Code of Practice for the Installation of Pressure Sensing Devices on Dry Gaseous and Liquid Chlorine Applications

7/24/2019 Code of Practice for the Installation of Pressure Sensing Devices on Dry Gaseous and Liquid Chlorine Applications

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CODE OF PRACTICE FOR THE

INSTALLATION OF PRESSURE SENSINGDEVICES ON DRY GASEOUS AND LIQUID

CHLORINE APPLICATIONS

GEST 94/207

Edition 2

February 2010

EURO CHLOR PUBLICATION________________________________________________________

This document can be obtained from:EURO CHLOR - Avenue E. Van Nieuwenhuyse 4, Box 2 - B-1160 BRUSSELS

Telephone: 32-(0)2-676 72 65 - Telefax : 32-(0)2-676 72 41


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GEST 94/207Edition 2

February 2010 Page 2 of 12

Euro Chlor

Euro Chlor is the European federation which represents the producers of chlorineand its primary derivatives.

Euro Chlor is working to:

improve awareness and understanding of the contribution that chlorinechemistry has made to the thousands of products, which have improvedour health, nutrition, standard of living and quality of life;

maintain open and timely dialogue with regulators, politicians, scientists,the media and other interested stakeholders in the debate on chlorine;

ensure our industry contributes actively to any public, regulatory orscientific debate and provides balanced and objective science-basedinformation to help answer questions about chlorine and its derivatives;

promote the best safety, health and environmental practices in themanufacture, handling and use of chlor-alkali products in order to assistour members in achieving continuous improvements (Responsible Care).

***********

This document has been produced by the members of Euro Chlor and should not be reproduced inwhole or in part without the prior written consent of Euro Chlor.

It is intended to give only guidelines and recommendations. The information is provided in goodfaith and was based on the best information available at the time of publication. The information is

to be relied upon at the users own risk. Euro Chlor and its members make no guarantee andassume no liability whatsoever for the use and the interpretation of or the reliance on any of the

information provided.

This document was originally prepared in English by our technical experts. For our membersconvenience, it may have been translated into other EU languages by translators / Euro Chlormembers. Although every effort was made to ensure that the translations were accurate, Euro

Chlor shall not be liable for any losses of accuracy or information due to the translation process.

Prior to 1990, Euro Chlors technical activities took place under the name BITC (BureauInternational Technique du Chlore). References to BITC documents may be assumed to be to EuroChlor documents.


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RESPONSIBLE CARE IN ACTION

Chlorine is essential in the chemical industry and consequently there is a need forchlorine to be produced, stored, transported and used. The chlorine industry hasco-operated over many years to ensure the well-being of its employees, localcommunities and the wider environment. This document is one in a series whichthe European producers, acting through Euro Chlor, have drawn up to promote

continuous improvement in the general standards of health, safety and theenvironment associated with chlorine manufacture in the spirit of ResponsibleCare.

The voluntary recommendations, techniques and standards presented in thesedocuments are based on the experiences and best practices adopted by membercompanies of Euro Chlor at their date of issue. They can be taken into account infull or partly, whenever companies decide it individually, in the operation of existingprocesses and in the design of new installations. They are in no way intended asa substitute for the relevant national or international regulations which should befully complied with.

It has been assumed in the preparation of these publications that the users willensure that the contents are relevant to the application selected and are correctlyapplied by appropriately qualified and experienced people for whose guidancethey have been prepared. The contents are based on the most authoritativeinformation available at the time of writing and on good engineering, medical ortechnical practice but it is essential to take account of appropriate subsequentdevelopments or legislation. As a result, the text may be modified in the future toincorporate evolution of these and other factors.

This edition of the document has been drawn up by the safety working group

(GEST) to whom all suggestions concerning possible revision should beaddressed through the offices of Euro Chlor.


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MAIN MODIFICATIONS IN THIS VERSION

Section Nature

AllInsure coherence with GEST 94/210 - Code of Prac tice for TheInsta l lat ion of Flow Measuring Devices on Dry Gaseous and

Liqu id Chlor ine App l icat ions

All General update on documents referred to

2. Add information on sealing fluids, including as source of errors

4.Clarifications added on branches (including in figures) in line withGEST on pipelines

TABLE OF CONTENTS1. SCOPE 5

2. DIAPHRAGM SEALS 52.1. Direct mount diaphragm seal 5

2.2. Remote diaphragm seal 5

3. LOCATION OF DEVICE 63.1. Ease of access 7

3.2. Local indication: visibility 7

3.3. Isolation, testing and removal 7

3.4. Support 9

3.5.

