To
Guidance with Patience
High structure integrity, safety and cost optimized static equipment
Learn with Passion
Practice and make perfect
PVE
LITE
T
RAINING
– P
RESSURE
Table of Content
Item
Description
Page
1.
Chapter 1: Static equipment, piping and
storage tank. Relevant Code and Standards.
Design Software
2- 3
2.
Chapter 2: Pressure Vessel Design , 2.1
Design by Rules or Formula, 2.2 Design by
Analysis
4-7
3.
Chapter 3: Types of loadings at Pressure
Vessel
8-11
4.
Chapter 4: Type of Stresses at Pressure Vessel
12-20
5.
Chapter 5: Basic feature and Operation of
PVElite
21-28
6.
Chapter 6: Common Design Code for Pressure
Vessel
29-31
7.
Tutorial 1: Vertical Pressure
Chapter 1 : Types of Equipment and Facilities,
Design codes and Application
software
Figure 1: Group of equipment and facilities at oil refinery plant
A process plant ( Oil & Gas refinery, petrochemical, chemical and
others) shall consists of following equipment and facilities.
2 Chimney Horizontal pressure vessel Vertical pressure vessel Piping Process column
Shell & Tube Heat
Air fin cooler
Above round storage tank Spherical
Code &
Standard
Equipment or facilities detail
Recomm
ended
defector
softwar
e
Pressur e Vessel ASME Sec VIII Div 1 or Div 2, PD5500, EN13445 Process Vessels – Trayed columns, reactors, packed columns
Drums and Miscellaneous Vessels – Horizontal and vertical vessels
Storage Vessels – Bullet and spheres tanks PVElite ®, Nozzle Pro, FEpipe Storag e Tank API 650, API 620 ,API630
Cone roof tank ( Self supported and Supported)
Dome roof tank
Flat roof tank
Floating roof tank (not in software yet)
TANK® Heat Exchan ger TEMA, PD5500,ASM E UHX, ASME Appendix A
Shell and Tube heat exchanger (Various configuration )
Hairpin Heat Exchanger
Jacketed Pipe Heat Exchanger
Mech -PVElite ® Thermal & flow- HTRI®-Xist, Xhep and etc Piping ASME B31.1 ( Power piping)
ASME B31.3 (Process piping)
ASME B31.4 (Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids)
ASME B31.5 ( Refrigeration Piping and Heat Transfer Components)
ASME B31.8 (Gas Transmission and Distribution Piping Systems)
CAESAR II®
Chapter 2 : Pressure Vessel Design
There are two types of mechanical design methods for pressure vessel
, namely design by formula (DBF) and design by analysis (DBA).
2.1 Design by Rule or Formula (DBF)
Design formula is governed by mandatory national code and
standards to ensure safety performance. Most the pressure vessels
are designed based on the concept of Design by Formulae (DBF),
which involves relatively simple calculations to achieve the required
component thicknesses via simple formulae or diagrams and by usage
of the concept of the nominal design stress, also termed as allowable
stress, allowable working stress, or limiting stress intensity; pressure
vessel design codes like ASME Div VIII Section 1 and Section 2, PD
5500 and EN 13445 use the principle of thin wall structure membrane
stress for determining the minimum thickness of structure such as
cylindrical shell , conical shell, body flange and dish head thickness
due to various loading conditions. The great benefit of the DBF
approach is still its simplicity, only in the recent past the formulae and
calculations in DBF have become more and more elaborate,
pretending accuracy that is often not there (Josef L. Zeman, 2004).
The basic idea of design by rule is that once the leading scantlings are
fixed in this way the designer simply obeys the rules laid down in the
procedures for specified components such as nozzles, dish head,
shells, etc. The methodology or reasoning behind the rules will not
always be apparent as we shall see. However, this is the most
common approach used in all national design codes.
The design by rule approach has the great advantage of simplicity and
being backed up by the long experience of users in many cases. The
greatest disadvantage is that the approach cannot easily be extended
either to different geometries or additional loadings beyond the
normal pressure cases, elastic –plastic and plastic state. For example,
ASME VIII Div 1, the design rules and formulas consider mainly the
loadings due to static internal pressure and external pressure within
elastic limit.
2.1.1 Design by Rule or Formula (DBF) using
PV Elite
Conventionally, most of the previous design of pressure vessel is done
using spreadsheet like Microsoft Excel to perform structural thickness
calculation and analysis for pressure vessel components.
Nevertheless, this option can save some initial cost compare to
commercial design software like PVElite, but it will be comparatively
non cost effectiveness in the long run. This is obvious, when we
compare PVElite to Microsoft Excel formatted design spreadsheet in
term of the quantity and quality of the performance. Some of the
points below are elaborate for getting better understanding about the
advantages of using PVElite in pressure vessel design.
