small chlorine containers construction and handling

SMALL CHLORINE CONTAINERS

CONSTRUCTION AND HANDLING

GEST 88/138

5th Edition

February 2004

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

GEST 88/138

5th Edition

February 2004 of 40

Euro Chlor Euro Chlor is the European federation which represents the producers of chlorine and its primary derivatives. Euro Chlor is working to:

improve awareness and understanding of the contribution that chlorine chemistry has made to the thousands of products, which have improved our 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 or scientific debate and provides balanced and objective science-based information to help answer questions about chlorine and its derivatives;

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

***********

This document has been produced by the members of Euro Chlor and should not be reproduced in whole 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 good

faith and was based on the best information available at the time of publication. The information is to be relied upon at the user’s own risk. Euro Chlor and its members make no guarantee and

assume 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 members’ convenience, it may have been translated into other EU languages by translators / Euro Chlor

members. 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 Chlor’s technical activities took place under the name BITC (Bureau

International Technique du Chlore). References to BITC documents may be assumed to be to Euro Chlor documents.

GEST 88/138

5th Edition

February 2004 of 40

RESPONSIBLE CARE IN ACTION Chlorine is essential in the chemical industry and consequently there is a need for chlorine to be produced, stored, transported and used. The chlorine industry has co-operated over many years to ensure the well-being of its employees, local communities and the wider environment. This document is one in a series which the European producers, acting through Euro Chlor, have drawn up to promote continuous improvement in the general standards of health, safety and the environment associated with chlorine manufacture in the spirit of Responsible Care. The voluntary recommendations, techniques and standards presented in these documents are based on the experiences and best practices adopted by member companies of Euro Chlor at their date of issue. They can be taken into account in full or partly, whenever companies decide it individually, in the operation of existing processes and in the design of new installations. They are in no way intended as a substitute for the relevant national or international regulations which should be fully complied with. It has been assumed in the preparation of these publications that the users will ensure that the contents are relevant to the application selected and are correctly applied by appropriately qualified and experienced people for whose guidance they have been prepared. The contents are based on the most authoritative information available at the time of writing and on good engineering, medical or technical practice but it is essential to take account of appropriate subsequent developments or legislation. As a result, the text may be modified in the future to incorporate evolution of these and other factors. This edition of the document has been drawn up by the Equipment Working Group to whom all suggestions concerning possible revision should be addressed through the offices of Euro Chlor.

GEST 88/138

5th Edition

February 2004 of 40

Summary of the Main Modifications in this version Section Nature

7 New section is added: Respiratory Protective Equipment

Appendix 2 List of plant contact in case of accidents was deleted

TABLE OF CONTENTS

1 INTRODUCTION 6

2 TYPES OF CONTAINERS UP TO 4 T CHLORINE 6

3 CONSTRUCTION CODE 12 3.1 Vessel Construction 12

3.1.1 Minimum Design Temperature 12 3.1.2 Test Pressure 12 3.1.3 Minimum Wall Thickness 12 3.1.4 Material of Construction 12 3.1.5 Welds 12

3.2 Accessories 13 3.2.1 Manhole or Handhole (if any) 13 3.2.2 Valves 13 3.2.3 Protection against Mechanical Damage during Transport and Storage 18 3.2.4 Relief Valves and Fusible Plugs 18 3.2.5 Thermal Insulation 18 3.2.6 Handling Consideration 18

4 COMMISSIONING AND LOADING 18 4.1 Initial Commissioning 18

4.1.1 Vessel 18 4.1.2 Valves 19 4.1.3 Drying 19 4.1.4 Leak Testing 19

4.2 Maintenance of the Vessel 19 4.3 Filling 20

4.3.1 Handling the Containers 20 4.3.2 Weight Control 20 4.3.3 Procedure 22 4.3.4 Safety Measures in the Factory 22

4.4 Taking out of Service for Maintenance 22

5 TRANSPORT 22 5.1 Specific Precautions for Transport 22

5.1.1 Cylinders 22 5.1.2 Drums 22 5.1.3 Spheres 24 5.1.4 Drums and Spheres Loading and Unloading 24

GEST 88/138

5th Edition

February 2004 of 40

6 USE AT THE CONSUMER'S PREMISES 24 6.1 Types of Installation 24 6.2 Location and Design of Storage Area 26 6.3 Leak Detection 28 6.4 Piping and Safety Devices 28 6.5 Pipework 28 6.6 Prevention of Suckback 30 6.7 How to Obtain Chlorine from a Drum 30 6.8 Vaporisers 31

