PSVPlus Manual

PSVPlusTM Users Manual Softbits Consultants Ltd.

PSVPlusTM Users Manual

Manual Version v 7.0.0

Revision Date: February , 2010

- Table of Contents -

PSVPlusTM Users Manual 2

1 Introduction ........................................................................................................ 5 2 Whats new.......................................................................................................... 6 3 Overview ............................................................................................................. 7 3.1 Installation Requirement .................................................................................... 7

3.1.1 Package Requirements ................................................................................. 7 3.1.2 System Requirements................................................................................... 7

3.1.2.1 Decimal Separator ................................................................................ 7 3.1.2.2 MS Access 2003 SP1 Issue ..................................................................... 7

3.2 Installing PSVPlus-Single User (Standalone) on Windows XP................................... 7 3.3 Installing PSVPlus-Single User (Standalone) on Windows Vista or Windows 7............ 8

3.3.1 Separate Installation of Security Drivers and Access Runtime.......................... 10 3.4 Installing PSVPlus - Network............................................................................. 10

3.4.1 Installing Server Software and Key .............................................................. 10 3.4.2 Installing PSVPlus Clients............................................................................ 11 3.4.3 Trouble Shooting Client .............................................................................. 11

3.5 Remotely Updating the Hardware Key................................................................ 12 4 PSVPlusTM Usage Instructions............................................................................ 13 4.1 Key Features .................................................................................................. 13 4.2 Usage modes of PSVPlusTM................................................................................ 16

4.2.1 Using PSVPlusTM in a disconnected mode....................................................... 16 4.2.2 Using PSVPlus in a connected mode ............................................................. 17

4.3 Calculation Options Screen ............................................................................... 18 4.4 Quick Start Tutorial ......................................................................................... 20

4.4.1 Step 1 Create a Database......................................................................... 20 4.4.2 STEP 2 Gas Relief CONTROL VALVE FAILURE............................................ 20 4.4.3 STEP 3 Gas Relief FIRE LOAD CALCULATION............................................ 25 4.4.4 STEP 4 Liquid Relief SHELL AND TUBE EXCHANGER TUBE RUPTURE............ 27 4.4.5 STEP 5 Liquid Relief THERMAL EXPANSION .............................................. 31 4.4.6 STEP 6 Steam Relief FAN FAILURE.......................................................... 32 4.4.7 STEP 7 Steam Relief GENERAL POWER FAILURE ....................................... 35 4.4.8 STEP 8 Mixed Phase Relief OPTIONS A & B .............................................. 37 4.4.9 STEP 9 Mixed Phase Relief OPTION C ...................................................... 40 4.4.10 STEP 10 Mixed Phase Relief OPTION D .................................................... 42 4.4.11 STEP 11 - Review the calculations and select sizing cases and Items for the Relief Load Summary ...................................................................................................... 44 4.4.12 STEP 12 - Create Process Data Sheets......................................................... 44 4.4.13 Aspen Hysys and Aspen Flarenet sample applications ..................................... 45

5 Using PSVPlusTM in the connected to database mode....................................... 47



5.1 Database creation and management.................................................................. 47 5.2 Exploring database connection key features - PSVPlusTM Calculation Engine side...... 48

5.2.1 How to Specify General Settings for the Database.......................................... 51 5.3 Exploring database connection key features - PSVPlusTM Access Environment side ... 54

5.3.1 PSVPlusTM Access Environment Main Features ................................................ 56 5.3.1.1 Process Data Sheets Group .................................................................. 56 5.3.1.2 Summary Calculation Sheets Group....................................................... 58 5.3.1.3 Relief Load Summary Group................................................................. 58 5.3.1.4 Non Sizing Emergency scenarios .......................................................... 58 5.3.1.5 Export to Excel Utility .......................................................................... 59

5.3.2 Customizing PSVPlusTM Access Environment................................................... 61 5.4 PSVPlusTM Interfaces to Aspen HYSYS and Aspen Flarenet .................................... 63

5.4.1 Overview .................................................................................................. 63 5.4.2 Starting an Import or Export ....................................................................... 63 5.4.3 Aspen HYSYS Interface............................................................................... 63

5.4.3.1 General Description............................................................................. 63 5.4.3.2 HYSYS Import Process Page 1, Select Case......................................... 64 5.4.3.3 HYSYS Import Process Page 2, Import Log ......................................... 66 5.4.3.4 HYSYS Import Process Page 3, Select Streams.................................... 67 5.4.3.5 HYSYS Import Process, Page 4 Select Data Items ................................... 70 5.4.3.6 HYSYS Import Process, Page 5 Import Data ........................................... 72

5.4.4 Aspen Flarenet Import Interface .................................................................. 74 5.4.4.1 General description ............................................................................. 74 5.4.4.2 Flarenet Import Process Page 1, Select Case........................................ 74 5.4.4.3 Flarenet Import Process Page 2, Import Log ....................................... 77 5.4.4.4 Flarenet Import Process Page 3, Select Sources .................................. 78 5.4.4.5 Flarenet Import Process, Page 4 Select Data Items ................................. 81 5.4.4.6 Flarenet Import Process, Page 5 Import Data ......................................... 84

5.4.5 Aspen Flarenet Export Interface................................................................... 86 5.4.5.1 General description ............................................................................. 86 5.4.5.2 Flarenet Export Process Page 1, Select Case ........................................ 86 5.4.5.3 Flarenet Export Process Page 2, Export Log ........................................ 89 5.4.5.4 Flarenet Export Process Page 3, Select Sources................................... 90 5.4.5.5 Flarenet Export Process, Page 4 Select Data Items.................................. 93 5.4.5.6 Flarenet Export Process, Page 5 Export Data .......................................... 95

5.4.6 Aspen Flarenet Results Comparison Interface ................................................ 97 5.4.6.1 General description ............................................................................. 97 5.4.6.2 Flarenet Results Comparison Process Page 1, Select Previous Comparison98



5.4.6.3 Flarenet Results Comparison Process Page 2, Flarenet Database ............ 99 5.4.6.4 Flarenet Results Comparison Process Page 3, Setup Check ...................101 5.4.6.5 Flarenet Results Comparison Process Page 4, Flow Results ...................103 5.4.6.6 Flarenet Results Comparison Process Page 5, Pressure Results..............104

5.4.7 Interfacing PSVPlus database with SPI one...................................................105 5.4.7.1 Link Definition ...................................................................................106 5.4.7.2 Link Properties settings.......................................................................107 5.4.7.3 Fields Mapping...................................................................................109 5.4.7.4 Importing data ..................................................................................110 5.4.7.5 Reviewing Import error.......................................................................111

6 Technical Reference......................................................................................... 112 6.1 Vapour or Gas Relief Calculations .....................................................................112 6.2 Liquid Relief Calculations.................................................................................113 6.3 Steam Relief Calculations ................................................................................114 6.4 Inlet / Outlet Lines Sizing criteria for single phase fluids......................................115 6.5 Mixed Phase Relief Calculations OPTIONS A & B ..............................................116 6.6 Mixed Phase Relief Calculations OPTION C ......................................................117 6.7 Mixed Phase Relief Calculations OPTION D......................................................118 6.8 Storage Tanks Normal and Emergency Venting (API 2000)..................................119 6.9 Inlet / Outlet Lines Sizing - Mixed Phase fluids ...................................................120 6.10 Lines Equivalent Length Calculation ...............................................................121 6.11 Emergency Cases calculation forms ...............................................................122

6.11.1 Fire Load Calculation .................................................................................124 6.11.2 Control Valve failure calculation ..................................................................125 6.11.3 Exchanger Tube Rupture calculation............................................................126 6.11.4 Thermal Expansion calculation....................................................................127

6.12 Physical Properties calculation.......................................................................128 6.12.1 GasMix Library..........................................................................................128 6.12.2 IF97 Library .............................................................................................130 6.12.3 RefProp Library.........................................................................................131 6.12.4 StanMix Library ........................................................................................134 6.12.5 TPSI Library .............................................................................................138

Introduction - Installation Requirement


1 Introduction

PSVPlusTM is designed to execute calculations for pressure relief valves in Vapour, Steam, Liquid or Mixed Phase Service.

