Basics of ASME Section VIII Division 1
Pressure Vessels
Structure & Usage of
The Code Book
For
BEGINNERS
This guide is exclusively prepared for training purpose. Relevant specifications, codes &
special requirements of specific project are to be referred for more detailed information
during construction. Examples provided are only for the purpose of illustration.
The objective is to be familiar with Basic / Fundamental concepts of the code.
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ASME Code
Definitions:
Specify
To State or Describe something
clearly and exactly.
Pressure
Vessel
U-1(a)(2) For the scope of this
Division, pressure vessels are
containers for the containment of
pressure, either internal or
external. This pressure may be
obtained from an external source, or
by the application of heat from a
direct or indirect source, or any
combination thereof.
Construction
An all inclusive term comprising
materials, design, fabrication,
examination, inspection, testing,
certification and pressure relief.
Mandatory
describes something which must be
done, or which is demanded by law
A S M E
American Society of Mechanical Engineers
Code Books: New issuance every 3 Years
Edition 2007: White pages (
loose-leaf format)
Addenda 2008:
Pink Pages (
replacement)
Addenda 2009:
Blue Pages (
replacement)
Edition 2010:
White pages ……..and so on
Contents:
(1) Mandatory requirements,
(2) Specific prohibitions
(2) Non-mandatory guidance
Interpretations:
ASME’s written replies to inquiries concerning
interpretation of technical aspects of the Code.
Issued semi annually (July and Dec) as
separate document.
CODE CASES:
Proposed additions and revisions to the Code.
(to clarify the intent of existing requirements)
or
.
The ASME Code Books
Sec I
Power Boilers
Sec II
Part A
Materials : Ferrous
Ref
Part B
Materials : Non Ferrous
Ref
Part C
Materials : Filler & Electrodes
Ref
Part D
Material Properties (US ) or (Metric)
Ref
Sec III
Rules for Construction of Nuclear Facility
Components
Sec IV
Heating Boilers
Sec V
Nondestructive Examination
Ref
Sec VI
Care and Operation of Heating Boilers
Sec VII
Care of Power Boilers
Sec VIII
Div 1
Pressure Vessels
Div 2
Alternative Rules - Pressure Vessels
Div 3
Alternative Rules – High Pressure Vessels
Sec IX
Welding and Brazing Qualifications
Ref
Sec X
Fiber-Reinforced Plastic Pressure Vessels
Sec XI
In-service Inspection of Nuclear Power Plant
Components
Sec XII
Construction and Continued Service of
Transport Tanks
The Sec VIII Div 1 Code Book
Foreword
Statement of Policy
Personnel
Summary of Changes
Introduction - U
Mandatory Appendix – Arabic Numerals
Non Mandatory Appendix – Alphabets
S.I Units
Index
Total Pages 40+675 = 715 (incl. front back cover)
Edition 2007
Sub section
A
General
Requirements
Sub section
B
Method of
Fabrication
Sub section
C
Classes of
Materials
Unfired Vessel:
U
General :
U
G
Welding :
UW
Carbon Steel:
UCS
……..and so on
Title
0
mm
4
mm
7
mm
12
mm
15
mm
SCOPE
U-1
U-1(a)
U-1(a)(1)
(a)
(1)
Numeric-(Alphabetic)-(Numeric)
(Alphabetic)
(Numeric)
The Code does not address all aspects of these activities and those aspects which
are not specifically addressed should not be considered prohibited.
The Code is not a handbook and cannot replace education, experience, and the use of engineering judgment. The phrase engineering judgment refers to technical judgments made by knowledgeable designers experienced in the application of
the Code.
Engineering judgments must be consistent with Code philosophy and such judgments must never be used to overrule mandatory requirements or specific
prohibitions of the Code.
The Code does not fully address tolerances. When dimensions, sizes, or other parameters are not specified with tolerances, the values of these parameters are considered nominal and allowable tolerances or local variances may be considered acceptable when based on engineering judgment and standard practices as determined by the designer.
Vessel Scope by application
:
U-1(c)(2)
Vessels not included
Listed U-1(c)(2) : (a) Thro (j)
Pressure below 3000 psi (in General)
Vessel scope by geometry: U-1(e)
First girth weld (Circumferential joint)-by welding
First threaded joint – for screwed connection
Face of First Flange – by bolting
Including covers – for Manholes
Code accepted Referenced editions : U-3
Sub Section A
PART UG :
General Requirements
(Common for Sub section B and C)
Materials
UG 4 - UG 15
Design
Openings
Stay
Ligament
Fabrication
Inspection & Tests
Marking & Reports
Pr Relief
Figures
Tables
Fill Here !
