CGA-G-6.4-2008.pdf

CGA G-6.42008 SAFE TRANSFER OF LIQUEFIED CARBON DIOXIDE IN INSULATED CARGO TANKS, TANK CARS, AND PORTABLE CONTAINERS THIRD EDITION COMPRESSED GAS ASSOCIATION, INC. 4221 Walney Road, 5th Floor Chantilly, VA 20151 Phone: 703-788-2700 Fax: 703-961-1831 E-mail: cgacganet.com PAGE ii COMPRESSED GAS ASSOCIATION, INC. CGA G-6.42008 PLEASE NOTE: The information contained in this document was obtained from sources believed to be reliable and is based on technical information and experience currently available from members of the Compressed Gas Association, Inc. and others. However, the Association or its members, jointly or severally, make no guarantee of the results and assume no liability or responsibility in connection with the information or suggestions herein contained. Moreover, it should not be assumed that every acceptable commodity grade, test or safety procedure or method, precaution, equipment or device is contained within, or that abnormal or unusual circumstances may not warrant or suggest further requirements or additional procedure. This document is subject to periodic review, and users are cautioned to obtain the latest edition. The Associa- tion invites comments and suggestions for consideration. In connection with such review, any such comments or suggestions will be fully reviewed by the Association after giving the party, upon request, a reasonable op- portunity to be heard. Proposed changes may be submitted via the Internet at our web site, www.cganet.com. This document should not be confused with Federal, state, provincial, or municipal specifications or regulations; insurance requirements; or national safety codes. While the Association recommends reference to or use of this document by government agencies and others, this document is purely voluntary and not binding. A listing of all publications, audiovisual programs, safety and technical bulletins, and safety posters is available via the Internet at our website at www.cganet.com. For more information contact CGA at Phone: 703-788-2700, ext. 799. E-mail: customerservicecganet.com Work Item 06-047 Carbon Dioxide Committee NOTETechnical changes from the previous edition are underlined. THIRD EDITION: 2008 SECOND EDITION: 2002 FIRST EDITION: 1992 © 2008 The Compressed Gas Association, Inc. All rights reserved. All materials contained in this work are protected by United States and international copyright laws. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical including photocopying, recording, or any informa- tion storage and retrieval system without permission in writing from The Compressed Gas Association, Inc. All requests for permission to reproduce material from this work should be directed to The Compressed Gas Association, Inc., 4221 Walney Road, Suite 500, Chantilly VA 20151. You may not alter or remove any trademark, copyright or other notice from this work. CGA G-6.42008 COMPRESSED GAS ASSOCIATION, INC. PAGE iii Contents Page 1 Introduction.1 2 Scope .1 3 Definitions.1 4 Special hazards3 4.1 Dry ice blocking.3 4.2 Trapped liquid3 4.3 Personnel overexposure3 4.4 Low temperature effects on materials .3 4.5 Overfilling containers.4 5 Physiology of carbon dioxide5 5.1 General5 5.2 Physiological effects of carbon dioxide5 5.3 Physical effects of overexposure to carbon dioxide.5 5.4 Regulatory standard5 5.5 Safety precautions.6 5.6 Rescue and first aid.6 6 Regulations 6 6.1 Regulatory agencies6 6.2 Product classification.6 6.3 Container specifications 6 7 Transfer facility design .7 7.1 General7 7.2 Hose and hose fittings.9 7.3 Valves9 8 Transfer procedures.9 8.1 General9 8.2 Filling carbon dioxide cargo tanks.9 8.3 Filling carbon dioxide storage containers from cargo tankstypical two-hose fill.13 8.4 Filling carbon dioxide storage containers from cargo tankssingle-hose fill14 8.5 Filling carbon dioxide tank cars at permanent locations17 8.6 Unloading carbon dioxide tank cars 20 8.7 Mobile storage containers .23 8.8 Portable containers (DOT/TC/CTC) 24 8.9 Filling small, stationary, insulated carbon dioxide supply systems25 9 Special handling procedures26 9.1 First-time fill procedure for liquid carbon dioxide storage tanks 26 9.2 Containers that have lost pressure27 9.3 Cross-contamination of carbon dioxide in distribution.27 10 References.29 11 Additional references30 Tables Table 1Volume expansion upon warming of liquid carbon dioxide saturated at 200 psig (1380 kPa) for a container with a 350 psig (2410 kPa) MAWP 4 Table 2DOT regulations pertaining to carbon dioxide 9 7 Table 3Piping materials commonly used for carbon dioxide transfer facilities 8 Table 4Fittings.8 PAGE iv COMPRESSED GAS ASSOCIATION, INC. CGA G-6.42008 Figures Figure 1Safe filling volumes for 350 psig (2410 kPa) carbon dioxide containers4 Figure 2Carbon dioxide cargo tank (transport trailer) DOT MC-330, MC-331, and TC-33111 Figure 3Typical carbon dioxide transfer piping schematic.12 Figure 4Typical automatic