PSVPlusTM includes six calculation modules in full compliance with API Recommended Practice 520, 521 and 526 calculation procedures. In particular there are three modules for Vapour, Steam and Liquid relief scenarios and other three modules to cover the 2-Phase relieving scenarios in accordance with Appendix D of API 520, in compliance with DIERS Methods (also known as Omega or Leung method).

Five Physical Properties calculation packages are included in the software to allow the user to define the composition of the relieving stream and estimate its properties at the specified conditions.

A number of pre-defined scenarios calculation forms will provide guidance to the user in estimating the relieving rates. Such scenarios modules are Fire Wetted and Unwetted, Reflux Failure, Fan Failure, Control Valve Failure (Liquid, Gas and Gas break-through), Exchanger Tube Rupture (for single and mixed phase) and Thermal Expansion. Others scenarios forms are available for recording purposes only, as described later in this document.

Both single and two phases calculation modules are provided with procedures for designing inlet and outlet lines sizes at the same time of relief valve orifice calculation and selection. This is particularly useful to check consistency between back pressures items, inlet / outlet PSV flanges sizes and hydraulic calculations.

When working on Projects ranging from few to several hundred items, the user will have the option to connect the calculation forms to a pre-defined database and update it during the calculation stage, automatically preparing the following documentation and reports:

Process Data sheet Specifications for the calculated valves, for issue to Vendors.

Summary Calculation Sheets, showing for each Relief Valve all the scenarios for which it has been calculated and the relevant main results;

Relief Load Summary, a document to be used for sizing or checking of relevant flare headers and sub-headers in the relief network.

Based on the above and on user specific working requirement, there are the following two main modes of Working with PSVPlusTM:

a) Disconnected: means that the user is interested only in the determination of relieving rate, calculation of the orifice and its selection based on standard API 526 orifices and flanges, and design of PSV associated inlet and outlet lines size. The calculation prepared in this mode of operation can be saved as normal files that can be later imported in a database, if needed.

b) Connected to a Database: in this mode of operation, the user is connected to a predefined MS Access database for automatic preparation of the final process specification sheets, summary calculation sheet and relief load summary.

In the connected mode links to Aspen HYSYS and Aspen Flarenet will be available for automatic import of physical properties and / or import / export of Flare headers hydraulic calculations and PSVs relevant data.

Whats new - Installation Requirement


2 Whats new

The following notes apply to Release 7.0 of PSVPlusTM, and earlier versions.

Backward Compatibility with earlier releases:

The calculation files with extensions .vap, .liq, .stm, .mxa, .mxc, .mxd, prepared with previous versions of PSVPlusTM can be immediately opened and used with this new release.

The MS Access databases (extension .mdb) created with versions from 5.1 and newer will be converted upon opening. The databases created with PSV Plus 4.2 or earlier also will be converted. However some information may be lost due to software architecture changes. You may contact us at [email protected] to recover version 4.2 or earlier databases.

Main New features of Releases 6.0 and 7.0

Added API 2000 for storage tanks normal and emergency venting;

Added Noise and reaction forces calculation;

Updated 2-phase calculations to be in compliance with API 520 8th Ed.

Added utilities for database better management such as DB duplication, merge and compact and repair functions;

Added in the General Settings the option to customize PSV's orifices;

Added Design Temperature and Valve material fields for better PSV type and flanges identification in full accordance with API 526.

Added the Overall Relief Load Summary report in the DB environment to summarize cumulative and maximum single discharges from each unit of the plant;

Interface to Aspen HYSYS to allow automatic import of physical properties;

Interface to Aspen Flarenet to allow automatic import / export of PSVs data and calculation results;

Added valve browser form to show all valves included in a database and open their calculations directly;

Improved Database Environment User Interface;

Added % orifice used field to give more visibility to available design margin;

Added Vessel / Safety valve Design Code field;

Added Total Backpressure calculated field;

Overview - Installation Requirement


3 Overview

3.1 Installation Requirement

3.1.1 Package Requirements

Before installation, check that you have the following elements of the PSVPlus package.

Program CD Rom

Hardware Key (USB)

3.1.2 System Requirements

The following system requirements must be met to allow installation and use of PSVPlus.

o Operating system: Windows XP or Windows Vista or Windows 7. o Disk space - program directory 100 MB o Disk space - system directory 15 MB o USB port available for the Hardware Key o PSVPlus install files Usually supplied on CD Rom

3.1.2.1 Decimal Separator

PSVPlusTM, when started, automatically changes the decimal separator to be the period . and not the comma. When PSVPlusTM session is finished the decimal separator setting is automatically returned to the User preference.

In case this automatic modification does not occur, the User shall change the decimal separator from Control Panel > Regional Setting to be the PERIOD .

3.1.2.2 MS Access 2003 SP1 Issue

Access 2003 Service Pack 1 has a known bug that will prevent the Relief Load Summary and Summary Calculation Sheet to show correctly. Install the SP 2 or the HOTFIX made available by Microsoft.

3.2 Installing PSVPlus-Single User (Standalone) on Windows XP

The single user version of PSVPlus is one where usage of the program is controlled by a hardware USB key attached on the PC on which PSVPlus is running.

The installation of PSVPlus is a two step process. First the software must be installed. Then the key shall be connected to activate the software.

PSVPlus needs to be installed utilizing the PC user profile (not the installer profile!). PC user profile needs to be given Administrative privileges for the time of installation. After the installation is completed, the user can be configured as a power user.

The installation of PSVPlus is similar to the installation of other Windows programs. The steps are:

1. Shut down other windows programs. The Windows Explorer program may be left open to start the PSVPlus Setup program if required.

2. Remove any other hardware keys attached to the computer ports.

3. Insert the PSVPlus CD Rom into your CD or DVD drive. If the AutoRun feature is enabled then step 4 will be performed automatically and should be skipped.

4. Start the setup program Setup.exe on the CD Rom.

This may be done through Windows Explorer by navigating to your CD or DVD drive, locating the setup.exe file in the root directory of the CD and then double-clicking it.

Overview - Installing PSVPlus-Single User (Standalone) on Windows Vista or Windows 7


Alternatively you can click the Windows Start button, select the Run option, type d:\setup.exe in the pop-up dialog and then click the Ok button. Note that your CD or DVD drive letter should be substituted if it is not d:

5. The Setup program will then start. To complete PSVPlus installation just follow instructions on the screen.

6. After PSVPlus has been successfully installed, plug the USB hardware key on one of the available ports. You are now ready to run the program.

Note: two required components of PSVPlus may not install automatically for a number of reasons and depending on user PC settings; these components will therefore require separate installation, if not installed during PSVPlus program installation. These are

Security Drivers

To install these, run the Sentinel Protection Installer 7.5.0.exe program from the PSVPlus disk (located at the following path: D:\program files\PSV Plus 6.0\PSV Plus 6.0\Server\) and follow the instructions for a Complete Install. If invited to Upgrade an existing Sentinel Drivers installation then click the Upgrade button to do this.

Access Runtime

To install this run the AccessRunTime.exe program from the PSVPlus disk (located at D:\program files\PSV Plus 6.0\PSV Plus 6.0\MS Access Runtime\)program from the PSVPlus disk and follow the instructions for a Complete Install.

3.3 Installing PSVPlus-Single User (Standalone) on Windows Vista or Windows 7

In order to successfully install PSVPlus under Windows Vista or Windows 7 the following preconditions are required.

1. That the user has Administrator Rights. Note that PSVPlus needs to be installed utilizing the PC user profile (not the installer profile!).

2. That the User Account Control (UAC) feature is disabled.

The UAC feature can be disabled as follows:-

Open the Control Panel and Select the User Accounts option. The screen below should appear.

