【正文】 No more than 177。 miter elbow (c)45176。 Other places: less than 3% outer diameter for high pressure pipe。 Tapping position should not be at welding seam when drilling a hole on main pipe. Quality of welding seam of reel pipe should be guaranteed, and back run welding in pipe should be carried out in case of inside nominal diameter more than or equal to 1000mm. No more than 2 longitudinal welding seams should be on reel pipe with diameter less than 2020mm, and the distance between seams should be more than 300mm. Dimension of reeled steel pipe should be in accordance with following requirements: Check should be made by replace outer diameter by perimeter which deviation should not exceed 177。 after bending。C when bending alloy steel pipe, and forced air cooling should be used. Normalization and temper treatment is required after bend is finished. When bending new type of steel pipe, test must be done for the Max. deformation of back arc of steel pipe, and bending process can only be established to bend the pipe after it had been confirmed that no defects such as intercrystalline fracture exists. Check by sampling (sample can be obtain at the place of bending section) is required after heat treatment is ended for the initial use of new steel type, or mon steel type which heat treatment specification had been changed, to obtain data specified in item (2), (3) and (4) in article of this code. External and internal surface must be cleaned after the preparation of bend pipe. Data such as out of roundness, wave degree, angle deviation and reducing value of wall thickness must be in concordance with following rules after the preparation of bend pipe: Out of roundness of bend section should not be more than: 5% for high pressure pipe。 Correct assembly, flexible action, and the indicating position of opening indicator should be accurate。 Whether the connection between valve stem and valve core is flexible and reliable。 Unqualified valve in the tightness test. Any dirt and foreign material must be removed thoroughly prior to dismounting valve, or opening/closing operation and dismounting are forbidden。 Obvious manufacturing defect is forbidden on the appearance of casting valve. Tightness checking must be made prior to the installation of valve used as closed circuit element (acting as isolation), to check the tightness of joint surfaces between valve seat and valve core, valve cover and padding chamber. Water pressure, which times more than pressure marked on nameplate, should be applied in the tightness test of valve. No less than 10% (at least 1 vale) in the same batch (the same manufacturer, specification and model) must be checked by sampling for tightness test for low pressure valve。 and its hardness should be less than the flange39。 pipe wall thickness which had been treated should not be less than the calculation wall thickness of straight pipe, and the checking report must be recorded and submitted. Thickness of no less than 3 cross sections should be measured and checked for medium or low alloy steel pipes which used as high pressure, and the recording is required. Qualified steel pipes should be stored according to their materials and specifications, to avoid corrosion. Checking of pipe fittings Following items must be checked to determine if they are in accordance with active national or trade technical standards prior to the pipe fittings used in the construction of medium or high pressure pipes: Analysis results of chemical position。 Concave depth should not be more than , and the Max. dimension should not be 5% more than the pipe perimeter, and not be more than 40mm, Spectrum reexamining is required and material marks should be made prior to the using of pipes, pipe fittings pipe accessories and valves which made of medium and low alloy steel. Checking of pies Following items must be to determine if they are in ac0dance with active national or trade technical standards prior to the construction of pipes which designing pressure is more than or equal to . Analysis results of chemical position。 Labor force, materials, machineries and checking means should be pleted on the whole。 Thermal meter pipes。 Composite metal pipes. For the special construction and acceptance of following types of pipes, regulations in corresponding section of the Code of Erection and Acceptance for Electric Rower Construction should be also plied besides the technology requirements in this code: All types of pipes in the steam turbine and electric generator body。 Reinforced concrete pipes。S REPUBLIC OF CHINA THE CODE OF ERECTION AND ACCEPTANCE FOR ELECTRIC POWER CONSTRUCTION PIPING SECTION DL 503194 Chief Editorial Department: Construction Cooperating Department of the Ministry of Power Industry Approved Department: The Ministry of Power Industry of 1994 Beijing 2 Note This book is the English translation of The Code of Erection and Acceptance for Electric Power Construction Piping section DL 503194 In the event of any inconsistency between the Chineselanguage text of the Code and the present Englishlanguage text of the Code, the Chineselanguage text shall be taken as ruling. 1 The Ministry of Power Industry of the People39。s Republic of China The Notification of Issuing the Electric Power Trade Standard The Code of Erection and Acceptance for Electric Power Construction (Piping section) Electric Power Technology [1994] All electric power administrations, all electric power bureau, electric power planning institutes, and electric power construction institutes of provinces (municipalities directly under the Central Government, autonomous regions) and Water and Electric Power Press: For adapting the development of electric power industrial technology and insuring the erection quality of pipes of th