Asme viii uw-ppt

Fion Zhang/ Charlie Chong

SUBSECTION BREQUIREMENTS PERTAININGTO METHODS OF FABRICATIONOF PRESSURE VESSELSMy Self Study Note

Sub-B


PART UWREQUIREMENTS FOR PRESSURE VESSELSFABRICATED BY WELDING.

UW


PART UWOverview

UW


Vessel

Joint efficiencies, E

Joint type, UW-12 type 1~8

Service limitations? UW-2

RT UW-11

Joint Categories UW-3

How ASME-UW works:

A vessel is to be built, next is to determine the intent of the vessel (UW-2), UW-2 set the limitations on type of joints, and the NDT requirements. Next proceed to UW-12, UW-12 provide a combinations of joint categories and extents of radiographic testing which give the value “E”, the joint efficiency.

UW


0.650.800.90A, B & C(b) Circumferential butt joints with one plate offset; see UW-13(b) (4) and Fig. UW-13.1, sketch (i)

0.650.800.90A, B, C & D(a) None except as in (b) below

•Single-welded butt joint with backing strip other than those included under (1)

2

0.70.851.00A, B, C & D•Butt joints as attained by double-welding or by other means which will obtain the same quality of deposited weld metal on the inside and outside weld surfaces to agree with the requirements of UW-35. Welds using metal backing strips which remain in place are excluded.

1

NoneSpotFull

Degree of RadiographicExamination.

Joint Categories

LimitationsJoint descriptionTypenumber

UW


ASME design codes are built around the idea of a joint efficiency factor denoted by the symbol “E”. The factor “E”appears in the internal pressure equations and depends on:

• The amount of NDE carried out on the weld.

• The weld joint arrangement (single or double groove, etc.).

UW


UW-2 SERVICE RESTRICTIONS.

UW-02


UW-2 gives guidance on which types of pressure vessels / parts haverestrictions on what type of weld should be used for each joint category. The four types of vessels referenced are:

(a) Vessels for lethal service (containing a lethal substance).(b) Low-temperature vessels that require impact testing.(c) Unfired steam boilers.(d) Direct-fired vessels.

UW-02


d

c

b

a

Class

Direct-fired vessels

Unfired steam boilers

Low-temperature vessels that require impact testing

Following key points:• Butt-welded joints must be fully radiographed.• Carbon or low alloy steel vessels need PWHT.• Cat “A” joints need to be type 1(double “V” or

equivalent) welds (the types are given in table UW-12).

• Cat B joints can be either type 1 or type 2 (single “V” with backing strip).

• Cat D joints must be full penetration welds.

vessels are to contain lethal substance.

Service restrictionsDescription.

UW-2 SERVICE RESTRICTIONS

UW-02


Lethal service

Cat. C

Cat. D

Cat. B

Cat. A

UW-2

UW-02

Following key points:1. Butt-welded joints must be fully radiographed.2. Carbon or low alloy steel vessels need PWHT.3. Cat A joints need to be type 1 welds (double

welded) (the types are given in table UW-12).4. Cat B joints can be either type 1 or type 2

(single welded - single V with backing strip).5. Cat D must be full penetration welds.* note1

Vessels are to contain lethal substance.

a

Service restrictionsDescription.UW-2 Class

Note1: For radiography joints only type 1 & 2 are allowed.



UW-3 WELDED JOINT CATEGORY.

UW-03


WELDED JOINT CATEGORYASME VIII pressure vessel welded joints are given a letterdesignation A, B, C or D depending on their location in thevessel.

UW-03


FIG. UW-3 ILLUSTRATION OF WELDED JOINT LOCATIONS TYPICAL OF CATEGORIES A, B, C, and D

UW-03


Cat “A” includes all longitudinal welds and critical circumferential welds such as hemispherical head to shell welds.

Cat “B” includes most circumferential welded joints including formed heads (other than hemispherical) to main shells welds.

Cat “C” includes welded joints connecting: . flanges to nozzles or shell components. one side plate to another in a flat-sided vessel.

Cat “D” includes welded joints connecting nozzles to shells, heads or flat-sided vessels.

UW-03


Cat A includes all longitudinal welds and critical circumferential welds such as hemispherical head to shell welds.

UW-03


Non-hemispherical head

Hemispherical head

UW-03

Critical Circumferential weld:


A

A

A

Hemispherical Heads

UW-03

Critical Circumferential weld:


Cat B includes most circumferential welded joints including formed heads (other than hemispherical) to main shells welds.

UW-03


Cat C includes welded joints connecting: . flanges to nozzles or shell components.

Flange Joint

UW-03


Cat D includes welded joints connecting nozzles to shells, heads or flat-sided vessels.

UW-03


UW-9 DESIGN OF WELDED JOINTS

UW-09


The main content relates to two areas: Taper transitions between welded sections of unequal thickness ‘Stagger’ of longitudinal welds in vessels

UW-09


(c) Tapered transitions requires that tapered transitions must have a taper of at least 3:1 between sections if the sections differ by the smaller of:

more than ¼ of the thickness of the thinner section or 1/8 in. (3.2 mm).

1

3

t2∆t > 1/8 in.

t1

∆t > .25t1.

UW-09


(d) Except when the longitudinal joints are radiographed 4 in. (100 mm) 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.

UW-09


d≥5t

Joint 1

Joint 2d<5t

if d<5t, RT radiographed 4 in. (100 mm) each side of each circumferential welded intersection.

UW-09


staggered or separated by a distance of at least five times the thickness of the thicker plate.

UW-09


UW-11 Radiographic & Ultrasonic Examinations

UW-11

Fion Zhang/ Charlie Chong UW-11

Based on the ASME Code requirement UG-116, manufacturers have to mark the type of RT i.e. RT1, RT2, RT3 and RT4 in the pressure vessel name plate and state the same in Pressure Vessel Data Report.

