DL 5190.8-2019Technical specification for electric power construction - Part 8: Processing and preparation (English PDF)

2.1 General rules

2.1.1 When materials and parts are transported, processed and stored, measures should be taken to prevent deformation, damage and corrosion.

2.1.2 When the working environment temperature is lower than the following temperature, the steel should not be cold worked.

1 Ordinary carbon steel -16°C.

2 Low alloy steel -12°C.

2.1.3 The machining of mechanical parts that do not indicate the technical requirements shall meet the following requirements.

1 The dimensional tolerances of linearity, angle and bore diameter without tolerances shall be in accordance with "Tolerance of inches" GB/T 1804 provides m-level accuracy.

2 The thread tolerances that are not specified shall comply with the 6-level precision requirements in the "Common Thread Tolerance" GB/T 197.

3 The surface roughness of the thread shall not be greater than Ra25µm.

4 The end of the thread should meet the requirements of GB/T 3 in "Ending, shoulder distance, undercut and chamfering of ordinary threads".

2.1.4 Forgings that do not indicate the technical requirements for dimensional tolerances, form and position tolerances and machining allowances shall be processed in accordance with the "Steel Die Forgings Tolerance and Machine Machining Allowance" GB/T 12362.

2.2 Green construction and finished product protection

2.2.1 The processing and preparation of green construction shall meet the following requirements.

1 New technologies, new processes, new processes, new equipment and new materials should be adopted, and highly polluting process technologies should not be used.

2 The construction site should adopt a circular channel, which is always combined with one another to reduce land occupation.

3 The layout of the site should optimize the process flow, shorten the transportation distance, and should be within the coverage of large hoisting machinery.

4 Turnover materials should be maintained regularly to increase the recycling rate.

5 Materials should enter the site in accordance with the processing flow and planned order, with a quota of materials, and a reasonable discharge to reduce waste.

6 Energy-saving and environmentally-friendly construction equipment and machinery should be used, and the utilization rate should be increased.

7 Temporary power lines should be reasonably arranged, and energy-saving lamps should be used.

8 Water-saving pipe fittings should be used to suppress dust, and test water should be recycled.

9 Sewage discharge should meet the requirements of "Integrated Wastewater Discharge Standard" GB 8978.

10 On-site noise control should be implemented in accordance with the "Environmental Noise Emission Standard for Construction Sites" GB 12523.

11 The electric welding arc light pollution during processing and preparation should be reduced.

12 Do not use materials, technologies and equipment that are explicitly prohibited by the state.

13 After the work is completed, the site is cleaned up, and the waste generated during the processing and preparation process should be legally disposed of.

2.2.2 The protection of processed and formulated materials and finished products shall meet the following requirements.

1 The stacking site should be level, with reasonable support pads, unobstructed roads, and complete drainage facilities.

2 Small parts such as bolts and pads should be stored indoors.

3 During on-site transportation, multi-point support measures should be taken for easily deformable materials and finished products.

4 When hoisting, the hoisting points should be arranged reasonably, and protective measures should be taken between the wire rope and the material and finished product.

2.3 Stakeout and blanking

2.3.1 The lofting platform should be stable and flat, the horizontality and verticality should meet the requirements of processing accuracy, and the surface should not have any attachments and impurities that hinder the laying out.

Things.

2.3.2 Stakeout should be designed by computer. When stake out on the stake out platform, the large sample should be drawn at a ratio of 1.1.When the stake out size is too large it is advisable to stake out in sections.

2.3.3 The production of samples and rods shall meet the following requirements.

1 The samples and rods should be made of flat, straight and rigid materials.

2 The finished template and sample rod should be clearly marked.

3 The allowable deviation of the sample plate and sample rod production should meet the requirements of Table 2.3.3.

2.3.4 The marking of parts shall meet the following requirements.

1 The material should be visually inspected before marking, and the allowable deviation of the material that needs to be corrected after correction should meet the requirements of Table 2.4.6.

2 The marking of stainless steel materials should have anti-carburization isolation measures, should not produce scratches and meet the surface accuracy requirements.

3 When scribing, the allowances for material cutting, machining and welding shrinkage should be considered.

4 The allowable deviation of part marking shall meet the requirements of Table 2.3.4.

2.3.5 The blanking of carbon steel and common alloy steel should be mechanical cutting or gas cutting; stainless steel and non-ferrous metal materials should be mechanical Cutting or plasma cutting.

2.3.6 For the parts processed on the edge, sufficient machining allowance should be reserved.

2.3.7 The cut surface of steel should be free of cracks, delamination, slag inclusions and missing edges greater than 1mm.

2.4 Splicing and correction

2.4.1 Material splicing should be spliced by equal-strength welding; when the strength of the connection weld is less than the strength of the base metal, reinforcement should be carried out.

2.4.2 When welding H-beams on site, the distance between flange plate splicing welds and web splicing welds shall not be less than.200mm. Flange plate splicing length the degree should not be less than 2 times the board width and not less than 500mm. The web splicing width should not be less than 300mm, and the length should not be less than 600mm. The web the spacing of splicing welds should not be less than.200mm.