7 RESPIRATORY PROTECTIVE EQUIPMENT 31 7.1 Breathing Apparatus with Filter 32

7.1.1 The Filter 32 7.1.2 Filter Saturation 32 7.1.3 Storage of Filters 33

7.2 Self-Contained Breathing Apparatus - SCBA 34

8 TRAINING OF THE PERSONNEL 34

9 REPORTING OF ACCIDENTS 35

10 EMERGENCY ORGANISATION 35

11 REFERENCES 35

12 REFERENCES TO EURO CHLOR GEST RECOMMENDATIONS 36

APPENDIX 1: DRYING OUT OF CHLORINE CONTAINERS 37 Principle: 37 Equipment: 37 1

st Example: Air at 0°C Saturated with Moisture in the Barrel 38

2nd

Example: Air at 20°C Saturated with Moisture Contained in the Barrel 39

TABLE OF FIGURES

FIGURE 1: CYLINDER – TYPICAL DRAWING 7 FIGURE 2: DRUM – TYPICAL DRAWING – FIRST EXAMPLE 7 FIGURE 3: DRUM – TYPICAL DRAWING – SECOND EXAMPLE 8 FIGURE 4: DRUM – TYPICAL DRAWING – THIRD EXAMPLE 8 FIGURE 5: CHLORINE CONTAINER - SAFRAP TYPE 10 FIGURE 6: CHLORINE CONTAINER - SPHERE TYPE 11 FIGURE 7: SCHEMATIC VIEW OF A VALVE 14 FIGURE 8: TYPICAL CYLINDER VALVE 15 FIGURE 9: TYPICAL DRUM VALVE 16 FIGURE 10: TYPICAL SPHERE VALVE 17 FIGURE 11: MANUAL ISOLATING VALVE PV) 24 FIGURE 12: EXAMPLE OF A TYPICAL INSTALLATION 25

GEST 88/138

5th Edition

February 2004 of 40

1 INTRODUCTION

The recommendations given in this code represent the various measures taken by the member companies of Euro Chlor for the construction and handling of liquid chlorine drums, cylinders and spheres. Study of chlorine accidents shows that small containers contribute to a relatively frequent number of minor accidents. Euro Chlor, aware of the continuing necessity to improve safety, has drawn up this guide. This recommendation does not replace the national or international regulations in force, such as the ADR, European Agreement concerning the international carriage of dangerous goods by road, which should be universally respected as standard practice (See GEST 74/31 - Tank Containers for the Transport of Liquid Chlorine under Pressure). In general, they reinforce the international codes and regulations by adding to them the experience gained by the chlorine producers of the different countries.

2 TYPES OF CONTAINERS UP TO 4 T CHLORINE

A large variety of containers are presently used but most of the recommendations detailed below apply to all types. At first, a brief description of the principal types in use is given. The advantages and disadvantages are compared to aid the choice of container for a particular application and also to allow for quick reference to the existing regulations. The containers are generally classified into cylinders, drums, and spheroid containers. Cylinders of various capacities are in use (less than 100 kg). A typical drawing is given in figure 1. Construction: forged or welded according to 3.1.5.

GEST 88/138

5th Edition

February 2004 of 40

Figure 1: Cylinder – Typical Drawing

Drums have a capacity between 500 and 3,000 kg. They are horizontal cylinders. Typical examples are shown in figures 2, 3, and 4. The ends are either convex or concave. The valves are either protruding or fully protected by the container itself. In both cases, the valves are protected by a cover.

Figure 2: Drum – Typical Drawing – First Example

Welded heads, 2 concave ends, 2 separate openings for the valves. Removable protection cover for the valves. Inspection and cleaning need particular attention, particularly due to the sharp angles between ends and cylinder.

GEST 88/138

5th Edition

February 2004 of 40

Figure 3: Drum – Typical Drawing – Second Example

convex ends, 1 cover plate with two openings for the valves, 1 valve protection cover. Total protection of both ends. Robust construction. 2 welded heads, 2 concave ends, 1 cover plate with 2 openings for the valves, 1 protection cover. The sharp angles between ends and cylinder need particular attention for cleaning and drying.

Figure 4: Drum – Typical Drawing – Third Example

GEST 88/138

5th Edition

February 2004 of 40

Totally forged robust construction. Convex ends, removable end plate allowing for easy inspection, valves on this concave plate protected with a cover; excellent protection of the valves.

Any new drum will have convex ends. Typical dimensions

Capacity kg Cl² Tare kg Diameter of the

vessel, mm Total length

mm

500 265 700 - 712 1350 - 1400

600 450 720 1600

850 650 880 1650

1000 650 750 - 830 2000 - 2200

2100 830 1150 2160

3000 1500 1270 2500

Spheres This category includes vertically standing vessels with valves on a manhole at the top of the container, normally not in contact with liquid chlorine.

Safrap type Sphere type

Diameter 1100 mm 1900 mm

Total height 1720 mm 2300 mm

Capacity 1250 dm³ 3600 dm³

Tare 750 kg 1300 kg

See figures 5 and 6.

GEST 88/138

5th Edition

February 2004 of 40

Figure 5: Chlorine Container - Safrap Type

GEST 88/138

5th Edition

February 2004 of 40

Figure 6: Chlorine Container - Sphere Type

CHARACTERISTICS OF THE CONTAINER Gross weight: 5800 kg Tare: 1300 kg Capacity: 3,6 m³ Maximum load (Cl2 liq.): 4500 kg Normal load (Cl2 liq.): 4250 kg Working pressure: 15 kg/cm² Test pressure 25 kg/cm²

550

222030°

500

2000

560

50

550

222030°

500

2000

560

50

Unit: mm

GEST 88/138

5th Edition

February 2004 of 40

3 CONSTRUCTION CODE

3.1 Vessel Construction

The transport vessels should be designed according to international regulations, ADR, and other national regulations as appropriate. The aim of this text is to indicate the principal usual rules and the further constraints which are imposed by the chlorine producers by way of additional safety measures.

3.1.1 Minimum Design Temperature

This has been set at minus 40°C.

3.1.2 Test Pressure

The test pressure should be at least 22 bar(g).