We have seen many professionals, from inspectors to quality control engineers who are confused between RT1 and RT2, specifically when they see ASME Pressure Vessel Joint Efficiencies for both RT1 and RT2 is the same and equal to 1(E=1).They say both RT1 and RT2 are categorized in the “Full Radiography” part in UW-11 clause ...

So why are some joints in RT2 radiographed in spots? We are making spot radiography, but it is categorized in full radiography!!! So in this "ASME Pressure Vessel Joint Efficiencies" article we want to answer this question in very simple way, but before this, we need review joint categories and summarize them as below:

RT1, RT2, RT3 and RT4


Category A: All longitudinal welds in shell and nozzles All welds in heads, Hemisphere-head to shell weld joint

Category B: All circumferential welds in shell and nozzles Head to shell joint (other than Hemisphere.)

Category C and D are flange welds and nozzle attachment welds respectively.

Longitudinal welds (Category A) are more critical than Circumferential welds (Category B) because they are under doublestress. This the reason why in different part of ASME code we have stringent rules in category A joint compared to category B joint. See the following Fig. for joint categories:


Now let's get back to the ASME Pressure Vessel Joint Efficiencies subject, to remove the above confusion about RT1 and RT2. We need to know: When and where is there a code requirement for full radiography?

Item 1: All butt welds in vessels used to contain a lethal substance (UW-11(a)).Lethal substances have specific definitions in ASME Code in UW-2 and it is the responsibility of the end user to determine if they ordered a vessel that contains lethal substances.

Item 2: All butt welds in vessels in which the nominal thickness at the welded joint exceeds 1 ½ in. (38 mm), or exceeds the lesser thicknesses prescribed in UCS-57,etc. For example, this value for P-No.1 in UCS-57 is 1 ¼ inch.


Item 3: All butt welds in an unfired steam boiler with design pressure > 50 psi (UW-11(a)).

Item 4: All category A and D butt welds in vessel when “Full Radiography” optionally selected from table UW-12(column (a) in this table is selected); and categories B and C which intersect Category A shall meet the spot radiography requirement (UW-11(a) (5) (b)).


The point is this: item 1, 2 and 3 are similar, but item 4 is completely different. In item 1, 2 and 3 it is mandated by code; to do fullradiography in all butt welds in vessel so it means it is mandatory for designer to select column (a) in UW-12 table.

But in item 4, there is no mandating rule. A manufacturer with its own decision has chosen to use column (a) in table UW-12 for full radiography. So here there is a concession or bonus to manufacturers for categories B and C.

RT2- categories B and C which intersect Category “A”shall meet the spot radiography requirement (UW-11(a) (5) (b)), instead of radiography of full length.


4

1,2,3

Item

43

2

1

RT

Optionally selected

Required by code

Note

Partial / No radiography.0.7Spot radiography butt welds.0.85

Category A and D butt welds full length radiography and category B and C butt welds spot Radiography.

1.0

All butt welds-full length radiography.

1.0

Radiography detailsJoint Efficiency (Type-1)

http://www.inspection-for-industry.com/asme-pressure-vessel-joint-efficiencies.html


All butt welds in vessels in which the nominal thickness at the welded joint exceeds 1 ½ in. (38 mm), or exceeds the lesser thicknesses prescribed in UCS-57,etc. For example, this value for P-No.1 in UCS-57 is 1 ¼ inch.

Item 2:

UCS-57 RADIOGRAPHIC EXAMINATIONIn 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.


UCS-57 RADIOGRAPHIC EXAMINATIONIn 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.


UG-116(e4) “RT 4”when only part of the complete vessel has satisfied the radiographic requirements of UW-11(a) or where none of the markings “RT 1,” “RT 2,”or “RT 3” are applicable.

RT 4

UG-116(e3) “RT 3”when the complete vessel satisfies the spot radiography requirements of UW-11(b); or

RT 3

UG-116(e2) “RT 2”when the complete vessel satisfies the requirements of UW-11(a)(5) and when the spot radiography requirements of UW-11(a)(5)(b) have been applied; or

RT 2

UG-116(e1) “RT 1”when all pressure-retaining butt welds, other than Category B and C butt welds associated with nozzles and communicating chambers that neither exceed NPS 10 (DN 250) nor 1 1⁄8 in. (29 mm) wall thickness [except as required by UHT-57(a)],satisfy the full radiography requirements of UW-11(a) for their full length; full radiography of the above exempted Category B and C butt welds, if performed, may be recorded on the Manufacturer’s Data Report; or

RT 1

UW-11


UW-11(a2) all butt welds in vessels in which the nominal thickness [see (g) below] at the welded joint exceeds 1 ½ 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 NPS 10 (DN 250) nor 11⁄8 in. (29 mm)wall thickness do not require any radiographic examination;

UW-11


UW-11(a2) …Categories B and C butt welds in nozzles and communicating chambers that neither exceed

• NPS 10 (DN 250) nor• 1 1/8 in. (29 mm) wall thickness

do not require any radiographic examination;

UW-11


UW-11 RADIOGRAPHIC AND ULTRASONIC EXAMINATIONUW-11 (a) Full Radiography. The following welded joints shall be examined

radiographically for their full length in the manner prescribed in UW-51:

UW-11(a5) 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:

UW-11(a5a) 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;

UW-11(a5b) 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. Spot radiographs required by this paragraph shall not be used to satisfy the spot radiography rules as applied to any other weld increment.

UW-11


UW-11 (a8) 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.

UW-11

This means that even though P-No. 5 for example requires RT in all thicknesses the small/thin nozzles are exempt.


