SY/T 6515-2001 Ignition characteristics of hydrocarbon gases in open-air hot surface environmentsSY/T6515-2001 standard download decompression password: www.bzxz.net

ILS 13.100
Record number: 9602——2001
Petroleum and Natural Gas Industry Standard of the People's Republic of China SY/6515—2001
Ignition risk of hydrocarbon vapors by hot surfaces in the open air2001~09-24 Issued
National Economic and Trade Commission
2002—0101 Implementation
SY/T6515—2001
This standard is equivalent to the American Petroleum Institute API Publ2216 "Ignition risk of hydrocarbon vapors by hot surfaces in open air" (1991 edition).
This standard describes the ignition characteristics of flammable hydrocarbon gases exposed to hot surfaces in open air. In the process of compiling this standard, the "Introduction", "Special Statement" and "Chapter 3 References" of API Publ 2216 (1991 Edition) were omitted according to the content requirements. In order to facilitate comparison, this standard is written in the format of API Publ 2216 (1991 Edition) as much as possible. This standard is proposed and submitted by the Petroleum Industry Safety Professional Standardization Technical Committee. Drafting unit of this standard: Safety and Environmental Protection Department of Shengli Petroleum Administration Bureau. Main drafters of this standard: Zhang Yong, Li Junrong, Dong Guoyonghao, Su Ting, Liu Yangming, Gao Shengxin, Zhao Zhong III
1 Overview Www.bzxZ.net
1.1 Date
Petroleum and Natural Gas Industry Standard of the People's Republic of China Ignition risk of hydrocarbon vapors by hot surfaces in the open This standard describes the ignition characteristics of flammable hydrocarbon gases exposed to hot surfaces in open air. 1.2 Introduction and Scope
Ignition of an accidental release of hydrocarbon gases in the atmosphere may result in a destructive fire. Frequently, hot surfaces in the area of ​​the hydrocarbon release are considered to be the ignition source. However, even hot surfaces at seven of the published and generally accepted hydrocarbon ignition temperatures may not ignite the flammable mixture. Even the exhaust system of a vehicle, which in most cases has a sufficiently high temperature to ignite hydrocarbon gases in an open air environment, will not be effective. Experimental studies and experience have shown that hot surfaces must be several degrees above the published minimum ignition temperature to ignite a mobile flammable gas in open air. However, the development of flames is not only related to temperature, but also to the area, geometry and surrounding conditions of the hot surface. This standard covers the technical basis for the study of ignition hazards and the subsequent practical implications. In particular, it is emphasized that the fire investigator should understand that flammable hydrocarbon gases are ignited by hot surfaces at the published minimum ignition temperature. It is unlikely that a hot surface will ignite. This knowledge may lead the fire investigator to more carefully explore other ignition sources for ignition conditions caused by suspected or unlikely hot surfaces.
When certain confined spaces exist, such as when oil-filled insulation is in an unventilated, confined space, hydrocarbon gases may glow white at the lowest published temperature: this standard does not include a discussion of this phenomenon because the mechanisms involved are similar to those involved in ignition in open air.
2 Summary of Studies
2.1 Ignition Temperature
The ignition temperature of a substance is the lowest temperature required to initiate or cause spontaneous combustion without the need for heating or heated elements. Some publications use the term autoignition or white ignition temperature (AIT) and sometimes the term white ignition temperature (SIT). In publications, the term "ignition temperature" has the same meaning as the autoignition temperature (AIT) and white ignition temperature (SIT). Although the definition of the ignition temperature is specific, the observed value is essentially condition-dependent. The conditions under which gas release occurs in the open air are very different from those of the standard laboratory ignition temperature test. 2.2 Standard Test Method
The standard ignition temperature test is conducted by heating a glass flask and filling it with a measured amount of a flammable or combustible liquid. If ignition occurs, the temperature of the flask wall and the time after the test sample is filled to ignite (the ignition lag) are recorded. The test is repeated at different flask temperatures to determine the lowest temperature at which ignition occurs within 10 minutes: this temperature is determined to be the minimum ignition temperature of the material. 2.3 Tests in the Open Air
The effect of the ignition lag time of several paraffin hydrocarbons in the open air is shown in Table 1. The data in Table 1 show that a combustible mixture, after being heated for a relatively short period of time, needs to be exposed to the highest surface temperature for ignition to occur. In the open air, the slow convection currents in front of the hot surface and the downward movement of normal wind currents cause the combustible gas and air mixture to quickly pass over the heated surface, so that the contact time may be only a few seconds or a fraction of a second. Because the contact time in the open air is so short, the surface temperature required for ignition is much higher than the acceptable ignition temperature. The State Economic and Trade Commission approved the 2001-9-24 and implemented it on 2002-01-01. Table 1 Effect of ignition delay on ignition temperature Ignition delay time, s The effect of wind speed has been measured in wind tunnel tests with alcohol (the published ignition temperature is 210°C), see Table 2. Table 2 Wind speed on hot surface Effect of alcohol wind speed test Surface temperature required for ignition Small-scale tests were conducted on relatively unconfined butane and air mixtures and gasoline and air mixtures (the published temperatures are 287°C and 280°C respectively). This test determined that the metal surface temperature reached 760°C before combustion occurred. Some more realistic tests have been conducted in open air environments with normal wind flow and convection currents. The results of these tests are shown in Table 3. In these tests, the results were similar for hydrocarbon droplets scattered on the surface and for gas and argon mixtures released onto the surface. Table 3 Open Air Ignition Tests Under Normal Air Flow and Convective Flow Material
Cavity Oil
Naphtha
Ethyl Ether
2.4 Industry Experience
Published Ignition Temperature
Hot Surface Temperature Without Ignition
Test data indicate that the temperature required to ignite hydrocarbon gas mixtures in the open air is several hundred degrees Fahrenheit higher than the lowest ignition temperature in laboratory tests. Years of practical experience support this conclusion. Many small seepage releases of flammable or combustible hydrocarbon gases have occurred in process units in the presence of hot equipment or other uninsulated hot surfaces hundreds of degrees above the published minimum ignition temperature and have not ignited. Releases of flammable hydrocarbon gases that have ignited usually occur because they encounter a heater or similar ignition source. 2.5 Oxidizers
In the case of recently added oxidizers, such as ethanol and methanol to gasoline, preliminary data indicate that gasoline blended with 10% ethanol behaves similarly to gasoline in that it does not ignite when in contact with hot surfaces 265°C above the published ignition temperature. However, gasoline alone containing 10% methanol/isobutane blends has shown a tendency to ignite when in contact with hot surfaces 200°C above the published ignition temperature because it wets the hot surface more effectively. 2
2.6 Conclusion
SY/T 65152001
Test data and field experience show that the temperature required for ignition of combustible hydrocarbon gas by hot surface in open air is much higher than the lowest ignition temperature of the material measured in the laboratory. According to experience, ignition by a hot surface in open air cannot be considered unless the surface temperature is above 200℃ of the lowest acceptable temperature. Fire researchers should be aware of the characteristics of ignition of hydrocarbon gas by hot surface in open air. Otherwise, the study of the accident may lead to the identification of the wrong ignition source and inappropriate and ineffective corrective actions.
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