As we all know, with the development of the oil and gas and petrochemical industries, with the west-to-east gas transmission project as a symbol, the peak period of China's long-distance pipeline construction has come. At present, mature manual down welding technology is already available, and semi-automatic gas shielded welding technology is being popularized. The combination of automatic gas shielded welding technology and down welding technology as the development trend of high pressure pipeline welding technology We introduce the following: natural gas pipeline welding technology and the price adjustment of pipeline gas.
Natural gas pipeline welding technology:
A. STT technology CO2 gas protection semi-automatic down welding technology
STT type CO2 semi-automatic welding uses STT welding technology for root welding of pipes. The protective gas used for root welding is CO2. A manual welding process for automatic wire feeding using a flux-cored wire (such as Lincoln's NR207). STT is the abbreviation of "Surface Tension Transfer", which means the transition of surface tension. It is a kind of transitional mechanism of welding deposited metal.
1 Process characteristics
STT welding is a cheap and efficient welding method in the welding of pressure pipes. Traditional CO2 gas shielded arc welding cannot fundamentally solve the problems of large welding spatter and unfavorable weld formation. The STT CO2 semi-automatic welding machine adopting the waveform control technology ensures the stability of the welding process, the appearance of the weld seam is beautiful, and the influence of the dry elongation change is small, which significantly reduces spatter and reduces the labor intensity of the welder.
2 Process principle
Since the droplet transfer of the STT technology is achieved by relying on the surface tension of the liquid metal, it has its own special welding method using dynamic control. Therefore, the weld pool produced on the weld bead is very small and concentrated. With its excellent performance, it broadens the application of CO2 semi-automatic welding in the construction of long-distance pipelines.
3 Project Example
The China Petroleum and Natural Gas Pipeline Bureau has used the STT type CO2 semi-automatic downsweep technology for the first time in the Sudan Muglad oil development project, and the Zhongyuan Petroleum Exploration Bureau Construction Group Company is using the Beijing-Shijiazhai Pipeline Project for the construction of the Shaan-Jing pipeline double-track line. STT semi-automatic down welding technology.
4 welding equipment
At present, according to the author's understanding, STT welding equipment is currently only Lincoln Corporation.
Second, automatic gas protection welding technology
Fully automatic gas shielded welding is a welding process that uses fully automatic welding machines and protective gas for pipe welding. Generally argon or CO2 is used as the protective gas.
1 Process characteristics
Because the protection of the welding zone during the gas metal arc welding is simple, the welding area is easy to observe, the production efficiency is high, the welding process is relatively simple, it is easy to control, and it is easy to realize all-position welding. However, the requirements on the quality of the pipe groove and the counterpart are high, that is, the pipe is required to be evenly distributed around the entire circumference; the shape of the groove is strictly required. When the wall thickness of the pipe is thick, the composite type or U-shaped groove is used to determine the process. Considering the reduction in workload, it is more important to consider the guarantee of the quality of the groove at the welding quality. Although the V-groove of the small angle simplifies the construction procedure, from the perspective of quality assurance, the composite slope L or U-shaped groove is better. In addition, it is influenced by the external climate, which is also a common problem of gas shielded arc welding. The problem of gas source is easier to solve in the eastern regions such as Shanghai.
2 Process principle
Pipeline automatic gas shielded welding technology uses a melting arc between the weldable wire and the metal to be welded as a heat source to melt the wire and the steel pipe. During the welding time, the shield gas is sent to the welding area to isolate the harmful effects of air, and welding is performed by continuous wire feeding. . The process can realize the simultaneous operation of all positions and multiple heads. The bottom welding can be welded from the inside of the tube, and the outside of the tube can also be welded. The adjustment of the welding process parameters is generally on the console or the control panel.
3 Project Example
The Zhengzhou-Yima gas pipeline project (eastern section) is made of 16Mn steel pipe, 426 mm in diameter, and H08Mn2SiA wire, with a diameter of 1.0 mm. In the “West-East Gas Pipeline†project, fully automatic gas-shielded welding has also been applied in a wide range of applications.
4 welding parameters
It should be noted that because of the difference in welding parameters for each bead, the welding parameters of the entire weld should be applied to the production after passing the welding test according to the pipe specifications and site conditions.
5 welding equipment
There is a British NOREAST automatic welding machine, Canada RMS automatic welding machine, PIPELINER automatic welding machine.
Pipeline natural gas price adjustment:
According to the volume of gas used, the first gear covering the third gear covers 80%
The Municipal Development and Reform Commission also stated that on the basis of adjusting the price of residential gas, the city plans to implement the natural gas ladder gas price simultaneously (since the city's artificial gas will be gradually withdrawn before the end of 2015, the current pricing method of artificial gas will not be adjusted, but will be artificial gas. After the user has converted to a natural gas user, he will follow the relevant regulations for residents' natural gas ladder prices).
In terms of sub-range gas volume, the “Guiding Opinions†of the National Development and Reform Commission made it clear that residents’ gas use was divided into three grades. Among them, the gas consumption of the first grade was determined based on the gas consumption of 80% of households in the covered area; the second grade was used. The amount of gas is determined according to the amount of gas used by 95% of households in the covered area. The amount of gas used in the third category is the part of the gas that exceeds the second level. According to the statistics and analysis of the City Information Center, after eliminating the zero-degree meter and other factors, the average annual gas consumption per household will be sorted and analyzed, and statistics will show that the first-stage gas consumption is 290 (inclusive) cubic meters and below, and the second-stage gas consumption It is 290-500 cubic meters, and the third gear is 500 cubic meters or more. The price of ladder gas is settled according to the annual split gas volume, and the gas consumption is not accumulated or carried forward during the annual cycle.
On the other hand, in terms of split gas prices, according to the current residents' natural gas price adjustment level and sub-range gas volume, the hearing has initially proposed two plans according to the different parity relationship of the three-step ladder, which is intended to be widely solicited for society in conjunction with hearings and other forms. The opinions of all parties shall be submitted to the municipal government for approval after revision and improvement. Among them, in accordance with the “Guiding Opinions†provided by the State, the first, second and third-tier price levels have a comparative relationship of 1:1.2:1.5; scheme 2 takes into consideration that the residents’ gas use is mainly used for basic activities such as cooking and bathing. A small amount is used for heating, and the consumption elasticity is small. In order to adapt to the city's climate change and the improvement of the residents' quality of life, and reduce the impact on residents, the price-to-price ratio of each stall is adjusted to 1:1.1:1.4.
Editor's summary: Natural gas pipeline welding technology and pipeline gas price adjustment are introduced here. I hope to help you. For more information, please pay attention to this site.
Leaking pipe leaking natural gas
BATHTUB&Whirlpool Bathtub
Bathtub,free standing tub,free standing bath,free standing bath tubs,stand alone tubs
Guangzhou Aijingsi Sanitary Products Co.,Ltd , https://www.comoxvalleyhottubs.com