesses. Since the value of t must be the lesser thickness

this decreases the size of the maximum acceptable

indication.

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

(3) any group of aligned indications that have an

aggregate (total) length greater than t in a length of 12t,..

Example: t = 1” total length (L) cannot exceed 1” in 12”

Also individual lengths cannot exceed the following:

(b)1/3t for t from 3/4 in. to 2-1/4 in. * In this example none

of the individual indications can exceed 1/3 x 1” = 1/3” (.333”

)

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

(3) ..except when the distance between the successive

imperfections exceeds 6L where L is the length of the

longest imperfection in the group; * This means that if the

two groups are isolated from each other they can be

evaluated separately within a length of 12t.

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

(4) rounded indications in excess of that specified by the

acceptance standards given in Appendix 4.

Example from Appendix 4: More on this during the Section V

Coverage.

UW-51 Radiographic and Radioscopic Examination

of Weld Joints

1. All welded joints to be radiographed shall be examined in

accordance with _______of Section _____except as

otherwise specified.

2. A complete set of radiographs and records, shall be

retained by the Manufacturer until the Manufacturer’s

Data Report has been signed by the____________.

a. Manufacturer

b. Inspector

c. Manufacturer and Inspector

3. While reviewing a radiograph an elongated indication was

found to have a length of .375” in a .750” thick plate weld.

This indication is Rejectable because the maximum

allowed is _______ for this thickness.

Class Quiz

UW-51 Radiographic and Radioscopic Examination of

Weld Joints

1. All welded joints to be radiographed shall be examined in

accordance with Article 2 of Section V except as

otherwise specified.

2. A complete set of radiographs and records, shall be

retained by the Manufacturer until the Manufacturer’s

Data Report has been signed by the Inspector.

3. While reviewing a radiograph an elongated indication was

found to have a length of .375” in a .750” thick plate weld.

This indication is Rejectable because the maximum

allowed is .250” for this thickness.

Solutions

UW-51 Radiographic and Radioscopic Examination of Weld

Joints

4. The welded joint below was radiographed and found to

have an elongated indication that was .243” in length.

The maximum allowable length of an indication for this

combination of thicknesses is ______ and this weld

considered _______________.

a. 1/3 t and this weld is considered acceptable.

b. 1/4 in. and this weld is considered acceptable.

c. 1/4 in. and this weld is considered rejectable.

Class Quiz

Radiographic and Radioscopic Examination of Weld Joints

4. The welded joint below was radiographed and found to

have an elongated indication that was .243” in length.

The maximum allowable length of an indication for this

combination of thicknesses is 1/4” and this weld

considered acceptable.

b. 1/4 in. and this weld is considered acceptable.

Class Quiz

Radiographic and Radioscopic Examination of Weld Joints

5. The length L, of the longest imperfection in the figure

below is .259”. Based on this value the largest imperfection

is _________ and since the aggregate (total) length is .504”

that is __________ but the weld is____________.

a. acceptable - also acceptable - acceptable

b. unacceptable - also unacceptable -rejectable

c. unacceptable – acceptable - rejectable

Class Quiz

Radiographic and Radioscopic Examination of Weld Joints

5. The length L, of the longest imperfection in the figure

below is .259”. Based on this value the largest imperfection

is unacceptable and since the aggregate (total) length is .

504” that is acceptable but the weld is rejectable.

a. acceptable - also acceptable - acceptable

b. unacceptable - also unacceptable -rejectable

c. unacceptable – acceptable - rejectable

Class Quiz

Radiographic and Radioscopic Examination of Weld Joints

6. What is the minimum distance D, between these two

groups of aligned imperfections for the groups to be

evaluated separately?

a. 7.5”

b. 1.872”

c. .312”

Class Quiz

Radiographic and Radioscopic Examination of Weld Joints

6. What is the minimum distance D, between these two

groups of aligned imperfections for the groups to be

evaluated separately?

b. 1.872”

Class Quiz

Radiographic and Radioscopic Examination of Weld Joints

(b) Minimum Extent of Spot Radiographic Examination

(1) One spot shall be examined on each vessel for each 50

ft increment of weld or fraction thereof for which a joint

efficiency from column (b) of Table UW-12 is selected.

