asme viii div. 1- 2 joint efficiency
DESCRIPTION
ASME VIII Div. 1- 2 Joint Efficiency pptTRANSCRIPT
Cairo Inspection Company
Eng. Ibrahim Eldesoky
ASNT –NDT-LEVEL III
ASME AUTHORIZED INSPECTOR
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Session Objectives
Determine when to apply a joint efficiency "E" in pressure vessel design calculations. Review and understand the terms joint "category“ and "type". Determine the correct "E" value based on joint type and degree of radiography. Review ASME stamping requirements when radiography is performed. Solve sample problems
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Referenced Code Paragraphs
UG-27 Shells under internal under pressure. UG-32 Formed heads, pressure on the concave side. UW-3 Welded joint category. Figure UW-3 Illustration of Welded Joint Location. UW-12 Joint efficiencies Table UW-12 Maximum allowable joint efficiencies UG-116(e) Required marking (nameplates or direct stamping)
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UG-27 Thickness of Shells Under
Internal Pressure
An efficiency value "E" applies only to shells
under internal pressure.
Shell in tension Shell in compression
Pressure
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E = joint efficiency for, or the efficiency of
appropriate joint in cylindrical or
spherical shells, or the efficiency of
ligaments between openings, whichever
is less.
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E = lowest efficiency of any joint in
the head; for hemispherical heads,
this includes head-to-shell joint compression tension Pressure
Convex Concave
UG-32 Formed Heads and
Sections,
Pressure on the Concave Side
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Example: Vessel subject to internal pressure
Convex Head Concave Head
UG-32 Formed Heads and
Sections,
Pressure on the Concave Side
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The term Category as used herein
defines the location of a joint in a vessel,
but not the type of joint.
Categories are assigned based on the
type and degree of stresses imposed at
various locations within a vessel.
Joints included in each category are
designated as A, B, C or D.
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(a) Category A Longitudinal joints within the main shell, communicating
chambers (eg. sumps), transitions in diameter, or nozzles, any joint in a sphere, formed or flat head or side plates in
flat sided vessels, circumferential welded joints connecting hemispherical
heads to shells, nozzles, or to communicating chambers.
(b) Category B Circumferential welded joints within the main shell,
communicating chambers or transitions in diameter, circumferential welded joints connecting formed heads
other than hemispherical to main shells, transitions in diameter, to nozzles, or to communicating chambers.
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Head attachment Category A joint
examples
any joint in a sphere hemi head to shell
Category B joint
Cylindrical
straight flange
(skirt) formed head other than hemi
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(c) Category C
Welded joints connecting flanges, Van Stone laps,
tube sheets, or flat heads to:
main shells, 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.
(d) Category D
Welded joints connecting communicating chambers
or nozzles to: main shells, spheres, transitions in
diameter, to heads, flat sided vessels, and nozzles to
communicating chambers
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8 Joint types are identified.
Type 1 has the highest efficient, type 6 has the
lowest efficient. Types 7 and 8 have no assigned
efficiency.
Types 1 through 3 are butt joints, types 4 through
6 are lap joints. Type 7 is a corner joint and 8 is an
angle joint.
Only type 1 and 2 butt joints may be radiographed
in order to improve efficiency.
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Joint Types
Examples: Type 1, Butt welded, both sides must be
visible
Examples: Type 2, butt welded with backing
Fig. UW-13.1 sketch (k)
"joggle joint" backing left in place
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Examples: Type 3, single welded butt welded
without backing
not viewed internally -eg. small diameter pipe or
assemblies with space or visibility restrictions
Examples: Type 4, double full fillet lap joint
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Examples: Type 5, single full fillet lap joints
with plug welds
Plug Weld
Examples: Type 6,single full fillet lap joint
without plug welds
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UW-12 Joint Efficiencies
Table UW-12 gives the joint efficiencies "E" to be used
in the formulas of this Division for joints completed by
gas or an arc welding process.