PVElite is “ user friendly” for both new and experienced user,
where the input menu is ready available in a systematic
arrangement ( if spreadsheet is used, you might enter the
information to the wrong cell at spreadsheet that will cause a
wrong output or even damage the whole program due to your
carelessness ). User just enter the information as stated in the
design datasheet and specification. Furthermore, if the user are
doubt about the input , just press function key f1 to get
technical advice from the help menu with useful statement,
diagram , graph and table relevant to design requirement or
national standard code ( if spreadsheet is used, you have to
refer to the hard copy of design codes which will spent time in
searching for the details .)
PVElite is “design oriented”, where the features allow the user to
maximize their time to design or re-rating the pressure vessel to
achieve cost- optimum design. That mean, minimize the time
spent in searching, confirming and entering the design
parameters for design calculation. To achieve this, PVElite
performs calculation base on various type of design codes and
corresponding material code with various addendum (ASME Sec
VIII Div 1, Div 2 , PD5500 and EN13445), hence designer will be
able to change and compare the pressure vessel design base on
different standards easily . In addition, user can select various
national codes for external loadings due to wind and/or seismic
forces (ASCE, UBC, NCB ,IS , GB and etc.), nozzle loadings (WRC
5107 , PD5500 Annex B and etc), and tubesheet design (TEMA,
ASME UHX, BS5500, ASME appendix A) Secondly, PVElite
provides a good traceability for the calculation results where a
negative answer is alerted in “red warning “, that the designer
has the possibility to understand which are parameters to be
changed in order to get the checking. While, a positive answer
shows the result the degree of possible overdesign, in order to
give the designer the possibly of decreasing excess thickness
when they are not needed.
PVElite interfaces with others popular software packages for
finite element analysis (Nozzle-Pro), heat exchanger design
(HTRI), pressure vessel drafting and material take off (PV
fabricator) and foundation design and drafting. PVElite also
shares a bi-directional link to COADE’s CADWorx Equipment
module. The significant benefit of this feature is the designer will
be able to convert the preliminary design into drawings and MTO
for cost estimation and proposal purposes using PV fabricator. In
addition, the changes made in the PVElite in pressure vessel
design will update the engineering drawing and bill of material
correspondently. The mathematical model of the pressure vessel
in the graphic form can be exported to Nozzle-Pro for meshing
and generating finite element model for stress analysis such as
nozzle to shell intersection, dome to shell intersection, skirt to
shell and etc. After the heat and fluid flow analysis of heat
exchanger using HTRI software, some relevant information can
be transfer to PVElite for stress analysis for tubesheet, tube,
tube to tubesheet joint and other components. The nozzle
loading from CAESAR II can be transfer to PVElite for WRC 107 or
annex B local stress analysis.
CodeCalc is an additional programs available within PVElite to
analysis the vessel components separately or things that
haven’t be included in PVElite . Typical cases would be
full-jacketed vessel, non-circular vessel, Lifting lugs and turnion
design, API579 (Fitness For Service), large opening at shell,
floating head and etc.
2.2 Design by Analysis (DBA)
Design by analysis (DBA) is mainly used to check the design of
pressure vessel which is operated under serve conditions like extreme
high pressure, and extreme high or low temperature where DBF can
not be used due to it limitations in design calculation, data and
coverage (Design by Analysis, 2004). The design by analysis can be
categorized into two: design base on elastic analysis, and design base
on plastic analysis. It is implemented to avoid eight possible failure
modes at pressure vessel by detail stress analysis as stated as in
ASME sec VIII Division 2 and subsequently BS 5500 Appendix A and
EN13445-3 Annex B (Direct Route Method) and EN13445-3 Annex C
(Elastic analysis & stress Categorization). The failure modes considered
are (base on ASME section VIII Div 2, Part 5)
:-
All pressure vessels within the scope of this Division,
irrespective of size or pressure, shall be provided with
protection against overpressure in accordance with the
requirements of this Part.
Protection Against Plastic Collapse – these requirements
apply to all components where the thickness and
configuration of the component is established using
design-by-analysis rules.
Protection Against Local Failure – these requirements
apply to all components where the thickness and
configuration of the component is established using
design-by-analysis rules. It is not necessary to evaluate
the local strain limit criterion if the component design is in
accordance with Part 4 (i.e. component wall thickness and
weld detail per paragraph 4.2).
Protection Against Collapse From Buckling – these
requirements apply to all components where the thickness
and configuration of the component is established using
design-by-analysis rules and the applied loads result in a
compressive stress field.
Protection Against Failure From Cyclic Loading – these
requirements apply to all components where the thickness
and configuration of the component is established using
design-by-analysis rules and the applied loads are cyclic.
In addition, these requirements can also be used to qualify
a component for cyclic loading where the thickness and
size of the component are established using the
design-by-rule
Requirements. Part 4.
PVElite can only dealt with requirements that are directly addressed
by the code and for cases where limitations prevent you from
obtaining the necessary result, a viable alternative would be to turn to
FEA (finite element analysis). PVElite does have interfaces with an FEA
program termed Nozzle-Pro and this is beyond the scope of his
manual.
