CGA-G-1.1-1998-R2004.pdf
CGA G-1.11998 COMMODITY SPECIFICATION FOR ACETYLENE THIRD EDITION REAFFIRMED 2004 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-1.11998 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. Docket 03-37 Gas Specifications Committee NOTETechnical changes from the previous edition are underlined. NOTEThis reaffirmed edition may include minor editorial changes; however, all technical information is the same as the 1998 edition. REAFFIRMED: 2004 THIRD EDITION: 1998 SECOND EDITION: 1990 FIRST EDITION: 1972 © 1998 BY THE COMPRESSED GAS ASSOCIATION, INC. ALL RIGHTS RESERVED. 4221 WALNEY ROAD, 5TH FLOOR, CHANTILLY, VA 20151 Printed in U.S.A. CGA G-1.11998 COMPRESSED GAS ASSOCIATION, INC. PAGE iii Contents Page 1 Scope .1 2 Classification 1 2.1 Quality verification levels (grades).1 2.2 Quality tests.1 3 Quality verification systems2 3.1 Production qualification tests.2 3.2 Analytical requirements of the production qualification tests.2 3.3 Lot acceptance tests2 4 Sampling 2 4.1 Sample size.2 4.2 Acetylene samples 3 5 Analytical procedures.3 5.1 Parameters of analysis3 5.2 Percent acetylene4 5.3 Phosphine/arsine content4 5.4 Hydrogen sulfide content.4 6 Cylinders 5 6.1 Acetylene cylinders5 6.2 Cylinder preparation5 6.3 Valves on acetylene cylinders.5 6.4 Pressure relief devices on acetylene cylinders6 7 References.6 Tables Table 1Directory of limiting characteristics1 Table 2Typical uses.1 This page is intentionally blank. CGA G-1.11998 COMPRESSED GAS ASSOCIATION, INC. PAGE 1 1 Scope This document describes specification requirements for gaseous acetylene as listed in Table 1. All future refer- ences should be to the current edition of CGA G-1.1, Commodity Specification for Acetylene. NOTEThis document does not attempt to recommend or establish end usage designations for specific types or grades of products. It is suggested that users requiring this kind of information contact individual gas acetylene suppliers. 2 Classification 2.1 Quality verification levels (grades) Table 1 presents the component maxima, in parts per million, ppm (v/v), unless shown otherwise for the quality verification levels of gaseous acetylene. A blank indicates no maximum limiting characteristic. The absence of a listed quality verification level does not mean to imply that the limiting characteristic is or is not present, but merely indicates that the test is not required for compliance with the specification. Table 1Directory of limiting characteristics (Units in ppm (v/v) unless otherwise stated) Quality verification levels (grades) Maxima for gaseous acetylene 1) Limiting characteristics A C H Acetylene minimum percent assay 95 98 99.6 Phosphine and arsine 500 2) 25 Hydrogen sulfide 500 2) 25 1) Cylinder acetylene entails variable percentage quantities of solvent (normally acetone, boiling point 133 °F 56.1 °C). The amount of solvent present in the expelled gas is de- pendent upon the vapor pressure of the solvent, the conditions of the cylinder, and the conditions of withdrawal. The purities listed in Table 1 are given on a solvent-free basis. 2) Acetylene manufactured from hydrocarbon feedstock is inherently free from phosphine, arsine, and hydrogen sulfide. However, phosphine, arsine, and hydrogen sulfide levels in acetylene produced from a water/calcium carbide reaction are not routinely checked by the acetylene producer (due to the noncritical nature of the usewelding and cut- ting). These purity levels traditionally have been based on the calcium carbide pro- ducers raw material information. Table 2Typical uses CGA grade Typical uses A Welding, cutting, and brazing C Welding, cutting, and brazing H Atomic adsorption analysis NOTETypical uses defined in this table are not all inclusive. 