3.1.3 Minimum Wall Thickness

For any cylindrical containers, the wall thickness of the ends should not be less than the thickness of the cylindrical section.

3.1.4 Material of Construction

The steel should be non-alloyed fine grain steel to meet at minus 40°C the requirements laid down by ADR for road tanks (see GEST 79/76 – Road Tank Wagons for the Transport of Liquid Chlorine under Pressure). To ensure good conditions for welding, as well as to provide a minimum thickness for mechanical impact resistance, steels with a low ultimate tensile strength are required. For example, ultimate tensile strength of the steel at rupture Rm has to be limited to 600 N/mm². The minimum elongation at fracture has to be greater than 1.000/Rm (recommendation of ADR) and preferably 20% for 570 N/mm² i.e. 1.150/Rm.

3.1.5 Welds

All welds should be 100% examined by radiography, and found free of flaws. If radiographic examination is not possible, use other methods like ultrasonic, magnetic or dye penetrant examination.

GEST 88/138

5th Edition

February 2004 of 40

3.2 Accessories

3.2.1 Manhole or Handhole (if any)

The hole should be realised by a pad welded directly to the tank. The manlid should have two openings for the valves. The gasket between manlid and manhole or handhole should be trapped.

3.2.2 Valves

3.2.2.1 Valves should preferably be made of steel, stainless steel or Monel.

Cylinders are equipped with one valve screwed on the top.

3.2.2.2 Drums are fitted with 2 valves screwed or bolted directly to the drum, or onto a handhole cover. The valves are fitted with dip-pipes to reach into the gaseous and liquid phases. The valve outlets should be aligned with the dip-pipes.

3.2.2.3 Spheres and drums larger than 1 m³.

For new large containers, ADR regulations ask that if capacity 1 m³, the valves should consist of two sections:

An internal security disc or ball, situated below the valve plate, which closes automatically,

A standard valve, fixed to the valve plate above the disc. The valves should be capable of remote rapid closure. A cap should be fixed on every valve.

Note: actually, this requirement is difficult to meet because of space limitation. This has to be carefully examined for new constructions. All valves should be of a type agreed for the country of origin. Usual types are represented on figures 7 to 10. Figure 7: schematic view Figure 8: typical cylinder valve Figure 9: typical drum valve Figure 10: typical sphere valve: to meet ADR regulation, additional

remote closure device should be added.

GEST 88/138

5th Edition

February 2004 of 40

Figure 7: Schematic View of a Valve

GEST 88/138

5th Edition

February 2004 of 40

Figure 8: Typical Cylinder Valve

Reference DESCRIPTION

1b Body

2 Insert Seat

3 Stem

4 Packing Ring

5 Gland Follower

6 Handwheel

7 Cover nut (Outlet cap)

8 Gasket

9 Gland Packing

10 Bush

11 Stem Nut (Left hand

thread)

12 Short chain

13 Split ring

14 Circlip

15 Washer

GEST 88/138

5th Edition

February 2004 of 40

Figure 9: Typical Drum Valve

Reference DESCRIPTION Reference DESCRIPTION

1 Body 7 Screwed bonnet

2 Disc 8 Hand wheel

3 Outside seal device

9 Washer

4 Ring 10 Hand wheel retaining nut

5 Gasket 11 Inlet dip tube

6 Internal screwed ring

12 Outlet cap

GEST 88/138

5th Edition

February 2004 of 40

Figure 10: Typical Sphere Valve

Reference DESCRIPTION Reference DESCRIPTION

1 Screw stem 12 Body

2 Screw key 13 Gasket

3 Bearing 14 Spring washer

4 Stop ring 15 Internal check body

5 Handwheel 16 Spring

6 Packing nut 17 Support nipple

7 Packing ring 18 Ball

8 Packing gland 19 Inlet dip tube

9 Outlet gasket 20 Bolt

10 Outlet screwed cap 21 Stud bolt

11 Stem 22 Nut

GEST 88/138

5th Edition

February 2004 of 40

3.2.3 Protection against Mechanical Damage during Transport and Storage

The valve(s) should always be protected by a cover of heavy thickness strongly fixed to the vessel.

3.2.4 Relief Valves and Fusible Plugs

The installation of relief valves or fusible plugs is emphatically not recommended. If this equipment is imposed for transport out of Europe by the IMDG - International Maritime Dangerous Goods Code of 1990 completed with the amendment 26/91, and the Chlorine Institute regulations, during the road or rail transport within Europe, it should be completely protected by a strong steel cover tightly fixed on the vessel or manlid.

3.2.5 Thermal Insulation

Thermal insulation of chlorine drums and cylinders is not recommended.

3.2.6 Handling Consideration

Adequate provision should be made for lifting and moving the containers. Drums may have rolling bands and lifting lugs as shown on figures 2 to 5. If rolling bands are fitted, they should be designed to collapse on impact rather than causing damage to the vessel wall. Similar considerations apply to lifting lugs. Care should also be taken to prevent corrosion under the rolling bands by continuous welding of the band.

4 COMMISSIONING AND LOADING

4.1 Initial Commissioning

Chlorine producers receiving a vessel from the manufacturer or from repair work should carry out a general inspection of the vessel and of the fittings. These operations can be carried out either by the chlorine producer or by a specialist organisation acting on their behalf and under their responsibility. They should proceed to the following inspection:

4.1.1 Vessel

Examination of the internal surfaces. The following should be excluded:

GEST 88/138

5th Edition

February 2004 of 40

Areas of rust or scale Traces of moisture Traces of grease or oil.