Overview - Installing PSVPlus-Single User (Standalone) on Windows Vista or Windows 7


Click on the the User Accounts heading as shown above. The following screen should appear:

Select the option Turn User Account Control on or off. The following popup will appear.

Click the Continue button and the following screen will appear.

Overview - Installing PSVPlus - Network


Clear the check box against Use User Account Control (UAC) and click ok. You will now be asked to Restart your system to complete the change. Click the Restart Now button to do this.

Once your system has restarted you can install PSVPlus as normal.

3.3.1 Separate Installation of Security Drivers and Access Runtime

Under Vista, two required components of PSVPlus may not install automatically and will require separate installation. These are

Security Drivers

To install these run the Sentinel Protection Installer 7.5.0.exe program from the PSVPlus disk (located at the following path: D:\program files\PSV Plus X.X\PSV Plus X.X\Server\) and follow the instructions for a Complete Install. If invited to Upgrade an existing Sentinel Drivers installation then click the Upgrade button to do this.

Access Runtime

To install this run the AccessRunTime.exe program from the PSVPlus disk (located at D:\program files\PSV Plus X.X\PSV Plus X.X\MS Access Runtime\) and follow the instructions for a Complete Install.

3.4 Installing PSVPlus - Network

The network version of PSVPlus allows the use of PSVPlus from multiple client systems with the total number of copies in use being controlled by a central PSVPlus USB Key server.

Installing the PSVPlus network version is a 3 step process. Firstly the server software must be installed. Then the USB Key must be attached to the server. Finally the PSVPlus client software must be installed on each machine that will run PSVPlus.

Note the PSVPlus license server is any PC on which the server software is installed. It does not have to be an existing network file server.

3.4.1 Installing Server Software and Key

The PSVPlus server software is the Sentinel SHK product from Safenet Technologies. Full details of this product are given in the online manuals in the SysAdminHelp directory which may be found in the PSVPlus CD.

Overview - Installing PSVPlus - Network


The following instructions are provided as a quick guide to installing your server software with a basic configuration. For more detailed information on the management of Sentinel SHK server consult the online manuals.

Note that a network key may also be used as a standalone one, just attaching it to the PC USB port where PSVPlusTM has been installed. In this case, please refer to paragraph 3.2 above.

The installation of the server software is similar to the installation of other Windows programs. The steps are:

1. Shut down other windows programs. The Windows Explorer program may be left open to start the server setup program if required.

2. Remove any other hardware keys attached to the computer ports.

3. Insert the PSVPlus CD Rom into your CD or DVD drive.

If the AutoRun feature is enabled then the introductory screen will appear inviting you to start a client installation.

If this happen, click the Cancel button to exit the client installation.

4. Open Windows Explorer, select the PSVPlus install CD and browse to the directory .PSV Plus X.X\PSV Plus X.X\Server. Double click on the program Setup.exe to run it. Alternatively you can click the Start button select Run and then type [Drive]:\Server\Setup.exe where [Drive] is the drive letter of your CD. Hit Enter to start the setup program.

On starting the server setup program, just follow instructions on the screen.

5. Click the Next button to continue.

6. To complete server software installation just follow instructions on the screen. At this point the server software is installed and the server service will have been started. Click the Finish button to close the window.

7. You may wish to confirm that the server service has installed correctly by checking the list of running processes as follows:

o From the Start menu, point to Settings and click Control Panel. o Double-click Administrative Tools. o Double-click the Services icon. The Services dialog box appears. o Locate the Sentinel Keys Server service. If the server is running, its status

will be shown as Started.

8. Attach the USB to one of the computer ports available on the server machine.

You have now completed the installation of server software and relevant Hardware Key and Clients need to be installed according to the following paragraph.

3.4.2 Installing PSVPlus Clients

The installation of the PSVPlus client software is similar to the installation of other Windows programs. Please refer to Paragraph 3.2 for installation under Windows XP or Paragraph 0 for installation under Windows Vista for details.

3.4.3 Trouble Shooting Client

In case of problems, please refer to the document: End-User troubleshooting guide for Sentinel SuperPro/UltraPro and Sentinel Hardware Keys by Safenet included in the PSVPlus CD for your convenience, in the directory \PSV Plus X.X\PSV Plus X.X\SysAdmin Help\SafeNet_Sentinel_EndUser_Guide.pdf.

Alternatively, please contact us at [email protected] specifying in detail the type of problem encountered.

Overview - Remotely Updating the Hardware Key


3.5 Remotely Updating the Hardware Key

In case your license has expired or you decide to purchase additional features, the Hardware Key that manages PSVPlus licenses can be updated remotely.

In order to initiate the update process follow these steps:

1. Remove all other keys attached to the PC or server leaving only the key to be updated;

2. Insert PSVPlus CD Rom into your CD or DVD drive in the same machine where the key is attached to;

3. Browse to the CD directory .\PSV Plus X.X\PSV Plus X.X\Secure Update Utility

4. Launch (i.e double click) the file SecureUpdateUtility.exe and generate the request file (.req exstension). Send this file to [email protected].

5. When you receive the update code file (.upw), repeat the steps above and load the received file to update your key.

PSVPlusTM Usage Instructions - Key Features


4 PSVPlusTM Usage Instructions

4.1 Key Features

PSVPlusTM is designed to help Process Engineers to calculate, design and prepare the Specification Sheets for Pressure Relief Valves.

Typical users are Process Engineers involved in the Design of Chemical / Petrochemical plants, Gas Plants, Refinery and similar industrial applications.

Calculation Codes

Pressure Safety Valves calculations are carried out in full accordance with APT RP 520, 521 and 526. Engineering recommendations are also provided to assist the process engineer in the proper Relief valve parameters and type selection and calculation.

PSVPlusTM TM provides a set of routines for the Gas, Liquid, Steam and Two-Phase relieving scenarios. The Two-Phase code provides four different calculation routines in accordance with Appendix D of API 520 latest edition.

Interface to Aspen HYSYS (***)

To automatically download physical properties calculated by Aspen HYSYS into a PSVPlus pressure relief valves database.

Interface to Aspen Flarenet (***)

To automatically download all PSVs and hydraulic calculations performed by Flarenet into a PSVPlus pressure relief valves database or, vice-versa, to populate a Flarenet database with a PSVPlus one.

Process Data Sheet, Summary Calculation Sheet and Relief Load Summary preparation

Based on actual working specific requirement, the calculation modules can be linked to an AccessTM (*) database for preparation of the following documents;

Process Specification Sheets (i.e. the data sheets normally prepared by the Process Engineer used by the Instrumentation Dept as basic information to purchase the PSVs);

Summary Calculation sheet for PSV: the calculation sheet that summarizes all the scenarios considered for each PSV sizing, along with the most relevant data. This document is normally required by end users, authorities and certifying entities to ensure that all applicable emergency scenarios have been duly taken into consideration;

Relief Load Summary: table normally used to show in a consistent format all the relieving rates and characteristics for plant general emergencies. Required for sizing and design of flare headers.

Pressure relief valve mechanical datasheet: the datasheet normally prepared by Instrumentation specialist that summarizes all the technical details of a pressure safety valve.

All the above reports will be generated automatically from the PSV calculation stage and can be exported to MS Excel.

Interface to Smart Plant Instrumentation (*)

The PSVPlus database has also been designed to be fully compatible with Smart Plant Instrumentation (ex-INToolsTM)(*) for automatic data download, if required.

Fluid Physical Properties

PSVPlusTM uses FluidPropTM(**) software for the calculation of single-components and mixture properties as defined by the user. More than 150 components and five



different thermodynamic models are available to estimate fluid properties at relieving conditions.

