Pipe cutting project

Lu Kuwait's Shuaibai Oil Terminal Project Special Pipeline Cutting Project Zhu Xiaodi, Lu Sanlong, Hui Kangping, Yu Yin (China-Hong Kong Third Navigation Engineering Bureau, Shanghai 200032) The project is the most dangerous project. No construction experience can be used for reference. Under the conditions required for the construction of the conventional process, the engineering and technical personnel envisaged the construction plan of cold cutting, sealing and separation, and implemented it after refinement, and achieved satisfactory results.

1 Project Overview The Shuaibai Oil Terminal Restoration Project is a pipeline cutting project for the transformation and reconstruction of the oil transportation system under normal production conditions of the North Terminal. It is cut and disconnected on the old pipe completion distributor of the original oil transportation system. Upper flange or flanged tee, then install ESD valve or connecting tube.

The ESD valve is installed to automatically cut off the pipeline in the event of a failure of the oil delivery equipment or a fire in the terminal refinery to prevent the oil pressure in the pipeline from rising and the fire spreading along the oil pipe.

1.1 ESD valve arrangement Installed 13 ESD valves on the newly installed pipeline at the No. 13 bay of the South Terminal. Install 12 ESD valves on the old pipeline at the No. 3 bay of the North Terminal.

1.2 Connecting the pressure buffering device The pressure buffering device is a newly installed device in the T-head area. In order to ensure a constant pressure during the oil transportation of each pipeline, each of the old pipelines along the road needs to be cut in. The connecting connecting pipe is connected to The interface of the pressure buffer device is on the 3rd North Terminal. The original oil transportation system is rebuilt. The 1994 terminal project department installs the technical main a>ublishingH North i head oil transportation system, the efe part uses the pipe but the oil delivery arm needs to be replaced at the oil platform. Renovation of the pipeline on the district, a total of 8 entry points, the formation of a new oil delivery system 1.4 technical parameters of the oil sheet 1 technical parameters of the oil product number media name flash point. [: boiling point. [: Spontaneous ignition point. 〔: Lower limit of explosive limit, gasoline light diesel, heavy diesel oil, naphtha lamp, kerosene, 2 pipeline cutting construction. Pipeline cutting project is the most dangerous project in the installation of this project. It is the key project to determine the success or failure of this project. Under the premise, it is implemented without fail. 1 Objective conditions Construction conditions: The project adopts the production side construction method. The pipelines of the approach bridge and the dock are filled with various oil media. Most of these oils are high-volatility, low-flame-point oils. Aviation kerosene is the main output oil of the terminal, which is very easy to cause fire and explosion. Old pipeline cutting conventional process: 1 row despite internal residual oil; 2 natural or mechanical ventilation; 3 water flushing; 4 steam purge; 5 nitrogen filling The reason why the project can not be constructed according to the conventional process: The project can only do two measures of draining oil and water flushing. The reasons are: 1 natural or mechanical ventilation, the valve at both ends of the pipeline must be removed, and the ventilation is open and the valve at one end of the project At the dock, the other end is at the refinery. Since the North Terminal and the refinery are in production operation, this method cannot be used. Only the vent hole on the pipe can be opened to reduce the oil and gas mixture in the pipe. The vent hole is only 20mm, and the effect is very poor. 2 Kuwait is a hot country with no steam. If the pipeline uses the steaming valve, the shortest distance is 2 000m, the time is long and the cost is high. 2 The construction scheme envisages the pre-cold cutting measures: the two processes of exhausting oil and water are used to achieve cold cutting. Cold cutting: 1 cut-in broken pipe The cold cutting process is used, and the annular pipe cutter is used to open the sealing scheme for the tool 2 by the deflation valve at both ends of the cutting pipeline: the residual oil and the oil and gas mixture are blocked in the pipe, so that the spark heat source generated by the hot work is isolated from the pipe.

Safety measures in hot work area: 1 Clean the end of the hot working pipe to ensure that there is no residual oil, and fill the area with the surrounding area: fill the surrounding area and the lower part of the working area with fireproof materials to develop safety technology and measures. : Develop strict and precise operational safety technology processes and measures to enable each process to be carried out under controlled conditions.

Test: After the plugging scheme is formulated, it is necessary to carry out tests, obtain various data and modify, and prepare the formal scheme 3. The cold cutting scheme is to cut the length of the pipeline to L temperature 25C as the standard, multiply by the thermal expansion coefficient and temperature difference. The actual cut length is shown. Since the length of the ESD valve varies with the pipe diameter, it is necessary to calculate the actual cutting length of each cutting point. The cutting point at the pressure buffering device must be calculated. The cutting point must be determined based on the center of the connection port of the pressure buffering device. Center, the tool uses the string and the line hammer, the cutting length must be calculated one by one. The cut nozzle must be cut vertically. The center line of the pipe must be cut into two groups. Tighten the cutter screws, four people move, balance the force to ensure uniform cutting around the pipe. , the whole cut.

Before the cut pipe is not completely cut, it is necessary to use the lifting equipment to hang the cutting section pipe 3.2 plugging scheme steam purge, must set up the boiler, lay special pipeline, engineering quantity and (1) use the cavity blind plate one by one in the conventional The cost of plugging in pipeline construction is too large to be implemented (3 such as small nitrogen pipes that need to close the pipeline bv for nitrogen filling of pipelines. The two aluminum alloy splints are clamped by t intermediate bolts, so that the rubber flanges reach out to reach the closed lumen, see second The layered tube is blindly blocked, the middle interval pipe is 700mm in length, and the inside is filled with nitrogen. As shown, the water is continuously watered during welding. As shown in the figure 3, the lower part of the cut-in area and the surrounding part of the pipeline are covered with scaffolding, paving the foot. The hand board is covered with a fireproof cloth on the scaffolding board under the hot work area.