The joint faces and gasket materials should be checked.

4.1.2 Valves

These should be removed to eliminate all traces of moisture or grease arising from the machining operation. On reinstallation, components which should be greased must employ a grease compatible with chlorine (chlorofluorinated grease). The correct alignment of dip-pipes should be checked.

4.1.3 Drying

After installing fittings on the vessel with new joint rings suitable for chlorine, the vessel and the accessories should be dried until a dew point minus than 40°C at atmospheric pressure has been obtained on the exit gas, after allowing sufficient delay for mixing off the gas within the vessel. See Appendix I for recommended drying procedure. After drying, the vessel should be maintained under a pressure of 0.2 bar(g), at least, with dry gas to avoid any ingress of moisture. For cylinders, with only one valve, adequate drying can be accomplished by successive filling with dry gas and emptying or by using vacuum. Drying can be accelerated by warming in an oven.

4.1.4 Leak Testing

Before filling, all of the valves and accessories can be tested in a fashion which will guarantee complete leak tightness in the conditions of service after drying. The following test methods can be used:

Test pressure of air at more than 4 bar(g) and less than the maximum operating pressure with detection of leaks by use of soap and water;

A final test with chlorine or a mixture of chlorine and dry gas with the joints being checked by the use of an ammonia bottle.

4.2 Maintenance of the Vessel

The objective should be to avoid any deterioration of materials due to the opening or maintenance.

For guidance one should refer to:

GEST 88/138

5th Edition

February 2004 of 40

GEST 79/78 – Code of Good Practice for the Operations to be Carried out before and after Maintenance on Road and Rail Tankers and Iso-Containers of Liquid Chlorine GEST 76/53 – Code of Good Practice for Installation, Removal and Maintenance of Pneumatic Valves on Road and Rail Tankers and Iso-Containers for Liquid Chlorine.

4.3 Filling

The container should be filled at a filling installation which generally meets the requirements laid down in chapter 6 of this recommendation.

4.3.1 Handling the Containers

Cylinders should normally be inspected after every trip to check for any contamination. For drums and spheres, the necessity of such an inspection depends on the confidence in the customer's procedure. Before opening the containers have always to be carefully emptied and degassed. After opening for internal inspection, the vessels have always to be cleaned and dried according to 4.1.3. If the container has not been opened, one must ensure by prior venting down that the vessel to be filled contains no residual liquid chlorine. After filling, the plugs or blank flanges on the valves should be put in place with new joint rings and their leak tightness confirmed. Before dispatch, one should make:

A final test on leak tightness and good state of the valves, A check on the labelling.

4.3.2 Weight Control

To improve safety during transport, specific attention is drawn to the control of the total weight as described below and the total load should normally not exceed 1.25 kg of chlorine per litre of capacity within the container, except if local regulations permit a higher figure (a lower figure may be required for tropical climates). For the net weight, it is essential that one takes into account the possible difference between the tare weight at the moment of filling and the original tare weight of the vessel.

Deviations in tare weight have to be investigated (see logigramme).

GEST 88/138

5th Edition

February 2004 of 40

A typical logigram for drums should be:

Note the possible effect of weight of gaseous chlorine. A second check on weight should be made on a different weighing machine to prevent any risk of overfilling.

CONTAINER ARRIVAL

DEGASSING AND PURGING

CLEANING

NEUTRALISATION

WEIGHING

DEPRESSURIZINGAsk supervisor

SCRAP DRYINGWEIGHING

EMPTYING WEIGHING

PERIODIC RETESTING

FILLING AND WEIGHING

NH3 LEAK CHECK

CHECK WEIGHINGLABELLING

STORAGE

>2% OVERTARE

>2% UNDERTARE

OK

Not OK

Not OK OK

TESTINGAbnormal

Normal

External visual examination

No

No

No

Yes

GEST 88/138

5th Edition

February 2004 of 40

4.3.3 Procedure

The safety of the filling operation should be ensured by handling of the returned containers with a written procedure and a check-list which may easily be controlled.

4.3.4 Safety Measures in the Factory

The chlorine containers should be stored in a location which is isolated and protected, that is to say sheltered from risks of collision or of fire or explosion.

4.4 Taking out of Service for Maintenance

All chlorine vessels sent for maintenance to an external non-specialist workshop should be initially emptied, vented down and neutralised.

5 TRANSPORT

5.1 Specific Precautions for Transport

5.1.1 Cylinders

Care must be taken to ensure that cylinders are securely anchored for transport. Vertical loading has the advantage that the valve is in the gaseous phase, which reduces the emission in case of a gaseous leak. However, because of the shape of the cylinders, special provisions are necessary for anchoring them. Cylinders may be strapped or chained to rings securely attached to the vehicle. Palletisation of cylinders is also widely used where the proper loading and unloading equipment is available.

5.1.2 Drums

The preferred methods of securing drums are to use fixed chocks or purpose made cradles. These can be used where the customer has suitable lifting equipment or with self-unloading trucks.

If there is a need to roll the container to the rear of the truck for offloading, a recommended method of containment in transit is to use chains with front and rear blocking. Straps should be limited to securing individual ton containers.