2.4.3 Measures to reduce welding deformation shall be taken for the splicing of materials, and the flatness, stagger, bending, etc. shall comply with the "Welding Technology for Thermal Power Plants" Regulations "DL/T 869".

2.4.4 The heating temperature of carbon structural steel and low-alloy structural steel should not exceed 900°C during heating correction. Low alloy structural steel is heating Cool down naturally after correction.

2.4.5 The minimum radius of curvature and maximum bending height of steel cold straightening and cold bending shall meet the requirements of Table 2.4.5.

2.4.6 The allowable deviation of the steel after correction should meet the requirements of Table 2.4.6.

2.5 Welding

2.5.1 The steel materials, welding materials, welding methods, welding heat treatment, etc. used for the first time shall be in accordance with "Welding Procedure Qualification Regulations" DL/T

868 Perform welding procedure qualification.

2.5.2 The form and size of welding grooves not indicated shall be in accordance with "Recommended grooves for gas welding, electrode arc welding, gas shielded welding and high energy beam welding" GB/T 985.1 and "Recommended Groove for Submerged Arc Welding" GB/T 985.2 shall be implemented.

2.5.3 The weld grades of steel structures shall be graded according to the load properties, stress conditions, working conditions and importance of the parts.

1 First-class welds. butt welds, butt and fillet welds that bear tensile and shear forces and are designed with equal strength.

2 Secondary welds. butt welds, butt welds and fillet welds that are designed with equal strength under pressure.

3 Third-level welds. welds other than the first and second-level welds.

2.5.4 The classification of welds for smoke and wind, material pipes, and soda pipes shall be implemented in accordance with DL/T 869 of the "Technical Specification for Welding of Thermal Power Plants".

2.5.5 When any of the following situations occurs during welding, effective measures shall be taken before welding.

1 The relative humidity is greater than 90%.

2 The surface of the weldment is wet or covered with snow and ice.

3 The wind speed during manual arc welding and submerged arc welding exceeds 8m/s.

4 The wind speed of argon arc welding and CO2 gas shielded welding exceeds 2m/s.

5 The ambient temperature of carbon structural steel is lower than -10°C; the ambient temperature of low-alloy structural steel is lower than 0°C.

2.5.6 The preheating before welding and the heat treatment after welding shall be in accordance with "Technical Regulations for Welding of Thermal Power Plants" DL/T 869 and "Welding of Thermal Power Plants" DL/T 819 "Technical Regulations for Heat Treatment" shall be implemented.

2.5.7 The unqualified welds can be repaired by digging and repairing. However, the number of excavations and repairs on the same position should generally not exceed three times.

If more than twice, quality analysis should be carried out before repairing, and the repairing process measures should be approved by the person in charge of welding technology before implementation.

2.5.8 The repaired welds should be inspected according to the original method.

2.5.9 Different types of welding rods should be classified and marked, and mixed use is strictly prohibited.

2.5.10 The allowable dimensions of the weld shape should meet the requirements of Table 2.5.10.

2.6 Metal detection

2.6.1 Non-destructive testing of welded joints shall meet the following requirements.

1 Carbon structural steel should be carried out after the welds are cooled to ambient temperature. For welds that are prone to delayed cracks, they should be carried out 24 hours after the completion of welding.

get on.

2 The first and second level welds with full penetration shall be inspected for internal defects by ultrasonic testing.

When judging, radiographic flaw detection should be used.

2.6.2 Welded joints of pipe fittings with working pressure between 0.1MPa and 1.6MPa for steam and water pipelines shall be subject to radiographic inspection of 1% of the total weld length.

The standards for non-destructive testing of welded joints shall comply with "Radiographic Inspection Technology and Quality Classification of Metal Fusion Welding Butt Joints" DL/T 821 and "Pipeline Technical Specification for Ultrasonic Inspection of Welded Joints" DL/T 820 Class B.

2.6.3 The non-destructive testing standards for welded joints of steel structures shall comply with the "Manual Ultrasonic Testing Method for Steel Welds and Classification of Testing Results" GB 11345 or "Radiography of Metal Fusion Welding Joints" GB/T 3323 Class B. The quality level should meet the requirements of Table 2.6.3.

2.6.4 The non-destructive testing of welded joints for steel atmospheric pressure vessels shall comply with the relevant regulations in Chapter 6 of this Part.

2.7 Surface treatment

2.7.1 When parts and steel need to be derusted, spray or projectile derusting and manual or power tools can be used to derust. Steel sheet after treatment the surface should be free of welding slag, welding bead, spatter, dust, oil and burrs.

2.7.2 Measures should be taken to prevent dust pollution when spraying and projecting rust on parts and steel surfaces. Relative humidity of construction environment is not it should be more than 85%, and there should be no condensation on the surface of parts and steel.

2.7.3 When spraying rust removal, the compressed air used should be free of visible oil, water and dirt.

2.7.4 After rust removal, the surface of parts and steel before primer coating should meet the current relevant national standards or design requirements, and the design documents are not specified the rust removal grade of the parts and steel surface of the steel should meet the requirements of Table 2.7.4.

