General Overview

With PVX you can design and model anything from single flanges, pipes or heads to complex projects with multiple vessels and shell and tube heat exchangers (HX).

PVX is based on the SnapCAD application. The name SnapCAD comes from the ability to snap individual parts together, much like building models out of LEGO blocks, to design a vessel or HX. The assembled parts are connected physically to each other and react to changes made in other parts of the vessel. If for example the temperature is changed in a cylinder, this change is noticed by any flanges or nozzles attached to it and they will make corresponding corrections to their design.

The ability to reuse and store individual parts, or groups of assembled parts, gives the user an enormous flexibility and ease of use. These parts or groups of parts (referred to as assemblies or assembly groups) are stored in the Assembly Toolbox and are added to a vessel or HX by simple drag and drop onto the 3D model.

 

Shell and tube heat exchangers can be created either by entering the initial design data manually or by reading an existing thermal design from a file. HTRI's IST, HTC's STX are examples of two supported thermal design program.

After the HX is built and designed the user can change any number of properties in the HX and all the individual parts it contains. One of the only things that cannot be changed after the HX is created is the TEMA type. Apart from that you can change or modify virtually all aspects of the HX. For example you can select an individual flange and change it's facing and gasket properties, or override the HX pressure and temperature properties for an individual pipe in order for it to fit some specific design criteria. Individual parts can be added and removed, and they can also be repositioned and resized to override the automatic placement and sizing done by SnapCAD. Length's, diameters, materials and virtually anything else that affects the design of a part can be changed.

Fundamental features:

• Design, rating and conceptual modeling.
• TEMA Class B, C, R calculations.
• ASME Sec. VIII Div. 1 calculations.
• Over 2000 ASME materials available.
• Import HX Design data from HTRI's IST, HTC's STX program.
• Real-time advanced reporting - customizable, distributable.
• Drag and Drop 3D modeling and active dimensional measurements.
• 2D Drawing templates with multiple 3D viewports, 2D drawing and macro data.
• Nozzle Schedule Editor

Code Calculations

The following types of parts can be designed, modeled and rated in SnapCAD:

• Tubesheets TEMA/ASME: Stationary, Fixed, Floating Head and U-Tube.
• Expansion Joints and Distributor Belts.
• Flanges (ASME and Special), Bolted Covers.
• Cylinders, Cones, Flanged and Dished Heads, Semi Elliptical Heads, Spherical Heads, Flat Heads.
• Nozzles, Couplings and Openings (ASME and Special).

For modeling purposes other types of non-calculating objects and parts can also be included in the 3D model. Among those are the following:

• Saddle Supports, Skirt Supports, Lug Supports, Valves, pumps, Piping, Internal/External Plates, Stiffening Rings (Internal/External), Platforms, Ladders, Baffles.
• 3D DXF objects.

3D Modeling

The reason for including the 3D modeling aspect into PVX is to ensure accuracy. A 3D model is a great way to ensure that nozzles and other parts are free from interferences and are properly dimensioned. The 3D geometry of a part is updated when ever the calculations are updated, and because of this the 3D geometry of the entire vessel is always up to date.

Example of pad interference between two nozzles.

Reporting

All components, vessels and HX's in a project can have one or more calculation reports. Each calculation report in a project is automatically updated when the part, vessel or HX that represents is updated. Each report is based on a template file that can be customized by the user to fit his needs.

Note:
This documentation is currently under review, the terms PVX and SnapCAD.Exchanger are used interchangeably.