REPUBLIC POLYTECHNICQEHS Work Instruction

WIKP-SEG-10 Rev 010

Effective Date: 19/08/2009

 

SEG GAS MANAGEMENT

  

1          PURPOSE  

To specify requirements for purchasing, receiving, storing, handling of gases and the monitoring of toxic and flammable gas.

  2          SCOPE 

This procedure is applicable to all functions and activities involving the use, and handling of gas and the procedures of the gas monitoring system used for the detection of toxic and flammable gas leakage.

  3          RESPONSBILITY        

3.1       The OES and Schools shall be responsible to ensure that contractors and employees under their respective management are aware of the hazards associated with the gases they are handling, and are trained to use, store and handle the gases responsibly (see Safety Data Sheets on the proper handling of all gases, Hardcopies of SDS of gases that are available in the laboratories are filed and indexed at designated storage cabinets at the laboratories. Up-to-date online versions of SDS can also be found at http://encyclopedia.airliquide.com ).

 3.2       All employees who handle gases need to follow the requirements that are laid down in

this procedure.  4          DEFINITIONS 

Hazardous Substance: any substance which owing to its nature, composition or quantity constitutes a danger to human health or the environment.

 A list of controlled and hazardous substances is found in Appendix I.

  5          RELATED DOCUMENTS/REFERENCES  5.1      http://www.airproducts.com/nr/rdonlyres/8d35ea4f-b95f-42c6-9087-6125c1f4123a/0/

safetygram10.pdf 

  

  

6.3       HANDLING & STORAGE OF GAS & GAS CYLINDER 6.3.1   All gas cylinders must be secured in designated areas at all times to prevent tipping. It

may be attached to a bench top, individually to the wall, placed in a holding cage or have a non-tip base attached. Chains or straps may be used to secure them.

 6.3.2   All compressed gas cylinders must be stored in an upright position. It should not be

subjected to any mechanical shock that could cause damage to their valves or pressure relief devices. It should not be dropped, dragged or permitted to strike each other or against other hard surfaces. Pressure is one of the greatest hazards associated with gas system.

 6.3.3   Cylinders should be placed with the valve accessible at all times. The main cylinder

valve should be closed as soon as it is no longer necessary (i.e., it should never be left open when the equipment is not operating for long periods). This is necessary not only for safety when the cylinder is under pressure, but also to prevent the corrosion and contamination resulting from diffusion of air and moisture into the cylinder after it has been emptied.

 6.3.4   Cylinder valves should be open slowly. When opening the valve on a cylinder

containing an irritating or toxic gas, the user should position the cylinder with the valve pointing away from them and warn those working nearby.

 6.3.5   Never use oil or grease on the regulator of a cylinder valve. No person, other than the

gas supplier, shall attempt to mix gases in a cylinder. 6.3.6   Empty cylinders should always be labeled to prevent accidental connection of an

empty cylinder to a pressurized system resulting in suck-back.  6.3.7   All empty cylinders must be returned to the supplier. Do not purchase non-returnable

cylinders from suppliers.  6.3.8   Cryogenic Liquid 

6.3.8.1            Always protect your eyes and skin. Wear safety glasses whenever you are working with cryogenic liquid. In addition, also wear a full-face shield if a cryogenic liquid is poured or if the cryogen may splatter.

 6.3.8.2            When transferring cryogenic liquids from one container to another,

always start slowly allowing the vaporization to chill the receiving container before filling it.

 6.3.8.3            Wear cryogenic resistant gloves and cryogenic aprons to prevent

splashed liquid from being absorbed and freezing the skin. 6.3.8.4            Unprotected skin can stick to metal that is cooled by cryogenic liquids.

The skin can then tear when pulled away. Even non-metallic materials are dangerous to touch at low temperature.

 6.3.9   Flammable Gas  

6.3.9.1            The basic condition for ignition of flammable gases are concentration of gas within the flammable limits, presence of air or oxygen, source of ignition. An absence of any of these conditions will not cause an ignition.

 6.3.9.2            All flammable gases have flammable limits known as the Lower

Explosive Limit (LEL) and Upper Explosive Limit (UEL). It is flammable

when it is within the limit. Concentration below or above this limits are either too lean or too rich to burn.

