Relevant Procedures of Pipeline Pressure Sealing Technology

(1) Non-stop pressurized sealing of excavation and closure pits

When digging and blocking operation pit, the construction leader should unify command the excavator, other personnel should be far away from the site, if there are injuries, immediately start the emergency plan; in order to avoid landslides in blocking operation pit, there must be a certain slope around the pit. If landslides occur, they should be cleaned up immediately.

(2) Sealing tees by welding under pressure

Before welding, according to the pipe material, operation parameters and welding material, the welding procedure instruction is compiled. After welding, the welding procedure qualification is carried out according to the welding procedure instruction, and the welding procedure specification is compiled according to the qualified welding procedure qualification. Welding should be carried out according to the welding procedure. Welders'protective equipment must be worn during welding to avoid the occurrence of eye damage caused by arc light. In case of injury, patients should be sent to hospital for treatment immediately. If the phenomenon of welding penetration occurs, the welding rod should be immediately blocked and welded to death. If the phenomenon of fire occurs, the emergency plan should be immediately activated.

(3) Closed opening

Pressure test should be carried out strictly in accordance with safety operation rules before opening. If oil leakage occurs during opening, measures should be taken immediately to find out the oil leakage point and eliminate it. If fire occurs, emergency plan should be started immediately. If the cutter is damaged, the cutter head should be lifted decisively, the splint valve should be closed and the spare cutter should be replaced.

(4) Closure

When plugging, we should follow the principle of "first high pressure and then low pressure, first inside and then outside", that is, first high pressure end, then low pressure end. When the plug is lowered, the deflation valve on the splint valve is not closed tightly or not closed, causing oil leakage or fire. At this time, the emergency plan is started immediately.

(5) Oil pumping

Oil discharge should be carried out after successful plugging. The oil discharge point should be at the bottom of the pipeline and the intake point should be at the top of the pipeline as far as possible. If oil spill or fire occurs, the emergency plan should be started immediately.

Before starting pumping, it is necessary to ensure that the insulation layer of the power line is not damaged and the grounding of the pumping pump is good. If electric shock occurs, the emergency plan should be started immediately.

(6) Tube cutting

Before bundling, first check the wheel spacing, after bundling check the positive and negative motor, to ensure that the chain is in a straight line, and to tighten, in order to prevent the vibration of the pipe cutter when walking.

When cutting the pipe, before turning on the power supply, it is necessary to ensure that the switch is not damaged and the power line is well connected. If electric shock occurs, the emergency plan should be started immediately.

(7) Building butter walls

Butter wall is built after pipe cutting and old pipeline or equipment lifting. Firstly, the dirty oil inside and outside the pipe mouth is cleaned up, and explosion-proof tools must be used when cleaning. If explosion occurs, the emergency plan should be started immediately.

(8) Pipeline contact

It is strictly forbidden to knock and shake the pipeline when the pipeline is aligned and welded; the construction should be fast and the shorter the time is, the better; if the ambient temperature is too hot, cooling measures should be taken for the pipeline at the butter wall.

Because of knocking vibration pipeline, construction time is too long, the weather is too hot and other reasons, may lead to cracks on the butter wall, or even the collapse of the butter wall, oil and gas spillover in the pipe, when there is electric welding fire, easy to cause explosion accident, at this time, emergency plan should be started immediately.

(9) Unplugging

Removal of plugging must be carried out after pipeline construction. In principle, the low-pressure end should be removed first, and now the high-pressure end should be removed. Before the equipment is dismantled, check whether the splint valve bypass is closed, and then nitrogen gas should be introduced from the oil outlet. After the oil drainage is completed, the equipment should be dismantled. If there is no nitrogen, there will be oil outflow or serious fire phenomenon, at this time, emergency plan should be started immediately.