2.2 Quality tests The supplier ensures, by standard practice, the quality verification level of gaseous acetylene. If otherwise re- quired, alternative control procedures are described in 3.3.1; 3.3.2; Section 4; and Section 5. Other control pro- cedures not listed in this specification are acceptable if agreed upon between the supplier and the customer. CAUTION: Acetylene is flammable and can be an asphyxiant. -,-,- PAGE 2 COMPRESSED GAS ASSOCIATION, INC. CGA G-1.11998 3 Quality verification systems 3.1 Production qualification tests These tests are a single analysis or a series of analyses performed on the product to ensure the reliability of the production facility to supply gaseous acetylene of the required quality verification level. This production qualification can be verified by the analytical records of product from the supplier; or, if required, by analysis of representative samples of the product from the facility at appropriate intervals as agreed upon between the supplier and the customer. Production qualification tests may be performed by the supplier or by a laboratory agreed upon between the supplier and the customer. 3.2 Analytical requirements of the production qualification tests These will include the determination of all limiting characteristics of gaseous acetylene. 3.3 Lot acceptance tests These are analyses performed on the gaseous acetylene from the cylinder, or a sample thereof that is repre- sentative of the lot. 3.3.1 Lot definitions One of the following is to be used: no specific quantity or any quantity of gaseous acetylene agreed upon between the supplier and the cus- tomer; all of the gaseous acetylene supplied during the contract period; all of the gaseous acetylene supplied or cylinders filled during a calendar month; all of the gaseous acetylene supplied or cylinders filled during seven consecutive days; all of the gaseous acetylene supplied or cylinders filled during a consecutive 24-hour period; all of the gaseous acetylene supplied or cylinders filled during a continuous work shift; all of the gaseous acetylene supplied in one shipment; all of the gaseous acetylene supplied in one shipping container; or all of the gaseous acetylene supplied in the container(s) filled at the same time. 3.3.2 Number of samples per lot The number of samples per lot is to be in accordance with one of the following: one sample per lot; or any number of samples agreed upon by the supplier and the customer. 4 Sampling 4.1 Sample size The quantity of gaseous acetylene in a single sample cylinder should be sufficient to perform the analyses for all the limiting characteristics. If a single sample does not contain a sufficient quantity of acetylene to perform all of the analyses for the required quality verification level, additional samples from the same lot shall be taken under similar conditions. -,-,- CGA G-1.11998 COMPRESSED GAS ASSOCIATION, INC. PAGE 3 4.2 Acetylene samples Gaseous acetylene samples shall be representative of the acetylene supply. Samples shall be obtained in ac- cordance with one of the following: By selecting a representative cylinder from the cylinders filled in the lot; By connecting the gas stream being sampled directly to the analytical equipment; or By withdrawing a sample from the supply source through a suitable connection into the sample container. The sample container shall have a working pressure of no less than 500 psig (3450 kPa).1, 2 The material of construction of the sample container should be compatible with acetylene 1. 4.2.1 To avoid formation of a flammable mixture, air shall be removed from the sample container by a suitable evacuation and/or purge procedure. 4.2.2 The acetylene pressure in the sample container shall not exceed 15 psig (103 kPa). 5 Analytical procedures 5.1 Parameters of analysis The parameters for analytical techniques contained in this section are: 5.1.1 percent (v/v) = parts per hundred by volume; 5.1.2 ppm (v/v) = parts per million; 5.1.3 Calibration gas standards containing the applicable gaseous components may be required to calibrate the ana- lytical instruments used to determine the limiting characteristic levels of gaseous acetylene. If required by the customer, the accuracy of measuring equipment used in preparing these standards is to be traceable to the National Institute of Standards and Technology (NIST);3 5.1.4 Analytical equipment is to be operated and properly calibrated in accordance with the manufacturers instruc- tions; and 5.1.5 Analytical methods not listed in this specification are acceptable if agreed upon between the supplier and the customer. 1 kPa shall indicate gauge pressure unless otherwise noted as (kPa, abs) for absolute pressure or (kPa, differential) for dif- ferential pressure. All kPa values are rounded off per CGA P-11, Metric Practice Guide for the Compressed Gas Industry 2. 