However, for identical vessels, each with less than 50 ft of

weld for which a joint efficiency from column (b) of Table

UW-12 is selected, 50 ft increments of weld may be

represented by one spot examination.

UW-52 Spot Examinations of Weld Joints

Page 153

(b) Minimum Extent of Spot Radiographic Examination

(1) One spot shall be examined on each vessel for each 50

ft increment ……..

* The idea of this rule is that each 50’ increment is to be a

hold point for approval, the next increment is not to be

started until the previous one has been accepted. The

drawing below is the simplest case, you will not see this

often.

UW-52 Spot Examinations of Weld Joints

 

(2) For each increment of weld to be examined, a

sufficient number of spot radiographs shall be taken to

examine the welding of each welder or welding operator.

Under conditions where two or more welders or welding

operators make weld layers in a joint, or on the two sides of

a double-welded butt joint, one spot may represent the work

of all welders or welding operators.

(3) Each spot examination shall be made as soon as

practicable…... The location of the spot shall be chosen by

the Inspector,… except that when the Inspector cannot be

present or otherwise make the selection, the fabricator may

exercise his own judgment in selecting the spots.

UW-52 Spot Examinations of Weld Joints

(2) For an increment of weld to be examined, a sufficient

number of spot radiographs shall be taken to examine the

welding of each welder or welding operator. ………

* Every welder in a given 50’ increment must have his work

radiographed. It can be a individual photo (radiograph) or a

group picture. Here welder A was radiographed alone and B

& C’s work was examined on the same radiograph.

UW-52 Spot Examinations of Weld Joints

W e ld e r A

A lo n e

(4) Radiographs required at specific locations to satisfy the

rules of other paragraphs, such as UW-9(d), UW-11(a)(5)(b),

and UW-14(b), shall not be used to satisfy the requirements

for spot radiography.

Note: UW-11(a)(5)(b), will be covered in depth later in this

lesson.

UW-52 Spot Examinations of Weld Joints

UW-9(d)

(d) Except when the longitudinal joints are radiographed 4 in.

each side of each circumferential welded intersection,

vessels made up of two or more courses shall have the

centers of the welded longitudinal joints of adjacent

courses staggered or separated by a distance of at least five

times the thickness of the thicker plate.

* Longitudinal Welds Aligned must be radiographed for at

least 4 inches on each side of the joint.

UW-52 Spot Examinations of Weld Joints

UW-14(b) Single openings meeting the requirements given in

UG-36(c)(3) may be located in head-to-shell or Category B or

C butt welded joints, provided the weld meets the

radiographic requirements in UW-51 for a length equal to

three times the diameter of the opening with the center of

the hole at mid-length. Defects that are completely removed

in cutting the hole shall not be considered in judging the

acceptability of the weld. ** UW-51, not 52 to grade film.

* UG-36 (c)(3) addresses small opening which do not require

reinforcement calculations.

UW-52 Spot Examinations of Weld Joints

Summary

The special radiography requirements given in UW-9 (d),

UW-11(a)(5)(b) and UW-14 (b) cannot be substituted for any

of the spot radiography required by UW-52.

* We will see why this is significant when we commence our

studies of “Joint Efficiencies” later.

UW-52 Spot Examinations of Weld Joints

(c) Standards for Spot Radiographic Examination.

Spot examination by radiography shall be made in

accordance with the technique prescribed in UW-51(a). The

minimum length of spot radiograph shall be 6 in.

(c)(3) Rounded indications are not a factor in the

acceptability of welds that are not required to be fully

radiographed.

UW-52 Spot Examinations of Weld Joints

 (d) Evaluations and Retests

When a spot, radiographed as required in (b)(1) or (b)(2)

above has been examined and the radiograph discloses

welding which does not comply……….The locations shall

be determined by the Inspector… if the two additional

pass, repair the failed spot, if either of the two additional

spots fail the entire rejected weld shall be removed and

the joint re-welded or the entire increment completely

radiographed and all defects corrected.