Excercise
Example: SA 516 Grade 70 (SA 516M Grade 485)
UTS
= 70,000 PSI
SMYS
= 38,000 PSI
S
(allowable stress used in design for Temperature upto 500°F) = 20,000 PSI[Page 16 of Sec II Part D – U.S Customary]
F.S
= 38 / 20
= 1.9
U-4: UNITS OF MEASUREMENT
For any single equation, all variables shall be expressed in a single system of units. When separate equations are provided for U.S. Customary and SI units, those equations must be executed using variables in the units associated with the specific equation.
70,000 PSI
= 482.633 MPa
485 - 482.633
= 2.367
2.367 MPa
= 343 PSI !!!
1 MPa = 145.0377 PSI
ThereforeDo not mix two system of units in calculations.
Sec II Part D ( The stress values) is issued in two versions
U.S Customary & Matric/S.I 70,000 PSI (70 KSI) UTS 485 MPa (70 KSI) UTS Metric
Basic approach of design
axial stress,
σ
a, sometimes called the longitudinal stress tangential stress,
σ
t, also referred to as the hoop or circumferential stress radial stress,σ
r . . . all of which are taken to be positive tensile.Cylinders are usually considered to be either thick - in which stress
concentration due to relative curvature is significant - or thin in which
stress concentration is negligible. Other differences are :
Thin
Thick
Limiting proportions (approx)
D
i/t > 20
D
i/t < 25
Analytic treatment
simple approximation
accurate
Statically determinate
yes
no
Stress state
membrane - ie.
biaxial
triaxial
Stress - radial, σ
rzero
varies with radius
- tangential, σ
tuniform
varies with radius
- axial, σ
auniform
uniform
σ
c = p Di/ 2 t (Circumferential Hoop stress acting on Long seam weld )
σ
l= p D
i/ 4 t (Longitudinal stress acting on cir seam weld)
Conclusion:
Cir seam weld is TWICE stronger than Long seam weld when subjected to pressure.
Therefore
Long seams are Category A : Cir seams are Category B
Basic Formula : σ
c= p D
i/ 2 t; therefore t = p R
i/
σ
cCode Formula: t = (
p R
i)/ (SE-0.6p) :
σ
c =S = allowable stress
pressure = 250 PSI (p) Radius (int) = 32 inch
Stress allowable = 20,000 PSI (SA 516 Gr 70) Basic Formula Code Formula
t= 0.4” (10.16 mm) t= 0.403” (10.24 mm) if FULL RT (E=1.0) t= 0.475” (12.06 mm) if SPOT RT (E=0.85) t= 0.578” (14.67 mm) if NO RT (E=0.7)
UG-32: FORMED HEADS, AND SECTIONS, PRESSURE ON CONCAVE SIDE
All formed heads concave to pressure and intended for butt welded attachment
need not have an integral skirt when the thickness of the head is equal to or less
than the thickness of the shell. When a skirt is provided, its thickness shall be at
least that required for a seamless shell of the same inside diameter.
Flat spot on head max allowable diameter
UG-32 (o) UG-34 Formula (1), C=0.25
UG-37:
REINFORCEMENT REQUIRED FOR OPENINGS IN SHELLS AND FORMED
HEADS
UG-80:
PERMISSIBLE OUT-OF-ROUNDNESS OF CYLINDRICAL, CONICAL,
AND SPHERICAL SHELLS
(Internal pressure)
UG-93:
INSPECTION OF MATERIALS
(a) Except as otherwise provided in UG-4(b), UG-10, UG-11, or UG-15,
requirements for acceptance of materials furnished by the material
manufacturer or material supplier in complete compliance with a material
specification of Section II shall be as follows.
(1) For plates,2 the vessel Manufacturer shall obtain the material
test report or certificate of compliance as provided for in the
material specification and the Inspector shall examine the Material
Test Report or certificate of compliance and shall determine that it
represents the material and meets the requirements of the
material specification.