 6.3.9.3            Cylinders containing flammable gases must not be stored in close

proximity to open flames, areas where electrical sparks are generated or where other sources of ignition may be present.

 6.3.9.4            For gas that is ignited when exposed to air, it is considered as

pyrophoric gas. The reason being its auto-ignition temperature is very low. Silane is an example of pyrophoric gas.

 6.3.9.5            All cylinders containing flammable gases should be stored in a well

ventilated area. It should not be stored with oxygen or nitrous oxide cylinders or adjacent to any oxygen charging facilities.

                        6.3.9.6            All flammable gas cylinders should be stored in areas equipped with

sprinkler system or by a non combustible barrier or fire wall.  6.3.10 Oxidizer gas 

6.3.10.1          Oxygen and other oxidizing gases shall not be stored in the same vicinity as flammable gases.

 6.3.10.2          This type of gas does not burn, but will support and accelerate

combustion of flammable materials or cause combustible materials to ignite and burn. Increasing the concentration of an oxidizer accelerates the rate of combustion.

 6.3.10.3          Greasy and oily materials shall never be stored around oxygen, nor

should oil or grease be applied to fittings.  6.3.11 Corrosive Gas  

6.3.11.1          Corrosive gas can attack various materials including fire resistant clothing. Some gases are not corrosive in their pure form, but can become extremely destructive if a small amount of moisture is added.

 6.3.11.2          Corrosive gases can cause damage to living tissues and certain metallic

material such as steel including stainless steel. 6.3.11.3          The means of exposure is via inhalation or skin contact. Most corrosive

gases when exposed to the air becomes white or yellowish smoke. 6.3.11.4          Exposure of corrosive gases through inhalation will cause irritation to the

throat. Continued exposure will damage the mucous membrane of the mouth, throat and lungs by reacting with water inside our body.

 6.3.11.5          For exposure to metal, it will corrode the material at a very fast rate.

  6.3.12 Toxic Gas  

6.3.12.1          The primary hazard of toxic gases is poisoning. Even in small concentrations, brief exposure to these gases can result in serious personal injuries or even death.

 6.3.12.2          The method of exposure for toxic gases are inhalation, absorption or

ingestion. 6.3.12.3          Acute toxicity in terms of short duration but high concentration will bear

immediate result. However, if the person is exposed to long term, repeated exposure, the warning may not be immediate and apparent.

            6.3.12.4          All toxic gas cylinders must be stored in a gas cabinet connected to

exhaust, sprinkler with leak detection and alarm system. 

6.3.12.5          Cylinders in the cabinet must be securely chained and the exterior of the gas cabinet labeled with the gas name.

 6.3.12.6          The Gas cabinet and valve manifold box provide a safe environment

during cylinder change or in the unlikely event of a hazardous gas leak. 6.3.12.7          The gas cabinet also provides a secondary containment for any leak

from the cylinder connection and pigtail, with the capability for cycle purge and vacuum-assisted vent during cylinder change or maintenance of the manifold.

 

 

 6.4      LABELLING OF GAS LINES AND CYLINDERS  6.4.1   All gases, gas cylinders and gas lines must be properly identified or labeled. 6.4.2   The contents of any compressed gas cylinder must be clearly identified. Such

identification are usually stenciled or stamped on the cylinder. No compressed gas cylinders should be accepted for use that does not legibly identify its contents by name. If the labeling on a cylinder becomes unclear to the point that contents cannot be identified, the cylinder should be marked ‘contents unknown’ and returned back to the supplier.

 6.4.3   Never rely on the color of the cylinder for identification. Color coding is not reliable

because cylinder colors may vary with different supplier. 6.4.4   All gas lines leading from a compressed gas supply should be labeled to identify the

gas. Distribution lines and their outlets should also be clearly labeled as to the type of gas contained.

 6.4.5   Flammable and toxic compressed gases are stored in gas cabinets connected to

emergency shut off system and equipped with sprinkler system. Signs should be posted in area where these gases are stored.

 6.4.6   Always check the SDS if you have any doubts about the gases after reading the label.  6.5       TRANSPORTATION OF GAS CYLINDERS 6.5.1   Before transporting any cylinders, check the Safety Data Sheet (SDS) of the gas for

any safety precaution and preventive measures. 6.5.2   The cylinders that contain compressed gases are primarily shipping containers and

should not be subjected to rough handling or abuse. Such misuse can seriously weaken the cylinder and render it unfit for further use. 