UW-52 Spot Examinations of Weld Joints

(d) Evaluations and Retests

When a spot, radiographed as required in (b)(1) or (b)(2)

above has been examined and the radiograph discloses

welding which does not comply……..two additional spots

shall be examined at locations away from the original spot.

UW-52 Spot Examinations of Weld Joints

(d) Evaluations and Retests

…The locations shall be determined by the Inspector… if

the two additional pass, repair the failed spot, ….

UW-52 Spot Examinations of Weld Joints

(d) Evaluations and Retests

…, if either of the two additional spots fail the entire

rejected weld shall be removed and the joint rewelded or

the entire increment completely radiographed and all

defects corrected.

UW-52 Spot Examinations of Weld Joints

(d) Evaluations and Retests

…, if either of the two additional spots fail the entire

rejected weld shall be removed and the joint rewelded or

the entire increment completely radiographed and all

defects corrected.

1. Minimum number of Spot Radiographs is/are __spot (s),

this rule must be applied on each vessel for each _____ ft

increment of weld or fraction thereof for which a joint

efficiency from column (b) of Table UW-12 is selected.

2. Who shall choose the location of Spot Radiographs?

a. The manufacturer and the Inspector will agree on the

locations.

b. The manufacturer or the Inspector depending on the type

of welds made.

c. The Inspector shall choose unless he is not available and

then the Manufacturer may do so.

Class Quiz

Spot Radiography

1. Minimum number of Spot Radiographs is one spot, this

rule must be applied on each vessel for each 50 ft

increment of weld or fraction thereof for which a joint

efficiency from column (b) of Table UW-12 is selected.

2. Who shall choose the location of Spot Radiographs?

c. The Inspector shall choose unless he is not available and

then the Manufacturer may do so.

Class Quiz

Spot Radiography

3. In the drawing below the total number of spot

radiographs needed to meet the minimum requirements

is/are ____?

* Keep in mind the goal is to Radiographically Test every

welder’s work in a 50’ increment.

Class Quiz

Spot Radiography

3. In the drawing below the total number of spot

radiographs needed to meet the minimum requirements

are 2.

* Keep in mind the goal is to Radiographically Test every

welder’s work in a 50’ increment.

Class Quiz

Spot Radiography

(a) Full Radiography. The following welded joints shall be

examined radiographically for their full length ….

(1) all butt welds in the shell and heads of vessels used to

contain lethal substances [see UW-2(a)];

* Remember, UW-2(a) demands that in lethal service the

welds be of Type 1 for Category A and must be of either

Type1 or 2 for Categories B and C.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints Page 117

Type 1 Type 2

Lethal Service

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

Full Radiography

(a) Full Radiography. The following welded joints shall be

examined radiographically for their full length ….

(2) all butt welds in vessels in which the nominal thickness

[ see (g) below] at the welded joint exceeds 1-1/2 in. (38mm),

or exceeds the lesser thicknesses prescribed in UCS-57…. *

This paragraph is on the examination.

(g) For radiographic and ultrasonic examination of butt

welds, the definition of nominal thickness at the welded

joint under consideration shall be the nominal thickness of

the thinner of the two parts joined. Nominal thickness is

defined in 3-2.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints Page 117

(c) nominal thickness – …….For plate material, the nominal

thickness shall be, at the Manufacturer’s option, either the

thickness shown on the Material Test Report {or material

Certificate of Compliance [UG-93(a)(1)]} before forming, or

the measured thickness of the plate at the joint or location

under consideration.

* Information only this is not on the exam.

From Mandatory Appendix 3

Definitions

(a) Full Radiography. The following welded joints shall be

examined radiographically for their full length ….