UW-11(a) Full Radiography(1) all butt welds in the shell and heads of vessels used to contain lethal substances. (2) all butt welds in the shell and heads of unfired steam boilers having design pressures

exceeding 50 psi (350 KPa). (3) all butt welds in nozzles, communicating chambers, etc., attached to vessel sections

or heads that are required to be fully radiographed under (1) or (2) above;

• however, except as required by UHT-57(a), Categories B and C butt welds in nozzles and communicating chambers that neither exceed NPS 10 (DN 250) nor 1 1⁄8 in. (29 mm) wall thickness do not require any radiographic examination;

Keywords:contain lethal substancesunfired steam boilers having design pressures exceeding 50 psi

UW-11


Full radiography:

all butt welds in the shell and heads of unfired steam boilers having design pressures exceeding 50 psi (350 KPa).

UW-11


Except as required by UHT-57(a), Categories B and C butt welds in nozzles and communicating chambers that neither exceed NPS 10 (DN 250) nor 11⁄8 in. (29 mm) wall thickness do not require any radiographic examination;

neither exceed NPS10 nor t >11⁄8 in. NO Radiography

UW-11


• all butt welds in vessels in which the nominal thickness at the welded joint exceeds 1 ½ 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 NPS 10 (DN 250) nor 1 1⁄8 in. (29 mm) wall thickness do not require any radiographic examination.

Keywords:Any vessel with welded joint exceeds 1 ½ in. (38mm).

UW-11


Any vessel with welded joint exceeds 1 ½ in.

UW-11


(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).

2

1

Joint Type

0.650.800.90A, B & C

0.650.800.90A, B, C & D

0.70.851.00A, B, C & D

NoneSpotFull


Joint Categories

UW-11


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;

(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. Spot radiographs required by this paragraph shall not be used tosatisfy the spot radiography rules as applied to any other weld increment.

UW-11


(6) all butt welds joined by electrogas welding with any single pass greater than 1 ½ in. (38 mm) and all butt welds joined by electroslag welding;

UW-11


(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.

(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.

UW-11


Full Radiography means UW-11(a-1, a-2, a-3, a-4)- lethal, unfired steam boilers having design pressures exceeding 50 psi and nominal thickness at the welded joint exceeds 1 ½ in. (38 mm).

Radiographically for their full length.

Requirements for spot radiography.

No radiography.

Except as required by UHT-57(a), Categories B and C butt welds in nozzles and communicating chambersthat neither exceed NPS 10 (DN 250) nor 11⁄8 in. (29 mm) wall thickness do not require any radiographic examination;

UW-11


Full Radiography means UW-11 (a-5): non lethal, non unfired steam boilers having design pressures exceeding 50 psi, nominal wall thickness less than 1 ½ in.

Radiographically for their full length.

Requirements for spot radiography.

No radiography.

Except as required by UHT-57(a), Categories B and C butt welds in nozzles and communicating chambersthat neither exceed NPS 10 (DN 250) nor 11⁄8 in. (29 mm) wall thickness do not require any radiographic examination;

UW-11


UW-11(b) Spot RadiographyExcept when spot radiography is required for Category B or C butt welds by (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 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 (DN 250) nor 1 1⁄8 in. (29 mm) wall thickness.

UW-11


Radiographic examination is not required of Category B and C butt welds in nozzles and communicating chambers that exceed neither NPS 10 (DN 250) nor 1 1⁄8 in. (29 mm) wall thickness.

UW-11


(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).


1

NoneSpotFull


Joint Categories


UW-11


When radiography is required for a welded joint in accordance with (a) and (b).

In addition to the requirements in (a) and (b)

ferritic materials

ferritic materials with any single pass greater that 11⁄2 in. (38 mm)

Conditions

ultrasonic examination examined throughout their entire length

Friction

ultrasonic examination examined throughout their entire length

Electron beam

ultrasonic examination examined throughout their entire length and shall be done following the grain refining (austenitizing) heat treatment or postweld heat treatment.

Electrogas

Electroslag

Welding Process

UW-11(d,e,f) Special welding processes.

UW-11


(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.


http://www.mechanicalengineeringblog.com/3635-welding-technology-electro-gas-welding-egw/

UW-11


UW-12 JOINT EFFICIENCIES

UW-12


Weld Types:Here is some clarification about the different type of welds that have specific definitions in ASME Code SEC VIII DIV 1 and related to the pressure vessel RT test.

The concept is to define the different types and then introduce some restriction for using them.

For example, a Type 1 weld is defined as a full penetration weld, typically double welded and Type 2 is welds with backing strips.

So when you go to service restriction for a vessel containing a lethal substance, you see there is a restriction there that says all category A joints shall be weld Type 1 and Category B and C shall be type 1 or type 2.You should take this point in to account, which is this: the same joint category with different weld types have different joint efficiencies.


Summary of weld types:Type 1: Full penetration welds (Typically Double welded).

Type 2: Welds with backing strip.

Type 3: Single welded partial penetration welds.

Type 4, 5 and 6: Various Lap welds (rarely used)


TABLE UW-12MAXIMUM ALLOWABLE JOINT

EFFICIENCIES FOR ARC AND GAS WELDED JOINTS

UW-12





2


1

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Joint Categories


UW-12





2

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Joint Categories


UW-12


0.55NANAB, C [note 3](b) Circumferential joints not over 5/8 in. (16mm) thick.

0.55NANAA(a) Longitudinal joints not over 3/8 in. (10mm) thick

Double full fillet lap joint.4

0.50NANAB(a) Circumferential joints [Note 4 (exclude hemispherical) ] for attachment of heads not over 24 in. (600 mm) outside diameter to shells not over 1⁄2 in. (13 mm) thick.

Single full fillet lap joints with plug welds conforming to

5

0.6NANAA, B, C Circumferential butt joints only, not over 5⁄8 in. (16 mm) thick and not over 24 in. (600 mm outside diameter)

Single-welded butt joint with out used of backing strip.

3

0.50NANAC(b) Circumferential joints for the attachment to shells of jackets not over 5⁄8 in. (16 mm) in nominal thickness where the distance from the center of the plug weld to the edge of the plate is not less than 1 ½ times the diameter of the hole for the plug.