(2) For all other product forms, the material shall be accepted as
complying with the material specification if the material
specification provides for the marking of each piece with the
specification designation, including the grade, type, and class if
applicable, and each piece is so marked.
UG-99:
STANDARD HYDROSTATIC TEST
(g) Following the application of the hydrostatic test pressure, an
inspection shall be made of all joints and connections. This
inspection shall be made at a pressure not less than the test
pressure divided by 1.3. Except for leakage that might occur at
temporary test closures for those openings intended for welded
visual inspection. Leakage from temporary seals shall be directed
away so as to avoid masking leaks from other joints.
Static head of water : 0.433 psi for every feet of height.
UG-102:
TEST GAGES
(b)
Dial indicating pressure gages used in testing shall be
graduated over a range of about double the intended
maximum test pressure, but in no case shall the range be less
than 11⁄2 nor more than 4 times that pressure. Digital
reading pressure gages having a wider range of pressure may
be used provided the readings give the same or greater
degree of accuracy as obtained with dial pressure gages.
UG-116:
REQUIRED MARKING
“
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 11⁄8 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 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 3
” when the complete vessel satisfies the spot radiography requirements of UW-11(b); or“
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.Sub Section B
PART UW :
Welding Requirements
UW-2:
SERVICE RESTRICTIONS
(a)
When vessels are to contain lethal1 substances, either liquid
or gaseous, all butt welded joints shall be fully
radiographed, except…….
UW-3:
WELDED JOINT CATEGORY
UW-11:
RADIOGRAPHIC AND ULTRASONIC EXAMINATION
(a)
Full Radiography
(b)
Spot Radiography.
(c)
No Radiography
UW-12:
JOINT EFFICIENCIES
UW-33:
ALIGNMENT TOLERANCE
Joint Categories
Thickness (mm)
A
B, C, & D
Up to 13, incl.
¼ t
¼ t
Over 13 to 19, incl.
3 mm
¼ t
Over 19 to 38, incl.
3 mm
5 mm
Over 38 to 51, incl.
3 mm
⅛ t
Over 51 Lesser of 1⁄ 16t or 10mm Lesser of ⅛ t or 19 mmUW-51:
RADIOGRAPHIC EXAMINATION OF WELDED JOINTS
(1) any indication characterized as a crack or zone of incomplete fusion or penetration;
(2) any other elongated indication on the radiograph which has length greater than:
(a) 1⁄4 in. (6 mm) for t up to 3⁄4 in. (19 mm)
(b) 1⁄3t for t from 3⁄4 in. (19 mm) to 21⁄4 in. (57 mm) (c) 3⁄4 in. (19 mm) for t over 21⁄4 in. (57 mm)
where
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.
(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 of the longest imperfection in the group;
(4) rounded indications in excess of that specified by the acceptance standards given in Appendix 4.
R
A
A
R
A
R
R
R
R
UW-52:
SPOT EXAMINATION OF WELDED JOINTS
1 spot in 50 feet RT
(1) any indication characterized as a crack or zone of incomplete fusion or penetration;
(2) Elongated > 2/3 t (thinner); ∑l >t in 6t …..; 19 max, 6 on any t..
(3) Rounded indications are not a factor in the acceptability of welds
not required to be fully radiographed.
Rectify original repair All weld is accepted
Remove entire weld and reweld… Or
Sub Section C
PART UCS :
Material Requirements
UCS-6:
STEEL PLATES
(b) Steel plates conforming to SA-36, SA/CSA-G40.21 38W, and SA-283 Grades A, B, C, and D may be used for pressure parts in pressure vessels provided all of the following requirements are met:
(1) The vessels are not used to contain lethal substances, either liquid or gaseous.
(2) The material is not used in the construction of unfired steam boilers [see U-1(g)].
(3) With the exception of flanges, flat bolted covers, and stiffening rings, the thickness of plates on which strength welding is applied does not exceed 5⁄8 in. (16 mm).
UCS-56:
REQUIREMENTS FOR POSTWELD HEAT TREATMENT
TABLE UCS-56POSTWELD HEAT TREATMENT REQUIREMENTS FOR CARBON AND LOW ALLOY STEELS
Material Normal Holding Temperature, °F (°C), Minimum
Minimum Holding Time at Normal Temperature for Nominal Thickness [See UW-40(f)]
Up to 2 in.