(2) all butt welds in vessels in which the nominal thickness

[see (g) below] at the welded joint exceeds 1-1/2 in. (38 mm),

or exceeds the lesser thicknesses prescribed in UCS-57,

UNF-57, UHA-33, UCL-35, or UCL-36 for the materials

covered therein, or as otherwise prescribed in UHT-57,

ULW-51, ULW-52(d), ULW-54, or ULT-57; however, except as

required by UHT-57(a), Categories B and C butt welds in

nozzles and communicating chambers that neither exceed

NPS10 nor 1-1/8 in. (29 mm) wall thickness do not require

any radiographic examination;

* If none of the rules in the paragraphs above apply then use

the default thickness of 1-1/2”.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints Page 117

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

This means that;

If the material of construction is not one of those referenced

UW-11(a)(2) then the default value for the thinner thickness

exceeded becomes 1-1/2”. Since the API 510 examination is

restricted to UCS materials (carbon and low alloy steels) this

rule will be demonstrated using a Carbon Steel that is

classified as a P-Number 1.

Turn now to page 187 of Section VIII

UCS-57

Section VIII Page 187

From paragraph UCS-57:

In addition to the requirements of UW-11, complete

radiographic examination is required for each butt welded

joint at which the thinner of the plate or vessel wall

thicknesses at the welded joint exceeds the thickness limit

above which full radiography is required in Table UCS-57.

Section VIII Page 187

UCS-57

For P No.1 materials the thinner of the two must exceed 1.25”

The girth weld at the 1.25 to 1.5” joint and all above it are

exempt.

(3) all butt welds in the shell and heads of unfired steam

boilers ………Steam Boilers are NOT on the Exam.

(4) all butt welds in nozzles, communicating chambers, etc.

, attached to vessel sections or heads that are required to

be fully radiographed under (1) or (3) above; however, .....

Categories B and C butt welds in nozzles and

communicating chambers that **neither exceed NPS 10

(DNS 250) nor 1-1/8 in. (29mm) wall thickness do not

require any radiographic examination;

** This only applies to circumferential welds in small (NPS

10 / 1-1/8” thick.) nozzles and chambers. Longitudinal

seams are not exempted by this rule.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

(5) all Category A and D butt welds in vessel sections and

heads where the design of the joint or part is based on a

joint efficiency permitted by UW - 12(a), in which case:

(a) Category A and B welds connecting the vessel

sections or heads shall be of Type No. (1) or Type No. (2) of

Table UW-12; * Just means they must be radiographable.

(b) Category B or C butt welds [but not including those in

nozzles or communicating chambers except as required in

(2) above] which intersect the Category A butt welds in

vessel sections or heads or connect seamless vessel

sections or heads shall, as a minimum, meet the

requirements for spot radiography in accordance with

UW-52.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

(5) all Category A and D butt welds in vessel sections

and heads where the design of the joint or part is based on a

joint efficiency permitted by UW - 12(a), in which case:

* This paragraph is only mandatory when it is desired by the

designer to use the highest joint efficiency possible for

calculations of thickness required or pressure allowed.

It is a choice the designer makes when there are no

mandatory requirements based on service or material as

found in UW-11 (a) (1)*Lethal Service, (2)*Thickness

exceeded

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

1. In the drawing below the paragraph that applies is;

a. UW-11(a)(1) Lethal Service

b. UW-11(a)(2) Thickness limit exceeded

c. UW-11(a)(5) The desire to take E from Column A of Table

UW-12

Class Quiz

UW-11 Radiographic and Ultrasonic Examinations

2. In the drawing below the paragraph that applies is;

a. UW-11(a)(1) Lethal Service

b. UW-11(a)(2) Thickness exceeded

c. UW-11(a)(5) Design using E from Col. A Table UW-12

Class Quiz

UW-11 Radiographic and Ultrasonic Examinations

(6) all butt welds joined by… electrogas welding is not on

the exam.

7) ultrasonic examination in accordance with UW- 53 may

be substituted for radiography for the final closure seam of a

pressure vessel if the construction of the vessel does not

permit interpretable radiographs in accordance with Code

requirements. The absence of suitable radiographic

equipment shall not be justification for such substitution.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

(8) exemptions from radiographic examination for certain

welds in nozzles and communicating chambers as

described in (2), (4), and (5) above take precedence over the

radiographic requirements of Subsection C of this Division.