Protection against Impact 93.6. Other relevant information 9

4. PRIMARY PROCESS CONNECTION 9

5. EXTENSION PIPEWORK 11

6. REFERENCES 11


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1. SCOPE

This guideline provides advice on the installation of pressure measuring anddetection instrumentation on dry gaseous and liquid chlorine applications.

The document does not include the selection of equipment and materials (seeGEST 79/82 Materia ls of Constru ct ion for Use in Contact with Chlorin e);however possible diaphragm locations are described.

2. DIAPHRAGM SEALS

The material of the diaphragm should be resistant to chlorine, including thepossibility of moisture entrance during maintenance, for example tantalum.

The fill fluids used should be totally inert for chlorine, like completely chloro-

fluorinated oils (Voltalef, Fluorolube)or, if the volume is lower than 3 cc, fluidsfor which the reactivity with chlorine has been confirmed to be very low may beused (Silicon DC200 for example).

2.1. Direct mo unt diaphragm seal

The direct mounted diaphragm seal is the first choice due to lower installationcosts and better general performance (see example in figure 1). The instrumentshould be designed to have a restricted leak path in the event of diaphragmfailure.

Figure 1: Direct mount diaphragm seal

2.2. Remo te diaphragm seal

The remote diaphragm is recommended for applications where vibration orpulsation in the pipe will damage the transmitter or the instrument connection. It


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shall be used if the process temperature at the direct mount transmitter will exceedmaximum allowed temperature (see figure 2).

Remote seal error

Temperature-induced errors are inherent to diaphragm seal systems due to

changes of volume of the seal system and density of the fill fluid with fluctuationsin the process and ambient temperatures.

Factors influencing this effect are:

the diaphragm stiffness, primarily size related

the coefficient of thermal expansion of the fill fluid

the fill fluid volume related to the diaphragm size

In addition, one needs to be aware of variables that affect the response time of thepressure measurement with capillary systems.

Figure 2: Remotely Installed Pressure Sensing Devices

3. LOCATION OF DEVICE

The installation and location of a pressure sensing device should be carried outafter consideration of the following general factors:

1. Ease of access

2. Local indication : visibility

3. Provision for isolation, testing and removal of the device

4. Adequate support of pipework and instrument to protect it againstexcessive stresses and reaction forces

5. Protection against impact

6. Other relevant information which could influence the performance of thedevice.


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3.1. Ease of access

The pressure sensing device should be located to allow access for maintenance orreplacement without the need for temporary access platforms or ladders unlessProcess/Plant conditions dictate otherwise.

3.2. Loc al indic at ion: visibi l i ty

Locally mounted indicating devices should be clearly visible from ground orplatform level. Where sensing devices are mounted at a distance in excess of 1metre from the primary process connection, a method to avoid transporting ofchlorine to the device should be considered at the design stage (remotediaphragm seal like in Figure 2).

The secondary pressure sensor is then equipped with a local indicator.

3.3. Isolation , testing and removal

The pressure sensing device should be installed to enable easy maintenance,testing or replacement. Consideration should be given to ease of isolation,cleaning and decontamination taking into account prevention of emissions duringdisconnection operations (see figure 3).

In case of gaseous chlorine with risk of liquefaction, vertical mounting is preferredin a way to avoid liquid chlorine accumulation in the measuring device.

Figure 3: Locally installed pressure sensing devices

In certain applications (when the process pipework cannot be depressurised), theneed to vent the instrument pipework may be desirable or alternatively purging of


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the system may be necessary. In these instances additional branch connectionsare necessary for connection to a venting system, especially if the quantity ofchlorine between valve and measuring system is considered as too high for thesafety of workers removing the equipment, even equipped with a protective mask(see Figure 4a).