GEST 88/138

5th Edition

February 2004 of 40

Wooden chocks or wedges should be placed under each container as an additional safeguard. The front bulkhead should be reinforced. Rear roll-off

GEST 88/138

5th Edition

February 2004 of 40

protection must be provided. A reinforced removable guard rail or a contour fitting steel chock anchored behind the rearmost containers to the truck bed with pins or chains is an effective restraint.

5.1.3 Spheres

Large spheres should only be transported on dedicated low bed trucks with special fixing or clamping systems for the spheres on the bed of the trucks.

5.1.4 Drums and Spheres Loading and Unloading

Lifting beams, travelling electric hoists or fork lift trucks are usually employed by shipper and customer. Proper design of the lifting beam is essential. Extreme care must be exercised when operating fork lift trucks. The preferred method is to use a purpose made lifting beam attachment on the forks.

6 USE AT THE CONSUMER'S PREMISES

6.1 Types of Installation

The containers may be used in various types of application:

a) Single cylinder or drum arranged to deliver gas. This type of installation is physically capable of only a low steady rate of supply or very occasional short periods of high supply rate. A manual isolating (auxiliary) valve mounted very close to the container is recommended to prevent moisture ingress when disconnected. See figure 11.

Figure 11: Manual Isolating Valve PV)

PI

PV

Air

Point of Use

Flexible Connection

PI

PV

Air

Point of Use

Flexible Connection

GEST 88/138

5th Edition

February 2004 of 40

b) Multiple Cylinders or Drums Arranged to Deliver Gas.

If a higher demand is anticipated than (a) can satisfy, several containers can be connected to a common manifold. A manual isolating valve may be sited at the outlet of the manifold. It is important to establish operating procedures to safeguard against passage of chlorine in significant quantities between vessels.

c) Drum Arranged to Deliver Liquid. Unless the liquid chlorine is to be used directly in the process (which is not recommended in a small installation), this arrangement usually serves a vaporiser, so as to supply chlorine gas continuously or intermittently at a higher rate than it is possible from either (a) or (b). The whole system is more complex, and requires greater safeguarding. On safety grounds, a system should never be arranged to draw liquid chlorine from more than one vessel at a time, because of the risk of accidental transfer of liquid chlorine between vessels, leading potentially to overfilling. Example of a typical installation is given in figure 12.

Figure 12: Example of a Typical Installation

PS

PDSL

PDSL

PS

PI

PDSL

PS

PV

Expansion chamber

with rupture disc

Hot

water

Gas

Liquid

Flexible

connection

Flexible connection

Vaporiser

Separator

Absorption

unit

Point of

use

Gas under

pressure

Liquid storage

TA

PI

PS

E

TI

TI Temperature

indicator

Pressure indicatorTA

Temperature alarm

Pressure switch

LEGEND

Air

Pressure difference switch low PV Pressure valve

To ensure continuity of supply in (b) or (c) above, a changeover panel can be provided to switch automatically to fresh vessel(s) when the pressure in the supply vessel falls to a pre-set pressure. This has to be sufficiently high to prevent suck-back, and a set pressure of 1 bar gauge or more is usual.

GEST 88/138

5th Edition

February 2004 of 40

6.2 Location and Design of Storage Area

In practice, most small storage and use areas are indoors so that containers are exposed to steady temperature. Outdoor storage of drums and cylinders not in use should be secure and under light cover to keep off rain. Chlorine should be kept separate from normal working areas and access should be limited to people working directly with it. The storage area should be dedicated to the storage of chlorine, immediately associated equipment and compatible materials and should be clearly identified. In the open, the storage areas should be at least 5 m away from flammable materials. Indoor storage areas and rooms in which chlorine containers are used should be constructed of substantially non-flammable materials and should provide shielding against radiant heat in case of fire nearby. Suitable separation of the store and process plant from the site boundary gives a good measure of protection to people off-site against the consequences of plant accidents such as pipe failure. Sizes of such separation distances will depend upon a number of factors including the number of containers stored and the rate of consumption, the size and distribution of the surrounding population, and the space available on site. The chlorine area should not be closer than 5 m to a roadway used by vehicles unless adequate barriers (crash barriers or substantial walls) are provided. If the walls of the store are intended to provide the impact protection, the structure should be such as not to collapse on to or damage the installation. Where vehicles have access into a store for loading and unloading, adequate high kerbs or other fixed wheel stops should be provided. Wherever possible, rooms for storage or use of chlorine should be at ground level and open directly to open air. Chlorine containers should not normally be stored below ground level or in the vicinity of basements. Rooms which are below ground level and near a chlorine store should not be used as workplaces. The storage should not be such as to allow the chlorine containers to stand in water. Vessels should be secured in their working position before being connected up. Drums should be used resting directly on properly designed chocks or cradles, and should not be double stacked on drums in use. Cylinders should be secured upright. They should be should be operated on a first-in / first-out basis. Care should be taken not to drop containers, and not to drop other loads on to them. Only properly designed purpose-made lifting gear recommended by the chlorine supplier should be used. Fork lift trucks without purpose-made

GEST 88/138

5th Edition

February 2004 of 40

adapters must not be used. Cylinders should be transported in suitable purpose-

GEST 88/138

5th Edition

February 2004 of 40

made cylinder trolleys or stillages. Hoists should preferably be arranged so that loads do not pass over chlorine vessels or pipework which is in use.