single-hose fill system .16 Figure 5Carbon dioxide tank car (rail car) CTC/DOT 105A500 and 105A500W.19 Figure 6Tank car dome .19 Figure 7Typical piping arrangement for rail car unloading 23 Figure 8Mobile storage container23 Figure 9Specification 4L portable container 24 Figure 10Small, stationary ASME container25 CGA G-6.42008 COMPRESSED GAS ASSOCIATION, INC. PAGE 1 1 Introduction Liquefied carbon dioxide is transported in insulated tank cars, cargo tanks, and portable tanks. Shipping this product requires transferring it from production plant storage to a variety of shipping containers and subsequent transfer to storage containers at consumer sites. Accidents that occur during transfer operations are usually attributed to failure to follow established safe procedures. 2 Scope The information contained in this publication is provided as a guide for personnel involved in transferring liquid carbon dioxide or in safety and training. General procedures recommended for the safe loading and unloading of the different types of carbon dioxide containers are presented. The special hazards of liquid carbon dioxide and its physiology and toxicology are explained so personnel can be properly trained for product handling. 3 Definitions For the purpose of this publication, the following definitions apply. 3.1 Approved Acceptable to the authorities having jurisdiction. 3.2 Appurtenances All system components (excluding the container) such as pressure relief devices, liquid level gauges, valves, pressure gauges, vaporizers, refrigeration systems, pumps, control equipment, and regulators. 3.3 Authorities having jurisdiction Federal, state, provincial, territorial, local, or other bodies having regulatory authority over the equipment being installed or used. 3.4 Blow-down valve Valve used to depressurize lines or systems. 3.5 Capacity Maximum weight of carbon dioxide a container will hold when filled to the proper level. 3.6 Carbon dioxide Chemical compound consisting of one atom of carbon bonded to two atoms of oxygen expressed by the chemical formula CO2. NOTEThe shipping name for carbon dioxide in uninsulated cylinders in the United States and Canada is “Carbon Diox- ide.” 3.7 Carbon dioxide, refrigerated liquid Shipping name for liquid carbon dioxide. 3.8 Cargo tanks Tank trucks and trailers that comply with U.S. Department of Transportation (DOT) specifications MC-330 and MC-331. In Canada, these are defined as highway tanks under specification TC-331 in CSA B620, Highway Tanks and Portable Tanks for the Transportation of Dangerous Goods 1.1 3.9 Container Insulated pressure vessel designed and constructed to Section VIII, Division I of the American Society of Me- chanical Engineers Boiler Cast iron or malleable iron fittings and pipe; PAGE 8 COMPRESSED GAS ASSOCIATION, INC. CGA G-6.42008 Cadmium plating for food service; A-120 galvanized steel pipe (A-106 galvanized is acceptable); Plastic pipe and fittings; and Carbon steel tubing (limited by external corrosion). NOTEFor more information, refer to CGA G-6.1, Standard for Insulated Liquid Carbon Dioxide Systems at Consumer Sites 14. Table 3Piping materials commonly used for carbon dioxide transfer facilities Material Sch Grade Type Joint type 40 A53 Types E and S A106 Type E and S A333 Type S Grade A and B Grade A or B Grade 6 Butt or socket weld (No threaded connections) Carbon steel 80 A53 Types E and S A106 Types E and S A333 Type S Grade A and B Grade A or B Grade 6 Threaded, butt, or socket weld 10 A312 welded or seamless 304 and 316 Butt weld only (no threaded connections) 40 A312 welded or seamless 304 and 316 Threaded, butt, or socket weld Stainless steel 80 A312 welded or seamless 304 and 316 Threaded, butt, or socket weld 40 B43 Seamless Brazed only Red brass 80 B43 Seamless Threaded, brazed Table 4Fittings Material Grade Type Connection type Carbon steel A 105 A 234 A 105 Class 2000 or 3000 forged Class 2000 or 3000 forged Class 2000 or 3000 forged Threaded Butt weld Socket weld Stainless steel A 182 A 403 A 182 Class 2000 or 3000 Class 2000 or 3000 Class 2000 or 3000 Threaded Butt weld Socket weld Copper ANSI B16.22 Wrought Brazed; flare or compression (1/2 in outside diameter OD) Brass Forged bar stock Threaded Brazed Flare (1/4 in OD) Compression (bite type) (1/2 in OD) NOTES 1 Plastic pipe is suitable only for warm carbon dioxide vapor service less than 100 psig (791 kPa). Properly sized and rated PRDs are required to prevent pressure buildup due to failure of pressure-reducing regulators. Low tem- peratures caused by gas expansion through pressure-reducing regulators, vaporizer malfunction, excessive with- drawal, etc. can cause piping temperatures to decline to unsafe levels. Cold plastic piping can become brittle and can fail catastrophically. Plastic piping can also fail from overheating at much lower temperatures than metallic piping. Plastic piping in carbon dioxide service should be used with extreme caution. 