Common defects and prevention of cold drawn seamless steel pipes
1 common vocabulary
1.GAS——gas in English
2.NG——abbreviation for natural gas
3.CNG——abbreviation for compressed natural gas
4.LPG——abbreviation for liquefied petroleum gas
5.LNG——abbreviation for liquefied natural gas
2 related terms
1. Density (ρ): The ratio of mass to volume.
2. Specific gravity (S): Gas specific gravity is the ratio of gas density to air density. S=ρ/1.293
The specific gravity of a liquid is the ratio of the density of the liquid to the density of water. S=ρ/1=ρ
3. Specific heat: The amount of heat absorbed (or released) by a unit quantity of a substance when the temperature changes by 1°C.
4. Combustion potential: combustion speed index.
5. Calorific value: The heat released by the complete combustion of 1 standard meter 3 gas is called the calorific value of the gas. It is divided into high calorific value and low calorific value. In engineering applications, calorific value is generally used.
6. Ignition temperature: refers to the lowest temperature at which the mixture of flammable gas and air (or oxygen) begins to undergo a combustion reaction.
7. Explosion limit: The concentration range in which a mixture of flammable gas and air (or oxygen) ignites to cause an explosion is called the explosion limit. Its lowest concentration is called the lower limit, and its highest concentration is called the upper limit.
8. Explosive gas environment: Under atmospheric conditions, a mixture of flammable gas, steam or mist and air will spread to a full range of combustion after ignition.
9. Ignition point, flash point, spontaneous ignition point:
Ignition point: According to standard test methods, the lowest temperature at which an explosive gas mixture ignites is called the ignition point.
Flash point: Under standard conditions, the temperature of a liquid that can cause the liquid to release enough vapor to form an explosive gas mixture that can flash is called the flash point.
Autoignition point: When a combustible substance reaches a certain temperature, it can be violently oxidized and burn automatically when in contact with air.
10. Peak shaving gas: In order to balance the peak gas consumption, it is an auxiliary gas source and gas storage used for peak shaving means.
11. Monthly peak coefficient: Calculate the ratio of the average daily gas consumption in the month to the average daily gas consumption in the year.
12. Daily peak coefficient: Calculate the ratio of the maximum daily gas consumption in the middle of the month to the average daily gas consumption in the month.
13. Hourly peak coefficient: Calculate the ratio of the maximum hourly gas consumption on the maximum gas consumption day in the middle of the month to the average hourly gas consumption on that day.
14. Pressure regulating box (pressure regulating cabinet): Place the pressure regulating device in a special box. Located near gas-consuming buildings, it is responsible for regulating gas pressure. Including pressure regulating device and box. The suspended or underground box is called a voltage regulating box, and the floor-standing box is called a voltage regulating cabinet.
15. Compressed natural gas storage and distribution station: a station with the function of unloading, heating, pressure regulating, storing, measuring, and odorizing the compressed natural gas transported by tank trucks and tank ships, and then sending it to urban gas transmission and distribution pipelines.
16. Compressed natural gas cylinder supply station: A facility that uses compressed natural gas cylinders as gas storage facilities and has the function of unloading, regulating, measuring and odorizing the compressed natural gas before sending it into urban gas transmission and distribution pipelines.
17. Urban gas: From regional gas source points in cities, towns or residential areas, through the transmission and distribution system, combustible gas is supplied for public use to various users such as residents, commerce, industrial enterprise production, heating, ventilation and air conditioning, and meets the gas quality requirements of this specification. Town gas generally includes natural gas, liquid petroleum gas and artificial coal gas.
18. Odorant: An organic compound or mixture with a strong odor. When added to the gas at a very low concentration, the gas will have a special, unpleasant warning odor, so that the leaked gas will be detected when it reaches 20% of its lower explosion limit or reaches the permissible harmful concentration to the human body.
19. Compressed natural gas bottle set: a combination of multiple compressed natural gas bottles fixed on the bottle basket with a compressed natural gas filling (unloading) system and safety protection and safe release facilities.
20. Pressure pipeline: Tubular equipment that uses a certain pressure to transport gas or liquid. Its scope is defined as gases with a maximum working pressure greater than or equal to 0.1PMa, liquefied gas vapor media or flammable, flammable, corrosive liquid media with a maximum working temperature or equal to the standard boiling point, and pipes with a nominal diameter greater than 25mm.
3 Pressure conversion
1kPa=103Pa 1kgf/cm2=105 1MPa=106Pa 1mbar=102Pa
1bar=11kgf/cm2=105 1mmH2O=10Pa 1mmHg=133Pa
4 Gas classification
1. Natural gas
The main component of natural gas is methane, which is a combustible gas buried underground and is a high-quality fuel gas. Calorific value is 8700—9000 KCal/m3, density is 0.7174Kg/Nm3.
According to gas source:
Gas field gas (pure natural gas)——Combustible gases extracted from natural gas wells
Petroleum associated gas——It is a gas that is precipitated during the oil extraction process and is further precipitated in the separator due to the reduction in pressure.
Condensate gas field gas——Gases containing light petroleum fractions.
mine gas——Combustible gases extracted from coal mines
Coalbed methane is a combustible gas produced during coal formation and accumulated in suitable geological structures. The main component is methane.
According to the state of existence: gaseous natural gas
LNG——Volume is 1/600 when in gaseous state
compressed natural gas——Volume is 1/250 when in gaseous state
2. Artificial gas
Solid retort gas: the main components are CH4 and H2
Solid fuel gasification gas: pressure gasification gas, water gas, generator gas.
The main components of pressure gasification gas are CH4 and H2
The main components of water gas and generator gas are CO and H2
Oil to gas: According to different production methods, it is divided into two types: heavy oil thermal cracking to produce gas, the main components are CH4, C2H4, C3H6; heavy oil thermal catalytic cracking to produce gas, the main components are CH4, H2, CO.
blast furnace gas
3. Liquefied petroleum gas
(1) Source: Liquefied petroleum gas is a hydrocarbon with C3 and C4 as the main components obtained as a by-product in the process of mining and refining petroleum;
(2) Components: The main components of liquefied petroleum gas are propane, propylene, butane, butene, and a small amount of pentane;
(3) State: It is in gaseous state under normal temperature and pressure (boiling point under normal pressure is -42.7~0.5℃). When the pressure increases or the temperature decreases, it can easily become liquid;
(4) Status parameters and characteristics
a. Gaseous liquefied petroleum gas is heavier than air. At normal temperatures and pressures, the density of gaseous liquefied petroleum gas is 1.5 to 2 times that of air. Therefore, once leaked into the atmosphere, liquefied petroleum gas will easily accumulate in low-lying areas and be difficult to spread. When mixed with air, explosive gas will be formed. When exposed to open flames, it will cause fires and explosion accidents. Liquid liquefied petroleum gas is lighter than water, and its density is 0.5 to 0.6 times that of water, which decreases as the temperature increases and increases as the temperature decreases.
b. The calorific value of liquefied petroleum gas is relatively high, and its low calorific value is 45.2~46.1MJ/Kg or 92.1~121.4KJ/m3. The amount of air required for combustion is large, and the amount of air required for combustion per unit volume is 7 to 8 times that of artificial coal gas and 2.5 to 3 times that of natural gas.
4. Biogas (biogas): A combustible gas with methane as the main component produced by microbial fermentation and decomposition of various organic matter under certain conditions of temperature, humidity, pH and isolation from air.