Determination of Relieving Rates, according to the applicable Emergency Scenario

The rate to be discharged from a PSV is normally to be calculated assuming all the applicable emergency scenarios. This is a time consuming task that requires experience and often complex calculations. PSVPlusTM provides a set of routines to quickly guide the user towards the proper determination of this relieving rate, by suggesting typical parameters and procedures to be considered, in addition to calculation methods:

Fire Load calculations

PSVPlusTM eliminates the need to perform any fire load related calculation. The options available will calculate fire loads for both Wetted and Unwetted vessel surface cases. The calculated fire load depends on selected Vessels geometry, dimensions, elevation and fluid latent heat.

Control Valve Failure

A detailed calculation form is available to rigorously calculate the consequences of the complete opening of a control valve. Calculation routines take into account control valve CV calculation, if not already available, and will cover also gas break-through situation, which is one of the most frequent scenarios encountered.

Fan Failure

In case of failure of one or more fans the loss of cooling or condensing may lead to pressure increase in the system and subsequent opening of Pressure Safety Valve.

Reflux Failure

Failure of a column top or side reflux causes pressure increase in the system as higher vapour rate than normal will be present into the column.

Exchanger Tube Rupture (Single and Mixed Phases)

When the differential pressure between the two sides of a S&T heat exchanger is high, tube rupture contingency is a main concern since, should it occur, the low pressure side may see a pressure higher than design. Determination of relieving load for this case is accomplished using complex calculation routines in PSVPlusTM.

Thermal Expansion

Should a liquid filled portion of piping or equipment be blocked-in under solar radiation or any other heat source, this will cause pressurization due to specific volume change of the liquid. Calculation of relieving rate can be easily calculated through PSVPlusTM routines.

General Power Failure, Cooling Water Failure, Fire, Blocked Outlet, etc

Other emergency scenarios can be selected from a comprehensive list. However no standard calculation method exists for them and the Engineer will have to calculate them. PSVPlusTM provides facilities to record all the considerations made to achieve the relieving rate figure, for later use or documenting purposes.

Seamless Integration between PSVPlusTM calculation module and MS Access(*) Database and Open Source Database Design

MS Access(*) database environment can be accessed directly from within PSVPlusTM calculation engine.

MS Access(*) database is distributed in the Open Source form, allowing the user to customize reports, adding Company logos and performing any kind of modification that is needed.



All the PSV emergency scenario calculations are handled by PSVPlusTM calculation modules. The required reports are then made available in the database provided application.

Inlet and Outlet lines Sizing

Inlet and outlet lines sizing routines for both single and two-phase fluids are also Inlet and outlet lines sizing routines for both single and two-phase fluids are also available to the user to ensure correct piping design, following valve orifice calculation and selection. PSVPlusTM will automatically check that the specified back pressure of the valve is consistent with the one calculated across the outlet line and will alert the engineer in case of improper valve selection, based on the back pressure to upstream pressure ratio criteria.

Inlet and outlet lines sizing is also checked against the pressure drop and velocity criteria commonly used. The option of sizing the outlet line for choked flow is also provided.

Global Settings and Calculation Parameters

Common calculation and parameter settings for all PSVs included in a database can be easily entered by the engineer. This ensures data and calculation consistency throughout the Project.

Pressure Safety Valves back-pressures settings and line sizing velocity and pressure losses design criteria can be specified to have full control over the performed sizing for PSVs and associated inlet / outlet lines.

API 2000 - Storage Tanks Normal and Emergency Venting calc's

A procedure for evaluation of normal and emergency venting requirement for storage tanks is provided.

Based on API 2000 Std., this procedure allows to calculate the normal in-breathing / out-breathing capacities and the maximum venting during a fire contingency.

A preliminary estimation of the size of normal and emergency breathing devices is provided as well.

On-line Guide and Quick Start

PSVPlusTM is provided with an online help and a comprehensive quick start section that will guide the user through main software capabilities. One-hour self-training, using this tutorial will be sufficient for an experienced engineer to use the software.

Technical reference and background is also provided in the manual.

Man-hours saving and Quality Improvement

PSVPlusTM has proven to be effective in saving man-hours up to 70% for the pressure safety valves calculation and process specification activities. Better quality assurance is also realised by the standardisation of calculation codes and data consistency among the various reports generated.

(*) ACCESSTM is a registered trademark by Microsoft Corp. SPI and INTOOLSTM is a registered trademark by Intergraph Corp.

(**) P.Colonna, T.P. van der Stelt, 2004, FluidProp: a program for the estimation of thermo physical properties of fluids, Energy Technology Section, Delft University of Technology, The Netherlands.

(***) Aspen HYSYSTM and Aspen FlarenetTM are registered trademarks by Aspentech Corp.

PSVPlusTM Usage Instructions - Usage modes of PSVPlusTM


4.2 Usage modes of PSVPlusTM

PSVPlusTM can be used in two ways, depending on job requirements.

Disconnected means that youre interested only in performing a single calculation session that involves no data collection and recording as normally associated with a complete Project requirement. In this mode of operation youll be able to use all calculation capabilities of PSVPlus (i.e. determination of relieving rate, calculation of the orifice, PSV selection based on standard API 526 orifices and flanges and design of PSV associated inlet and outlet lines size). The calculation prepared in this mode of operation can be saved as normal binary files that can be later imported in a database, if needed.

Connected to Database: in this mode of operation, the user is connected to a predefined MS Access database for automatic preparation of the final process specification sheets, summary calculation sheet and the relief load summary.

4.2.1 Using PSVPlusTM in a disconnected mode

When using PSVPlusTM in the disconnected mode, the user can perform calculations on PSVs and lines and save these calculations as a normal file for later retrieval and use or import in a database, if required. Each generated file will be relevant to only one calculation scenario.

In this mode PSVPlus will use the following file extensions, based on the type of calculation module utilized:

filename.vap for Vapour Relief Calculations;

filename.stm for Steam Relief Calculations;

filename.liq for Liquid Relief Calculations;

filename.mxa for Mixed Phase Calculations Options A & B;

filename.mxc for Mixed Phase Calculations Option C;

filename.mxd for Mixed Phase Calculations Option D.

where filename is the name given by the user to the calculation file.

Typically, this mode of operation is used when a valve has to be quickly checked against different relieving scenarios and no special reporting is needed. However, if required by the user, each of this calculation file can be later included in a database application using the Import command as discussed later in this document.

Examples of file naming can be:

a) 12_PRV_021 (Fire).vap for Pressure Relief Valve Item 021 in Unit 12, calculated against a Fire scenario Gas / Vapour Case;

b) 12_PRV_021 (CV Fails Open).liq for the same Item as above, calculated against a CV failed open scenario Liquid Case;

PSVPlusTM Usage Instructions - Usage modes of PSVPlusTM


4.2.2 Using PSVPlus in a connected mode

This operating mode differs from the previous one in that the calculation data for applicable emergencies for all valves are part of a Project and will be saved and stored together in a single database in a structured way.

The connected database will be used to provide automatically the following additional documents and reports:

Process Specification Sheet

Document normally issued by the engineer, showing all the process data required for PSVs mechanical definition.

Summary Calculation Sheet

Document showing all the scenarios considered for PSV design along with relevant calculation results. The summary calculation sheet is normally required by Authorities and Customers to verify emergencies associated with PSVs design.

Relief Load Summary

Table showing the most significant relieving rates calculated for each safety valve, with special consideration to the general emergencies such as Power Failure, Cooling Water Failure and Fire occurrence in a given plot area. This report is normally used for designing flare headers, sub-headers and stacks.

It is recommended that the user creates the database in a selected working directory and names it using some sort of convention (for example psv_1000.mdb may indicate all the PSVs for project 1000, or psv_1000_010.mdb may indicate PSVs in Proj. 1000 Unit 010). On large scale Projects, we recommend to create one database per process unit.

The Database is designed to support multiple access from within the PSVPlus calculation engine, meaning that several engineers can update the same project database simultaneously.

You may create as many databases as needed, without any limitation. The database reports can also be customized to accomplish to specific project needs. For example Company and Client logo can be easily added to the reports as well as any document numbering or identification code, as later discussed in this manual.