Note: This means that even though P-No. 5 for example requires RT in all

thicknesses the small/thin nozzles are exempt.

(b) Spot Radiography. Except as required in (a)(5)(b) above,

butt welded joints made in accordance with Type No. (1) or

(2) of Table UW-12 which are not required to be fully

radiographed by (a) above, may be examined by spot

radiography. Spot radiography shall be in accordance with

UW-52. * If full RT is not mandatory Spot Radiography done

because the the designers choose it.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

If spot radiography is specified for the entire vessel,

radiographic examination is not required of Category B and

C butt welds in nozzles and communicating chambers that

exceed neither NPS 10 nor 1-1/8 in. wall thickness

(c) No Radiography. Except as required in (a) above, no

radiographic examination of welded joints is required when

the vessel or vessel part is designed for external pressure

only, or when the joint design complies with UW-12(c).

* The designer can choose not to do RT if there is no

mandatory requirement such as lethal, thickness, or desire

for a higher joint E.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

Before starting shell and head calculations let’s have a look

at the types of welds and the weld joint efficiencies that

apply based on the amount of radiography applied.

These E values are found on Table UW-12 of Section VIII

Division 1.

* The following is a simplification for the API Exam, it does

not reflect all of the possible combinations of radiography,

weld types and the resulting joint efficiencies.

UW-12 Radiographic and Ultrasonic

Examinations of Weld Joints

Table UW-12 gives the joint efficiencies E to be used in the

formulas of this Division for joints completed by an arc or

gas welding process. Except as required by UW-11(a)(5), a

joint efficiency depends only on the type of joint and on the

degree of examination of the joint and does not depend on

the degree of examination of any other joint.

(a) A value of E not greater than that given in column (a)*

of Table UW-12 shall be used in the design calculations for

fully radiographed butt joints [seeUW-11(a)], except that

when the requirements of UW-11(a)(5) are not met, a value

of E not greater than that given in column (b) of Table UW-12

shall be used. * Known as Full Radiography

So now we are sent back to UW-11(a)(5)…….

UW-12 Joint Efficiencies Page 119

UW-11(a)(5) all Category A and D butt welds in vessel

sections and heads where the design of the joint or part is

based on a joint efficiency permitted by UW -12(a), in which

case:

(a) Category A and B welds connecting the vessel sections

or heads shall be of Type No. (1) or Type No. (2) of Table

UW-12; * (simply means it can be radiographed)

(b) Category B or C butt welds [but not including those in

nozzles or communicating chambers except as required in

(2) above *(excludes small/thin nozzles)] which intersect the

Category A butt welds in vessel sections or heads or

connect seamless vessel sections or heads shall, as a

minimum, meet the requirements for spot radiography in

accordance with UW-52.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints Page 117

Background

UW-11(a)(5) This rule is pointed toward Code manufacturers

who buy parts from other “Code Shops” and basically

assemble a vessel. The concern is as follows;

Code Shop A buys a rolled and welded shell from Code

Shop B, Shop B fully radiographs the Type 1 weld and the

shell part will be delivered to Shop A with a joint E of 1.0.

which is essentially equal to a seamless shell.

Code Shop A welds on two seamless formed heads. Unless

Shop A performs at least Spot RT on the Category B welds

connecting the heads to the shell there will have been no

radiographic testing of Code Shop A’s welders. A graphical

representation follows.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints Page 117

UW-11(a)(5)

Example 1: The longitudinal seam weld is of Type 1. It has

received Full RT at Code Shop B. Shop A has not performed

the required Spot RT on the head to shell welds.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

UW-11(a)(5)

Example 2: Now the Spot RT has been performed by Shop B.

Therefore and E = 1.0 is allowed for the shell.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

UW-11(a)(5) So this means that Shop A cannot simply weld

the heads, nozzles etc. and never do any radiographic

testing of the Shop A welders. To make things consistent

this rule applies even if the entire vessel is made by one

Code Shop.