NoneSpotFull


Joint Categories


UW-12


NANANAB, C, DDesign per U-2(g) for Category B and C joints

Angle joints8

NANANAC, D[Note (5)]

As limited by Fig. UW-13.2 and Fig UW-16.

Corner joints, full penetration, partial penetration, and/or fillet welded.

7

0.45NANAA, B (b) for attachment of heads having pressure on either side, to shells not over 24 in. (600 mm) inside diameter and not over 1⁄4 in. (6 mm) required thickness with fillet weld on outside of head flange only.

0.45NANAA, B (a) For the attachment of heads convex to pressure to shells not over 5⁄8 in.(16 mm) required thickness, only with use of fillet weld on inside of shell; or

Single full fillet lap joints without plug welds

6

NoneSpotFull


Joint Categories


UW-12


Summary Maximum Weld Joint Efficiency: Joint Type 1~6


Summary of weld types:

Type 1: Full penetration welds (Typically Double welded)

Type 2: Welds with backing strip

Type 3: Single welded partial penetration welds

Type 4, 5 and 6: Various Lap welds (rarely used)

http://www.inspection-for-industry.com/asme-pressure-vessel-joint-efficiencies.html


Butt joints as attained by double-welding or by other means which will obtain the same quality of deposited weld metal on the inside and outside weld surface. Backing strip, if used, shall be removed after completion of weld.

Single-welded butt joint with backing strip which remains in place after welding.

Single-welded butt joint without backing strip.

Double-full fillet lap joint.

Single-full fillet lap joint with plug welds.

Single-full fillet lap joint without plug welds.

Type 2: For circumferential joint only

Fion Zhang/ Charlie Chong UW

-12


WithillustrationsUW-13 ATTACHMENTDETAILS

TABLE UW-12MAXIMUM ALLOWABLE JOINT

EFFICIENCIES FOR ARC AND GAS WELDED JOINTS

UW-12



1

NoneSpotFull


Joint Categories


UW-12


Weld type number 1: Single “V” with back-gouge.

UW-12





2

NoneSpotFull


Joint Categories


UW-12


0.6NANAA, B, C Circumferential butt joints only, not over 5⁄8 in. (16 mm) thick and not over 24 in. (600 mm outside diameter)

Single-welded butt joint with out used of backing strip.

3

NoneSpotFull


Joint Categories


UW-12


If the type number 3 weld was radiographed the full length, could it be grouped as type 1 weld?

•Butt joints as attained by double-welding or by other means which will obtain the same quality of deposited weld metal on the inside and outside weld surfaces to agree with the requirements of UW-35. Welds using metal backing strips which remain in place are excluded.

1

Joint descriptionTypenumber

UW-12


0.55NANAB, C [note 3](b) Circumferential joints not over 5/8 in. (16mm) thick.

0.55NANAA(a) Longitudinal joints not over 3/8 in. (10mm) thick

Double full fillet lap joint.4

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Joint Categories


UW-12


0.50NANAC

0.50NANAB(a) Circumferential joints [Note 4 (exclude hemispherical) ] for attachment of heads not over 24 in. (600 mm) outside diameter to shells not over 1⁄2 in. (13 mm) thick.

Single full fillet lap joints with plug welds conforming toUW-17

5

NoneSpotFull


Joint Cat.


(b) Circumferential joints for the attachment to shells of jackets not over 5⁄8 in. (16 mm) in nominal thickness where the distance from the center of the plug weld to the edge of the plate is not less than 1 ½ times the diameter of the hole for the plug

UW-12


0.45NANAA, B

0.45NANAA, B (a) For the attachment of heads convex to pressure to shells not over 5⁄8 in.(16 mm) required thickness, only with use of fillet weld on inside of shell; or

Single full fillet lap joints without plug welds

6

NoneSpotFull


Joint Categories


(b) for attachment of heads having pressure on either side, to shells not over 24 in. (600 mm) inside diameter and not over 1⁄4 in. (6 mm) required thickness with fillet weld on outside of head flange only.

UW-12


NANANAB, C, DDesign per U-2(g) for Category B and C joints

Angle joints8

NANANAC, D[Note (5)]

As limited by Fig. UW-13.2 and Fig UW-16.

Corner joints, full penetration, partial penetration, and/or fillet welded.

7

NoneSpotFull


Joint Categories


UW-12


GENERAL NOTES:

(a) The single factor shown for each combination of joint category and degree of radiographic examination replaces both the stress reduction factor and the joint efficiency factor considerations previously used in this Division.

(b) E = 1.0 for butt joints in compression.

NOTES:1. See UW-12(a) and UW-51.2. See UW-12(b) and UW-52.3. For Type No. 4 Category C joint, limitation not applicable for bolted flange

connections.4. Joints attaching hemispherical heads to shells are excluded.5. There is no joint efficiency “E” in the design formulas of this Division for

Category C and D corner joints. When needed, a value of E not greater than 1.00 may be used.

UW-12


(i) Butt Weld With One Plate Edge Offset

NOTES:(1) See UW-13(b)(4) for limitation whenweld bead is deposited from inside.(2) For joints connecting hemispherical headsto shells, the following shall apply:(a) t or t1 = 3/8 in. (10 mm) maximum(b) maximum difference in thickness between t or t1 = 3/32 in. (2.5 mm);(c) use of this figure for joints connecting hemispherical heads to shells shall be noted in the “Remarks”part of the Data Report Form.

UW-12


UW12(d) Seamless vessel sections or heads.


UW12(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 calculationsinvolving 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.


UW12(d) all Category A welds are Type No. 1.

- hemispherical head- Category “A”- non-hemispherical head- Category “B”

E = 1.0 when the spot radiography requirements of UW-11(a)(5)(b) are met. - non-hemispherical head- Category “B” as 11(a)(5)(b) applicable to category “B” and “C” only.