This database has also been configured to be compatible with Smart Plant Instrumentation, formerly INTools (by Intergraph Corp.) for automatic data download, if required.

Details on how to use the database follow in the Quick Start Examples Section and in a dedicated session.

PSVPlusTM Usage Instructions - Calculation Options Screen


4.3 Calculation Options Screen

When starting PSVPlus the following introductory screen will appear:

The Relief Calculation Options area can be used to select the calculation option of interest (i.e. Vapour, Steam, Liquid and Mixed Phases), the lower area Database Operations is used to manage PSVPlus linked database as described later in this document.

By selecting one of the Relief Valve calculation option and then pressing the Start Calculation button the relevant calculation form will be shown.

Note that the above screen can be used to access more than one calculation form at a single time. If required, all the six calculation forms for Vapour, Steam, Liquid and Mixed Phases can be opened at the same time in a multiple windows operating mode.

Under the Database Operations group of buttons you will have the tools to manage the database application that can be invoked when using PSVPlus in a connected mode.

Use the Create New Database button to generate a new database to be used for a new project. When accessing a previously generated database the Connect button shall be used instead.

PSVPlusTM Usage Instructions - Calculation Options Screen


Should you require to make a disconnected calculation during a connected session, just click on the Disconnect button.

To make a safety copy of the database just use the Backup Database.

Click on Start Database Environment to switch from PSVPlus calculation engine to PSVPlus database application. Note that the connected database is a normal .mdb file that can be started also from the Windows Explorer environment, just double clicking on it.

When working in the connected mode, a number of commands are available to interact with Aspen Hysys(*) and Aspen Flarenet(*) programs as discussed later in this manual.

Additionally some Database utilities commands are provided to manipulate PSVPlus databases. Using these commands, databases can be Duplicated for parallel trains, Merged and Compacted and Repaired.

(*) Aspen HYSYSTM and Aspen FLARENETTM are registered trademarks by Aspentech Corp.

PSVPlusTM Usage Instructions - Quick Start Tutorial


4.4 Quick Start Tutorial

4.4.1 Step 1 Create a Database

Start PSVPlus and from the introductory screen (see par. 4.3) select select the button adjacent to the selected database field.

The following form will appear:

Select any location in your PC or LAN and enter the desired Database Name. A possible name convention could be based on Project number and unit number (such as 1000 PSV 20, meaning PSV's in Unit 20 of Project n1000).

Note that it is usually recommended to create one database per each process unit.

Click on the 'Create' button and the DB will be created and connected.

Note that a 'Database Navigation Form' will appear. This form is intended to show key for calculated PSV's and to navigate easily among them. As you can see, it is initially empty, but will be populated as PSV's are calculated.

The file generated in this example is distributed with the program and located in the installation sub-directory (e.g. C:\Program Files\PSV Plus x.x\PSV Plus x.x\DB & EXAMPLES) and is named 1000 PSV 20.mdb.

4.4.2 STEP 2 Gas Relief CONTROL VALVE FAILURE

This section shows how PSVPlusTM handles the Safety Relief Valve Sizing for Vapour or Gas relieving scenario.

After completing 'Step 1' you're now connected to the database "1000 PSV 20" and calculations can be started.

In the Start-up form, select the Vapour calculation option and click the Start Calculations button; the Vapour calculation module will then appear.

Enter the following data:

Valve Item 001 PSV 010 A



Service Column Protection

Fluid Name Hydrocarbon

Click on the button adjacent to the Fluid Name Field and the Properties calculation Form will be opened. Enter the following data

Calculation package RefProp

Composition Basis MassFract

1st Component Name Hexane

1st Component Concentration

0.5

2nd Component Name isopentane

2nd Component Concentration 0.5

PSV Set Pressure: 18 barG

Overpressure 10% properties will be calculated at set pressure plus accumulation

Relieving Temperature 190 C

Clicking on Calculate button will give the following main results: Molecular Weight=78.54, Z=0.657, Viscosity=0.013 cP K(Cp/Cv) = 1.29. Now press the Confirm button to save and return back to the main form. Then enter the following data:

Valve Type Conventional

Conventional or Pilot Operated sets Kb = 1, by User. Balanced-Bellow sets Kb as Calculated.

Body Material Carbon Steel the body material will affect PSV and flanges rating selection

Design Code API 520, 521

Fire Case No allowable Over Pressure No sets to 10% F (F=Yes) sets to 21%.

Emergency Case Control Valve Failure

select by scrolling down on the Emergency Case field or by using the top menu bar under the Calcd Scenario menu or dedicated button on toolbar

Click on the button adjacent to the Emergency Case Field and the scenario calculation Form will be opened. Enter the following data:

Scenario Description

PV-001 Fails Open and causes excess flow to low pressure side

Type of Calculation: Check the option Control Valve CV Unknown

failing control valve CV is not available. PSVPlusTM provides a method for estimating it



rigorously.

The following data are relevant to the Control Valve (not the PSV) design data (i.e. during control valve normal operation).

Control Valve Calculation option

Check the option Control Valve in Gas / Vapour Service

Contr. Valve Design rate:

14000 kg/h

Gas Mol. Weight: 65

Gas Inlet Temperature 135 C

Gas Inlet Pressure: 25 barG

Diff Press. Across Contrl. Valve:

5.0 bar

Gas Compressibility (Z): 0.85

Critical Flow Coeff (Kv): 0.75 typical coefficient for control valves. For most applications use 0.75

The following data are relevant to the Control Valve (not the PSV) process data during emergency scenario (i.e. when the valve fails open).

Relieving Fluid Mol. Weight:

78.5

Relieving Fluid Inlet Temperature 190 C

Relieving Fluid Inlet Pressure

28 barG

Gas Compressibility (Z): 0.65

PSV Set Pressure 18 barG

PSV Allowable Overpressure 10%

CV Selected to CV calc. Ratio

2.5

ratio of CV Selected to CV Calculated. Data is first assumed and then checked with valve Vendor for critical systems. 2.5 is normally a conservative figure

Normal Flow to Process 1850 kg/h

the rate normally feeding the downstream process units that can be deducted from calculated relieving rate, according to API.

Clicking on Calculate the value of 49101.4 kg/h will be shown. Confirm it and return back to the main form

Discharge to LP Flare low pressure flare header

Atmospheric Pressure 1.013 bar A site barometric pressure



Relieving Flow 49101.4 kg/h

Relieving Temp 190 C

Design Temp 190 C PSV flange rating selection is based on design temperature.

Compressibility Factor 0.65

Molecular Weight 78.5

Specific Heat Ratio 1.29

Fluid Viscosity 0.013 cP

Rupture Disk Upstream No No automatically sets Kc = 1.0

Disk factor Kc 1.0 Kc = 0.9 when a rupture disk is installed upstream.

Set Pressure 18 bar G

Allowable Over Pressure 10 %

Superimposed Const. Back Pressure 1.013 bar A

constant superimposed pressure in the discharge system. Can be the atmospheric pressure for a system discharging to atmosphere or the atmospheric pressure plus the hydraulic seal head for a flare system.

Superimposed Variab. Back Pressure

0 bar

varying back pressure that is a function of the emergency scenario considered (i.e. general power failure, cooling water failure, etc..). This will be added to the Superimposed Constant Back pressure.

Builtup Back Pressure 0.3 bar

DP across the outlet line during relieving scenario. This is a first estimate and will be later checked against the outlet line sizing calculation.

Discharge Coefficient Kd 0.975

Back Pressure Factor Kb 1.0 applies only to Balanced-Bellows type valves

Calculated Orifice UOM in2

Changing the Units Of Measurement to cm2 will automatically re-execute valve sizing.

Once all the above data have been entered, press the Run Orifice Sizing button on the top graphical menu. The calculated orifice is 2.795 in2 and the flow is found to be Critical.

The user now selects the next larger size orifice i.e. 2.853 in2 size (4 L 6). Inlet flange rating is 300 / Outlet flange rating is 150.

