21氧气管道及附件安装施工说明.doc

氧气管道及附件安装施工说明1 管道、阀门、管件的质量检验1.1 管道、阀门、管件必须具有制造厂的合格证书，其指标应符合现行中国国家标准。钢管外径及壁厚的尺寸偏差应符合中国国家制造标准。1.2 管道、阀门、管件等在使用前需对其作规格、材质、型号及外观的检查。要求其表面不得有裂纹、缩孔、气泡、夹渣，折迭、重皮等缺陷；锈蚀或凹陷不得超过壁厚的负偏差；螺纹密封面良好，精度及光洁度应当达到制造标准。1.3 安全阀在安装前应按设计规定个进行测试。当设计无规定时，其开启压力为工作压力的1.05-1.15倍，回座压力应大于工作压力的0.9倍，调试时压力应稳定，每个安全阀启闭实验不应少于三次，调试后须进行铅封，调试介质采用无油空气或氨气。1.4 法兰密封面应平整光洁，不得有毛刺及径向沟槽，法兰螺栓孔应完整、无损伤。凹凸法兰应能自然嵌合，奥免得高度不得低于凹槽深度。2 管道焊接安装2.1 氧气管道90o头，三通、异径管全部采用钢质压制成型产品，其质量应符合工业金属管道工程施工及验收规范（GB50235）的规定。2.2 焊工必须经过国家有关部门考试合格后方准参加焊接作业。2.3 管道对接应符合以下要求：A 壁厚相同的管道，管件组对应做的内壁齐平。当工作压力不大于1.6Mpa时，内壁错边量不应超过壁厚的20，且不大于2；当工作压力大于1.6Mpa时，内壁错边量不应超过壁厚的10, 且不大于1;对于钢管、不锈钢管、铝合金管其内壁错边量不应超过壁厚的10，且不大于1。B 壁厚不同的管道、管件组对应遵照工业金属管道工程施工及验收规范（GB50235）的规定进行。2.4 焊接方法及材料选用见表一2.5 焊缝高度除特殊注明外，等于被焊接中薄件的厚度。2.6 管道焊接后必须对焊缝进行外观检查。焊缝不得有裂缝、气孔、夹渣等，咬肉深度不得大于0.5.2.7 焊缝外观检查合格后，须对焊缝进行无损探伤检查。当设计无规定时，应对焊缝按比例进行抽查。每条管线上最低探伤长度不得小于一个焊口。2.8 管道安装时焊缝须在二个支架间1/4处以内，管道环焊缝距支，吊架的距离不得小于100mm，支架处不准有管道的环焊缝。2.9 对厂区埋地敷设氧气管道还应采取一定的防腐措施，以确保安全使用，其管顶距地面不小于0.7米。3 试压与吹扫3.1 管道安装完毕后，按强度试验、严密性试验、泄露量试验的顺序进行试压，以检查管道系统及各连接部位的工程质量，实验前，应将不能参与试验的系统、设备、仪表及管件等加以隔离，安全阀等防爆装置应拆卸。3.2 强度试验3.2.1 强度试验一般采用无油干净水或无油干燥空气、氮气进行。3.2.2 采用水压试验法试验的管道应在实验前进行钝化处理。试验压力为工作压力的1.25倍。试验时，升压要缓慢，达到试验压力后稳压10分钟，以无渗漏、目测无变形为合格。试验合格后，应将水及时排尽并用无油气体将管道吹干。3.2.3 采用气压法做强度试验时，应有安全措施，同时得到相关安全管理部门批准。试验压力为工作压力的1.15倍，试验时压力应逐渐缓升，首先升压至试验压力的50%，经检查无泄漏及异常现象，继续按10%的试验压力级差逐级升压，直升至试验压力，每一级稳压3分钟，达到试验压力后稳压5分钟，以无泄漏、目测无变形为合格。3.3 严密性试验3.3.1 强度试验合格后进行严密性试验，试验压力等于工作压力。3.3.2 当强度试验用水进行时，严密性试验应单独进行。试验介质可用无油干净水或无油干燥空气、氮气。试验应缓慢升压，待压力升至试验压力时，全部焊缝以肥皂水检查（铝合金管应用中性肥皂水），如无渗漏，稳压30分钟压力不降即为合格。3.3.3 当强度试验用气体进行时，在强度试验合格后将压力降至工作压力，按上述方法和标准检查。3.4 泄漏量试验3.4.1 泄漏量试验以无油干燥空气或氮气进行，试验压力为工作压力，稳压24小时，每小时平均泄漏率以不大于0.25%为合格。3.5 管道在系统严格性试验合格后，应以无油干燥空气或氮气进行分段吹扫。吹扫前应将系统内的仪表隔离保护，将孔板，过滤器、节流阀及止回阀等阀芯拆除。吹扫气体的压力不得超过设计压力，流速不小于20m/s,在排气口处用白布或涂白漆的靶板检查，如5分钟内其上无铁锈、尘土、水份及其他脏物为合格。36 管道投产前，必须再用氧气进行置换，置换用的氧气量应不小于被置换管道总体积的三倍。4 防护涂漆4.1 架空管道在各项试验合格后，除不锈钢管、钢管、铝合金管外，均应进行管道外表涂漆。4.2 涂漆前须彻底清除管道表面的铁锈、焊渣、毛刺、油水等污物。施工时先涂两遍红丹防锈漆，再涂两遍天兰色调和漆。4.3 涂漆施工宜在5-40度的环境温度下进行，并应有防火、防冻、防雨措施。4.4 涂料应有质量保证，涂层均匀、颜色一致。5 氧气管道接地保护51 氧气管道安装完成后应有良好的接地保护，并按相关专业设计图及要求施工。5.2 当每对法兰或螺纹接头间电阻超过0.03欧时，应安装跨接导线。1 Quality inspecting of piping, valves and fittings1.1 Valves, pipes and fittings must have factory certification, the indicators should be consistent with existing national standards in china.The outer diameter and wall thickness of pipes shall be in compliance with the national standards of manufacturing in china.1.2 Before use pipes, valves and fittings materials, types and appearance should be inspected . The surface shall not have cracks, shrinkage, bubble, slag, folding, double skin defects; Corrosion or depression may not exceed the wall thickness of the negative deviation; Thread sealing surface is good, precision and the smoothness of the shall meet the manufacturing standards.1.3 Safety valve should be tested one by one bofore installation according to the design requirements. If no design requirements, the opening pressure is 1.05-1.15 times the working pressure , and the back seat pressure should be greater than 0.9 times the working pressure.When debugging the pressure should be stable, opening-closing experiment for each valve should be done more than three times. The lead seal protection should be carried out after debugging. The debugging medium is no oil air or nitrogen.1.4 The flange sealing surface should be smooth, no burr and radial grooves. Flange bolt holes shall be complete, without injury. Concave and convex flanges should be natural chimeric, and the height of convex surface shall not be less than the depth of concave.2 Pipe welding installation2.1 90elbow head for Oxygen pipeline, tee and different-diameter pipe should be the pressed steel molding products, its quality should be consistent with the regulations of“construction and acceptance of industrial metallic piping specification” ( GB50235 ).2.2 Welding workers must go through the examination of the relevant departments of the State before welding.2.3 Pipeline butt shall meet the following requirements:A The same thickness pipeline and pipe group,its inner wall should be flat to ensure alignment. When the work pressure is not more than 1.6Mpa, the thickness of the inner wall of the wrong side should not be more than 20% the wall thickness , and not more than 2 mm; When the pressure is greater than 1.6Mpa, the thickness of the inner wall of the wrong side should not be more than 10% the wall thickness , and not more than 1 mm; For steel pipe, stainless steel