Technical Operating Regulations for Pressure Opening
1.Construction personnel, equipment and fire safety equipment shall enter the site ahead of time, and fire seeds shall be prohibited, smoking shall be prohibited and wireless communication equipment such as mobile phones shall be shut down.
2. Remove idle and miscellaneous personnel, vehicles and inflammable and explosive articles in the construction area, set up guardrails and warning signs, and isolate the construction area as necessary.
3. Suitable opening equipment and location should be selected according to pipeline material, transportation medium, laying process and operation parameters, and construction organization plan should be formulated.
4. Before operation, the construction pipes, fittings and sealing materials shall be checked and checked, and the construction machinery and equipment shall be debugged.
5. simulation test should be carried out for the first time in gas pipelines with different pipe materials, pipe diameters and operating pressures.
6. Remove the anticorrosive coating at the opening position of natural gas pipeline and avoid weld beads and corrosive parts to ensure welding quality and safety.
7. Installation and welding of steel pipe fittings shall meet the following requirements:
1）The allowable welding pressure of steel pipeline should not exceed 1.0 MPa, and the residual wall thickness of pipeline should be more than 5 mm. The gas flow rate in the pipe should be strictly controlled during the welding of plugging pipe fittings.
2）The special tee pipe fittings used for pipe opening operation should adopt mechanism pipe fittings.
3）When working on large diameter and high pressure pipelines, the reinforcement of pipe opening should be done, and equal area reinforcement method can be used.
4）pening flange and plugging pipe fittings must be vertical to the cut pipe and should be welded according to qualified welding process. Its welding technology, welding quality and weld detection should meet the requirements of the current national standards.
5）When assembling the opening and blocking equipment, the joints should be wiped clean, and the bolts should be tightened evenly. When large-scale equipment is hoisted, it is strictly forbidden to stand under the hoisting parts.
6）According to the pipeline medium, pressure, select the matched valve;
7）Manual or electric drilling rigs are used according to the site conditions and pipe diameters.
8）According to the requirements of the drawings, the size of the openings is determined, and the appropriate cutting speed is selected according to the requirements of the openers.
9）After the hole is finished, the hole cutter and the cut saddle block are simultaneously put into the connecting box, the valve is closed and the hole drilling rig is dismantled.
10）After closing the valve, flange blind plate should be used to close and isolate.
8、The operation of pressurized perforation must be carried out in accordance with the operating rules and the following provisions shall be observed:
1）Before opening, integral pressure test should be carried out on the pipe fittings welded to the pipeline and the valves and openers assembled on the pipe fittings (pre-fabricated valves, short joints and flanges that need to be connected before welding, pre-fabricated and pressed after completion of pre-fabrication, then the blind plate is opened for opening). The test pressure shall not exceed the pressure in the pipe during operation. Power;
2）Before disassembling the upper equipment between splints, the gas pressure in the chamber must be released.
3）Pressure on both sides of valve should be balanced before opening between splints.
4）After completing the above operation and confirming that there is no leakage in the pipe fittings, the insulation and anticorrosion of the pipe fittings and pipelines shall be done, and the grade of the anticorrosion layer shall not be lower than that of the original pipeline.
9、Preventive measures in welding operation:
1）Welders must have the ability to work under pressure and be on duty with certificates.
2）Before welding, grounding device must be done well to prevent electric shock.
3）In order to prevent the signs of excessive current, such as excessive melting, expanding, perforation or too small current without penetration, the welding current should be pre-modulated so as to avoid explosion or unqualified weld joint.
4）In order to prevent abnormal situation, normal pressure must be stabilized in the pipeline during the whole process of fire welding construction.
5）In order to prevent the occurrence of accidents, the fire fighting equipment on site must be in place and fully prepared for fire fighting.
10、Preventive measures in opening operation:
1）In order to prevent leakage of equipment when opening, the sealing parts of equipment must be checked before opening.
2）In order to prevent scratch and leakage of pipe fittings by the opener when opening, the main pipe fittings must be welded.
3）In order to prevent the opening of the through pipe, the size of the opening should be aligned during the construction.
4）In order to prevent the improper placement of gaskets and debris on gaskets and flanges when gaskets are tightly connected, leakage occurs in the sealing area after opening. When gaskets are installed, they should be put in place to remove debris on gaskets and flanges.
11、In the opening operation of polyethylene plastic pipes, the following requirements shall be met in addition to the relevant provisions mentioned above:
1）When the hole opener assembled with the tool is installed on the rack, it can be screwed in when the interface between the hole opener and the rack is concentric.
2）The air tightness test should be carried out after the connection between the perforator and the frame to check the sealing of the perforator and its connecting rod components.
3）Oil lubricants shall not be used in the installation of racks, openers, etc. Vaseline may be applied to the parts requiring lubrication.
4）When installing the protective sleeve of pipe fittings, the operator's head shall not be directly above the pipe fittings.
5）The pipeline to be operated should be grounded effectively during welded pipe operation.