Warning:the orifice and flanges rating selection must be considered preliminary and shall always be checked against Valve Mfr. Calculations.



Inlet / Outlet lines Sizing

Based on the selected valve PSVPlusTM auto initialises the diameter of the In / Out lines.

There are a number of predefined fields such as equivalent length and roughness that the user can change to match the calculation case, along with their own Units of Measurement.

By executing the lines sizing with respectively 4 and 6 sizes for inlet and outlet lines, the following message will appear:

Outlet Line Error: Fluid Velocity at Pipe Exit is higher than Critical Velocity. Do you want to design the line for sonic flow ? Click No

Change outlet line size to 10 in and repeat the calculation.

Inlet Line Error: Calculated Pressure Drop is higher than 3% of Set Pressure. Modify Your Specifications.

Outlet Line Error: Calculated Pressure Drop is Higher than Specified Builtup Back-pressure.

For the inlet line the size has to be changed to 6 in.

For the outlet line, as shown on the screen the calculated Pressure Drop is 0.408 bar, which is higher than the Builtup back-pressure of 0.3 bar estimated during PSV orifice calculation. Revise the latter figure from 0.3 to 0.5 bar and re-execute the orifice sizing. The orifice calculation will not be affected by the revised figure.

Re-executing the line sizing results in no Error messages, indicating that the PSV and line calculations are now correctly completed for 6 in (inlet) and 10 in (outlet).

Save the valve calculation in the database using the relevant button on the bottom left of the screen. A Valve Sizing calculation report is available for printing.

Scenario and Properties Reports are also available from the top menu.

Note: to correctly preview and print these Reports, you must open the relevant scenario or properties form and click on the Cancel or Confirm button at least once during the calculation session.

Please refer to the Technical Reference section of this manual for details relevant to Inlet / Outlet lines sizing criteria.



4.4.3 STEP 3 Gas Relief FIRE LOAD CALCULATION

It is assumed that your are still connected to the database generated in previous steps. Should this not be the case, start PSVPlus and from the initial screen press the 'Connect' button. In the database selection screen select the sample database generated in previous steps.

Start the Vapor Calculation option, locate the calculation performed at step 2 and click on the 'Duplicate' button. In the 'New Valve Item' screen leave the pre-defined one, 001 PSV 010 A, meaning that you will create a new calculation for the same valve item.

Change the field Emergency Case to Fire. This will automatically change the Fire Case field to F and change the Allowable Over Pressure to 21 %.

Click on the button adjacent to the Fluid field and the properties calculation form will show.




1st Component Name Hexane


0.5

2nd Component Name isopentane

2nd Component Concentration

0.5

PSV Set Pressure: 18 barG



Clicking on 'Calculate' button will give the following main results:

Relieving Temperature=187.57 C, Molecular Weight=78.54, Z=0.582, Viscosity=0.013 cP, K(Cp/Cv) = 1.5.

Click the button adjacent to Emergency Case (Fire) to open the Fire calculation form and enter the following data (vessel n1 only):

Wetted Surface Checked Note that the un-wetted surface calculation option is also available

Adequate drainage. Checked

Vessel n1 Active Checked active includes the calculation results in the total fire load.

Vessel n1 Item D-301

Vessel Type Horizontal

Diameter 4800 mm

Height 12000 mm horizontal vessel length

Liquid Level 4500 mm from tan or bottom (H)



Vessel Elev. from Grade 1000 mm to tan or bottom

Flame Height from Grade

7620 mm

Include Piping Contribution 15%

Environmental Factor F by User

Fluid Latent Heat 45.4 kcal /kg imported from the properties calculation form

Leave the other two vessels fields unchanged to exclude them from calculations (i.e. one PSV protects only one vessel).

Click the Calculate button and you will get 70917 kg/h as a fire load.

Click Confirm button and this figure will be automatically imported in the Vapour Relief Calculation form.

Leave the other fields unchanged.

Execute the Valve sizing: calculated orifice will now be 3.301 in2.

Select the orifice 4 M 6, use the inlet and outlet lines sizes of 6 in and 10 in respectively and run the lines sizing. The following error messages will be shown:

Outlet Line Error: Calculated Pressure Drop (0.819 bar) is higher than specified Builtup Back Pressure (0.5). Modify your specifications !

To fix the sizing, we can revise the specified builtup back pressure term from 0.5 to 1.0 bar, an re-run the valve sizing to ensure that this change does not affect the orifice sizing.

Now run again the line sizing to confirm that the proposed sizing is suitable for the service.

Valve calculation details, Properties and Fire Scenario data can now be reviewed by previewing the relevant Report.

Note: to correctly preview and print these Reports, you must open the relevant scenario or properties form and click on the 'Cancel' or 'Confirm' button at least once during the calculation session.

Save the generated calculation.



4.4.4 STEP 4 Liquid Relief SHELL AND TUBE EXCHANGER TUBE RUPTURE

This section shows how PSVPlusTM handles the PSV Sizing for Liquid relieving scenario.


Start the Liquid Calculation option.


Valve Item 001 PSV 011 A

Service Surge Vessel Protection

Fluid Name Liquid Hydrocarbon




1st Component Name cyclohexane


0.25

2nd Component Name decane

2nd Component Concentration

0.45

3rd Component Name heptane

3rd Component Concentration

0.3

PSV Set Pressure: 4.5 barG



Clicking on Calculate button will give the following main results: Molecular Weight=109.56, Vapour Quality=0 (all liquid), Specific Gravity= 0.651. Confirm it to return back to the main form

Valve Type Balanced-Bellow

conventional or Pilot Operated sets Kb = 1, by User. Balanced-Bellow sets Kb as Calculated.

Body Material Carbon Steel



Emergency Case Exchanger Tube Rupture

select by scrolling down on the Emergency Case field or by using



the top menu bar, under the Calcd Scenario menu



Low Pressure Side of 100-E-201 fails and liquid flows from Shell to Tube

Fluid Flowing from Shell to Tube

Checked

Design Press @ Low Press Side

4.5 barG

Allowable Overpressure 10%

Tube Inside Diameter 1.2 in

Operating Press @ High Press Side

105 bar G

Liquid Spec. Gravity 0.651

Click on the Calculate button and get the result that should be 359326 kg/h. Press Confirm and return to the main form.

Discharge to Sewer

Relieving Flow 359326 kg/h automatically entered, based on Exchanger Tube Rupture provided information

Relieving Temp 100 C

Design Temp 100 c

Specific Gravity 0.651 automatically entered, based on Exchanger Tube Rupture provided information

Fluid Viscosity 400 cP

Rupture Disk Upstream No No sets Kc = 1.0 Yes sets Kc = 0.9


Set Pressure 4.5 bar G automatically entered, based on Exchanger Tube Rupture provided information

Allowable Over Pressure 10 % automatically entered, based on Exchanger Tube Rupture provided information

Superimposed Const. Back Pressure

1.013 bar A

constant superimposed pressure in the discharge system. Can be the atmospheric pressure for a system discharging to atmosphere or the atmospheric pressure plus the hydraulic seal



head for a flare system.

Superimposed Variable. Back Pressure

0 bar


Builtup Back Pressure 0.3 bar



Back Pressure Factor Kw 1.0 this factor applies only to Balanced-Bellow type valves

Kw Calculation Option Calculated

Calculated Orifice UOM in2

changing the Units Of Measurement to cm2 will results in the automatic execution of valve resizing

Once all the above data have been entered, press the Execute button. The calculated orifice is 10.149 in2.

It should be noted that the program automatically calculates the Balanced-Bellow factor Kw = 1.0 and the Viscosity correction factor Kv = 0.957

The user should now select a larger size orifice i.e. the 11.058 in2 size (6- 150# Q 8 150#).

Warning: the orifice selection must be considered preliminary and shall always be checked against Valve Mfr. Calculations.