pipe, aluminum tube whose thickness of the inner wall of the wrong side should not be more than 10% the wall thickness , and not more than 1 mm.B If the wall thickness of the pipe is not the same as , in accordance with the construction and acceptance of industrial metallic piping specification ( GB50235 ) .2.4 Welding method and material selection see table one2.5 In addition to specified, the weld height is equal to the thickness of the thin piece welding.2.6 After welding the pipe appearance shall be inspected. Weld shall not have cracks, porosity, slag. The butt depth shall not exceed 0.5 mm.2.7 If the weld appearance is qualified, nondestructive inspection of weld can be carried out. When no design rules,do proportional checks. The minimum detecting length on each line shall not less than the length of a crater.2.8 When installing the pipeline ,welds shall be between two bracket of the 1 / 4 place . The distance between pipeline girth weld and support , hanger shall not be less than 100mm, and there are no girth welds of pipeline at the support.2.9 Some measures should be taken to prevent the oxygen buried pipeline in the factory from corrosion. The distance from the top of the pipe to the ground is not less than 0.7 meters to ensure the safe use .3 Pressure test and blowing3.1 After installation of pipeline, the pressure test must be carried out according to the test sequence as the strength test, tightness test, leakage test to check the engineering quality of pipeline system and the connecting parts. Before the experiment the system, equipment, instrument and fittings which are not available in this experiment shall be isolated , and explosion-proof device as safety vavle should be removed.3.2 Strength test3.2.1 Strength test is generally used no oil clean water or dry air, nitrogen as medium .3.2.2 The pipeline used the hydrostatic test method to test must be done passivation before the experiment . Test pressure is 1.25 times the working pressure.When testing ,the pressure must boost slowly to the test pressure and keep the test pressure for 10 minutes. If no leakage and no deformation inspection , it is qualified. After passing test, the water in the pipe should be timely drained out and blow the pipeline clean with no oil gas.3.2.3 Doing the test for strength in pneumatic method, security measures must be done and the test have been approved by safety management departments . The test pressure is 1.15 times the working pressure , test pressure should be incresed slowly. Firstly boost the pressure to 50% test pressure , if there is no leaks and abnormal phenomenon ,increase the pressure according to 10% pressure differential straight to the test pressure,at each level keep for 3 minutes. If there is no leakage,no deformation in visual at the test pressure for 5 min,it is qualified.3.3 Tightness test3.3.1 If the strength testing is qualified ,then do the tightness test, the test pressure is equal to the pressure of work.3.3.2 when the strength test uses water as medium , tightness test must be conducted separately. The test medium can be no clean water or oil-free dry air, nitrogen gas. Test pressure shall be increased slowly until the pressure to test pressure, all welds with soapy water to check (for aluminum alloy pipe with neutral soapy water ). If ther is no leakage, and the pressure can keep for 30 minutes ,it is qualified.3.3.3 If use gas to do the strength test ,after the tightness test has passed , drop the pressure to the working pressure, according to the above method and standard .3.4 Leakage test3.4.1 Leakage test used no oil dry air or nitrogen as meduim, the test pressure is equal to the working pressure, keep 24 hours, the average leakage rate per hour must be less than 0.25% .3.5 After the tightness test of pipes qualified,blowing should be carried out with no oil dry air or nitrogen .Before sweeping isolation protection shall be taken for the instrument, the orifice plate, filter, throttle valve and all valve spools shall be removed. The purge gas pressure shall not exceed the design pressure, flow rate shall not less than 20m / s, use white cloth or white paint target board at the vent to do examinations for 5 minutes .It is qualified if no rust, dust, water and other dirt on the cloath or board.3.6 Before the operation , using oxygen for the replacement is necessary, the amount of oxygen for replacement should not be less than three times the total vo