(50 mm) Over 2 in. to 5 in.(50 mm to 125 mm) Over 5 in. (125 mm)
P-No. 1
Gr. Nos. 1, 2, 3 1,100 (595)
1 hr/in. (25 mm), 15 min minimum
2 hr plus 15 min for each additional inch (25 mm) over 2 in. (50 mm)
2 hr plus 15 min for each additional inch (25 mm) over 2 in. (50 mm)
Gr. No. 4 = not applicable None None None
NOTES:
(1) When it is impractical to postweld heat treat at the temperature specified in this Table, it is permissible to carry out the postweld heat treatment at lower temperatures for longer periods of time in accordance with Table UCS-56.1. (2) Postweld heat treatment is mandatory under the following conditions:
(c) for welded joints of all thicknesses if required by UW-2, except postweld heat treatment is not mandatory under the conditions specified below: (1) for groove welds not over ½in. (13 mm) size and fillet welds with a
throat not over ½in. (13 mm) that attach nozzle connections that have a finished inside diameter not greater than 2 in. (50 mm), provided the connections do not form ligaments that require an increase in shell or head thickness, and preheat to a minimum temperature of 200°F (95°C) is applied;
(2) for groove welds not over 1⁄2 in. (13 mm) in size or fillet welds with a throat thickness of 1⁄2 in. (13 mm) or less that attach tubes to a tubesheet when the tube diameter does not exceed 2 in. (50 mm). A preheat of 200°F (95°C) minimum must be applied when the carbon content of the tubesheet exceeds 0.22%.
(3) for groove welds not over 1⁄2 in. (13 mm) in size or fillet welds with a throat thickness of 1⁄2 in. (13 mm) or less used for attaching nonpressure parts to pressure parts provided preheat to a minimum temperature of 200°F (95°C) is applied when the thickness of the pressure part exceeds 11⁄4 in. (32 mm);
(4) for studs welded to pressure parts provided preheat to a minimum temperature of 200°F (95°C) is applied when the thickness of the pressure part exceeds 11⁄4 in. (32 mm);
(5) for corrosion resistant weld metal overlay cladding or for welds attaching corrosion resistant applied lining (see UCL-34) provided preheat to a minimum temperature of 200°F (95°C) is maintained during application of the first layer when the thickness of the pressure part exceeds 11⁄
4 in. (32 mm).
UCS-57:
RADIOGRAPHIC EXAMINATION
TABLE UCS-57THICKNESS ABOVE WHICH FULL RADIOGRAPHIC EXAMINATION OF BUTT WELDED JOINTS IS MANDATORY
P-No. & Group No. Classification of Material
Nominal Thickness Above Which Butt Welded Joints Shall Be Fully Radiographed, in. (mm) 1 Gr. 1, 2, 3 11⁄ 4(32) 3 Gr. 1, 2, 3 3⁄4 (19) 4 Gr. 1, 2 5⁄8 (16) 5A Gr. 1, 2 0 (0) 5B Gr. 1, 2 0 (0) 5C Gr. 1 0 (0) …….and so on
LOW TEMPERATURE OPERATION
UCS-66:
MATERIALS
FIG. UCS-66.2 DIAGRAM OF UCS-66 RULES FOR DETERMINING LOWEST MINIMUM DESIGN METAL TEMPERATURE (MDMT) WITHOUT IMPACT TESTING
Establish nominal thickness [Note (1)] of welded parts, non welded parts, and attachments under consideration both before and after corrosion allowance is deducted (tn and tn – c, respectively), and other pertinent data applicable to the nominal thickness such as:
All applicable loadings [Note (2)] and coincident minimum design metal temperature (MDMT)
Materials of construction
E= joint efficiency [Note (3)]
t
n= nominal non-corroded thickness [Note (1)], in. (mm)t
r= required thickness in corroded condition for all applicable loadings [Note (2)], based on the applicable joint efficiency [Note (3)], in. (mm)Applicable curve(s) of Fig. UCS-66
c= corrosion allowance, in. (mm) Step 1
Select MDMT from Fig. UCS-66 [Note (4)] for each nominal non-corroded governing thickness [Note (5)].
Using Ratio from Step 3 to enter ordinate of Fig. UCS-66.1, determine reduction in Step 2 MDMT [Note (9)]. Step 6 Step 5 Step 4 Step 3 Step 2
Determine Ratio: (trE*) /( tn – c) [Notes (3), (6), (7), and (8)]
Determine adjusted MDMT for governing thickness under consideration.