Based on selected Pressure Relief Valve (i.e. 6 Q 8) PSVPlusTM initialises the In / Out lines diameter.

There are a number of predefined fields such as equivalent length and roughness that the user can change to match properly the calculation case, along with their Units Of Measurements.

By executing the lines sizing with respectively 6 and 8 sizes for inlet and outlet lines, the following messages will appear:

Inlet Line Error: Maximum Pressure Drop exceeded.

Outlet Line Error: Calculated Pressure Drop (0.806 bar) is higher than Specified Built-up Back Pressure (0.3 bar). Modify Your Specifications.

The above shows that there are problems with both Inlet and Outlet Line sizing.

Please refer to the Technical Reference section of this manual for details relevant to Inlet / Outlet lines sizing criteria.

Change inlet line size to 8 in and outlet to 10 in and repeat the calculation.

The same error messages as above will appear.



Change the initial estimate for the inlet line equivalent length from 50m to 5m and the outlet line length from 50m to 25m. Re-run the line sizing and no error messages will appear.




4.4.5 STEP 5 Liquid Relief THERMAL EXPANSION

This section shows how PSVPlusTM handles the Safety Relief Valve Sizing for Liquid relieving scenario.


Start the Liquid Calculation option, locate the calculation performed at step 4 and click on the 'Duplicate' button. In the 'New Valve Item' screen leave the pre-defined one, 001 PSV 011 A, meaning that you will create a new calculation for the same valve item.


Emergency Case Thermal Expansion


Scenario Description Blocked in liquid filled vessel under solar radiation

Heat Input 620,000 kcal/h

Liquid Spec. Gravity 0.668

Liquid Specific Heat 0.1 kcal/ (kg C)

Cubical Expansion Coefficient

0.0008 1/F

Click on the Calculate button and get the result that should be 8936 kg/h. Press Confirm and return to the main form. Enter the following data:

Discharge to Sewer

Relieving Flow 8936 kg/h automatically set by the program

Leave the other fields unchanged

Press the Execute button. The calculated orifice is 0.275 in2. Select the orifice 0.307 in2 corresponding to 1 - 150# F - 2 - 150#.

It should be noted that the program automatically calculates the Balanced-Bellow factor Kw = 1.0 and the Viscosity correction factor Kv = 0.867.


For this scenario, a 3 in inlet line and 4 in outlet line sizing is adequate.




4.4.6 STEP 6 Steam Relief FAN FAILURE

This section shows how PSVPlusTM handles the Safety Relief Valve Sizing for Steam relieving scenario.


In the Start-up form, select the Steam calculation option and click the Start Calculations button; the Steam calculation module will then appear.

Valve Item 001 PSV 035

Service Steam Header

Fluid Name Steam


Calculation package IF97 IF97 is property package to be used when handling water / seam related calculations


1st Component Name Water


1.0

PSV Set Pressure: 1600 psiG


Relieving Temperature 620 F

Clicking on Calculate button will give the following main results: Molecular Weight=18.02, Vapour Quality=1 (all steam), Compressibility (Z) = 0.618, Viscosity = 0.021 cP. Confirm it to return back to the main form


Body Material Carbon Steel the body material will affect PSV and flanges rating selection


Fire Case No

Emergency Case Fan failure


Scenario Description Steam Condenser EA-230 fan fails.

Design Air Cooler Condensing Rate

Rate 87020 kg/h

% of Rate still condensed by Natural Convection

20% percent rate (referred to the design one) of condensation still achieved by natural convection heat exchange when the fans



fail.

Click on the Calculate button and get the result that should be 69616 kg/h. Press Confirm and return to the main form.

Discharge to Atmosphere


Relieving Flow 69616 kg/h

Relieving / Design Temp 620 F

Compressibility Factor 1.0

Molecular Weight 18

Specific Heat Ratio 1.4


Rupture Disk Upstream No setting this figure to No will automatically set Kc = 1.0

Set Pressure 1600 psi G



1.013 bar A


Superimposed Variab. Back Pressure 0 bar


Built up Back Pressure 5 bar


Valve Coeff (Ksh) 1

Coeff Ksh Option Calculated


Back Pressure Factor Kb 1.0 this factor applies only to Balanced-Bellow type valves


Calculated Orifice UOM In2 changing the Units Of Measurement to cm2 will results in the automatic execution of valve resizing



Once all the above data have been entered, press the Execute button. The calculated orifice is 1.726 in2 and the flow is found to be Critical.

The user is now allowed to select a larger size orifice i.e. the 1.838 in2 size (3 1500# K 6 300#).



Based on selected Pressure Relief Valve (i.e. 3 K 6) PSVPlusTM initializes the In / Out lines diameter.

There are a number of predefined fields such as equivalent length and roughness that the user can change to match properly the calculation case.

Change the Inlet / Outlet lines size to respectively 4 in XS and 8 in 80S. Change the inlet line equivalent length to 20 mt; change the Specified Built-up Back Pressure from 5 to 8 bar and accept sizing the outlet line for Sonic Flow.

Line sizing will be executed without any Warning message. However be aware that the outlet line has been sized considering sonic flow, and it must be properly addressed on Project documentation.




4.4.7 STEP 7 Steam Relief GENERAL POWER FAILURE

Start PSVPlus and from the initial screen press the 'Connect' button. In the database selection screen select the sample database generated in previous steps.

Start the Steam Calculation option, locate the calculation performed at step 6 and click on the 'Duplicate' button. In the 'New Valve Item' screen leave the pre-defined one, 001 PSV 035 A, meaning that you will create a new calculation for the same valve item.

Change the field Emergency Case to General Power Failure.

Click on the button adjacent to the Fluid field and the properties calculation form will show.

Click on the button adjacent to the Fluid Name Field and the Properties calculation Form will be opened. Enter the following data:

Calculation package IF97 IF97 is property package to be used when handling water / seam related calculations



1st Component Concentration 1.0


1st Component Concentration 1.0

1st Component Name water

PSV Set Pressure: 1600 psiG


Relieving Temperature 620 F

Clicking on 'Calculate' button will give the following main results: Molecular Weight=18.02, Vapour Quality=1 (all steam), Compressibility (Z) = 0.618, Viscosity = 0.021 cP, k (Cp/Cv) = 2.7.

Confirm it to return back to the main form.

Back in the main PSV form, change the Relieving Flow figure to 120,000 kg/h and leave the others parameters unchanged.

Now press the Run Valve Sizing button on the top graphical menu. The calculated orifice is 2.975 in2 and the flow is found to be Critical.

The user is now allowed to select a larger size orifice i.e. the 3.6 in2. However, when this orifice is selected, the following warning message will appear:

Warning. Set pressure too high for this valve selection.

This means that the selected valve cannot be designed for such a high set pressure, in accordance with standard design presented in API 526.

The solution here is to split the valve into two smaller PSV's each designed for half of the capacity, since smaller valves can be designed for higher set pressures, as depicted on API 526.



So, revise the Relieving Flow figure to 60,000 kg/h.

Also the Overpressure term shall be changed to 16% in accordance with API 520 instructions for multiple devices installation.

Run again the valve sizing and get a calculated orifice of 1.401 in2. A larger orifice of 1.838 in2 can be selected, resulting in a 3" - 1500# K 6" - 300# PSV selection.

Running the Line Sizing for different pipe sizes, you'll find a suitable solution with 4" for the inlet line and 14" for the outlet one.

Now you need to size also the second valve. So 'Duplicate' this one and change the prefix to 'B'. For the valve 'B' you need to increase the set pressure by 5% to 1680 psig and the overpressure to 10%, in accordance with API 520.

Run the valve sizing and get a calculated orifice of 1.408 in2. Same PSV selection and line sizing as for valve 'A' apply.



4.4.8 STEP 8 Mixed Phase Relief OPTIONS A & B

This section shows how to handle PSV Sizing for Mixed Phase Options A & B.

The following example is the same as the one shown on API RP 520 7th Ed. Appendix D.