6.3 Leak Detection

Chlorine detectors and alarms should be provided in unmanned buildings housing chlorine drums or vaporisers, and should be considered for cylinder installations. Their value outdoors depends on the size of the installation and the manning levels and response times achievable. Recommended alarm actions are a distinct local audible alarm and a warning light outside the building. The detector system should activate the alarm at 3-5 ppm chlorine. Lower settings are liable to activate the system at every cylinder or drum change and lead to mistrust in the alarm when it gives a real warning of a malfunction.

6.4 Piping and Safety Devices

At sites taking liquid chlorine from drums or spheres, consideration should be given to provide remotely-operable valves, in order to minimise the size of a release. It is desirable that ventilation should go to an absorption system. The need for an automatic system arranged to shut off the chlorine supply and the airchange ventilation when a leak is detected will depend on the likelihood and size of potential leaks and the proximity of any neighbours. If this arrangement is provided, it must be possible to switch on and lock on the ventilation before anyone enters the room to work on the chlorine system. In all installations the pipework between the supply vessels and the point of use should be as short as practical. Where a relatively long run is unavoidable, as much as possible of the run should be low-pressure gas. If remotely operable shut-off valves are used, they should be as close as practical to the storage containers. Arrangements should be made and maintained to operate these valves as appropriate from remote manual operating points outside the chlorine area or, for an unmanned facility, from chlorine detectors. Care must be taken to avoid trapping liquid between valves.

6.5 Pipework

Pipework for lines carrying liquid chlorine or gaseous chlorine under pressure should be constructed generally in accordance with Euro Chlor GEST 79/81 – Dry Liquid Chlorine Piping Systems Located Inside Producer's or Consumer's Plants. Pipe runs should be kept short and protected against impact. Plastic pipes should not be used.

GEST 88/138

5th Edition

February 2004 of 40

As with other parts of the installation, pipework should be subject to routine inspection and maintenance. All pipework should be kept clean and dry inside.

GEST 88/138

5th Edition

February 2004 of 40

After any exposure to moisture the pipework should be thoroughly dried; the joint rings should be changed after any hydraulic test. For gaseous chlorine at atmospheric pressure or slightly below, plastic pipeworks (preferably reinforced) may be considered when there is a risk of moisture. Advice should be sought from the chlorine suppliers on suitable materials. All packings, gaskets and diaphragms, and all components of pipes, valves and fittings should be resistant to the action of chlorine between the foreseeable extremes of operating temperature and pressure. Gaskets should never be used for liquid chlorine service. Flexible connector pipes are often made from copper or alloys which are subject to work hardening. They should be inspected at each cylinder change, periodically heat treated and replaced if necessary.

6.6 Prevention of Suckback

Precautions must be taken to avoid damage to cylinders and drums due to suckback of water or other chemicals present in the reaction or absorption system.

6.7 How to Obtain Chlorine from a Drum

The correct working position of a drum is with the two valves in a vertical plane so that one dip pipe goes to the bottom of the drum and the other to the top. Therefore, the lower valve always delivers liquid chlorine and the upper gaseous chlorine. The inflow of heat from the atmosphere limits the amount of chlorine that vaporises. Therefore, the normal rate of continuous gas withdrawal from a drum is limited to 5-10 kg/h. Higher flow rates can be achieved if withdrawal is intermittent. When the installation is shut down, the valves on the containers have to be carefully closed. Before disconnecting the flexibles, it is recommended to purge them with dry inert gas. Otherwise, one has to wait at least 20 minutes to eliminate the risk of liquid chlorine spillage. The pipe should be immediately closed with a blank or plug.

GEST 88/138

5th Edition

February 2004 of 40

Where the installation is shut down for a long period, it has to be fully purged with dry air or dry nitrogen. Tightness has to be periodically tested with diluted ammonia bottle.

Use always a correct gasket material and never use the same gasket twice. See GEST 94/216 – Experience of Non-Asbestos Gaskets on Chlorine. If a valve does not open easily, never use too much force. Do not use too long a key on drums and spheres. Do not use keys for cylinders. If you cannot open the valve without too much forces, return the cylinder to the supplier. Use key recommended by the supplier. Never use naked flames in the chlorine area. The valves should always be either full open or closed.

6.8 Vaporisers

Vaporisers (also known as evaporators) are discussed in a separate GEST 75/47 – Chlorine Vaporisers.

7 RESPIRATORY PROTECTIVE EQUIPMENT

This section is an extract of GEST 92/171 - Personnel Protective Equipment for Use with Chlorine.

Chlorine is a toxic substance which can be rapidly fatal in acute exposure. Work practices and precautions need to be considered carefully when it is necessary to enter enclosed storage spaces. The most common risk arises at operations involving the making and breaking of lines.

Breathing apparatus should always be worn when entering an enclosed store or chlorine room in which a significant leak has been detected.

In such situations, whilst forced ventilation systems may still be operational, reliance must not be placed on this alone to disperse the chlorine. This is because the chlorine detector may be some distance from the source of the leak and consequently concentrations of chlorine at the leak are always higher than those detected by the alarm system.

For installations with multi-stage alarms the forced ventilation system will have been switched off on activation of the high level alarm. Entry will be by means of personnel wearing breathing apparatus whose function will be to identify and eliminate the source of the leak.