Repeat for all governing thicknesses [Note (5)] and take warmest value as the lowest allowable MDMT to be marked on nameplate for the zone under consideration [Note (10)]. See UG-116. See UG-99(h) for coldest recommended metal temperature during
hydrostatic test [Note (6)].
See UG-100(c) for coldest metal temperature permitted during pneumatic test [Note (6)].
FIG. UCS-66 IMPACT TEST EXEMPTION CURVES (CONT’D)
NOTES:
(1) Curve A applies to:
(a) all carbon and all low alloy steel plates, structural shapes, and bars not listed in Curves B, C, and D below;
(b) SA-216 Grades WCB and WCC if normalized and tempered or water-quenched and tempered; SA-217 Grade WC6 if normalized and tempered or water-quenched and tempered.
(2) Curve B applies to:
(a) SA-216 Grade WCA if normalized and tempered or water-quenched and tempered SA-216 Grades WCB and WCC for thicknesses not exceeding 2 in. (50 mm), if produced to fine grain practice and water-quenched and
SA-217 Grade WC9 if normalized and tempered SA-285 Grades A and B
SA-414 Grade A SA-515 Grade 60
SA-516 Grades 65 and 70 if not normalized SA-612 if not normalized
SA-662 Grade B if not normalized SA/EN 10028-2 P295GH as-rolled;
(b) except for cast steels, all materials of Curve A if produced to fine grain practice and normalized which are not listed in Curves C and D below;
(c) all pipe, fittings, forgings and tubing not listed for Curves C and D below; (d) parts permitted under UG-11 shall be included in Curve B even when
fabricated from plate that otherwise would be assigned to a different curve. (3) Curve C applies to:
(a) SA-182 Grades 21 and 22 if normalized and tempered SA-302 Grades C and D
SA-336 F21 and F22 if normalized and tempered SA-387 Grades 21 and 22 if normalized and tempered SA-516 Grades 55 and 60 if not normalized
SA-533 Grades B and C SA-662 Grade A;
(b) all material of Curve B if produced to fine grain practice and normalized and not listed for Curve D below.
(4) Curve D applies to: SA-203
SA-508 Grade 1 SA-516 if normalized SA-524 Classes 1 and 2 SA-537 Classes 1, 2, and 3 SA-612 if normalized SA-662 if normalized SA-738 Grade A
SA-738 Grade A with Cb and V deliberately added in accordance with the provisions of the material specification, not colder than −20°F (−29°C)
SA-738 Grade B not colder than −20°F (−29°C)
SA/AS 1548 Grades 7-430, 7-460, and 7-490 if normalized SA/EN 10028-2 P295GH if normalized [see Note (e)(3)] SA/EN 10028-3 P275NH
UCS-68(c) If postweld heat treating is performed when it is not otherwise a
requirement of this Division, a 30°F (17°C) reduction in impact testing exemption temperature may be given to the minimum permissible temperature from Fig. UCS-66 for P-No. 1 materials. The resulting exemption temperature may be colder than −55°F (−48°C).
MANDATORY APPENDIX 8
METHODS FOR
LIQUID PENETRANT EXAMINATION (PT)
8-3 EVALUATION OF INDICATIONS
An indication of an imperfection may be larger than the imperfection that causes it; however, the size of the indication is the basis for acceptance evaluation. Only indications with major dimensions greater than 1⁄16 in. (1.5
mm) shall be considered relevant.
(a) A linear indication is one having a length greater than three times the width.
(b) A rounded indication is one of circular or elliptical shape with the length equal to or less than three times the width.
(c) Any questionable or doubtful indications shall be reexamined to determine whether or not they are relevant.
8-4 ACCEPTANCE STANDARDS
These acceptance standards shall apply unless other more restrictive standards are specified for specific materials or applications within this Division. All surfaces to be examined shall be free of:
(a) relevant linear indications;
(b) relevant rounded indications greater than 3⁄16 in. (5 mm);
(c) four or more relevant rounded indications in a line separated by 1⁄16 in. (1.5 mm) or less (edge to edge).
Indication size > 5.0 mm
Relevant: Noted & Not Acceptable (Rejected / Repair)
1.5 – 5.0 mm Relevant: Noted & Acceptable