PN Designated Valves - Pressure Temperature Ratings

[Benjooles]

I am trying to determine in which standard the p/T ratings of PN designated valves is given. Or in other words, when a valve is stated to be PN16 Rated - to which standard is is rated as such?

I am aware of BS EN standards that cover the face to face dimensions etc. but I cannot seem to find anything that allows you to look up the material, class, temperature and the corresponding pressure rating for any given PN designation. (Like one does with the tables in ASME B16.5)

I am aware that EN1092-1 covers the p/T ratings of the flanges. Do these extend automatically to the valve as the valve body and components are assumed to be always stronger than the flanges?

Or is there some other theory behind the determination of a PN designated valves p/T rating?

 

[btrueblood]

You don't say where you are from, but from the nomenclature, it appears you are talking about European (CE)specs? The CE Pressure Equipment Directive is 97/23/EN (google on those terms, you should be able to find a copy of this from the CE servers, in the language of your choice). The PED has tables that specify the pressure and temperature limits for a part to fall within a particular classification. Moreover, the manufacturer is supposed to maintain the certification, which should include the details of the calculations done to show certification, as well as the temperature and pressure limits defined for the part, in order to comply with the PED.

Hope that helps. Though, being from the wrong side of the pond, it probably doesn't.

 

[Benjooles]

Thank you btrueblood.

I am working out of the UK - I am currently writing up valve and piping specifications.

Using the ASME system in this regard is A LOT simpler in that one can simply state - Class 150# as per ASME B16.5 Table 2..... etc. when specifying a valve. Proof of compliance with this is then up to the manufacturer. Also ensuring that you are specifying something that meets both the pressure and temperature conditions you require is then taken care of.

Most of the components that I am specifying fall into Class 0 of the PED with a limited number falling into Class I. In other words they only require sound engineering practice in terms of their design - with those in Class I not requiring a CE marking as far as I understand.

So if I understand you correctly what you are saying is:
Ensuring p/T compliance using the EN 'method' would then require specification of a nominal rating of PN16 (for example) and going out, finding products that comply with this spec. Then requesting p/T curves for the product/s and ensuring that the product meets the worst case scenario (WCS) for p/T that you are trying to cater for. Alternatively you could state what your WCS is then go out on enquiry with that p/T information - which means that you may end up getting a valve with a nominal pressure rating of PN40 in order to meet the pressure requirements at elevated temperature.
Either method requires the PN rating to be updated on the datasheet based on the limitations of the final chosen product - unless you get it right first time; with the first requiring considerably more work in terms of picking the final chosen product.

Now - before I look like one of the guys on these forums trying to get a quick and easy solution - I am not trying to get out of doing the work by any means - my basic problem is trying to figure out the industry standard way of specifying the pressure rating of valves to EN specifications so that I can ensure I get the same thing every time with minimal trawling through the limitless number of valves available out there.

 

[BigInch]

The original source is ISO 7268.

http://www.engineeringtoolbox.com/flanges-pn-pressure-ratings-d_46.html

PN does not mean Pressure Number, as shown in Engineering Tool Box.

http://www.aquatext.com/tables/pipepres.htm

http://www.nzweta.org.nz/page49925.html

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[europipe]

Try to get a copy of EN-13480,
the European standard for piping systems.
(like the B31.3 in USA)

Greetings

 

[Benjooles]

To All

I have found this in BS EN 13942 - 2009. 7.2 pg.28
Petroleum and natural gas industries - Pipeline transportation
systems - Pipeline valves (ISO 14313:2007 modified)

"Pressure-temperature ratings for class-rated valves shall be in accordance with the applicable rating table for the appropriate material group in ASME B16.34.
Pressure-temperature ratings for PN-rated valves shall be in accordance with the applicable rating table for the appropriate material group in EN 1092-1."

In general that Paragraph of the standard covers exactly my problem by stating what the recognised codes are for valve design and what p/T ratings are applicable depending on whether you choose to specify the valve using the Class system or the PN system.

This confirms my initial assumption that the pressure rating of the flanges is assumed under EN methods as the weakest point of the valve - albeit I only have confirmation on this for Gate, Plug, Ball and Check valves as these are the valves covered by the above standard.