GEST 88/138

5th Edition

February 2004 of 40

The user of a breathing apparatus shall be trained and tested for lung function.

There are two main types of equipment:

breathing apparatus with filters, self-contained breathing apparatus.

Both groups use a device: the mask (which is different for non-pressurised and pressurised systems).

7.1 Breathing Apparatus with Filter

They are made up of two elements:

the mask the filter (cartridge) connected to the mask

7.1.1 The Filter

The filter, or cartridge, absorbs contaminants on active carbon during inhalation. With this type of equipment, protection is obtained only if the four following conditions are met:

filter or cartridge suitable for chlorine oxygen content at least 19% volume. Make sure oxygen content is

sufficient chlorine content under 0.5% volume. For higher chlorine or lower

oxygen concentrations or presence of CO or for extended use, self-contained breathing apparatus should be worn

carbon monoxide (CO), or substances for which filter is inefficient must not be present at concentration higher than occupational exposure level.

7.1.2 Filter Saturation

Filter life depends on the concentration of the contaminating gases and of the breathing rate. It is also influenced by secondary factors such as humidity or temperature of the inhaled air. The effective life of a filter can therefore not be specified. It is strongly recommended that after any significant chlorine exposure, the cartridge should be changed.

Due to all these limitations, the cartridge mask should only be used for a quick, easy operation as shutting down a valve or as an escape mask. Escape masks must never be used for any intervention!

GEST 88/138

5th Edition

February 2004 of 40

7.1.3 Storage of Filters

The filter should not be used after expiry date marked on it by the manufacturer, which usually occurs, according to the type of filter, between four to six years after delivery.

GEST 88/138

5th Edition

February 2004 of 40

Any unused filter which has been opened must be replaced within six months unless the mask has been stored in an airtight container.

7.2 Self-Contained Breathing Apparatus - SCBA

This equipment enables the user to work in a highly contaminated atmosphere without using ambient air. There are two types of self-contained breathing apparatus:

o Closed-circuit apparatus The expired air is purified of its carbon dioxide, enriched with oxygen from a bottle contained within the equipment and reinjected into the breathing circuit.

o Open-circuit apparatus The expired air is exhausted through a valve into the ambient air.

8 TRAINING OF THE PERSONNEL

See GEST 74/31 – Regulations for Tank Containers for the Transport of Liquid Chlorine under Pressure

Specific training on chlorine should be periodically given to all the personnel working with chlorine. This includes the packers at the filling station, the drivers of the vehicles dedicated to transporting the containers, and the users. The training schedule should be formally drawn up and should include classroom training as well as practical instruction during normal work. The drivers have to know that they transport chlorine, to possess the chlorine Tremcard and to know what to do in case of incident, for instance to call the right emergency team immediately. For all the other concerned people, the training programme should include: An understanding of the properties and characteristics of chlorine An understanding of the possible accidents which could arise during

transport, and the precautions which need to be taken. The precautions to take in the event of an accident - initial procedures. Training in the use of safety equipment. An understanding of the national

and/or international emergency procedures and the network set up in order to provide assistance in the event of need.

This training should be under the control of a competent person who is specifically responsible for this topic. A proper record of the training should be kept by the company with a copy to the personal.

GEST 88/138

5th Edition

February 2004 of 40

9 REPORTING OF ACCIDENTS

Any accident or other incident involving liquid chlorine should be the subject of a proper report, even when no liquid chlorine leak results. These reports should be made out on the standard form provided by Euro Chlor for this purpose (see GST Form

10 EMERGENCY ORGANISATION

The European chlorine producers have set up an international security organisation to take account of any accident in which liquid chlorine is involved. Emergency vehicles are permanently available for going out to the scene of an accident, and personnel specifically trained in dealing with such emergencies are available at the request of local authorities. The geographical layout of the emergency system should be listed amongst the documents in the possession of the driver, as well as the initial steps to be taken in the event of an accident whilst waiting for assistance. The driver should be trained in the application of these emergency plans in order to be able to call for their application by the competent authorities. The emergency vehicles must be equipped with the special material needed for all kind of chlorine containers used in their geographic zone. The emergency team has to be aware of the existence of special devices to isolate a leaking valve or even to totally enclose a leaking cylinder.

11 REFERENCES

Following documents were largely used for the preparation of present recommendation a) Le chlore (October 1996) b) Health and Safety Executive - Guidance Note on chlorine from drums

and cylinders (1988) c) Chlorine Institute - Pamphlet 76 (August 81) d) Dr M. Tyblewski - Umwelttechnik 22 (2) 46 (April 1988).