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. - non-hemispherical head- Category “B”


UW-11(a)(5)(b), Category B or C butt welds…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. …


Q. Given a seamless head or shell section, other than a hemispherical head (see UG-32), what is the design efficiency of the seamless section?

A. Paragraph UW-12(d) answers this question with a question, as follows: Was the weld(s) joining the seamless head or seamless shell spot examined per the rules given in UW-11(a)(5)(b)? If yes, the seamless head or shell efficiency is set at 100 percent E=1. If no, the seamless head or shell efficiency will be set at 85 percent E=0.85.

http://www.nationalboard.org/PrintPage.aspx?NewsPageID=144


Q. Given a seamless head or shell section of hemispherical head (see UG-32), what is the design efficiency of the seamless section?

100% RT UW-51, E= 1 ?

Spot RT UW-52, E= 0.85 ?

No RT, E= 0.7 ?


Hemispherical head

100% RT UW-51, E= 1

Spot RT UW-52, E= 0.85

No RT, E= 0.7

Ellipsoidal & Torispherical

Spot RT UW-52, E= 1

No RT, E= 0.85


UW-16 MINIMUM REQUIREMENTS FOR ATTACHMENT WELDS AT OPENINGS.

UW-16

Fion Zhang/ Charlie Chong UW-16UW-16

FIG. UW-16.1 SOME ACCEPTABLE TYPES OF WELDED NOZZLES AND OTHER CONNECTIONS TO SHELLS, HEADS, ETC.UW-16.1 sketches (i), (j), (k), and (l).


These are variables that will apply to the Exam.

t = nominal thickness of vessel shell or head, in.tn= nominal thickness of nozzle wall, in.

• tmin= the smaller of 3/4 in. or the thickness of the thinner of the parts joined by a fillet, single-bevel, or single-J weld, in.

• tc= not less than the smaller of 1/4 in. or 0.7tmin• t1 or t2 = not less than the smaller of 1/4 in. or 0.7tmin• tc= t1 or t2


tc= not less than the smaller of 1/4 in. or 0.7tmin


UW-16.1 sketches (i), (j), (k), and (l).2 conditions to satisfied;

• t1 or t2 ≥ smaller of ¼ in. or 0.7 tmin• t1 + t2 ≥ 1 ¼ tmin ( not applicable to all sketched)

UW-16(d) Neck Attached by Fillet or Partial Penetration Welds(1) Necks inserted into or through the vessel wall may be attached by fillet or

partial penetration welds, one on each face of the vessel wall. The welds may be any desired combination of fillet, single-bevel, and single-J welds.

The dimension of t1 or t2 for each weld shall be not less than the smaller of 1⁄4 in. (6 mm) or 0.7tmin, and their sum shall be not less than 11⁄4tmin. See Fig. UW-16.1 sketches (i), (j), (k), and (l).


Exercise:Problem: A nozzle is being attached to a shell as shown in Fig.UW-16.1 (i)

using two equal size fillet welds. The shell's thickness is 7/8 in. and the nozzle's thickness is 1/2 inch. The fillet welds are 3/8 inch in leg size. Does this meet Code?

tmin = smaller of ¾ in. or ½ in. ( used ½ in. in this case).Fillet throat sizes t1 = t2 = 0.707x0.375 = 0.265 in.

Conditions to satisfied;1. t1 or t2 ≥ ¼ in. or 0.7 tmin ( used 0.25 in. in this case)2. t1 + t2 ≥ 1 ¼ tmin ( equal to 0.625 in.)

Actual;t1 & t2 = 0.265 in. (condition 1 – ok)t1 + t2 = 0.53 in. (condition 2 – Not ok)

Conclusion: the fillet leg sizes are undersized.#


Leg size ≠ throat sizeFillet


FIG. UW-16.1 SOME ACCEPTABLE TYPES OF WELDED NOZZLES AND OTHER CONNECTIONS TO SHELLS, HEADS, ETC.


t = nominal thickness of vessel shell or head tn = nominal thickness of nozzle wall te = thickness of reinforcing plate tw = dimension of attachment welds (fillet, single-bevel or single-J),

measured as shown in figure UW-16.1

tmin = the smaller of ¾ in (19 mm) or the thickness of the thinner of the parts joined by a fillet, single-bevel or single-J weld

tc = not less than the smaller of ¼ in. (6 mm) or 0.7 tmin t1 or t2=not less than the smaller of ¼ in. (6 mm) or 0.7tmin

tw = 0.7tmin (see fig.UW-16.1)tc = t1 or t2=not less than the smaller of ¼ in. (6 mm) or 0.7tmin

UW-16


tmin = the smaller of ¾ in (19 mm) or the thickness of the thinner of the parts joined by a fillet, single-bevel or single-J weld

tc =t1 = t2= not less than the smaller of ¼ in. (6 mm) or 0.7tmin

UW-16


where it meets a set-on nozzle, by a full penetration butt weld plus a fillet weld with minimum throat dimension tw = 0.7tmin

if it does not meet the nozzle. The fillet weld will have a minimumthroat dimension of ½ tmin.

UW-16


Integral reinforcement (also known as self-reinforcement).

UW-16


Q3. ASME VIII section UW-16 (c) figure 16.1(a) A vessel is manufactured from P1 Grade 2 material. It has a shell thickness of 18 mm and is used to contain lethal substances. A set-on (abutting) nozzle of 12 mm thickness is attached using a category D full penetration weld with reinforcing fillet. What is the minimum required throat thickness of the reinforcing fillet weld?