2 Pipe unions of a minimum 2000 class rating may be used on pipe sizes up to 2 in (5.1 cm). ANSI Class 300 flanges are recommended for use on pipe sizes larger than 2 in (5.1 cm). 3 For more information refer to CGA G-6.1 14. CGA G-6.42008 COMPRESSED GAS ASSOCIATION, INC. PAGE 9 7.2 Hose and hose fittings All hoses used in carbon dioxide service shall be designed for a bursting pressure of at least five times the pressure to which they can be subjected in service. Refer to CGA G-6.6, Standard for Elastomer-Type Carbon Dioxide Bulk Transfer Hose 15. All couplings used on hoses shall be designed for a pressure not less than 125% of the design pressure of the hose. They shall be constructed and installed to prevent leakage when in use. Hose and fixed-end fittings shall conform to the recommendations of CGA V-6, Standard Bulk Refrigerated Liq- uid Transfer Connections 16. Each transfer station hose shall be equipped with hose restraints fastened to solid fixtures. Hoses should be fitted with vented dust caps when not in use. Each transfer station hose shall be equipped with blow-down valves to enable depressurization of hoses after completion of the transfer. To prevent plugging of the blow- down valve, the valve shall be at least a 1/2-in (1.3-cm) ball-type valve, and for systems with more than 2-in (5.1-cm) pipe size, larger valves may be required. Installation of cross-over lines is highly recommended to as- sist in safe depressurization of the liquid hoses. PRDs shall also be installed to prevent line rupture from trapped liquid carbon dioxide. Elastomer (rubber) transfer hoses shall be manufactured in accordance with CGA G-6.6 and be requalified and have a service life in accordance with CGA P-7, Standard for Requalification of Cargo Tank Hose Used in the Transfer of Carbon Dioxide Refrigerated Liquid 15, 17. 7.3 Valves Liquid carbon dioxide piping systems normally use ball- and globe-type valves. Valves shall be designed to allow liquid that can be trapped in the ball or stem cavity to relieve safely. This is typically achieved in ball valves by drilling a small vent hole through the ball in the direction of the high pressure side when closed or by using valves equipped with self-relieving seats. 8 Transfer procedures 8.1 General The following transfer procedures are based on piping configurations generally used in the carbon dioxide in- dustry. The procedures may be used to prepare company operating procedures but shall be amended for the specific piping configurations. Personnel shall wear appropriate safety equipment such as safety glasses with side shields, safety shoes, gloves, hard hats, and ear protection for all transfer procedures. All containers and transfer equipment should be in good repair and free of defects that can cause an accident or injury. The vessels should be in carbon dioxide service and at normal operating pressures. If unusual condi- tions are noted, observe appropriate caution and procedures before attempting any product transfer. See 9.1. The disconnecting of pressurized hoses has been the cause of many accidents and injuries. As it is common to all filling and unloading transfer procedures, it is particularly important that personnel be trained in an adequate and safe procedure for disconnecting the transfer hoses. 8.2 Filling carbon dioxide cargo tanks A typical cargo tank is shown in Figure 2. A typical piping schematic is shown in Figure 3. For the purposes of filling carbon dioxide cargo tanks, the supply container is the facility storage vessel (A side) and the receiving container is the cargo tank (B side). PAGE 10 COMPRESSED GAS ASSOCIATION, INC. CGA G-6.42008 To fill carbon dioxide cargo tanks: a) Park the cargo tank so loading can be performed safely. A STOP UNIT CONNECTED sign should be placed in front of the cargo tank. Place chocks under cargo tank wheels to prevent unintended movement unless other means are provided to stop the vehicle from moving; b) Check the cargo tank content markings. Be certain that the product being filled (liquefied carbon dioxide) agrees with the label and placards on the cargo tank; c) Check cargo tank pressure to ensure the vessel is in service and that the pressure is within normal operat- ing ranges and more than 200 psig (1380 kPa); d) Relieve pressure that may exist between liquid and vapor shutoff valves and the dust caps on the piping by opening the blow-down valves; (3A, 3B, 4A, and 4B); e) Remove the dust caps from all liquid and vapor connections. Inspect the connections for cleanliness. Re- move foreign objects and material and clean them if necessary. Do not apply glycol or other lubricants to the connections; f) Connect hoses so the liquid filling line on the cargo tank is connected to the liquid line on the storage con- tainer and the vapor line from the cargo tank is connected to the vapor line on the storage container. Attach safety restraints; g) Purge both vapor and liquid hoses through the