3.0 Type of loadings at Pressure Vessel
All structure include pressure vessel are subjected to two basic types of loading: Steady or static and unsteady (variable, cyclic or impact). Figure 3.1 shows loadings which are grouped into steady and unsteady loads. Most of the pressure vessels encounter variable or cyclic loading, may assumed to be statically load without introducing serious error. This is significantly stated in the standard ( ASME Section VIII, Division 2, AD-160) that the fatigue analysis is required provided the conditions of the cyclic loading are exceed the limits at the fatigue evaluation stage. These limits is depend upon the number of cycle loads in term of fluctuate operating pressure and temperature, as well as the degree of the cyclic load which is mainly due to the gap of maximum and minimum operating pressure or temperature. Figure 3.2 shows types of general loads and local loads at pressure vessel.
Internal pressure load is common for all the pressure vessel above, since all the static equipment operates at certain elevated pressure and temperature due to chemical processes and hydrostatic pressure of storage content ( ASME Section VIII, Division 1, Part UG20 and UG21, 2007). In addition, hydrotest pressure load is elevated at 30% from the vessel working pressure at corroded or new condition as stated in ASME Division 1, Part UG99.
Types of loading
Steady load – long-term duration, continuous Non steady loads—short term duration, variable
Pressure loads – Internal or external pressure (design, operating, and hydrostatic head of liquid)
Dead weight, vessel content
Loadings due to attached piping and equipment.
Loadings to and from vessel support
Thermal load – Head to skirt joint, piping expansion load at nozzle.
Wind load
Shop and field hydrotest
Earthquake, Vibration Lifting and erection
Transportation Start up, shut down .
Thermal load – short term during service or testing
Upset, emergency Constant cyclic pressure or thermal load
Dynamic/ impact load
Despite the availability of vacuum valve, the external pressure is considered for pressure vessel design in vacuum condition where the outlet nozzle is connected to pump. The atmosphere pressure is sufficient to compressively deform a pressure vessel due to large volume vessel with insufficient thickness and/or stiffener, furthermore metallic materials have relatively low compressive strength compare to its tensile strength (ASME Section VIII Division 1, Part UG28, 2007).
External load like wind and seismic load is more critical for process vessels like process columns and reactor. The deflection and vibration analysis of tall slender column (H/D>15) are commonly checked to ensure the structural is not over deflected. In conjunction, the stresses induced by wind and seismic loads are always combined with other stresses (i.e. longitudinal, circumferential and shear stress) due to internal pressure, external pressure, and hydro test pressure to ensure the possible combined stresses are not more than allowable stress (ASME Section VIII Division 1, Part UG22-23, 2007).
Categories of loading at pressure vessel
General loads – Load applied continuously across a vessel section.
Pressure loads- Internal or external pressure load (design, operating, hydrotest, and hydrostatic head or liquid.)
Moment loads- Bending moment due to wind, seismic, erection, transportation and horizontal support.
Compressive/tensile loads- Due to dead weight, installed equipment, ladders, platforms, piping, and vessel content.
Thermal loads- Skirt to head attachment.
Local loads – Load applied to a small portion .of the vessel and normally fall off rapidly in distance of applied load.
Pressure radial loads- Internal and external pressure for thick wall pressure vessel.
Shear loads- Longitudinal and circumferential shear at shell, dish head and conical section, where saddle and support lugs, and nozzle to shell juncture.
Torsional loads- torsional load at vessel nozzle due to the twist of external piping.
Moment loads- load due to moment at discontinuities, nozzle to shell section.
Thermal loads- Thermal expansion restricted regions likes piping at nozzle connection. Figure 3.1: Types of Loading at pressure vessel
Figure 3.2: Categories of Loading at pressure vessel
In addition to the above major analysis, nozzle opening reinforcement at shell is important to avoid mechanical failure due to internal pressure, external pressure and nozzle loading due to external piping connection and other equipment likes reboiler due to various forces and moment at nozzle to shell junctures (K.R.Wichman., A.G. Hoper., J.L.Mersho, 1979). This concept is applicable to other attachments at the pressure vessel walls which have rectangular, square or circular cross sectional area.
For horizontal supported pressure vessel, the distributed weight implement bending load at the mid span of the pressure vessel and the saddle support. Furthermore, the concentrated load at the horn of saddle and the tip of the wear plate. The above loads are significant for large diameter and long horizontal pressure vessel. ( L.P. Zick, 1951)
Local stresses analysis is important for lifting lugs and turnion to ensure safe lift during the site installation.
Fatigue analysis is performed for those pressure vessels which have severe and significant cyclic loadings in the form of fluctuating pressure and temperature condition. These cyclic loads would decrease the service life of a pressure vessel as stated in the S-N curve of specific material. ( ASME
Section VIII, Division 2, Appendix 5)
Thermal loads is only concerned for DBF likes ASME Division for tube sheet design. ASME Division 2, part 5 – Design By Analysis Requirements (2007) checks the stresses induced by cyclic thermal loads, and the ratcheting for pressure vessel components.