A movable bracket and a thin steel plate form a wall on both sides.

Both ends of the cut-in area are blocked with a fireproof cloth.

Open oil tanks, valves, distributors and other equipment are covered with fireproof cloth.

3.4 Before the construction process is completed, the hot work is carried out; 3 At each stage of the cut-in, the process and various technical safety assurance measures are tabulated and the inspection items are listed. Each inspection item is signed by the construction staff and submitted to the supervision signature.

Before each stage, it is necessary to check the contents of both parties on a case-by-case basis and sign the inspection before the cold cutting. The cold cutting tool has been placed in place; the cleaning agent, etc.; the explosion detector and the operator are turned on, the instrument has no alarm; the operating platform and the passage are qualified; the cutting operator is on the scene; the oil drain and water flushing in the pipeline are checked: a pipeline valve closed; b open the oil cut valve at the nearest cut point, visually check the discharge is water; check the exhaust valve in the pipeline has been opened; welding faucet; c open normal; check oxygen, acetylene device: a normal instrument; b temper The device has it; Check the nitrogen device: a table is normal; b pressure is normal; The nighttime lighting system is normal; clean again with detergent, dry the pipe wall; open the first layer of pipe clamp screw cap to release the gas-oil mixture in the pipeline; the detector is inserted into the pipe for inspection, no alarm; The clamping end cap of the second pipe plug is inserted into the nitrogen pipe, and the nitrogen is filled in the middle of the second layer pipe; the water is cooled to cool the pipe wall; after the above inspection items are signed, the pipe joint or the tee can be polished and welded as much as possible. Avoid daytime work to remove all the tools and other miscellaneous items, wash and clean; metal boring plate to seal the flange mouth, at least six bolts are fastened; then the welding is filmed, the film report proves that the welding is qualified before the first One layer of plugging, ESD valve or connecting pipe installation 4 test implementation and program improvement 400mm steel pipe each 3m long, as shown in the blockage. Then, two kinds of mediums of gasoline and diesel are poured into the steel pipe, and then sealed later.

After the first layer was plugged, the oil was observed by the naked eye, and the leak of the oil and gas mixture was checked with a gas detector.

The steel pipe that has been filled with oil is heated by flame, the temperature of the outer pipe wall reaches 45C, and the oil pipe is repeatedly rotated, so that the concentration of the oil and gas mixture in the pipe is increased. Two welders simultaneously perform grinding and continuous vertical welding, and require: welding current Increase to the normal 1.2 times; speed up the welding speed to 1.5 times normal; continuous vertical welding without stopping; welding at noon. The heat generated by the welding during the test is greater than the heat during the normal operation, and the heat transfer causes the temperature rise of the oil and the oil and gas mixture in the pipe wall and the pipe. The heat transfer temperature is measured: a is the first test at 300 mm from the second layer. The temperature point; b is wrapped with wet tops at a distance of 400 mm from the second layer, and is continuously poured with water during welding to reduce the heat transfer from the electric heat to the rear side; c is set at the first layer of sealing For the second temperature measurement point; d record temperature: 25C, wall temperature: 35C; e total of 6 welding tests, each test time is 45 ~ 60min, test results: the maximum temperature rise of the first temperature measurement point is 10.3C The second temperature measurement point has no temperature rise.

From the above test, it can be concluded that the two-layer plugging has prevented the leakage of gas-oil mixture and residual oil, and can safely avoid the danger caused by hot working Mars.

The heat of the welding will not be transmitted to the back of the first layer after the above measures are taken. The heat transfer of the welding will not cause the temperature rise of the residual oil and the oil and gas mixture in the pipeline.

5 Construction Practice and Evaluation In the case of scientific construction plan and construction technology, in order to ensure the perfection of cutting construction, the project department also adopts the following organization and disciplinary measures. 5.1 Construction organization The construction personnel are relatively fixed, and the person in charge is responsible for the entire cutting work. After the post, 2 heavy workers and 2 assistant workers. The personnel who cut into the group are fixed accordingly and cannot be transferred to ensure the proficiency of the operation. All safety training is carried out before the cut-in. The entire scheme and process are detailed and simulated, and qualified for the job.

5.2 Special rules and regulations for the cut-in project After the owner's safety officer and supervisor arrive at the scene, we can start work and supervise the owner during the whole cut-in period. The safety officer does not leave the scene. If it leaves in special circumstances, we must stop the construction process. Process check form.

For each construction process, the workers will complete the self-inspection after construction, and then the construction workers will conduct special inspections. After passing the inspection, they will be signed and approved and submitted to the supervisor. After the supervision and inspection, the signatures will be signed and confirmed by both parties, and the next process can be constructed. A full-time security officer, equipped with a blast detector, cannot leave the site.

Our construction workers cannot leave the scene after the start of the cut.

The entire construction process is strictly and meticulously carried out in accordance with the construction plan, process and organization discipline measures. 5.3 Construction evaluation The construction of the thermal work barrier inside and outside the pipe is assumed to be reliable and reasonable. In particular, the two-layer sealing of the blind tube of the lumen is filled with nitrogen, which effectively overcomes the risk of explosion of the gas-oil mixture in the tube due to thermal work.

Yangzhou Chengde (YC) is one of the best pipe manufacturers in the world, and the production diameter from 8" to 48" in OD and wall thickness from 9.53 mm up to 140mm. We can produce all the carbon steel pipes according to the ASME, ASTM and EN standards, Such as the 106B/C steel pipe,GR.6 steel pipe,S235JRH steel pipe,S275J0H steel pipe,S275J2H steel pipe,S355J0H steel pipe,S355J2H steel pipe,E355 steel pipe,P235GH steel pipe and P265GH steel pipe.