2 References are shown by bracketed numbers and are listed in order of appearance in the reference section. 3 NIST, 100 Bureau Dr., Stop 3460, Gaithersburg, MD 20899. www.nist.gov -,-,- PAGE 4 COMPRESSED GAS ASSOCIATION, INC. CGA G-1.11998 5.2 Percent acetylene The percent of gaseous acetylene shall be determined by one of the following procedures: 5.2.1 By a volumetric or manometric gas absorption (Orsat-type) analyzer using one of the following as the absorbing solution: fuming sulfuric acid; acetone; or dimethylformamide (DMF); or CAUTION: The reagents and reaction products involved in the previous analyses may be hazardous. 5.2.2 By a gas chromatograph. The analyzer must be capable of separating and detecting the specified component. Appropriate impurity concentrating techniques may be used to attain the required sensitivity. The analyzer is to be calibrated at appropriate intervals by the use of calibration gas standards, see 5.1.3. The analyzer shall be operated in a manner to accurately measure the limiting characteristics as defined in Table 1. 5.3 Phosphine/arsine content The phosphine/arsine content shall be determined by one of the following: 5.3.1 By a chemical test in which a pre-determined quantity of gaseous acetylene is passed through a filter paper moistened with a 5% silver nitrate solution. If the filter paper turns black, it is a positive indication of hydrogen sulfide and/or phosphine/arsine content. This test cannot differentiate between phosphine/arsine content and hydrogen sulfide content; 5.3.2 By an apparatus employing a detector tube filled with a color reactive chemical. The degree of accuracy is de- pendent on the precision of the measurements and the analytical bias of the tube. This test cannot differentiate between phosphine/arsine content. A detector tube that does not have cross-sensitivity to hydrogen sulfide should be used; 5.3.3 By a suitable wet chemical method. The system shall be calibrated at appropriate intervals using calibration standards, see 5.1.3. The analyzer shall be operated in a manner to accurately measure the limiting character- istics as defined in Table 1; or 5.3.4 By a gas chromatograph in accordance with 5.2.2. This analysis will differentiate between phosphine/arsine and hydrogen sulfide. 5.4 Hydrogen sulfide content The hydrogen sulfide content shall be determined by one of the following: -,-,- CGA G-1.11998 COMPRESSED GAS ASSOCIATION, INC. PAGE 5 5.4.1 By a chemical test in which a pre-determined quantity of gaseous acetylene is passed through a filter paper moistened with a 5% silver nitrate solution. If the filter paper turns black, it is a positive indication of hydrogen sulfide and/or phosphine/arsine content. This test cannot differentiate between phosphine/arsine content and hydrogen sulfide content; 5.4.2 By an apparatus employing a detector tube filled with a color reactive chemical. The degree of accuracy is de- pendent on the precision of the measurements and the analytical bias of the tube. A detector tube that does not have cross-sensitivity to arsine and/or phosphine should be used; 5.4.3 By a suitable wet chemical method. The system shall be calibrated at appropriate intervals using calibration standards, see 5.1.3. The analyzer shall be operated in a manner to accurately measure the limiting character- istics as defined in Table 1; 5.4.4 By a gas chromatograph in accordance with 5.2.2. This analysis will differentiate between phosphine/arsine and hydrogen sulfide; or 5.4.5 By an electrochemical-cell-type sulfur ion analyzer. The range used should be no greater than ten times the specified sulfur compound content. The analyzer shall be operated in a manner to accurately measure the limit- ing characteristic as defined in Table 1. This test is specific for hydrogen sulfide content only. 6 Cylinders 6.1 Acetylene cylinders Acetylene cylinders offered in transportation shall comply with the regulations of the appropriate authority. 6.1.1 In the United States, the Department of Transportation (DOT) regulations describe how cylinders shall be manufactured, maintained, filled, packaged, marked, labeled, and shipped to comply with current DOT regula- tions (49 CFR 100-180) and CGA C-7, Guide to the Preparation of Precautionary Labeling and Markin