(a) 12 mm (tmin)(b) 8.4 mm (0.7tmin)(c) 6 mm (tc)(d) 12.6 mm

tmin = 12mm (the smaller of 3⁄4 in. (19 mm) or the thickness of the thinner of the parts joined.)tc = 6mm (not less than the smaller of 1⁄4 in. (6 mm) or 0.7tmin)

UW-16


Q4. ASME VIII section UW-16 (c)(2)(c)A vessel has a shell thickness of 3 4 in (19 mm). A set-on (abutting)nozzle of ½ in. (13 mm) thickness is attached using a category D full penetration weld. A reinforcing plate of 1/4 in. (6 mm) is required. What welds will be required to attach the reinforcing plate to the nozzle?

(a) A full penetration weld plus a fillet with a 4.2 mm throat &(b) A full penetration weld plus a fillet with a 6 mm throat &(c) A fillet weld with a 3 mm throat &(d) A full penetration weld plus a fillet with a 3 mm throat &

• tc =4.2 (not less than the smaller of 1/4 in. (6 mm) or 0.7t min.)

• tmin = 6 mm.

UW-16


Q5. ASME VIII section UW-16 (d)(1)A nozzle of NPS 10 (DN 250) is inserted through a vessel wall and protrudes into the vessel by an amount equal to the nozzle thickness. The nozzle thickness is one half of the shell thickness. Which of the following weld combinations are acceptable to attach the nozzle?

(a)Partial penetration groove or fillet weld on inside and outside face(b)Partial penetration groove with reinforcing fillet on outside face(c)Partial penetration groove with reinforcing fillet on inside face(d)Any of the above is acceptable

• t1+ t2≥ 1 ¼ tmin.• t1 or t2 not less

than the smaller of ¼ in. (6 mm) or 0.7tmin.

UW-16


UW-40 PROCEDURES FOR POSTWELD HEAT TREATMENT.


UW-40(f ) The term nominal thickness as used in Tables UCS-56, UCS-56.1, UHA-32, and UHT-56, is the thickness of the welded joint as defined below. For pressure vessels or parts of pressure vessels being postweld heat treated in a furnace charge, it is the greatest weld thickness in any vessel or vessel part which has not previously been postweld heat treated.

See also: UCS-56 REQUIREMENTS FOR POSTWELD HEAT TREATMENT


UW

-40


UW-40(a), the soak band shall contain the weld, heat affected zone, and a portion of base metal adjacent to the weld being heat treated. The minimum width of this volume is the widest width of weld plus 1t or 2 in. (50 mm), whichever is less, on each side or end of the weld.

widest width of weld plus 1t or 2 in. (50 mm), whichever is less

UW-40


Mr. “t” the nominal thickness UW-40(f)

1. it is the greatest weld thickness in any vessel or vessel part which has not previously been postweld heat treated.

2. Same thickness, using a full penetration butt weld, the nominal thickness is the total depth of the weld exclusive of any permitted weld reinforcement.

3. For groove welds, the nominal thickness is the depth of the groove.

4. fillet welds, the nominal thickness is the throat dimension.

5. If a fillet weld is used in conjunction with a groove weld, the nominal thickness is the depth of the groove or the fillet throat dimension, whichever is greater.

UW-40


fillet welds, the nominal thickness is the throat dimension

UW-40


the nominal thickness is the total depth of the weld exclusive of any permitted weld reinforcement

UW-40


The nominal thickness6. When a welded joint connects parts of unequal thicknesses (a) the thinner of two adjacent butt-welded parts including head to shell

connections;

the thinner of two adjacent butt-welded

UW-40


The nominal thickness(b) the thickness of the shell or the fillet weld, whichever is greater, in connections to intermediate heads of the type shown in Fig. UW-13.1 sketch (e);

UW-40


Mr. “t” the nominal thickness

(c) the thickness of the shell in connections to tubesheets, flat heads, covers, flanges (except for welded parts depicted in Fig. 2-4(7), where the thickness of the weld shall govern), or similar constructions;

UW-40


Mr. “t” the nominal thickness(d) in Figs. UW-16.1 and UW-16.2, the thickness of the weld across the nozzle neck or shell or head or reinforcing pad or attachment fillet weld, whichever is the greater;

UW-40


Mr. “t” the nominal thickness

e) the thickness of the nozzle neck at the joint in nozzle neck to flange connections;

f) the thickness of the weld at the point of attachment when a non pressure part is welded to a pressure part;

g) the thickness of the weld in tube-to-tubesheet connections.

UW-40


Nominal thickness Defects

Depth of excavation

(6) For repairs, the nominal thickness is the depth of the repair weld.

UW-40


UW-50 NONDESTRUCTIVE EXAMINATION OF WELDS ON PNEUMATICALLY TESTED VESSELS.


On welded pressure vessels to be pneumatically tested in accordance with UG-100, the full length of the following welds shall be examined7 for the purpose of detecting cracks:

a) all welds around openings;b) all attachment welds, including welds attaching non-pressure parts to

pressure parts, having a throat thickness greater than ¼ in. (6 mm).

Note:7 Examination shall be by magnetic particle or liquid penetrant methods

when the material is ferromagnetic, or by the liquid penetrant method when the material is nonmagnetic.

UW-50


UW-51 RADIOGRAPHIC EXAMINATION OF WELDED JOINTS.

UW-51


• UW-51 (a1) A complete set of radiographs and records, as described in Article 2 of Section V, for each vessel or vessel part shall be retained by the Manufacturer, as follows:

a) films until the Manufacturer’s Data Report has been signed by the Inspector;

b) records as required by this Division (10-13).

Records;(10-13) at least 3 years

RT films; After signing of MDR

MDR


10-13 RECORDS RETENTIONa) The Manufacturer or Assembler shall have a system for the

maintenance of radiographs (UW-51), Manufacturer’s Data Reports (UG-120), and Certificates of Compliance/Conformance (UG-120) as required by this Division.

