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Software for Mechanical Design of: · Pressure Vessels · Shell & Tube Heat Exchangers · Tall Towers

Available standards: · ASME VIII Division 1, American Standard · EN13445, European Standard · PD5500, British Standard · AD2000 German Standard · EN13480 Metallic Industrial Piping · TKN, Swedish Standard · TBK2, Norwegian Standard

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Program History

The first version of Visual Vessel Design (VVD) was introduced in 1984 and the software has been continuously updated and improved ever since. Today VVD is a solid established program with users in every field. Our reference list includes vessel fabricators, petroleum refiners, engineering companies, varies process companies, government agencies and a number of independent consultants. The software is in use by over 40 notified bodies and has also been certified by a notified body.

Visual Vessel Design (VVD) Highlights

VVD is a true 32 bit MS Windows program for design of both pressure vessels and shell & tube heat exchangers. Some highlights includes:

· Integrated Vessel Drafting Utility ­ VVD can as the name implies produce a scaled drawing in both 2D and 3D of the complete vessel and of individual components to visualize the design and enable the designer to easily check and verify the dimensions and location of components as the design progresses. Drawings can be exported to other CAD systems using one of the export file formats, i.e. using DXF or AutoCADTM file formats. Flexible Printout ­ VVD can produce a detailed output in English or any other selected languages including graphical elements. The level of extent of calculation results to be produced is determined by the user, and ranges from a brief summary to a "detailed hand calculation" with all intermediate calculation formulas and values put into all formulas. A built in PDF file generator is also included. Vessel Geometry ­ Almost any odd type of vessel geometry can be implemented in the design model, including separators with a sump and any type of heat exchanger geometry with floating heads, fixed tubesheets, or U-tube bundle.




Integrated Databases - The VVD database includes a comprehensive collection of dimensional and

physical properties for metric and unified bolts, flanges to ANSI and DIN Standards, gasket properties, flange facing data including RTJ facing, pipes and tubes, nozzle forgings, chairs on skirt, saddles, lifting lugs and over 2000 different materials to ASME, PD5500 and EN standards, material densities, module of elasticity and thermal expansion coefficients. A material library manager is also included to allows the user to create

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user defined material libraries.


Report Generator ­ instant generation of

reports including index of printed calculations, weight, volume, centre of gravity analysis, history of revisions, max. allowable pressure, test pressure, warning and error message summary, material data list, nozzle schedule list, NDT requirements, component locations list and parts list (BOM).

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External Loads Module ­ Add any number of loads and load combinations/load cases to the vessel. Tall Tower Analysis ­ Instant analysis of each major vessel component subjected to any load and load combinations/load cases. Shear forces, moments and deflections can be plotted along the vessel centre line. VVD Code Assistant - is an integrated database with technical articles to help and aid the user in the design process. Section Sensitive on line Help ­ Just press function key F1 and section sensitive help is readily available. Extensive Code Checks ­ VVD checks against code limitations and geometric restrictions. Extremely Easy to Use - Building even complex vessel models is quick and easy with the VVD software. The graphical display is updated as each component is designed. Vessel Optimisation & Rerating ­ is easily performed in VVD, change any process parameter in the process card and all components can be recalculated for the new condition. User Manual - A comprehensive, indexed User Manual is supplied with the software. Utilization Charts - The utilization charts provides the user with instant feedback on the utilization of each component. Visual Mode - Visual Mode and Normal Mode are the two modes of operations available in VVD. Visual mode introduces a new concept of pressure vessel design with a unique subroutine which will easily identify the component location based on a minimum of input. Each component can be drawn and viewed on the screen as the design progresses ensuring correct dimensions and location. VVD is based on attaching components to each other to reduce number of inputs and share common input data.

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Component Analysis Capabilities

Shells & Heads ­ under internal and external pressure, calculates the minimum required thickness, maximum allowable pressure in new & cold and hot & corroded conditions and required minimum and maximum allowable hydraulic test pressure. Conical Shells ­ under internal and external pressure, calculates the minimum required thickness, maximum allowable pressure in new & cold and hot & corroded conditions, required minimum and maximum allowable hydraulic test pressure and reinforcement requirements at cone-to-shell junctions. Stiffener Rings ­ Most stiffener geometries consisting of rectangular sections can be defined, and both internal and external rings included. The relevant corrosion allowance is deducted from all surfaces of stiffeners. The stiffener proportions are also checked against code requirements.