4 Type of stresses at Pressure Vessel
Generally the design of pressure vessel is to decide the minimum
thickness which will fulfill the design requirement as per design code
through DBF or DBA. The pressure vessel components thickness are
depend upon the stress(es) incurred at the material due to internal
pressure, external pressure and other external forces. It is not
necessary to find every stress but rather to know the governing
stresses and how they related to the pressure vessel and its
respective parts, attachments, and supports. Hence, the basic
understand of the stresses at pressure vessel is importance for design
and they are further elaborated as below. Generally, there are three
types of
- General Primary Stress
- Secondary Stress
- Peak Stress
4.1 General Primary Stress
These stresses act over a full cross section of the vessel and they are produced by the imposed loading (load-induced) and are necessary to satisfy the law of equilibrium. In addition, they are the most hazardous of all types of stress.
The basic characteristic of primary stresses that it is not self limiting (i.e. they are not reduced magnitude by the deformation they produced). Hence, the gross distortion or failure of the structure will occur if its value substantially exceeds the yield stress . In the other word, if a primary stress exceeds the yield strength of the material through entire thickness, the prevention of failure is entirely dependent on the strain- hardening properties of the material or stress distribution. Primary stress are generally due to internal or external pressure or produced by sustained external forces and moment.
The primary stress is divided into two subcategories in ASME Sec VII-Div 2. They are primary general membrane and primary general bending
stresses. Primary general membrane stress ,Pm. This stress occurs across the entire cross section of the vessel. It is remote from discontinuities such as head-shell intersections, cone-cylinder- intersections, nozzles, and supports. For instance, circumferential and longitudinal stress due to pressure; compressive and tensile axial stresses due to wind or seismic; longitudinal stress due to the bending of the horizontal vessel over the saddles; membrane stress in the center of the flat head; membrane stress in the nozzle wall within the area of reinforcement due to pressure or external loads and axial compression due to the weight.
Figure 3.3: General membrane stress at the pressure vessel parts
Primary general bending stress, Pb. Primary bending stresses are due to sustained loads and are capable of causing collapse of the vessel. There are relatively few areas where primary bending occurs. For instance, bending stress in the center of the flat head or crown of a dished head; bending stress in a shallow conical head and bending stress in the ligaments of closely spaced openings.
Local primary membrane stress, PL. Local It is a combination of two stresses, primary membrane stress, Pm, plus secondary membrane stress, Qm which is produced from sustained loads. These have been grouped together in order to limit the allowable stress for this particular combination to a level lower than allowed for other primary and secondary stress application. It was felt that local stress from sustained not self limiting loads presented a great enough hazard for the combination to be classified as a primary stress. Examples of primary local membrane stresses are primary membrane stress plus membrane stresses at local discontinuities (i.e. head to shell juncture and nozzle to shell juncture), primary stress plus membrane stresses from local sustained loads (i.e. platform and ladder support; piping and equipment attached to the nozzle).
4.2 Secondary Stress
19
Secondary stress is developed when the deformation of a component due to the applied loads is restrained by other components. It must satisfy an imposed strain pattern rather than being equilibrium with an external load. Secondary stress is self-limiting (i.e. they are reduced magnitude by the deformation they produced) in that local yielding can be redistribute the stress to a tolerable magnitude without causing failure.
Secondary mean stresses are developed at the junctions of major components of a pressure vessel. Secondary mean stresses are also produced by sustained loads rather than internal or external pressure. Secondary stresses are strain-induced stresses.
Secondary stresses are divided into two additional groups, membranes and bending. Examples of secondary membrane stress are axial stress at the juncture of the flange and the hub of the nozzle; thermal stresses due to restricted expansion; membrane stress in the knuckle area of the head and membrane stress due to local relenting (self-limiting) loads. Examples of secondary bending stress, Qb are bending stress at a gross structural discontinuity (i.e. nozzle and lugs); the non uniform portion of the stress distribution in a thick walled vessel due to internal pressure; the stress variation of the radial stress due to internal pressure in thick- walled vessels; discontinuity stresses at stiffening or support rings.
20
4.3 Peak Stress
Peak stress is the highest stress in the region under consideration. The basic characteristic of peak stress is that it causes no significant distortion and is objectionable mostly as sources of fatigue failure. It applies to both sustained load and self- limiting load. Peak stress is additive to primary and secondary stress present in the point of the stress concentration. Peak stress is only significant in fatigue conditions or brittle materials. It is the sources of fatigue cracks and applies to membrane, bending, and shear stress. Example are stress at the corner the discontinuity; thermal stresses in a wall caused by the sudden change in the surface temperature; thermal stresses in cladding or weld overlay; stress due to the notch effect .