6.5.3   Valve protection cap shall not be used for lifting of cylinders from one position to another. Cylinder valve must be close before transportation. The valve of the cylinder should be protected during transportation, with the cover cap screwed on hand tight and remain capped until the cylinder is in place and ready for use. 

6.5.4   Never drag or slide cylinders, even for short distances. 

6.5.5   When moving large cylinders, they should be strapped to a properly designed wheeled cart to ensure stability. Only one cylinder should be moved at a time to prevent cylinders to strike each other violently. 

 7          TOXIC AND FLAMMABLE GAS DETECTION SYSTEM 7.1       All toxic and flammable gases are stored in gas cabinets equipped with appropriate

gas leak detectors to detect the presence of flammable and toxic gases at or below the permissible limit.

 

7.2       All flammable and toxic gas connections and distribution are enclosed in the ventilated gas cabinet or valve manifold box (VMB) connected to the gas detection system.

 7.3       Exhaust treatment devices such as burn box and scrubber system is installed to

remove specific toxic particles and gases from an exhaust stream for environmental and safety consideration.

 7.4       Ventilated gas cabinets equipped with sprinkler system are installed to house and

contain the toxic and flammable gas cylinder which allows safe delivery of the gas from cylinder to the process and allows proper purging of the gas so that cylinder change and maintenance can be performed.

 7.5       The gas detection monitoring system is installed to continuously monitor an area for

the presence of hazardous and toxic gases at or below a specific concentration limit, and if necessary, warn personnel through both visual and audible alarms.

 7.6       Detection sensors are connected to the gas cabinets. If a specified gas concentration

or set point is exceeded, alarm will be triggered.  7.7       Detector is also located at or near points where there is the possibility of a gas

release. It is used to detect the presence of gas at or below the permissible exposure limit.  If a specified gas concentration or set point is exceeded, gas detection alarm will be triggered.

 7.8       There are two level of alarm, the first alarm level is to provide an early warning of a

developing hazard and notify the lab personnel to initiate corrective actions. The second level of alarm is used to warn personnel and automatically shut down the gas supply.

 7.9       Gas leak alarm can only be reset or stop after deliberate action is taken. 7.10    Accidental Release Measures 

a.         In cases of accidental release, attempt to shut-off the source of gas but do not endanger yourself.

             b.         Eliminate all sources of ignition, and ventilate the area. 

c.         Staff in charge will rectify the cause of leak or with the help and service from the gas equipment suppliers.

 d.         If the situation is beyond control or presents an immediate danger, evacuate

the area immediately. Cordoned off the area and inform the staff in charge and the campus security and Fire Command Centre giving the name, location and all related information.

 e.         Do not attempt to extinguish a leaking gas flame unless absolutely necessary.

Spontaneous/ explosive re-ignition may occur. f.          If the gas leak is major and the gas detector is activated, it will shut down the

gas supply and at the same time staff will be alerted through messaging system connected to the building management system.

 

g.         Inform the Campus security and fire command centre giving all related information.

 h.         Evacuation will be done and warning to all others in the immediate area. i.          Gas equipment suppliers and SCDF will be called in for help, and assist them

with the exact location and provision of shut down point, etc. 

 

 8          APPENDIX 

Appendix I List of controlled and hazardous substances

Appendix II Form for recording inventory of hazardous substances

Appendix III Amendment History 

   APPENDIX I

LIST OF CONTROLLED and HAZARDOUS SUBSTANCES          Please refer to http://app2.nea.gov.sg/data/cmsresource/20090629934087284535.pdfhttp://app.nea.gov.sg/cms/htdocs/article.asp?pid=1428 for the complete list of hazardous

substances controlled by the Environmental Pollution ControlProtection and Management Act (EPCAEPMA).

         Please refer to http://www.scdf.gov.sg/content/scdf_internet/en/building-professionals/fire-

safety-licensing-and-enforcement/Petroleum-Storage-Tpt/_jcr_content/par/download/file.res/Latest%202010%20Copy%20of%20complete%20list%20of%20licensable%20chemicals(Revised).xls http://www.scdf.gov.sg/downloads/FS_Licensing/ Revised_HS_Code_18Apr2006.xls for a complete list of flammable materials licensable under the Singapore Civil Defence Force (SCDF).