Figure 4a: Locally installed pressure sensing devices with ventingconnection

Warning: Any emission has to be reduced to the strict minimum. During thedisconnection operation, personnel should be adequately protected (see GEST92/171Person nel Protect ive Equipment for Use with Chlo rine).

Alternatively, a flush ring design can be used (see figure 4b).


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Figure 4b: Locally installed pressure sensing devices with flush ring

3.4. Support

Whenever possible, the pipework design shall be constructed to be self

supporting. If not possible, adequate support of the equipment shall be provided.Vertical mounting is preferred to minimize stress in the nozzle on the main pipe.

3.5. Protec tion agains t Impact

Devices should be located to avoid mechanical damage.

3.6. Other relevant info rmation

When installing the pressure sensing device, reference to the manufacturersspecification regarding its installation, orientation, safety clearances andtemperature tolerances should be observed.

4. PRIMARY PROCESS CONNECTION

The primary process branch connection for the pressure sensing device should bedesigned according to GEST 79/81Liqu id and Dry Gaseous Chlor ine Pip ingSystems Located inside Producers or Consumers Plants.

The following will be taken into account:

1) Screwed connections shall not be used between the process pipe andthe isolation valve, and should be avoided wherever possible after theisolation valve.


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2) A forged flanged pipeline branch having a diameter of minimum 25 mm(recommended 40 mm) installed to the appropriate engineeringspecification and to the Euro Chlor piping recommendations (GEST79/81 Liqu id and Dry Gaseous Chlor ine Pip ing Systems LocatedInsid e Prod ucersor ConsumersPlants)..

3) The length of the branch should be minimised but sufficient to allow fora correct thermal insulation of the pipe.

4) The primary isolation valve and the venting valve shall be in compliancewith the Euro Chlor valve recommendations (see GEST 06/318 - Globeva lves for use on l iqu id ch lor ine).

Notes

Pressure sensing devices do not require valves with high Cv ratings, therefore, it isacceptable to have a smaller valve trim within the 40 mm flanged body, butpotential for blockage should be considered (depending on the process).

In certain applications where the pressure sensing device forms part of criticalsafety system, provision of a locking facility should be considered to preventaccidental closure of the valve.

Exceptions

In certain instances, the pressure sensing device forms part of bursting discarrangement or a bursting disc / safety valve combination that is used to monitorthe interspace between the devices. In these applications isolating valves for thepressure sensing equipment shall not be installed or shall be locked to preventaccidental closing (see Figures 5a and b).

Figure 5: Pressure Sensing Devices Installed on Bursting Disc / Safety ValveInstallations

a) pressure sensor on bursting disk in series


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b) pressure sensor on bursting disk with safety valve in series

5. EXTENSION PIPEWORK

In all cases, pipework shall be minimised. When there is a requirement forextending instrument pipework (after the isolation valve), the design criteria for thepipework is as follows:

1. Extension pipework and flanges to have a recommended diameter of 40mm, with a minimum of 25 mm;

2. The maximum extension length of the pipework should be minimised tolimit the chlorine volume trapped;

3. Suitable supports shall be provided if required,

For more information see GEST 79/81 Liqu id and Dry Gaseous Chlor inePiping Systems Located Inside Producers or Consumers Plants.

6. REFERENCES

GEST 79/81 Liqu id and Dry Gaseous Chlor ine Pip ing SystemsLoc ated Insid e Produ cers orConsumersPlants

GEST 79/82 Materia ls of Construct ion for Use in Contact withChlor ine

GEST 92/171Person nel Protect ive Equipm ent for Use with Chlorine

GEST 06/318 - Globe valves for use on l iquid chlo r ine


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Industrial consumers of chlorine, engineering and equipment supply companiesworldwide and chlorine producers outside Europe may establish a permanentrelationship with Euro Chlor by becoming Associate Members or Technical

Correspondents.

Details of membership categories and fees are available from:

Euro ChlorAvenue E Van Nieuwenhuyse 4Box 2B-1160 BrusselsBelgium

Tel: +32 2 676 7211

Fax: +32 2 676 7241e-mail: [email protected]: http://www.eurochlor.org

Documents

Code of Practice for the Installation of Pressure Sensing Devices on Dry Gaseous and Liquid Chlorine Applications