5 Basic features and operation of PV Elite
Generally, there are five major input processors in PVElite. There arei) Heading
ii) Design Constraint iii) General Input iv) Load Cases v) Seismic Data vi) Wind Data
Figure 4.1: Input Processors for the Pressure Vessel design
Before the user start to enter the design parameters into the input
processors as stated above , it is important to configure the settings at the start. The configuration is at the tools option control utility processor as shown in figure 2.2.
5.1 Configuration
Figure 4.2 : Configure the settings of PVElite behaves when analyzing a vessel
It is important to configure the settings at the start. From the tools option control utility processor, options are given to customize how PVElite behaves when analyzing a vessel. The settings are related to the pre and post processing of the design or analysis for pressure vessel. Pre-processing is the settings of the design requirements before the analysis, likes alternative rules in design of pressure vessel components (i.e. use ASME Code case2260/2261, 2286, 2004-A06 Addenda for Division 2, pre-99 Addenda (Division 1 only) , Eigen solver and use OD as the basis for shell radius for Zick’s analysis) or the setting allowable value such as material database, graph for determining MDMT and allowable tower deflection. In addition, post –processing involves filter or keep certain results or details to be appear in the report such as no MDMT, no MAWP calculation, print equation and substitution. It is important for the user to be familiar to the design standards, practice and client required specification before perform any setting in the configuration section.
5.2 Design/ Analysis Constraints
Figure 4.3: Design constraints for setting general design information for pressure vessel
5.3 Design Data
24The input screen is divided into two areas. They are design data and design modification. The design data section is related to general design parameter like internal and external pressure /temperature, hydrotest type and position, projection from to/ bottom for UG99-C . This information is very common seen and indicated in the design data of vessel GA drawing and this core information for pressure vessel design. The user can specific their client preferred MAWP, MAPnc and hydrotest pressure, where these values will overwrite/ replace the calculated values. Others inputs like construction type, special service, degree of radiography are just for information only, it is reported in the report echo.
If the user check the box of “Use Higher Longitudinal Stresses ?”, PVElite will use higher allowable longitudinal stress for combined stresses analysis . The ASME Code Section VIII, Division 1, Paragraph UG-23(d) allow the allowable stress for the combination of earthquake loading, or wind loading with other loadings to be increased by a factor of 1.2.
If the user check the box of “Consider Vortex Shedding ?”, PVElite will compute fatigue stresses based on loads generated by wind flutter. In addition, the program will compute the number of hours of safe operation remaining under the wind vibration conditions. This section is suitable for high column design with h/d (overall high over the vessel diameter) equal or more than 15. For low vertical vessel like drum, it is advisable not to check the box because the program will generate extreme non logical high value which will cause overdesign for the structure.
If the user check the box of ”Is This a Heat Exchanger ?”, PVElite will write out an ASCII text file that contains the geometry and loading information for this particular vessel design.
If user check the box of “Hydrotest allowable is 90% yield”, PVElite will consider 90% of the material yield stress for the hydrostatic test allowable. This will generate higher allowable stress for hydrotest than the normal value which is 1.3 time the material minimum allowable stress. ( This applies only for Division 1 vessel design).
If user is designing a cylindrical ASME stack steel stack and wish to have PVElite analyze allowable and stress combinations per ASME STS-2003(a), then check this box. (This applies for Division 1 vessel design).
The 2009 version do not allow any modification of design code in this input screen, but it is shown at the column for information. The reason of this new feature is to remind the designer to select the design code at the earlier stage (Refer to figure 2.4).
Figure 4.4: Selection of design code at “New” column and pull down menu
Any modification at design data will affect design of the whole pressure vessel and it components. For example, the change of internal design pressure and temperature at this section will generate global change for all the components of the pressure vessel at general input processor. In addition, the change of design code for whole vessel is done by reselecting the required design code at pull down menu. However, the user needs to reselect the material before running the analysis.
5.4 Design Modification
Design modification provides the user with the option to intelligently design the vessel whenever a specific section fails the code. The program will prompt a thickness that will be suitable for use or a location (s) of stiffening rings so that the code requirement can be met. For the stiffening rings, the program will allocation the ring(s) after run the analysis, where the program will ask for user permission before the changes take place.
(Note: For most Advance users, the options included are usually not used.)
5.5 Load Cases
Figure 4.5: Load cases for stress combination at pressure vessel
5.5.1 Stress Combination Load Cases
This input processor is used to deal with various combinations of loads
that contribute toward the membrane stress of the vessel at
longitudinal direction. The calculated maximum principle stresses
based on different combination of loads will be compared with the
corresponding allowable stress.
There can be as many as twenty cases, combining pressure loads,
weight loads, and moments in various ways. Generally, the load cases
stated are more than adequate to deal with all the combinations that
the user are likely to encounter in both operational and hydrotesting
conditions.
A fairly complete set of load cases is included as a default:
The difference between wind loads and hydrotest wind loads is simply
a ratio (percentage) defined by the user. This percentage is specified
in the Wind Data definition of Global Data - usually about 33% (thus
setting the hydrotest wind load at 33% of the operating wind load).