         Please refer to http://www.scdf.gov.sg/content/scdf_internet/en/building-professionals/fire-

safety-licensing-and-enforcement/Guidebook-App-Petroleum-Flammable/_jcr_content/par/download_0/file.res/Exemption_quantities_for_FM.xls http://www.scdf.gov.sg/ downloads/FS_Licensing/Exemption_quanties_for_FM.xlsfor a list of exemption quantities for flammable materials, located at the SCDF website.

         Information on the licensing and type of flammable materials controlled by the SCDF are

found here http://www.scdf.gov.sg/scdf_internet/en/building-professionals/fire-safety-licensing-and-enforcement/Guidebook-App-Petroleum-Flammable.html http:// www.scdf.gov.sg/Building_Professionals/Fire_Safety_Licensing_and_Enforcement/Guidebook_App_P&FM_Licence.html.

         Please refer to

http://www.spf.gov.sg/licence/AE/others/Licensing_of_Explosive_Precursors.pdf for a lists of substance which are classified as explosive precursors and controlled by the Singapore Police Force. 

        Information on the frequently asked questions and the exclusion amount of the explosive precursors are found here http://www.spf.gov.sg/licence/AE/FAQ/FAQ_on_Licensing_of_Explosive_Precursors.pdf

         Please refer to the Register of Permits and Licenses, SEG document for the hazardous

and flammable substance permit issued by NEA, SPF and SCDF.   

  Commonly used gases in the electronics industries and its classification:  No Gas Toxic Corrosive Flammable Oxidising1 Acetylene C2H2     Y  2 Ammonia NH3   Y Y  3 Arsine AsH3 Y     Y4 Diborane B2H6 Y   Y  5 Boron TriChloride BCl3 Y Y    6 Boron Trifluoride BF3 Y Y    7 Trymethysilane C3H1OSi Y   Y  8 Octafluoro-

cyclopentemoC5F8 Y      

9 Difluorethane CH2F2     Y  10 Fluoromethane CH3F     Y  11 Methane CH4     Y  12 Chlorine Cl2 Y Y   Y13 Chloride Trifluoride ClF3 Y Y    14 Chloride Monoxide CO Y      15 Fluorine mixture <10%F2 Y Y    16 Germane GeH4 Y   Y  17 Hydrogen H2     Y  18 Hydrogen Bromide HBr Y Y    19 Hydrogen Chloride HCl Y Y    20 Hydrogen Sulfide H2S Y   Y  21 Nitrogen Trifluoride NF3 Y     Y22 Nitric Oxide NO Y      23 Phosphine PH3 Y   Y  24 Silicon

TetrachlorideSiCl4   Y    

25 Silicon Tetrafluoride

SiF4 Y Y    

26 Dichlorosilane SiH2Cl2   Y Y  27 Disilane Si2H6     Y  28 Silane SiH4     Y  29 Trichlorosilane SiHCl3 Y   Y  30 Tungsten

HexafluorideWF6 Y Y   Y

   

  APPENDIX II  

FORM FOR RECORD OF PURCHASE, STORE AND USE OF HAZARDOUSSUBSTANCE KEPT BY A PERSON AUTHORISED TO

STORE AND USE HAZARDOUS SUBSTANCES 

 

Name of Hazardous Substance: _____________________________________________

 Percentage of purity: ______________________________________________________  

DateQty

Rec’d

Invoice / Delivery Order No

Name / Address of

Supplier

Qty Used

Qty Stored

Signature of Permit

Holder   

      

   

   

      

   

   

      

   

   

      

   

   

      

   

   APPENDIX III - AMENDMENT HISTORY

 S/

No.Amendment Description Rev No. Effective Date

(dd/mm/yyyy)

1. New Issue 00 19/08/2009 Approval2. Amended URLs for the following clauses: Appendix I

Paragraph 1, Appendix I Paragraph 2, Appendix I Paragraph 3, Appendix I Paragraph 4

01

Last amended by: Teoh Kum Weng, Cleanroom Manager, SEG Approved by: Dr. Wang Jianguo, Deputy Director, SEG