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Out off Roundness Check ­ This module calculates the out of roundness of the shells based on at least 24 measurements of shell radius equally spaced around the circumference of the vessel. If the out-of-roundness of the vessel is greater than 0.5% of the radius measured from the true centre, the allowable external pressure will be recalculated based on the actual out-of-roundness values. Nozzles ­ VVD can accommodate design of any nozzle type, including set in, set on and protruding constructed from plate material, pipe or LWN forgings. The nozzle can be connected to any shell or end, and angled/oblique in any direction. The contributing area along the shell and nozzle will be checked(can also be reduced if required), and distances to discontinuities calculated. Nozzle to shell weld can be included in the design and the minimum weld size calculated. Single sided or double sided reinforcement pads can be included, and the pad limitations on thickness and width will be displayed and checked. Groups of Nozzles ­ A check of nozzle group reinforcement is easily performed in VVD, since the location of all nozzles are known in visual mode no additional input is required. The software will calculate the inter-distance between all nozzles on each major components, and if the nozzle pair is classified as a group, a detailed reinforcement analysis of the nozzle group is performed. Nozzle Loads ­ for nozzles located in both cylindrical shells and dished ends. Calculates local stresses due to external loads according to PD5500 Annex G and EN13445 section 16 and compare results with calculated allowable stresses. The applicability of the PD5500 Annex G method has been extended to cover the entire range of geometries up to Co/r=0.25 for all values of r/t up to 250 according to the procedure given in reference [46] in Annex G. Flanges - Taylor Forge Method This module includes design of flanges with full face (also metal to metal contact) and narrow face flanges for virtually any geometry, subject to both internal and/or external pressure. Also included are reverse flanges, split flanges, lap joints and seal welded flanges. The bolts are designed to produce enough load for gasket seating in the Bolting Up Condition and sustaining both the hydrostatic end force and maintaining sufficient gasket pressure to ensure a leak-free joint in Operating Conditions. The recommended minimum clearance is based on TEMA (Standard of the Tubular Manufacturer Association) TABLE D-5. The program can also calculate the required bolt torque for bolting-up, operating, and hydro test conditions. Flanges - Alternative method to EN13445-3 Annex G and EN1591-1 This method has a number of advantages compared with the Taylor Forge method. It considers the gasket as a static compressive element with a non linear behavior, takes into account the thermomecanical loads, takes into account external loads other than Pressure (Axial Forces and Bending Moments given by the assembly), considers the creep factor of the Gasket, computes the overload break of the assembly according to the plastic theory of the limit load and is also able to consider the transient working conditions. Saddle Support ­ The types of saddle support covered by the program includes plain saddle support, saddle supports with internal stiffening rings in the plane of the saddle and adjacent to saddle, saddle supports with external rings adjacent to saddle, integrated saddle ring and hinged support. The saddle may be subjected to any number loads and any load combinations, including wind, blast, seismic and acceleration loads.