Start PSVPlus and connect to the Database of previous steps. In the Start-up form, select the Mixed Phase Relief calculation option; the '2-Phase Calculation Options' will be enabled: select Option A under the column API 520 7th Ed. and click the Start Calculations button; Mixed Phase Options A & B calculation module appears.



Service Column Protection

Valve Type Balanced Bellow

conventional or Pilot Operated sets Kb = 1, by User. Balanced-Bellow sets Kb as Calculated.


Emergency Case User Defined


Scenario Description Operational Upset

Relieving Flow 477430 lb/h

Press Confirm and return to the main form.

Discharge to: Flare


Relieving Flow 477430 lb/h automatically filled-in by the program

Relieving Temp 200 F

Spec. Heat Ratio K 1.25


Rupture Disk Upstream No setting this figure to No automatically sets Kc = 1.0




1.013 bar A




Superimposed Variab. Back Pressure

0 bar


Built-up Back Pressure 15 psi

P across the outlet line during relieving scenario. This is a first estimate and will be later checked against the outlet line sizing calculation.


Back Pressure Factor Kb 1.0 applies only to Balanced-Bellows type valves


Calculated Orifice UOM in2 changing the Units Of Measurement to cm2 will results in the automatic execution of valve resizing

Select the Flashing multi-component system with Nominal Boiling Range greater than 150 F option. The non-required 2-phase fields will be automatically disabled.

Enter the following 2-Phase related data:

Vapour Mass Fraction (xo)

Not required Vapour mass fraction

Specific Vapour Volume (V vo) Not required specific volume of the Vapour

Specific Liquid Volume (V lo)

Not required specific volume of the liquid

Specific 2 Ph Volume (Vo)

0.3116 ft3/lb specific volume of the 2-Phase system

Latent Heat of Vap. (H vlo) Not Required latent heat of Vapourization

Liquid Spec Heat (Cp) Not Required Liquid specific heat at constant pressure

Specific 2 Ph Volume (V9)

0.3629 ft3/lb

specific volume of the 2-Phase system at 90% of PSV inlet pressure (i.e. set pressure + allowable over pressure)


Since the calculated orifice is larger than the maximum available orifice on the market, the flow must be split in at least two valves and the orifice re-calculated.

Therefore set the Relieving flow as follows:




Also change the Allowable Overpressure to 16%.

Run again the valve sizing and an orifice of 18.612 in2 will be calculated. Now select a 26 in2 PSV (8T10 with inlet and outlet flange of rating 150).



Click on the Line Sizing button to enter the form to calculate inlet and outlet line sizes. Change inlet pipe diameter to 10 in and outlet pipe diameter to 12 in and run the calculation. Satisfactory results will be found for the maximum allowable equivalent lengths. Click Confirm to go back to main calculation form.

Save the valve calculation.

Now you need to size also the second valve. So 'Duplicate' this one and change the prefix to 'B'. For the valve 'B' you need to increase the set pressure by 5% to 63 psig and the overpressure to 10%, in accordance with API 520.

Run the valve sizing and get a calculated orifice of 18.645 in2. Same PSV selection and line sizing as for valve 'A' apply.



4.4.9 STEP 9 Mixed Phase Relief OPTION C

This section shows how to handle PSV Sizing for Mixed Phase Option C scenario.

The following example is based on API RP 520 7th Ed. - Appendix D.

Start PSVPlus and connect to the Database of previous steps. In the Start-up form, select the Mixed Phase Relief calculation option; the '2-Phase Calculation Options' will be enabled: select Option C under the column API 520 7th Ed. and click the Start Calculations button; Mixed Phase Option C calculation module appears.



Service Vessel Protection

Fluid Name Propane


conventional or Pilot Operated sets Kb = 1, by User.

Balanced-Bellow sets Kb as "Calculated".




Scenario Description Blocked in pump

Relieving Flow 11612 kg/h


Discharge to: Flare


Relieving Temp 60 F

Specific Gravity 0.512






1.013 bar A


Superimposed Variable. Back Pressure 0 bar

varying back pressure that is a function of the emergency scenario considered (i.e. general



power failure, cooling water failure, etc..). This will be added to the Superimposed Constant Back pressure.






Calculated Orifice UOM

in2 changing the Units Of Measurement to cm2 will results in the automatic execution of valve resizing

Select the Single component far from thermodynamic critical point option. The non-required 2-phase fields will be automatically disabled.


Saturation Pressure (Ps) 107.6 psi A saturation (Vapour) pressure corresponding to inlet temperature

Specific Vapour Volume (V vs) 1.001 ft3/lb specific volume of the Vapour

Specific Liquid Volume (V ls)

0.03160 ft3/lb specific volume of the liquid

Latent Heat of Vap. (H vls)

152.3 Btu/lb latent heat of Vaporization

Liquid Spec Heat (Cp) 0.6365 Btu/(lb F) Liquid specific heat at constant pressure at PSV inlet

Liquid Density (Rho l9) Not required liquid density evaluated at 90% of saturation pressure


The user can now select a larger size orifice (i.e. 1.5 F 2).



Click on the Line Sizing button to enter the form to calculate inlet and outlet line sizes. Change inlet pipe diameter to 2 in and outlet pipe diameter to 6 in and run the calculation. Satisfactory results will be found for the maximum allowable equivalent lengths. Click Confirm to go back to main calculation form.

Save the valve calculation.



4.4.10 STEP 10 Mixed Phase Relief OPTION D

This section shows how to handle PSV Sizing for Mixed Phase Option D scenario.

The following example is based on API RP 520 7th Ed. - Appendix D.

Start PSVPlus and connect to the Database of previous steps. In the Start-up form, select the Mixed Phase Relief calculation option; the '2-Phase Calculation Options' will be enabled: select Option D under the column API 520 7th Ed. and click the Start Calculations button; Mixed Phase Option C calculation module appears.



Service Gas Oil Hdt


conventional or Pilot Operated sets Kb = 1, by User.

Balanced-Bellow sets Kb as "Calculated".

Fire Case No

allowable Over Pressure

"No" sets to 10%

"F" (F=Yes) sets to 21%.




Operational Upset



Discharge to: Flare


Relieving Temp 450 F

Specific Heat Ratio (K) 1.0





Superimposed Const. Back Pressure 1.013 bar A


Superimposed Variab. 0 bar varying back pressure that is a function of the emergency



Back Pressure scenario (i.e. general power or cooling water failure, etc..). This is added to the Superimposed Constant Back pressure.






Calculated Orifice UOM in2 changing the Units Of Measurement to cm2 will results in the automatic execution of valve resizing

Select the False option, since the system has a nominal boiling range greater than 150 F. The non-required 2-phase fields will be automatically disabled.


Gas/Vap Mass Fraction (xo)

0.5596 combined gas / Vapour mass fraction

Specific Vapour Volume (V vo) Not required

specific volume of the Vapour only (no gas)

Specific Liquid Volume (V lo)

Not required specific volume of the liquid

Specific 2 Ph Volume (Vo)

0.1549 ft3/lb specific volume of the 2-Phase system

Specific Vap/gas Vol. (V vo) 0.2462 ft3/lb

specific volume of the combined Vapour / gas system

Gas mole fraction (Y go) Not required gas mole fraction in the Vapour phase

Saturation Pressure (P vo)

Not required

Saturation (Vapour) pressure corresponding to inlet temperature. For multi-component systems use bubble point pressure

Latent Heat of Vap. (H vlo) Not Required latent heat of vaporization

Liquid Spec Heat (Cp) Not Required at constant pressure

Specific 2 Ph Volume (V9) 0.1737 ft3/lb

specific volume of the 2-Phase system at 90% of PSV inlet pressure (i.e. set pressure + allowable over pressu

PSVPlus Manual

Documents

psvplustm usage instructions

usage modes of psvplustm

psvplus network

psvplus clients

psvplussingle user standalone

liquid relief shell

steam relief fa

windows vista