Likewise, the hydrotest earthquake load is a percentage of the
earthquake load; this percentage is defined in the Seismic Data
definition of Global Data. Some steps that are not applicable for
horizontal vessels, such as natural frequency, will not be printed. Also,
if a vessel has no supports, then there will be no calculations that
involve wind or seismic loads.
5.5.2 Nozzle Design Options
The nozzle design option dealt with the design criteria that determine
the selection of nozzle wall thickness and reinforcement pad. The top
deals with design pressure that is used to calculate the thickness
(nozzle or clip) base on MAWP+ Static head to Bottom Element,
Design Pressure + Static head, Overall MAWP + Static head
(governing Element), MAWP + Static head to Nozzle (note: user must
select either one for their vessel’s nozzle design). The least of the
boxes is optional for vessel design.
If the user checks the box of ”Consider MAPnc in Analysis “, PVElite
will check to see if the nozzle is reinforced adequately using MAPnc
generated during the internal pressure calculation. When the area of
replacement calculations are made for this case, cold allowable
stresses are used and the corrosion allowance is set to 0. Designing
nozzles for this case helps the vessel to comply with UG99 or
appropriate (hydrotest) requirements.
If the user check the box of “Modify Tr based on the Maximum Stress
Ratio”, PVElite will looks at all of the defined load cases (combined
stresses) and select the highest stress ratio (actual stress/ allowable
stress). It will then use this number as a multiplier on the shell
thickness. Thus the nozzle design is based on the precise loading at
the bottom of that shell course. The reason for the above work is to
comply with ASME Section VIII Division 1 paragraph UG-22 that deals
with supplemental loadings. One factor in ASME nozzle design is the
required thickness of the shell (tr). Usually internal pressure (hoop
stress) governs. In some cases, such as when a nozzle is located on a
shell course at the bottom of a tall tower, longitudinal stresses will
govern. In this case the shell required thickness must be based on
longitudinal stresses and not the hoop stress.
6 Common design Code for Pressure Vessel
29ASME Section VIII Div 1, Ed 2007, Ad 09
ASME Div 1 is the most common use standard for pressure vessel
design, the following are some of the common consideration in
pressure vessel design.
Tutorial (1) : Design for vertical pressure vessel
Tasks to be complete :
To determine the structural thicknesses of cylindrical shell and semi
ellipse head due to internal and hydrostatic pressure conditions.
Check shell thickness against hydrotest pressure.
MDMT checking for all pressure vessel components.
To determine the allowable external pressure of the structure and
compare to the actual external pressure load due to vacuum
condition at pressure vessel.
Design skirt support and base ring design for vertical pressure
vessel due to wind and seismic load. (refer to PVElite database or
handbook data if possible).
Nozzle reinforcement at dome shell due to shell opening, Nozzle
minimum thickness.
Installation of internals – trays and packing, platform and ladder,
longitudinal. After that determine the combined stresses condition
at bottom structure. Do the necessary correction, if there is a
need.
Perform rigging analysis to check the shear stress and bending
stress of the vertical vessel during critical lifting position.
Learning Outcome:
After completion of this topic, student will be able to use PVelite for :
Input all the design parameters to the correct input cursor.
Run the analysis and correct the design error by adjusting the
design parameter accordingly.
Obtaining an cost optimize design for pressure vessel components
due to internal pressure, external pressure, nozzle reinforcement ,
external loadings and skirt support. (target :+-10% greater than
actual load/stress/deflection rate)
(Note: Indicate the results with yellow highlight for printed
copy and save a PVE. file in CD for further evaluation)
Design Parameter Variable 1) Vessel name / number Distillation column / WRG-100
2) Design Code & Addenda ASME Section VIII Division 1, Addendum 2007
3) Operating Pressure & Temperature 10 bar (internal), 300oC / -1 bar (vacuum), 300oC
4) Vessel Design Pressure &
Temperature 15 bar (internal), 300
oC/ -1 bar (vacuum), 300oC