2.7.5 The milled end faces of the parts shall be protected by varnish after milling.

2.7.6 The primer should be painted in time after the surface treatment, and the logo should be transplanted before and after the primer.

2.7.7 The following parts shall not be painted with primer, and protective measures shall be taken.

1 High-strength bolts connect the friction surface.

2 The contact surface between the base plate of the column foot and the foundation.

3 Fully enclosed inner surface of parts.

4 Machined surface required for mechanical installation.

5 Design requirements not to be painted.

2.7.8 The surface of the parts within 50mm on both sides of the welding seam (before the test is qualified) and the installation welding seam shall not be painted with primer for the time being.

And should take protective measures.

3.1 General rules

3.1.1 When materials enter the site, they shall be inspected in accordance with the contract or inspection standards. The variety, specification, quality, performance, etc. of the material should conform to the country Product technology and quality standard requirements. The quality of imported materials shall meet the design requirements and contractual agreements.

3.1.2 When the design documents have low-temperature impact toughness requirements for materials, the low-temperature impact toughness value in the product quality certification documents should meet the design documents Requirements.

3.1.3 The material shall not be used when one of the following conditions exists.

1 The characteristic data of the quality certification document does not conform to the product standard or ordering technical conditions.

2 There are objections to the characteristic data of the quality certification document.

3 The physical label is inconsistent with the label in the quality certification document.

4 The materials that require re-inspection have not been re-inspected or are unqualified.

3.1.4 The site for storing materials should be level, free of stagnant water, and the road should be unblocked. The identification of the material should be clear and accurate, and the support pad should be reasonable.

3.1.5 Boxed parts and standard fasteners for connection should be stored indoors.

3.2 Steel

3.2.1 The rust level of the steel surface should comply with the "Visual Evaluation of Surface Cleanliness of Steel Surface Treatment Before Coating Part 1.

The corrosion grade and treatment grade of the uncoated steel surface and the steel surface after the original coating has been completely removed" GB/T 8923.1 set.

3.2.2 The surface appearance quality of steel should meet the following requirements in addition to the relevant national standards.

1 When there are defects such as rust, pitting or scratches on the surface of the steel, the depth shall not be greater than the allowable negative deviation of the thickness of the steel.

2 There should be no defects such as delamination or slag inclusion at the edge or fracture of the steel.

3.2.3 When steel has one of the following conditions, sampling re-inspection shall be carried out, and the re-inspection results shall meet the national product standards and design requirements.

1 The design requires re-inspection.

2 Those who disagree with the quality.

3.2.4 The steel should be kept properly, and steels of different specifications and materials should not be mixed.

3.2.5 Anti-carburization measures should be taken for stainless steel storage.

3.3 Welding materials

3.3.1 The surface of the welding wire should be smooth and clean, and it should be degreasing and derusting before use. Deteriorated by damp, damaged coating, rusted core Welding rods, rusty welding wires, and damp, agglomerated fluxes with debris shall not be used.

3.3.2 The storage of welding materials shall meet the following requirements.

1 The temperature and humidity of the welding material warehouse should be controllable. The temperature in the warehouse should not be lower than 5°C, and the relative humidity should not be greater than 60%.

2 Welding materials should be classified and stored according to grades and specifications, with clear identification. The distance between the storage location and the ground and external walls should not be less than 300 mm.

3.3.3 Welding materials should be kept by special personnel, and baking, distribution and recycling should be recorded.

3.3.4 Welding materials that should be baked before welding, put them aside at room temperature for more than 4 hours after baking, and should be re-baked during use; alkaline after baking the welding rod should be re-baked if it is placed in the holding tube for more than 4 hours, and the number of re-baking should not exceed 2 times.

3.3.5 After baking, the welding rod should be stored in a constant temperature box at 100°C~150°C, and should be placed in a 80°C~110°C welding rod insulation cylinder when used.

Take it and use it.

3.3.6 The purity of welding shielding gas should meet the process requirements. The argon gas used in argon arc welding should meet the requirements of "Argon" GB 4842.

3.4 Standard fasteners for connection

3.4.1 After the bolts, nuts and washers have passed the inspection on arrival, they should be stored according to materials, specifications and models, with clear identification and prevent rust.

Eclipse and damage.

3.4.2 In the process of transportation and storage, the bolts should be protected from thread damage.

4.1 General rules

4.1.1 This chapter is applicable to the processing and preparation of process pipes and their parts such as flue gas, materials and desulfurization and denitration systems of the boiler system.

4.1.2 Before making the pipeline, it should be reasonably segmented according to the design drawings, and meet the transportation and installation requirements.

4.1.3 The pipe coil system should be formed at one time using new equipment.

4.1.4 The bolt holes on the pipe parts shall be machined.

4.1.5 The sealing welds of the flue gas and material pipes should be checked for tightness, and an inspection certificate should be applied for.

4.1.6 Temporary supports should be provided for the production of large parts. The lifting lugs should be made of the same material as the base material. Temporary ears should be designed or strength check, and non-destructive inspection should be carried out if necessary.

4.1.7 Parts should be marked with part drawing number, part number and weight; deformation should be prevented during tran...