From a quick survey it would seem that butterfly valve standards along the same lines are still being developed.
"08/30187521 DC
BS EN 593. Industrial valves. Metallic butterfly valves"

BS EN 13397 may cover the same information for metallic Diaphragm Valves - but unless I fork out the cash to buy it I am not going to be sure. Anyone know for a fact?

As all EN standards are supposed to be harmonized with the PED - I am confident that the correct way to do things would be to use the method stated in BS EN 13942 to specify my valve pressure ratings/classes as per ASME B16.5 or EN1092-1.

Any arguments against that?

 

[LSThill]

Pipe Class Component (PCC)

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The PCC software is used to calculate pipe class components for internal and external pressure.

Click this link to view a 5 minute introduction to PCC.

PCC calculates components and complete pipe classes with the click of one button. The PCC calculations can be selected by the engineer from ASME B31.3 (USA), EN13480 (Europe), and RToD (Netherlands).



For basic feature information please review the fact sheet: A4 or letter (PDF 33kB)

Basic work principle of the application is indicated in the Getting Started Guide: A4 or letter (PDF 1.7 MB)

The calculation results can be shown in a summary sheet. Colors indicate the amount of design margin used. Reports and calculation details provide the engineer all information as is depicted in the design code. All overviews, reports and calculation details can be printed or exported to MS Office tools for further processing. Also import and export to XML format is available for interfacing with other software applications.



Prime goal for the development of PCC was the ease of use. Pipe classes consist of many components such as pipe, elbow, reducer, cap, tee and weldolet. The amount of components and the branches are handled in an efficient and structured manner. The presentation of the data has the looks of a pipe class specification.



For more information see detail PCC page on the menu at the left.

Public issue of the user manual



Index (this page)
Introduction
Introduction - WHAT'S NEW and Overview
Introduction - Getting started
Building pipe class
Pipe class - Project
Pipe class - Class
Pipe class - Line size
Pipe class - Component selection
Pipe class - Branch table
Summary sheet
Summary - Verification of input and calculation
Calculation
Calculation - Critical pressure temperature combination
Calculation - Summary calculation
Calculation - Component detail calculation
Calculation - Assessment of calculations
Report
Report - Preparation of overall report
Export
PCC Software - Purpose
PCC Software - Structure
PCC Software - Database
PCC Software - Objects
PCC Software - Interfaces
User Interface Description - Summary Fittings
User Interface Description - Summary Valves
User Interface Description - Summary Notes
User Interface Description - File Menu
User Interface Description - File Project Edit
User Interface Description - File Project List
User Interface Description - Pipe Class Menu
User Interface Description - Pipe Class Edit General
User Interface Description - Pipe Class Edit PT rating
User Interface Description - Pipe Class Edit Component Settings
User Interface Description - Pipe Class Edit Defaults
User Interface Description - Pipe Class Edit Notes
User Interface Description - Pipe Class Import/Export XML
User Interface Description - Pipe Class Copy
User Interface Description - Tables Menu
User Interface Description - Table Line Size
User Interface Description - Table Pipe Schedule Wizard
User Interface Description - Table Flange
User Interface Description - Table Pipe
User Interface Description - Table Elbow
User Interface Description - Table Elbow Detail
User Interface Description - Table Reducer
User Interface Description - Table Reducer Detail
User Interface Description - Table Weldolet
User Interface Description - Table Weldolet Detail
User Interface Description - Table Tee
User Interface Description - Table Tee Detail
User Interface Description - Table Cap
User Interface Description - Table Branch Table
User Interface Description - Table Gasket
User Interface Description - Table Gasket Material
User Interface Description - Table Fastener
User Interface Description - Table Valve
User Interface Description - Table Valve Details
User Interface Description - Table Valve User Fields
User Interface Description - Execute menu
User Interface Description - Execute List All Calculations F6
User Interface Description - Execute Detail Calculation Output F7
User Interface Description - Execute Export All Detail Calculations F7
User Interface Description - Material Selection
User Interface Description - Material Editor
User Interface Description - Settings Menu
User Interface Description - Settings Database
User Interface Description - Settings Hardlock
PCC Object Data Definition
Contact
Contact - Help
Contact - F.A.Q.
Contact - Bug reports