5) Minimum Metal design Temperature MDMT = -25oC 6) Vessel dimension ( Inside Diameter
(ID) x Length tangent to tangent (L))
Conical sectional height (L)
3500 mm (diameter) x 30,000 mm (L) 2500 mm (diameter ) x 10,000 mm (L) 1500 mm (L)
7) Design Liquid Level /
content specific gravity 3500 mm from bottom TL / 0.85 8) MAWP / MAP(N &C) ( ) N/mm2
9) Hydrotest pressure (shop/field) UG99(b), Shop ( ) N/mm2
10) Heat treatment ( Applicable/ Not Applicable0
11) Joint Efficiency Dome end : meridoinal seam (Full RT) circumferential seam ( spot RT)
Cylindrical shell : meridoinal seam (spot RT)
circumferential seam ( spot RT)
11) Corrosion Allowance 3 mm for all parts 12) Material - Cylindrical shell - Dome end - Nozzle - Nozzle flange - Bolting - Skirt SA 516 GR70 SA 516 GR70 SA 106 GR B SA 105 SA193/ SA194 SA283 GRC
13) Weights Fabrication : ( ) tones Empty: ( ) tones Operating: ( ) tones Test: ( ) tones
14) Wind load Wind Design Code: ASCE-93
Wind for Hydrotest: 33%
Design Wind Speed: 120 km/hr
Base Elevation : 3 meters from sea level Important factor: 1, Roughness factor: 1 15) Seismic load Seismic Design Code: ASCE-93
Seismic for Hydrotest: 0% 34
Seismic Coefficient Av: 0.2 Seismic Coefficient Cc: 2 Performance Factor: 1
35
Cage ladder , appx – 10kg/m
Platform – used open lattice (lightest option). PL width = 1000 mm PL Height = 1200 mm Clearance = 4” Packing support Height =50mm , weight =585 kg Elevation =6000 mm from lower TL.. percentage of holding liquid =65% Tray – space =400mm, QTY = 10 trays , Holding height = 50 mm CS ratchet ring – 45lb/ft3 Volume = 43.3 m3 4500 mm from 6th Platform 0o to 180o 4500 mm from 5th Platform 180o to 0o 4500 mm from 4th Platform 0o to 180o 4500 mm from 3rd Platform 180o to 0o 5500 mm from ground oo to 180o 4500 mm from 1st Platform 180o to 0o 4500 mm from 2nd Platform 0o to 180o 5,000mm 2,500 mm 1,500mm 30,000m m 10,000m m M1 2:1 Semielliptical Head, SF=50mm, min thk ( ) mm, Nominal thk ( )mm. 2:1 Semielliptical Head, SF=50mm, min thk ( ) mm, Nominal thk ( )mm. N1 N2
(Indicate the shell thickness of the shell section)
ID =3,500 mm
Nozzle Detail
No Nozzle
Description Dia x Sch X L rating (#)Pound Orientation Elevation from lower SF 1. Inlet ( N1) 18” x sch 40 x
200L ANSI, WNRF,300# 600CL (120 fromo) Top dish head 3. Outlet (N2) 20” x sch 10 x 250L WNRF,f150ANSI, # CL Bottom dish head 4. Manhole (M1) 24” x 12thk x 300L WNRF 150#ANSI, 0 o 5000 mm 36 1
Tutorial (2): Design for horizontal pressure vessel
Tasks to be complete :
Internal pressure, hydrotest , external pressure calculation as practical 1.
Nozzle opening and reinforcement , Nozzle loading WRC 107 checking. Longitudinal stresses at horizontal supported pressure vessel at the mid span and saddle support during the operation and hydrotest
respectively. Tangential stress at the shell at
saddle support, Circumferential compression at bottom of shell and in plane of saddle
and circumferential bending at horn of saddle. Corrective methods in reducing the stress at horn of saddle – add wear plate, increase the contact angle and support width, move saddle toward the head, add stiffer ring at the saddle, add the saddle support(s). Design for the saddle support, base plate, rib plate, wed plate.
Learning Outcome:
After completion of this topic, student will be able to use PVelite for : Input all the design parameters to the correct input cursor.
Run the analysis and correct the design error by adjusting the design parameter accordingly.
Obtaining an cost optimize design for pressure vessel components due to internal pressure, external pressure, horizontal supported conditions, nozzle reinforcement , nozzle loading, external loadings and saddle support. (target :+-10% greater than actual load/stress/deflection
rate)
(Note: Indicate the results with yellow highlight for printed copy and save a PVE. file in CD for further evaluation)
1) Vessel name / number Slug Catcher
2) Design Code & Addenda ASME Section VIII Division 1, latest Addendum
3) Operating Pressure &
Temperature 3.5 bar (internal), 120
oC / 1 bar (external),60oC
4) Vessel Design Pressure &
Temperature 5.5 bar (internal), 120
oC/ 1 bar (external), 60oC
5) Minimum Metal design
Temperature MDMT = -35
oC 6) Vessel dimension ( Inside
Diameter (ID) x Length tangent to tangent (L))
4200 mm (diameter) x 18,000 mm (L)
7) Design Liquid Level / content
specific gravity 3800 mm from bottom / 1
8) MAWP / MAP(N &C) ( ) N/mm2