So no matter what the circumstances this Spot RT must be

performed to take a joint efficiency from Col. A of to Table

UW-12 for seamed shell course.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints Page 117

UW-11(a)(5)

Example 3: One last comment. On the shop floor these two

shells both have the potential for a Joint E of 1.0 . You will

see this again in UW-12(d) Seamless Shells and Heads.

UW-11 Radiographic and Ultrasonic

Examinations of Weld Joints

S e a m e d S h e l l C o u r s e T y p e 1 F u l l R T

S e a m l e s s S h e l l C o u r s e

(b) A value of E not greater than that given in *column (b)

of Table UW-12 shall be used in the design calculations for

spot radiographed butt welded joints [see UW-11(b)].

* Known as Spot Radiography

(c) A value of E not greater than that given in * column (c)

of Table UW-12 shall be used in the design calculations for

welded joints that are neither fully radiographed nor spot

radiographed [see UW-11(c)]. * No Radiography

Now let’s examine the first three Types listed on Table

UW-12 and examine the joint types, the amount of

radiography and the resulting Joint Efficiencies.

UW-12 Joint Efficiencies

 

1. A Type 1 weld has received Spot Radiographic Testing

the resulting Joint E _______?

a. 1.0

b. 0.80

c. 0.85

2. A Type 3 weld can be spot radiographed.

___True ___False

3. A Type 2 weld has been Fully Radiographed, the Weld

Joints E is ______.

a. 0.85

b. 0.90

c. 0.80

Class Quiz

UW-12 Joint Efficiencies

1. A Type 1 weld has received Spot Radiographic Testing

the resulting Joint E _______?

c. 0.85

2. A Type 3 weld can be spot radiographed.

___False

3. A Type 2 weld has been Fully Radiographed, the Weld

Joints E is ______.

b. 0.90

Class Quiz

UW-12 Joint Efficiencies

4. A Type 2 weld has received Spot Radiographic Testing

resulting in a Joint E of 0.80, this E could be improved to a

1.0 by _____________________.

a. applying full radiography

b. removing the backing and double welding and then

applying Spot RT.

c. removing the backing, double welding thus creating a

Type 1, and then applying Full RT.

Class Quiz

UW-12 Joint Efficiencies

4. A Type 2 weld has received Spot Radiographic Testing

resulting in a Joint E of 0.80, this E could be improved to a

1.0 by _____________________.

c. removing the backing, double welding thus creating a

Type 1, and then applying Full RT.

Class Quiz

UW-12 Joint Efficiencies

Next we will discuss Nameplate RT markings and how to

determine the joint E to be used in the thickness or pressure

calculations to follow. These RT markings and their

descriptions are found in paragraph UG-116 on page. We will

now discuss these accompanied by graphical

representations.

Joint Efficiencies based on RT Marking

"RT 1" when all pressure retaining butt welds, other than B

and C associated with nozzles and communicating

chambers that neither exceed NPS 10 nor 1-1/8 inch

thickness have been radiographically examined for their full

length in a manner prescribed in UW 51, full radiography of

the above exempted Category B and C butt welds if

performed, may be recorded…...

Joint Efficiencies based on RT Marking

"RT 2" Complete vessel satisfies UW-11(a)(5) and UW-

11(a)(5)(b) has been applied. The spot RT rules of UW-52

must be applied to the spot RT and the Full RT rules of

UW-51 to the long seams. So the 50’ increments apply and

all welders in that increment must be examined by

radiography.

Joint Efficiencies based on RT Marking

"RT 2" Complete vessel satisfies UW-11(a)(5) and

UW- 11(a)(5)(b) has been applied.

This is the second Case of RT 2 resulting in E = 1.0, again the

rules of UW-52 apply.

Joint Efficiencies based on RT Marking

"RT 3" Complete vessel satisfies spot radiography of

UW-11(b). The simplest example, one welding operator and

only three radiographs in 122’ of weld. The following

assumes Type 1 welds for all weld seams.