UW-51


10-13 RECORDS RETENTION

b) The Manufacturer or Assembler shall maintain the documents outlined below for a period of at least 3 years:1. Manufacturer’s Partial Data Reports.2. manufacturing drawings.3. design calculations, including any applicable Proof Test Reports.4. Material Test Reports and or material certifications.5. Welding Procedure Specifications and Procedure Qualification Records.6. Welders Qualification Records.7. RT and UT reports.8. repair procedure and records.9. process control sheets.10.heat treatment records and test results.11.postweld heat treatment records.12.non-conformances and dispositions.13.hydrostatic test records.

UW-51


(c) For manufacturers of UM stamped vessels or vessels constructed under the provisions of UG-90(c)(2) rules, the records listed in (b) above, for six representative vessels per year, shall be maintained as follows:

1. UM stamped vessels for a period of 1 year.2. vessels constructed under the provisions of UG-90(c)(2) rules for a

period of 3 years.

UW-51

ASME certification is symbolized by the “U Stamp” for pressure vessels and “UM Stamp” for miniature pressure vessels.


When do you need full RT

UW-51


UW-11, (a1) all butt welds in the shell and heads of vessels used to contain lethal substances [see UW-2(a)].

UW-51


UW-11, a(2). All materials; welded joint exceeds 1 ½in. (38 mm)

UW-51


UCS-57 RADIOGRAPHIC EXAMINATIONIn 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.

UW-11, a(2)………

UW-51


UW-11 (a3) all butt welds in the shell and heads of unfired steam boilers having design pressures exceeding 50 psi (350 kPa) [see UW-2(c)].

UW-51


UW-11 (a5) 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), ….(RT2)

0.650.800.90A, B & C

0.650.800.90A, B, C & D2

0.70.851.00A, B, C & D1

NoneSpotFull


Joint Categories

Typenumber

UW-51


UW-11 (a6) all butt welds joined by electrogaswelding with any single pass greater than 1½in. (38 mm)

UW-51


UW-11 (a6) ….. all butt welds joined by electroslagwelding;

UW-51


UW-51 (a2) A written radiographic examination procedure is not required. Demonstration of (1) density and (2) penetrameter image requirements on production or technique radiographs shall be considered satisfactory evidence of compliance with Article 2 of Section V.

UW-51

Fion Zhang/ Charlie Chong UW-51A written radiographic examination procedure is not required.


Demonstration of (1) density and (2) penetrameter image requirements on production or technique radiographs shall be considered satisfactory evidence of compliance with Article 2 of Section V.

Density

Penetrameter


Demonstration of (1) density and (2) penetrameter image requirements on production or technique radiographs shall be considered satisfactory evidence of compliance with Article 2 of Section V.


Demonstration of (1) density and (2) penetrameter image requirementson production or technique radiographs shall be considered satisfactory evidence of compliance with Article 2 of Section V.


Repaired weld radiographic testing substituted by UT?

UW-51


• Repaired welding, at the option of the Manufacturer, ultrasonically examined in accordance with the method described in Appendix 12 and the standards specified in this paragraph, provided;

The defect has been confirmed by the ultrasonic examination to the satisfaction of the Authorized Inspector prior to making the repair.

For material thicknesses in excess of 1 in. (25 mm), the concurrence of the user shall be obtained.

This ultrasonic examination shall be noted under remarks on the Manufacturer’s Data Report Form.

Repaired weld radiographic testing substituted by UT?

UW-51


(1) indication characterized as a crack or zone of incomplete fusionor penetration;(2) any other elongated indication on the radiograph which has length greater than:

(a) ¼ in. (6 mm) for t up to ¾ in. (19 mm)(b) ⅓ t for t from ¾ in. (19 mm) to 2 ¼ in. (57 mm)(c) ¾ in. (19 mm) for t over 2 ¼ in. (57mm)

(3) any group of aligned indications that have an aggregate length greater than “t” in a length of 12t, except when the distance between the successive imperfections exceeds 6L where L is the length ofthe longest imperfection in the group;(4) rounded indications in excess of that specified by the acceptance standards given in Appendix 4.

Full

Unacceptable imperfections Degree of RadiographicExamination.

UW-51 (b)

UW-51


UW-51 (b1)

UW-51 (b4)

UW-51

UW-51 (b1) indication characterized as a crack or zone of incomplete fusion or penetration;

Unacceptable imperfections


UW-51 (b1)

UW-51 (b2)

UW-51

UW-51 (b1) indication characterized as a crack or zone of incomplete fusion or penetration;



UW-51 (b2) any other elongated indication on the radiograph which has length greater than:



UW-51 (b2)

UW-51


UW-51 (b1)

UW-51 (b2)

UW-51





UW-51 (b1)

UW-51 (b2)

UW-51

UW-51 (b3) any group of aligned indications that have an aggregate length greater than “t” in a length of 12t, except when the distance between the successive imperfections exceeds 6L where L is the length of the longest imperfection in the group;



UW-51 (b3) any group of aligned indications that have an aggregate length greater than “t” in a length of 12t, except when the distance between the successive imperfections exceeds 6L where L is the length of the longest imperfection in the group;

UW-51


UW-51 (b1)

UW-51 (b4)

UW-51

UW-51 (b4) rounded indications in excess of that specified by the acceptance standards given in Appendix 4.



UW-51 (b4) rounded indications in excess of that specified by the acceptance standards given in Appendix 4.



UW-51 (b1)

UW-51 (b2)

UW-51


http://www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/TechCalibrations/RadiographInterp.htm

UW-51 (b2)

UW-51 (b2)

UW-51


UW-52 SPOT EXAMINATION OF WELDED JOINTS

UW-52


In-progress RT for quality improvement.NOTE: Spot radiographing of a welded joint is recognized as an effective inspection tool. The spot radiography rules are also considered to be an aid to quality control. Spot radiographs made directly after a welder or an operator has completed a unit of weld proves that the work is or is not being done in accordance with a satisfactory procedure. If the work is unsatisfactory, corrective steps can then be taken to improve the welding in the subsequent units, which unquestionably will improve the weld quality.

