As we all know, with the development of petroleum, natural gas and petrochemical industry, the west to east gas transmission project is a symbol, and the peak period of China’s long distance pipeline construction has arrived. At present, there is a mature manual down welding technology, and semi-automatic gas shielded welding technology is being popularized. The combination of automatic gas shielded arc welding technology and downward welding technology is the development trend of high pressure pipeline welding technology
Below we will introduce: natural gas pipeline welding technology and pipeline gas price adjustment.
Welding technology of natural gas pipeline:
First, STT technology, CO2 gas protection, semi-automatic downward welding technology
STT type CO2 semi-automatic welding is based on STT welding technology for root welding of pipe, and the welding gas used in root welding is CO2. Manual welding of the automatic wire feed using a flux cored wire (such as Lincoln’s NR207). STT is “ Surface Tension Transfer” English abbreviation, that is surface tension transition meaning, is a kind of welding deposited metal transition mechanism.
1 process characteristics
STT welding is a cheap and efficient welding method in pressure pipe welding. Traditional CO2 gas shielded welding can not fundamentally solve the problems of large spatter spatter and imperfect weld formation. The STT type CO2 semi-automatic welding machine adopting waveform control technology ensures the welding process to be stable, the weld formation is beautiful, the change of the dry elongation is small, the spatter is reduced remarkably, and the welding labor intensity is reduced.
2 process principle
Because the droplet transfer in STT technology depends on the surface tension of liquid metal, there is a special method of welding with dynamic control. Therefore, the weld pool produced on the bead is very small and very concentrated, and its excellent performance widens the application field of CO2 semi-automatic welding in the construction of long distance pipeline.
3 engineering examples
Chinese Petroleum Pipeline Bureau in Sultan Muglad petroleum development project for the first time the use of STT type CO2 semi automatic welding technology of pipeline to pipeline backing welding, Shaanxi Beijing pipeline of Zhongyuan Petroleum Exploration Bureau Construction Group Company is the construction of Beijing – stone pipeline project using STT type semi automatic welding technology to.
4 welding equipment
At present, according to the author’s understanding, STT welding equipment is currently only one Lincoln Company.
Two 、 automatic welding under the direction of gas protection
Full automatic gas shielded welding is a kind of welding process using automatic welding machine and protective gas for pipeline welding. Argon or CO2 is used as protective gas.
1 process characteristics
Because the protection of the welding zone is simple in the process of the MIG welding, the welding area is easy to observe, the production efficiency is high, the welding process is relatively simple, the control is convenient, and the whole position welding is easy to realize. But the pipeline groove counterparts, high quality requirements, which requires the whole week to pipe uniform; strict requirements on the slope type, when the thick wall pipe, determine the process when using composite type or U type groove, can not only consider reducing the workload, it is more important to consider the groove on the welding quality that small angle V groove while simplify the construction process, but from the quality perspective, composite slope L or U groove is better; influenced by climate. In addition, it is also a common problem in gas protection welding; and the gas supply problem in the East region such as Shanghai surrounding is easy to solve.
2 process principle
The arc between the pipeline automatic welding technology using molten metal to be welded with wire as a heat source to melt welding wire and steel pipe, welding time welding to the harmful effects on regional transport of protective gas to isolate air, through continuous wire welding. The process can realize the simultaneous operation of all positions and multiple heads. The backing welding can be welded from the inner part of the tube to the outside, and the welding process parameters can be adjusted on the console or the control panel.
3 engineering examples
Zhengzhou Yima gas pipeline project (East Section) steel pipe material is 16Mn, diameter 426 mm, welding wire is H08Mn2SiA, welding wire diameter 1 mm. In &ldquo, the west to east gas pipeline (&rdquo) project, automatic gas shielded welding has also been widely used.
4 welding parameters
It should be noted that, because each welding parameter is different, the welding parameters of the whole weld shall be applied to the production according to the specification of the pipe and the site conditions.
5 welding equipment
NOREAST automatic welding machine, RMS automatic welding machine, PIPELINER automatic welding machine.
Pipeline gas price adjustment:
According to the first gear cover 80% third gear gas
Municipal Development and Reform Commission said at the same time, based on the adjustment of residents gas prices, the simultaneous implementation of the proposed residential natural gas price ladder (due to the artificial coal gas before the end of 2015 will gradually complete exit, artificial gas current valuation methods are not adjusted to artificial gas users for natural gas users is in accordance with the relevant provisions residential natural gas price ladder implementation).
In the file volume, the national development and Reform Commission “guidance” clearly, the gas is divided into three levels, including residents, the first tranche of gas consumption, according to 80% of the coverage area of the user households consumption; second tranche of gas consumption, according to 95% of the coverage area of the residents of the home user consumption; third use the second tranche of gas consumption is beyond the gas part. According to the statistics and analysis of the information center, after excluding zero table and other factors, the average annual consumption statistics analysis summary ranking, the first tranche of gas consumption of 290 cubic meters (inclusive) and below the second tranche of gas consumption is 290-500 (inclusive) cubic meters, 500 cubic meters above the third. The gas price of the ladder is settled according to the annual gas output, and the gas consumption is not accumulated or carried over between the annual cycles.
In the sub file gas prices, according to the resident natural gas price adjustment level and grade gas, the hearing on the proposed two schemes according to the different third gear ladder price relations, intends to combine the hearings and other forms of social solicit opinions from all sides and revise and improve the report after the municipal government approved. Among them, a scheme of “guidance” in accordance with national regulations, comparison between the first, second, third of the price level is 1:1.2:1.5; scheme two considering the city residents with gas is mainly used for cooking, bathing and other basic living, a small amount of consumption for heating, less flexibility, in order to adapt to the climate change and living quality improvement trend, reduce the impact for residential users, the price relationship between gas prices stall adjusted to 1:1.1:1.4.
Editor’s summary: gas pipeline welding technology and pipeline gas price adjustment introduced here, hope to help you, more information, please pay attention to Qijia network.
The pipeline of natural gas pipeline leakage Water Leakage