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Skirt, Base Ring, Chairs & Ancor Bolts ­ The skirt design module calculates the stresses in two sections in the vessel shell adjacent to the skirt and 2 sections in the skirt. In addition this module calculates the stresses in the base ring, the anchor bolts, and the anchor bolt chairs. The method for calculating the stresses in the vessel shell and skirt is according to EN13445 Section 16.12 Vertical Vessels with Skirt. Any number, size and location of openings can be accommodated in the analysis, the system will check all sections and find the location of the maximum weakening. The displacement eps of the neutral axis due to the openings is also calculated to enable calculation of the additional moment due to this displacement. Anchor bolts are designed based on the maximum forces and required bolting area. The VVD database includes dimensions for both metric and imperial bolts. The selection of bolt diameters provides a sizing criteria for the chairs. Two type of chairs are accommodated, skirt with separate chairs and skirt with chairs that has a continuously welded top ring. A table with suggested dimensions for chairs is available to the user, and the chair selection is based on the bolting size. The program will calculate the minimum thickness of the top plate on the chair and the stresses in the vertical stiffeners on the chair based on the bolt loads. The minimum thickness of the basering is based on the bearing pressure taken by the ring, the width and the allowable stresses of the ring. Vessel Attachments ­ Lifting lugs and lifting trunions. Calculates the stresses in the shell and in the lug/trunions to verify stress values to be within acceptance limits. Tall Tower Analysis - VVD calculates the static effects of external loads on tall towers/vertical vessels. The software can accommodate any type of loads and include the effects of wind, blast, seismic, weights, operating liquid heads, internal & external pressures, and the user can add any additional loads. User Specified components are used to include additional loads to accommodate trays, external piping, ladders and platforms. The user can generate any loads and load cases covering Erection, Hydrotest, Transportation, and Operation in combination with Blast condition and/or Seismic. Seismic loads can also be calculated to Unified Building Code UBC 1997. The loading on external vessels are calculated at discrete intervals along the vessel centreline (z-axis). Seismic and accelerations loads consider elemental weight and shear calculations along the vessel length. The stresses are calculated at the base of each component (shell, end or cone section), except for conical shells were the stresses also are checked at the top section. The stresses are also checked in the section of the vessel just below the skirt. In this section the weight of the content of the vessel causes tensional stresses. Both the internal and external pressure cases are checked. The external pressure case will add compressive stresses and may govern the

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design analysis. The internal pressure is the pressure at the top increased by the static head of test/operating liquid at the elevation considered. Stresses are calculated in all components for all load cases. For the code PD5500 the stress calculations and stress limits are in accordance with Annex A3.5 & A3.6 and Annex B. For the code EN13445 the stress calculations and stress limitations are in accordance with sections 16.14.6 (internal pressure case) and section 16.14.7 (external pressure case). The deflection is calculated for each loading case. The system will accommodate any vessel geometry with variations in thickness, diameters and unevenly weight distribution and flexibility. A numerical integration is carried out along the vessel centreline (z-axis) to determine the shear forces, moments and deflection. The software will plot shear forces, moments and deflection along the z-axis of the vessel in both the x- and y- directions. The maximum values are calculated by vectorial additions. For vertical vessels the first natural period/resonance frequency of vibration is calculated for each loading case, and compared against the actual wind loading to determine if wind induced vibration is a potential problem. Tubesheets ­ covers design of floating heads, U-tube bundle and fixed tubesheets with and without expansion bellow. This module calculates the required thickness of the tubesheet and flanged extension, determines the tube stresses, tube-to-tubesheet joint loads and allowable loads. Corrosion allowance on both sides and pass partition grooves are considered in the tubesheet design. Tubesheet calculations are performed to ASME part UHX, EN13445 Section 13 and PD5500 section 3.9. Floating Heads - includes design of the spherical domed end and the flange section of the floating head. Design of both narrow faced flanges and full-faced flanges are included. The domed end and flange are designed for both internal pressure and external pressure. The methods included are: PD5500: Section 3.5.6 Spherically domed and bolted ends of the form shown in figure 3.5-36 and EN13445: Section 12 ­ Bolted Domed Ends. Fatigue Analysis - The fatigue analysis module can accommodate both constant amplitude loading and variable amplitude loading. Based on the loading data and data for the different components included in the analysis, the allowable number of cycles will be calculated for each component. In the case of variable amplitude loading the total fatigue damage index due to the cumulative effect of the cycles that form the design stress range spectrum will be calculated. Default values for all the input data in the components input table can be automatically generated based on previous calculation data for each component.

Available License Types

VVD is available as a single user license, a network license for use in local area network environments, or as a limited run licence.

Quality Assurance

OhmTech AS has operated and maintained a quality assurance system since the start in 1984. EN-ISO 9001 in general and EN-ISO 9000-3 in particular sets the requirements for our current QA system. A copy of our Quality Control Plan is available upon request. The software has also been certified by a notified body.

Maintenance and Technical Support

Full technical support is available by e-mail, telephone and fax.

Demo CD

Demo CD is available upon request.

Ogmund Finnsonvei 16

N-4009 Stavanger, Norway Telephone: +47 51530103 Fax: +47 51531577 e-mail : [email protected] Internet:



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