Spot radiography doe not ensure defect free welds.Spot radiography in accordance with these rules will not ensure a fabrication product of predetermined quality level throughout. It must be realized that an accepted vessel under these spot radiography rules may still contain defects which might be disclosed on further examination. If all radiographically disclosed weld defects must be eliminated from a vessel, then 100% radiography must be employed.


UW-52 (b1) Minimum Extent of Spot Radiographic Examination (1) One spot shall be examined on each vessel for each 50 ft (15 m) increment of weld or fraction thereof for which a joint efficiency from column (b) of Table UW-12 is selected. However, for identical vessels or parts, each with less than 50 ft (15 m) of weld for which a joint efficiency from column (b) of Table UW-12 is selected, 50 ft (15m) increments of weld may be represented by one spot examination.

0.650.800.90A, B & C

0.650.800.90A, B, C & D

2

0.70.851.00A, B, C & D

1

None(b) Spot(a) Full


Joint Categories

Typenumber

Table UW-12 One spot shall be examined on each vessel (or other identical vessels) for each 50 ft (15m) increment of weld.


One spot shall be examined on each vessel (or other identical vessels) for each 50 ft (15 m) increment of weld.

This rule also addresses smaller, often machine welded vessels such as small air receivers. One is picked at random for spot radiography. If it passes, all are approved.


One spot shall be examined on each vessel for each 50 ft (15 m) increment of weld.


UW-52 (b2) 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.


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.

Welder-A

Welder-B

Welder-C


Welder-A

Every welder in a given 50’ increment must have his work radiographed. It can be a individual radiographed or a group picture. Here “welder A” was radiographed alone and welders B & C’s work was examined on the same radiograph.


UW-52 (b3) Each spot examination shall be made as soon as practicable after completion of the increment of weld to be examined. The location of the spot shall be chosen by the Inspector after completion of the increment of welding to be examined, except that when the Inspector has been notified in advance and cannot be present or otherwise make the selection, the Manufacturer may exercise his own judgment in selecting the spots.


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 (c) L=6” min.


UW-52 (b4) 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.

UW-9 DESIGN OF WELDED JOINTS(d) Except when the longitudinal joints are radiographed 4 in. (100 mm) 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.

UW-52

4 in4 in

five times the thickness of the thicker plate



UW-11 (a5b) 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. Spot radiographs required by this paragraph shall not be used to satisfy the spot radiography rules as applied to any other weld increment.

UW-52


UW-14 OPENINGS IN OR ADJACENT TO WELDSUW-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-52

Length equal to three times the diameter of the opening with the center of the hole at mid-length.



UW-52(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. Spot radiographs may be retained or be discarded by the Manufacturer after acceptance of the vessel by the Inspector. The acceptability of welds examined by spot radiography shall be judged by the following standards:

UW-52


UW-52 (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. Spot radiographs may be retained or bediscarded by the Manufacturer after acceptance of the vessel by the Inspector.

discardedSpot radiographic examination films discard after acceptance by the Inspector

UW-52


UW-52 (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. Spot radiographs may be retained or be discarded by the Manufacturer after acceptance of the vessel by the Inspector.

UW-52


Spot radiographs may be retained or be discarded by the Manufacturer after acceptance of the vessel by the Inspector.

UW-52


1. indication characterized as a crack or zone of incomplete fusion or penetration.

2. Welds having indications characterized as slag inclusions or cavities are unacceptable when;

a. the indication length exceeds 2/3 t, where t is defined as shown in UW-51(b)(2).

b. For all thicknesses, indications less than ¼ in. (6 mm) are acceptable, and indications greater than ¾ in. (19 mm) are unacceptable.

c. Multiple aligned indications meeting these acceptance criteria are acceptable when the sum of their longest dimensions indications does not exceed t within a length of 6t (or proportionally for radiographs shorter than 6t), and when the longest length L for each indication is separated by a distance not less than 3L from adjacent indications.

(3) Rounded indications are not a factor in the acceptability of welds not required to be fully radiographed.

Spot

Unacceptable imperfections Degree of RT

UW-52 (c)

UW-52


UW-51 (b2)t = the thickness of the weld excluding any allowable reinforcement. For a butt weld joining two members having different thicknesses at the weld, t is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in t.

UW-52


Spot RT acceptable

Spot RT unacceptable, 2 additional spots in the same increment

Any of the Spot RT unacceptable

Both Spot RT acceptable

the entire weld increment represented the radiographic testing is acceptable

the entire weld increment represented by the three radiographs is unacceptable

UW-52(d) Evaluation and Retests

UW-52



UW-52(d2b) If either of the two additional spots examined shows welding which does not comply with the minimum quality requirements of (c)(1) or (c)(2) above, the entire increment of weld represented shall be rejected.

1. The entire rejected weld shall be removed and the joint shall be re-welded or, at the fabricator’s option,

2. the entire increment of weld represented shall be completely radiographed and only defects need be corrected.

UW-52(d2c) Repair welding shall be performed using a qualified procedure and in a manner acceptable to the Inspector. The reweldedjoint, or the weld repaired areas, shall be spot radiographically examined at one location in accordance with the foregoing requirements of UW-52.

UW-52



UW-52(d a) If the two additional spots examined show welding which meets the minimum quality requirements of (c)(1) and (c)(2) above, the entire weld increment represented by the three radiographs is acceptable provided the defects disclosed by the first of the three radiographs are removed and the area repaired by welding. The weld repaired area shall be radiographically examined in accordance with the foregoing requirements of UW-52.

UW-52



(1)全部拍片,修复或 (2)全部清除,重焊,再次执

行抽样拍片UW-52(d2c)

UW-52

Asme viii uw-ppt

Engineering

Transcript of Asme viii uw-ppt