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Oxygen Valve Leakage Causes And Troubleshooting

Ningbo Fenfa Valve Co.,Ltd | Updated: Aug 01, 2017

  Oxygen valve leakage causes and troubleshooting:

  Failure phenomenon

  Oxygen pipeline connected to the normal operation of about 1 year, there has been a leak phenomenon.

  (1) DN250mm oxygen special closing valve closed lax. Although the valve is closed, the gas leakage at the downstream side flange is large.

  (2) DN100mm oxygen release valve root cracking. The main reason is that the pipeline is located in the piston oxygen compressor outlet section, Oxygen valve the vibration is large, long-term vibration caused by the bottom of the valve connection pipe and the main pipe junction cracking, a large number of pressure oxygen dispersion, a greater security risk.

  Due to the production line with a large amount of oxygen, and in the 3 sets of 21000m3 / h air separation equipment side is not installed valve to supply its oxygen pipe network gas source cut off, there is no time to rule out this security risk. Oxygen valve A temporary steel chuck was then made temporary for the oxygen piping dispersion and a temporary alert area was set in the surrounding area of 10 m.

  2. Handling measures and processes

  Oxygen repair process has been with the steel, iron and stainless steel and other main line of the maintenance process in parallel. The above security risks for processing, the specific measures are:

  (1) the original DN250mm oxygen special cut-off valve as a section of the pipeline, the valve year in the open state; and tighten the flange on both sides to ensure that the flange connection does not leak oxygen. Oxygen valve In the pipeline to re-install a pressure of 614MPa DN250mm oxygen dedicated shut-off valve, this valve as a normal operation with a shut-off valve (intermediate contact valve).

  (2) repair welding pipe drain, and this section of the pipeline and the valve to be fixed; replacement 6000m3 / h air separation equipment oxygen pipeline three-way valve.

  Before the construction, the preparation of the relevant materials and spare parts, and the argon arc welding machine, chain and other equipment shipped to the scene, in advance of the new oxygen contact valve degreasing, pressure, Φ273mm × 8mm carbon steel pipe, 90 ° stainless steel Valve, 45 ° elbow and 45 ° Y-shaped three-way valve for rust, degreasing, and polished groove. According to the construction site of the pipeline, in the pipeline cutting and the new oxygen valve, the production of mobile maintenance platform or build scaffolding. Advance production of new oxygen contact valve blind plate. In the new oxygen contact valve inlet side flange welding length of about 115m stainless steel pipe, Oxygen valve the other end of the stainless steel pipe welding a 4MPa, DN250mm flange. Early removal of the original 4MPa, DN250mm oxygen contact valve on the north side of the east side of the bracket beam, and will need to remove the lower part of the pipe plate removal, while the necessary support for the platform to ensure that the removal of the pipeline can be vertical drop. With 12mm steel plate made of raw oxygen contact valve blind plate, blind plate diameter slightly larger than the flange diameter, blind plate according to the flange screw hole size drilling, and tapping. At the same time, in order to prevent the oxygen pipe gas can not be completely ruled out the accident, in front of the preparation of two blowers, to ensure timely forced to change the scene. Early release 6000m3 / h air separation equipment 4 oxygen press oxygen valve inside the flange, and the oxygen valve and flange between the corresponding gap, for the network to provide blown points.

  Construction, in accordance with the pressure relief 2 hours, replacement 1 hour, the pipeline removed 6 hours, the new valve and pipe installation 6 hours, purge 1 hour, press the leak 1 hour and restore air (pumping blind and pumping) 1 hour Of the procedures for the construction of a total of 18 hours. After the pressure relief, after the replacement, the construction workers in the distance from the network pipe three-way valve at 6m oxygen pipe outlet pipe and 6000m3 / h air separation plant oxygen pipeline 6m, the pipeline slanting cutting. And set the baffle at the above two incisions to prevent the oxygen from dropping into the pipeline when the contact valve flange is disassembled. Remove the original oxygen contact valve 6000m3 / h air separation equipment side flange screws, from the flange, the blind plate fastened to the valve flange, to ensure that the blind plate does not fall off. Will remove the pipe after the vertical fall, in order to prevent the contact valve flange disassembled after the oxygen into the pipeline, to retain the pipeline two slant cut set at the baffle, Oxygen valve  remove the original oxygen contact valve blind plate. The stainless steel short section and the flange and the new oxygen contact valve (the valve is fully open) are connected to the original oxygen contact valve flange. After confirming the flange tightening, slowly close the new oxygen contact valve, and in the new oxygen contact valve 6000m3 / h air separation equipment side of the blind plate.

  After the completion of the construction, polished the original pipe welding, while welding oxygen pipe outlet pipe Φ273mm × 8mm, 45 ° elbow and oxygen pipe on the Φ273mm × 8mm, 45 ° Y-shaped three-way valve. After welding, maintenance personnel in the crane with the new oxygen contact valve outlet flange (flange in advance with the export pipeline welding) and the valve connected. After the connection is completed, the other end of the outlet pipe is welded with the 45 ° Y-shaped three-way valve and the oxygen pipe outlet pipe is welded to the 45 ° Y-shaped three-way valve.

  3. Effect of implementation

  After the completion of the operation, to restore the gas operation, remove the new oxygen contact valve blind plate, oxygen ball tank blind plate, restore the oxygen pressure machine oxygen valve, open the new oxygen valve, Oxygen valve with oxygen on the pipeline residual nitrogen replacement. 10 minutes later, in the pipeline at the dissipation of gas composition testing, qualified to return to normal oxygen. The oxygen pipeline relief valve root cracking treatment and installation of contact valve technology transformation success.

Ningbo Fenfa Valve Co.,Ltd