Shandong Zhongjie liquefied gas storage tank manufacturer provides integrated installation quotation for liquefied gas storage tanks

Description :

　　Purging and cleaning of pipelines

　　1 General Provisions

　　one.one After the pipeline passes the pressure test, the construction unit shall be responsible for organizing the blowing or cleaning (referred to as blowing) work, and shall prepare a blowing plan before blowing.

　　one.two The blowing method should be determined based on the requirements for the use of the pipeline, the working medium, and the degree of dirt on the inner surface of the pipeline. Liquid pipelines with a nominal diameter less than 600mm should be flushed with water; Gas pipelines with a nominal diameter less than 600mm should be purged with air; Steam pipelines should be purged with steam; Non thermal pipelines shall not be blown with steam.

　　one.three Equipment and pipelines that are not allowed to be blown should be isolated from the blowing system.

　　one.four Before pipeline flushing, orifice plates, flange connected regulating valves, important valves, throttle valves, safety valves, instruments, etc. should not be installed. For welded valves and instruments mentioned above, protective measures such as bypassing or removing valve heads and seats with protective sleeves should be taken.

　　one.five The order of blowing should be in the order of the main pipe, branch pipe, and drainage pipe. The dirt blown out must not enter the qualified pipeline.

　　one.six Before blowing, the firmness of pipeline supports and hangers should be checked, and reinforcement should be carried out if necessary.

　　one.seven The dirty liquid discharged during cleaning must not pollute the environment, and it is strictly prohibited to discharge it anywhere.

　　one.eight A restricted area should be set up during blowing.

　　one.nine During steam blowing, flammable materials must not be placed on or near the pipeline.

　　one.ten After the pipeline is blown and reset, no other operations that may affect the cleanliness inside the pipeline shall be carried out.

　　one.eleven When resetting the pipeline, the construction unit should jointly inspect it with the construction unit, and fill in the "Pipeline System Blowing and Cleaning Record" in the format specified in Appendix A, Articles A.0.9 and A.0.4 of the GB50235 standard.

　　two water charge wash

　　two.one Clean water should be used for flushing pipelines. When flushing austenitic stainless steel pipelines, the chloride ion content in the water should not exceed 25 × 10-6 (25PPm).

　　two.two When flushing, it is advisable to use a flow rate, which should not be lower than 1.5m/s.

　　two.three The discharged water should be directed into reliable drainage wells or ditches, and the cross-sectional area of the discharge pipe should not be less than 60% of the cross-sectional area of the flushed pipe. During drainage, negative pressure must not be formed.

　　two.four The drainage branches of the pipeline should be completely flushed.

　　two.five Water flushing should be carried out continuously, and it is qualified if the color and transparency of the water at the outlet are visually consistent with the inlet water.

　　two.six When the pipeline is temporarily not in operation after passing the water flushing, the water should be drained completely and dried in a timely manner.

　　three Air blowing

　　three.1 Air blowing should use the large compressor of the production equipment, or use the large container in the equipment to store air and perform intermittent blowing. The blowing pressure should not exceed the design pressure of the container and pipeline, and the flow rate should not be less than 20m/S.

　　three.2 During the air blowing process, when the exhaust is visually free of smoke and dust, a wooden target board with white cloth or white paint should be installed at the exhaust port for inspection. If there is no rust, dust, moisture, or other debris on the target board within 5 minutes, it should be considered qualified.

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