【正文】 ts or marks to measure the creep deformation of pipes, which installed on motoring section pipes or steam pipes Pipe classification electric power plant pipes can be classified according to designing pressure p as main parameter, refers to table . Table Pipe classification Pipe classification Main parameter High pressure pipe p8 MPa Medium pressure pipe 8 MPa≥p MPa Low pressure pipe p≤ MPa Note: reheating section and heating section pipes should be looked upon as high pressure pipes. Checking of pipes, pipe fittings, pipe accessories and valves General regulations Qualified certificate of manufacturer must be provided for pipes, pipe fittings, pipe accessories and valves, and corresponding indexes should be in concordance with active national or trade technical standards, Specification, material and technical parameter must be checked according to the design requirements prior to the using of any pipe, pipe fitting, pipe accessory and valve. Appearance inspection is required prior to the using of any pipe, pipe fitting, pipe accessory and valve, and the appearance demands are as following: Without any defects such as crack, shrinkage cavity, included slag, adhering sand, folding, missing welding, coldlap and so on。 Oil pipes and all types of water treatment pipes。 General steam and water pipes, thermal power work pipes and pressed air pipes in thermal power plant。 Temporary pipes used in construction. The code does not apply to the following: Cast iron pipes。 All types of pipes of hydrogen generating system and hydrogen supply system。 The surface should be smoothness without any sharp scratches。 and any defect such as buckle and wrinkle is forbidden on surface. Visual inspection should be made for the surface of metal shim with leveling rule, the good contact is necessary and defects such as crack, burr, rust or coarse processing are not allowed。 Safety valve and throttle valve。 Opening/closing stroke and end position must be checked for throttle valve, and mark should be made as far as possible. Following quality requirements should be satisfied after the dismounting checking and eliminating defects had been finished: Material of alloy steel should meet the requirement of design。176。 figure ) of verticality of pipe end surface should not b more than the specified value in Table . Figure Diagram of the verticality deviation of pipe end surface Mechanical damage on pate surface should be avoided during the processing of reel pipe, and place with serious scratch must be ground, and transition area should be roundness and smoothness. Ground depth of pressure pipe should exceed 10% of plate thickness, and the wall thickness after ground should not be less than the Min. thickness of straight pipe. Plane deviation P and end surface deviation Q of all type of elbow should not be more than the specified values in Table (see figure ). Out of roundness of pushed elbow and pressed elbow should be in accordance with following demands in case of no design requirement provided: End: less than 1% outer diameter of pipe and no more than 3mm。6mm in case of DN 1000mm。 miter elbow (d)30176。40mm。 7% for medium and low pressure pipe。 Whether the valve is bend and corrosion, and the tightness degree of matching between valve stem and padding material cover is suitable, and there are some defects such as broken thread on the thread of valve stem。 additional 20% should be checked by sampling in case of someone is unqualified, and if someone does still not pass, all valves should be checked one by one. Tightness test must be done one by one for all valves used on high pressure pipe. Tightness test of sealing surface of valve core can be carried out with color painting method for safety valves and valves which nominal pressure no more than MPa and inside nominal diameter no less than 800mm。 Heat treatment condition or metallurgical phase analysis results of alloy steel pipes。 Construction should satisfy the demands of environment。 All types of pipes in boiler body, and pipes of fume exhaust system, ventilation system, coal system, fuel system, gas burning system and dust removal system。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 thermal Power plant, the Code of Erection and Acceptance for Electric Power Construction (piping section) DJ 5679 issued in 1979 had been revised by the ministry. The new code should be looked upon as electric power trade standard and the code number is DL 503194. The standard is approved and issued now and will be go into effect from Oct.!, 1994 and the older version should be abolished at the same time. Any question in the performing should be notified the Construction Cooperating Department of the ministry please. Apr. 9,1994 2 Contents General rules ...................................................................................................................................................... 3 Glossary.............................................................................................................................................................. 5 Checking of pipes, pipe fittings, pipe accessories and valves ............................................................................. 5 General regulations .......