Joint Efficiencies based on RT Marking

"RT 4" When only part of the vessel satisfies any of the

above. * Only part of the vessel has been radiographed due

to a thickness limit being exceeded as listed in UCS 57 or

the desire to use E = 1.0 .

Joint Efficiencies based on RT Marking

The next consideration are the shells and heads of vessels

which are considered seamless. The Efficiencies used to

calculate these vessel parts are not found on Table UW-12

but are instead listed in paragraph UW-12(d).

UW-12 Joint Efficiencies

(d) Seamless vessel sections or heads shall be considered

equivalent to welded parts of the same geometry in which

all Category A welds are Type No. 1.

For calculations involving circumferential stress in

seamless vessel sections or for thickness of seamless

heads, E=1.0 when the spot radiography requirements of

UW-11(a)(5)(b) are met. E= 0.85 when the spot radiography

requirements of UW-11(a)(5)(b) are not met, or when the

Category A or B welds connecting seamless vessel sections

or heads are Type No. 3, 4, 5, or 6 of Table UW-12.

UW-12 Joint Efficiencies

(d) Seamless vessel sections or heads shall be considered

equivalent to welded parts of the same geometry in which

all Category A welds are Type No. 1. For calculations

involving circumferential stress in seamless vessel sections

or for thickness of seamless heads, E = 1.0 when the spot

radiography requirements of UW-11(a)(5)(b) are met.

* Note this rule applies to the Code Shop A and B issue.

UW-12 Joint Efficiencies

(d) Seamless vessel sections or heads shall be considered

equivalent to welded parts of the same geometry in which

all Category A welds are Type No. 1. For calculations

involving circumferential stress in seamless vessel sections

or for thickness of seamless heads, E=1.0 when the spot

radiography requirements of UW-11(a)(5)(b) are met.

UW-12 Joint Efficiencies

(d) Seamless vessel …………. E= 0.85 when the spot

radiography requirements of UW-11(a)(5)(b) are not met, or

when the Category A or B welds connecting seamless

vessel sections or heads are Type No. 3, 4, 5, or 6 of Table

UW-12.

* 3 to 6 are can not be radiographed by Code rules.

UW-12 Joint Efficiencies

(e) Welded pipe or tubing shall be treated in the same

manner as seamless, but with allowable tensile stress taken

from the welded product values of the stress tables, and the

requirements of UW-12(d) applied.

* If the spot RT is applied use E = 1.0, if not E = 0.85

UW-12 Joint Efficiencies

••

For the purposes of choosing joint efficiencies when doing

vessel section or head calculations on the API 510

Examination the following can be said.

RT 1

Full Use 1.0 if joints are of Type 1 or 0.90 if Type 2

RT 2

Case 1: Use 1.0 with Seamless Heads and Shells

Case 2: Seamed Shells/Seamless Heads

Shells Use 1.0 if joints are Type 1or if Type 2 Use 0.90

Use 1.0 for seamless heads

UW-12 Joint Efficiencies

RT 3

Use 0.85 if Joints are of Type 1 or 0.80 if of Type 2

Use 0.85 for Seamless heads

RT 4

* Special case of selective radiography *

Use Table UW-12 based on Joint Type and RT described in

the exam question.

No RT

Go to Table UW-12 and look up the E to be used for the type

of weld under consideration.

Case1: Type 1 Use 0.70

Case 2: Type 2 Use 0.65

Seamless heads use 0.85 Per UW-12(d)

UW-12 Joint Efficiencies

Remember that there only two (2) joint efficiencies possible

for Seamless Shell and Seamless Heads they are;

1.0 or 0.85

1.0 when the rules of UW-11(a)(5)(b) have been applied

(UW-52 Spot RT applied).

0.85 when the rules have not been applied.

(UW-52 Spot RT not applied)

DO NOT GO TO TABLE UW-12 FOR THE E TO USE IN

SEAMLESS HEADS OR SEAMLESS SHELLS

UW-12 Joint Efficiencies