Except as required by UW-11(a)(5), a joint efficiency
depends only on the type of joint and the degree of
examination of the joint and doesn't depend on the
degree of examination of any other joint.
The user or his designated agent [U-2(a)] shall
establish the type of joint and the degree of
examination when the rules of this Division do not
mandate specific requirements.
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(a) full radiography
(b) spot radiography
(c) no radiograph
(d) seamless pressure vessel
sections and heads
(e) welded pipe or tubing
(f) welds completed by pressure
welding processes
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UW-12(b) Spot radiography
Per column (b) of Table UW-12
Performed per UW-52* [see UW-11(b)]
* Minimum one film (at least 6 inches long) per
welder for each 50 foot increment of deposited weld
metal.
UW-12(c) No Radiography
Per column (c) of Table UW-12
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UW-12(f) Pressure Welding Processes
A value of E not greater than 0.80 for welds
completed by any of the pressure welding
processes listed in UW-27(a).
UW-12( a) Full Radiography
Use the efficiency specified in column (a) of
Table UW12, except when the requirements of
UW-11(a)(5) are not met, a value not greater
than that listed in column (b) of Table UW-12
shall be used.
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UW-11(a)(5) applies to all Category A or D butt welds in
vessel sections and heads designed per UW-12(a), in which
case:
(a) Category A and B welds connecting vessel sections
or heads shall be Type 1 or 2 of Table
(b) Category B or C butt welds which intersect 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 per UW 2.
UW-52(b)(4) Radiographs required at specific locations
to satisfy the rules of other paragraphs, such as UW-9(d),
UW11(a)(5)(b). and UW-14(b), shall not be used to satisfy
the rules for spot radiography.
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UW-12(a) Full Radiography
Use column (a) of Table UW-12, except when UW-
11(a)(5) is not met, use column (b) of Table UW-12.
UW 12(d) Seamless Vessel Sections and Heads
are considered equivalent to welded parts of the same
geometry, in which and all Category A welds are type 1.
Formed head
other than hemi Hemi head
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UW-12(d) can't... For calculations involving circumferential
stress in vessel sections or for the thickness of seamless
heads, E = 1.0 when the spot radiography requirements of UW
11(a) (5)(b) are met, or 0.85 when they are not met.
Formed head
other than hemi Hemi head
UW-11(a)(5)(b) spot RT performed, E= 1.0
UW-11(a)(5)(b) spot RT not met, E= 0.85
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UW-12(e) Welded pipe or tubing* shall be treated in the
same manner as seamless, but with the allowable tensile
stress taken from the welded product values of the stress
tables, and the requirements of UW-12(d) applied.
* Manufactured in accordance with a material
specification permitted by this Division, not fabricated by
the vessel manufacturer as a vessel part. (eg. ERW pipe)
Welded, but treated
like seamless
[UW-12(d)]
UW-11(a)(5)(b) spot RT performed, E= 1.0
UW-11(a)(5)(b) spot RT not met, E= 0.85
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UG-116(e) Required Marking
When a vessel has been radiographed in
accordance with UW-11, marking shall be
applied under the Code symbol
as follows:
RT-1
RT-2
RT-3
RT-4
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UG-116(e) Required Marking
RT-l, Full radiography of all pressure retaining butt welded
joints, except Category B & C butt welds in nozzles and
communicating chambers that neither exceed IMPS 10
(DN 250) nor 1-1/8 in. (29mm).
RT-2, when the complete vessel satisfies the
requirements of UW 11(a)(5) and when spot RT rules of
UW 11(a)(5)(b) have been applied.
Formed head,
Other than
Hemi
Hemi head
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UG-116(e) Required Marking
RT-3, when the complete vessel satisfies the spot
radiography rules of UW-11(b).
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
Formed head,
Other than
Hemi
Hemi head
Formed head,
Other than
Hemi
Hemi head
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