GEST 88/138

5th Edition

February 2004 of 40

12 REFERENCES TO EURO CHLOR GEST RECOMMENDATIONS

GEST 74/31 – Tank Containers for the Transport of Liquid Chlorine under Pressure

GEST 75/47 – Chlorine Vaporisers GEST 76/53 – Code of Good Practice for Installation, Removal and

Maintenance of Pneumatic Valves on Road and Rail Tankers and Iso-Containers for Liquid Chlorine

GEST 79/76 – Road Tank Wagons for the Transport of Liquid Chlorine under Pressure

GEST 79/78 – Code of Good Practice for the Operations to be Carried out before and after Maintenance on Road and Rail Tankers and Iso-Containers of Liquid Chlorine

GEST 79/81 – Dry Liquid Chlorine Piping Systems Located Inside Producer's or Consumer's Plants

GEST 92/171 - Personnel Protective Equipment for Use with Chlorine. GEST 94/216 – Experience of Non-Asbestos Gaskets

GEST 80/84 – APPENDIX – Page 1 of 3

3rd

Draft of the 5h Edition

February 2004 of 40

APPENDIX 1: DRYING OUT OF CHLORINE CONTAINERS

Principle:

Drying out is carried out by displacing air which is more or less wet contained within the barrel by means of dry air (dew point less than minus 40°C at atmospheric pressure). It is carried out on the assumption that the barrel no longer contains liquid water (walls carefully wiped down following the previous operations of inspection).

Equipment:

The installations comprise: 1. An air compressor, non-lubricated, in order to avoid the contamination of

the air dessiccator with oil or contamination of the barrel itself.

This equipment includes the following accessories:

A water heat exchanger which will keep the air temperature at approximately 30°C before the drier

A water separator and air reservoir 2. An air dryer to provide the dry air required (dew point minus 40°C)

including filter. Operation of the installation Taking into account the arrangement of pipework within the barrel, it can appear very difficult to displace all the moist air within the container by a simple dry air purge. It is, therefore, necessary to carry out a number of successive complete purgings of the vessel. The theoretical number of purges required is calculated for an initial air temperature of 0°C or 20°C for example, and assuming that the air is saturated (which is an unfavourable circumstance). The number of purges which are actually necessary is found to be very little different from the theoretical requirement, provided that sufficient time is allowed before each purge for equilibrium conditions to be attained.


3rd


February 2004 of 40

1st Example: Air at 0°C Saturated with Moisture in the Barrel

Pressure supplied by a compressor at 7 bar(a).

1st purge For 1 m³ of air saturated at 0°C, i.e. a water content of 4.868 g/m3, 6 Nm³ of dry air with a dewpoint of minus 40°C (0,86 m3 of air under a pressure of 7 bar(g)), containing 0,117 g of water per Nm³, are discharged into the barrel giving 7 Nm³ of gas mixture at atmospheric pressure, or 1 m³ at a pressure of 7 bar(a). The water content of the mixture is: 1 m³ * 4,868 = 4,868 6 m³ * 0,117 = 0,702 Total 5,570 That is: 5,570 / 7 = 0,7957 g/m³ corresponding to a dewpoint of minus21°C.

2nd purge The calculation can be carried out in the same manner but beginning with a moisture content of air 0,7957 g of water per m³. The water content of the mixture becomes: 1 m³ * 0,7957 = 0,7957 6 m³ * 0,117 = 0,702 Total 1,4977 That is 1,4977 / 7 = 0,2129 g/m³ corresponding to a dewpoint of minus 34°C.

3rd purge Beginning with air at 0,2129 g/m³ The water content of the mixture becomes: 1 m³ * 0,2129 = 0,2129 6 m³ * 0,117 = 0,702 Total 0,9149 That is: 0,9149 / 7 = 0,1307 g/m³ corresponding to a dewpoint of minus 39°C.


3rd


February 2004 of 40

2nd Example: Air at 20°C Saturated with Moisture Contained in the Barrel

Pressure supplied by a compressor at 7 bar(a)

1st purge For 1 m³ of air at 20°C, i;e; a water content of 17,148 g/m³,. 6 Nm³ of dry air (0,86 m³ at 7 bar(a) pressure), with a dewpoint of minus 40°C, containing 0,117g of water per Nm³ are discharged into the barrel giving 7 Nm³ of gas mixture at atmospheric pressure , or 1m³ at a pressure of 7 bar(a). The water content of the mixture is: 1 m³ * 17,148 = 17,148 6 m³ * 0,117 = 0,702 Total 17,850 That is: 17,850 / 7 = 2,55 corresponding to a dewpoint of minus 8°C.

2nd purge 1 m³ * 2,55 = 2,55 6 m³ * 0,117 = 0,702 Total 3,252 The water content of the mixture is: 3,252 /7 = 0,464 corresponding to a dewpoint of minus 27°C.

3rd purge 1 m³ * 0,464 = 0,464 6 m³ * 0,117 = 0,702 Total 1,166 The water content of the mixture is: 1,166 /7 = 0,165 corresponding to a dewpoint of minus 37°C. It can be seen that in the two cases the approach to a dewpoint of minus 40°C is almost the same with three purges, even if one assumes that the air at the beginning of the operation was saturated with water vapour which itself is very rare in Western Europe. After the 3rd purge, it is necessary to maintain the barrel under a pressure of air for a minimum of one hour and then, by further venting down, to confirm, by dew point measurement, that the drying operation has been sufficiently well carried out.

GEST 88/138

5th Edition

February 2004 of 40

Industrial consumers of chlorine, engineering and equipment supply companies worldwide and chlorine producers outside Europe may establish a permanent relationship with Euro Chlor by becoming Associate Members or Technical Correspondents. Details of membership categories and fees are available from:

Euro Chlor Avenue E Van Nieuwenhuyse 4 Box 2 B-1160 Brussels Belgium

Tel: +32 2 676 7211 Fax: +32 2 676 7241 e-mail: [email protected] Internet: http://www.eurochlor.org

small chlorine containers construction and handling

Documents