9) Hydrotest pressure (shop/filed) UG99(c), Shop ( ) N/mm2
10) Heat treatment ( Applicable/ Not Applicable0
11) Joint Efficiency Dome end : meridoinal seam (Full RT) circumferential seam ( spot RT)
Cylindrical shell : meridoinal seam (spot RT) circumferential seam ( spot RT) 11) Corrosion Allowance 0 12) Material - Cylindrical shell - Dome end - Nozzle - Nozzle flange - Bolting - Saddle SA 240 SS304 SA 240 SS304 SA 312 TP304 SA 182 F304
SA320 B8 with SA-194 B SA283 GRC
13) Weights Fabrication : ( ) tones Empty: ( ) tones Operating: ( ) tones Test: ( ) tones
14) Wind load Wind Design Code: ASCE-93
Wind for Hydrotest: 33%
Design Wind Speed: 120 km/hr Base Elevation : 3 meters from sea level
Important factor: 1, Roughness factor: 1
15) Seismic load Seismic Design Code: ASCE-93 Seismic for Hydrotest: 0% Seismic Coefficient Av: 0.2 Seismic Coefficient Cc: 2 Performance Factor: 1
Nozzle Detail
No Nozzle
Description Dia x Sch X L rating (#)Pound Orientation distance from left SF 1. Inlet ( N1) 20” x sch 10 x
200L ANSI, WNRF,150# 0
O 4500 mm
3. Drain pipe (N2) 3” x sch 10 x
250L WNRF,150#ANSI, CL Boot dish head
4. Boot (B1) 30” x 12thk x ANSI, 0o 12,000 mm
38
3000L WNRF 150#
(Indicate the shell thickness of the shell section) Nozzle Loading (WRC 107) Dead Weight No Nozzle Description P (N) VL (N) Vc (N) Mt(N/m) ML(N/m) Mc(N/m) 1. Inlet ( N1) 800 1200 1200 120 150 150 3. Drain pipe (N2) 300 500 500 50 60 60 4. Boot (B1) NA NA NA NA NA NA Thermal No Nozzle Description P (N) (N)VL Vc (N) Mt(N/m) ML(N/m) Mc(N/m) 1. Inlet ( N1) 1,800 2,40 0 2,400 2,600 3,000 3,000 3. Drain pipe (N2) 750 1,00 0 1,000 1,115 1,300 1,300 4. Boot (B1) NA NA NA NA NA NA
Topic (3): Design of high wall thickness pressure vessel (t >
100 mm)
Sub-topic:
Dish head selection for high pressure operation. 39 N1 18,000 3600 mm 4,200 500 mm User estimated the size, thickness of the saddle and its components. The distance from saddle centre line to 12,000 B1 2:1 Semielliptical Head, SF=50mm, min thk ( ) mm, Nominal thk ( )mm. N2
Code case – 2260 “Alternative design rules for Ellipsoidal and Torispherical formed heads.
Saddle type nozzle/ insert plate for nozzle opening reinforcement, Support lugs design.
LOC: After completion of this topic, student will be able to Input all the design parameters to the correct input cursor.
Run the analysis and correct the design error by adjusting the design parameter accordingly.
Obtaining a cost optimize design for pressure vessel components due to high pressure operation.
Contents 1.0
Design of high wall thickness pressure vessel (t > 100 mm) ( Division 1 , 2 and PD5500)
3.1 Dish head selection for high pressure operation - semi ellipse, torispherical, hemispherical formed head. 3.2 Nozzle design for thick wall pressure vessel.
3.2.1 Self- reinforcement nozzle design. 3.2.2 Saddle nozzle or insert plate design.
3.3 Change the previous design of ASME Div 1 to ASME Div 2 and PD 5500. Material nominal strength/ allowable stress calculation - PD 5500 Annex K. ASME Section VIII Div 1 and Div 2.
3.4 Support lugs design and local stress calculation (WRC 107).
1) Vessel name / number Inlet Gas Separator
2) Design Code & Addenda ASME Section VIII Division 1, Addendum 2007
3) Operating Pressure & Temperature
125 bar (internal), 120oC / NA(external)
4) Vessel Design Pressure &
Temperature 138 bar (internal), 120
oC/ NA (external)
5) Minimum Metal design
Temperature MDMT = -15
oC 6) Vessel dimension ( Inside
Diameter (ID) x Length tangent to tangent (L))
2760 mm (diameter) x 7600 mm (L)
7) Design Liquid Level / content
specific gravity 2000 mm from bottom / 0.85 8) MAWP / MAP(N &C) TBA
9) Hydrotest pressure (shop/filed) TBA
10) Heat treatment As per ASME code
11) Joint Efficiency Dome end : meridoinal seam (Full RT) circumferential seam (Full RT)
Cylindrical shell : meridoinal seam (Full RT) circumferential seam ( Full RT) 11) Corrosion Allowance 0 12) Material - Cylindrical shell - Dome end - Nozzle - Nozzle flange - Bolting - Support Lugs SA 516 GR70N SA 516 GR 70N SA 105 SA 105 SA 193 SA283 GRC
13) Weights Fabrication : tones Empty: tones Operating: tones Test: tones
14) Wind load Wind Design Code: ASCE-93
Wind for Hydrotest: 33%
Design Wind Speed: 120 km/hr Base Elevation : 3 meters from sea level
Important factor: 1, Roughness factor: 1
15) Seismic load Seismic Design Code: ASCE-93 Seismic for Hydrotest: 0% Seismic Coefficient Av: 0.15 Seismic Coefficient Cc: 2 Performance Factor: 1
41
