1 Raw materials
The selection of materials in item 11 complies with the relevant standards of the country where the pipe is produced and the raw material standards required by the owner.
Upon arrival at the factory, the inspection personnel first verify the original material certification issued by the manufacturer and the material inspection report from the importing company. They check whether the markings on the materials are complete and consistent with the quality certificate.
The newly purchased materials are subject to re-inspection, with strict examination of their chemical composition, length, wall thickness, outer diameter, inner diameter, and surface quality in accordance with ASMEDIN17175 standards. The batch number and pipe number of the materials are recorded. Materials that do not meet the requirements are not allowed to be stored or processed for production. The inner and outer surfaces of steel pipes must be free of cracks, folds, kinks, nodules, delamination, and hairlines. These defects should be completely removed, and the actual wall thickness at the cleaned area must not be less than the minimum allowable value for wall thickness. The dimensions allowed on the inner and outer surfaces of steel pipes should not exceed the relevant provisions in the corresponding standards; otherwise, they will be rejected. The oxide scale on the inner and outer surfaces of steel pipes should be removed, and anti-corrosion treatment should be carried out. The anti-corrosion treatment should not affect the visual inspection, and it can be performed.
To ensure compliance with the specified material indicators, the following tests should also be conducted on materials with special requirements from customers:
1. Mechanical properties: The mechanical properties shall comply with DIN17175 and ASME requirements respectively. For alloy steel pipes, transverse mechanical property tests, including transverse impact tests, shall be conducted. The impact test shall be Charpy V test, and the number of inspections shall be the same as that for tensile tests.
2 Process performance
Each of the 21 steel pipes should undergo 100% ultrasonic non-destructive testing according to SEP1915, and standard test samples for ultrasonic testing should be provided. The standard test samples should have a wall thickness of 5mm, and the maximum size should not exceed 15mm.
22. Conduct flattening test on steel pipes. 3. Actual grain size. The actual grain size of alloy steel finished pipes should not be coarser than Grade 4, and the grade difference for steel pipes from the same heat number should not exceed 2 grades. The grain size inspection shall be conducted in accordance with ASTM I 1295, with one inspection per heat number and each heat treatment batch.
2 Cutting and blanking
Before cutting high-temperature and high-pressure alloy pipe fittings for power plants, accurate material calculation is required first. Based on the analysis of the pipe fitting strength calculation results and considering factors such as thinning and deformation that may occur during production, the thickness of key parts of the pipe fittings, such as the outer arc of the elbow and the shoulder of the tee joint, should be analyzed. Materials with sufficient margin should be selected, and factors such as whether the stress enhancement coefficient after forming the pipe fittings meets the pipeline design stress coefficient and the flow area of the pipeline should be considered. For hot-pressed tees, radial material compensation and shoulder material compensation during the pressing process should be calculated.
For high alloy pipe materials, a gantry-type band saw cutting machine is used for cold cutting. For other materials, flame cutting is generally avoided, and band saw cutting is employed to prevent the formation of hardened layers during the cutting process or cracks caused by improper operation.
23. During cutting and blanking, according to design requirements, make proper identification and transfer of the outer diameter, wall thickness, material, pipe number, furnace batch number, and serial number of the raw material and pipe fitting blank. The identification shall be made using low-stress steel stamps and paint spraying. Additionally, record the operation details on the production process flow card.
After the first piece of material is cut, the operator conducts a self-inspection and reports it to the dedicated inspector for a special inspection. Only after passing the inspection can the cutting of other pieces proceed, and each piece must be inspected and recorded.
3. Hot pressing (pushing) forming
The hot pressing process of high-pressure pipe fittings, especially tees, is an important process. The billet can be heated using a fuel-fired heating furnace. Before heating the billet, first use tools such as hammers and grinding wheels to clean the surface of the billet pipe of debris, oil rust, and low-melting-point metals such as copper and aluminum. Check whether the identification of the billet meets the design requirements.
Clean up the debris inside the heating furnace chamber, check whether the heating furnace's electrical circuit, oil circuit, trolley, and temperature measurement system are normal, and whether the oil supply is sufficient.
Place the billet in a heating furnace for heating, using refractory bricks to isolate the workpiece from the furnace table for 20 hours. Strictly control the heating rate according to different materials for 150 hours, and heat the material to a temperature above AC3 for 30-50 minutes, with heat retention for more than 1 hour. During the heating and heat retention processes, monitor with a digital display or infrared thermometer, and adjust as necessary.
When the billet is heated to the specified temperature, it is removed from the furnace for pressing. The pressing is completed using a 2500-ton press and a pipe tire mold. During the pressing process, an infrared thermometer is used to measure the temperature of the workpiece, which should not be less than 850°C. If the workpiece fails to meet the requirements in one attempt due to too low a temperature, it is returned to the furnace for reheating and heat preservation before being pressed again.
The hot forming process of product 35 fully considers the law of metal flow during thermoplastic deformation in the finished product forming process. The forming mold exerts minimal resistance to deformation caused by thermal processing of the workpiece, and the pressing tire molds are all in good condition. Regular verification of the tire molds is conducted according to the requirements of the ISO9000 quality assurance system to control the amount of thermoplastic deformation of the material, ensuring that the actual wall thickness of any point on the pipe is greater than the minimum wall thickness of the connected straight pipe.
For large-diameter elbows, medium-frequency heating is used for pushing and forming, and the pushing equipment is a large-scale elbow pushing machine. During the pushing process, the heating temperature of the workpiece is adjusted by adjusting the power of the medium-frequency power supply. The pushing is generally carried out at 950-1020°C, and the pushing speed is controlled at 60-100 mm/min.
4 Heat treatment
For finished products made of materials such as 10CrMo910 and 12Cr1MoV, our company strictly follows the heat treatment procedures specified in DIN17175 and ASME standards. Generally, small pipe fittings can be heat treated in a resistance furnace, while large-diameter pipe fittings or bends can be heat treated in a fuel-fired heat treatment furnace.
The interior of the heat treatment furnace is clean, and there is no oil, ash, rust, or other metals different from the treated materials inside the furnace.
Heat treatment shall be conducted strictly in accordance with the heat treatment curve specified in the "Heat Treatment Process Card", with the temperature rise and fall rate for alloy steel pipe fittings controlled to be less than 200 hours.
The automatic recorder keeps track of temperature fluctuations at all times and automatically adjusts the furnace temperature and holding time based on preset parameters. During the heating process of the pipe fittings, a fire wall is used to block the flame, preventing it from directly spraying onto the surface of the pipe fittings, thus ensuring that the pipe fittings do not experience overheating or overburning during the heat treatment process.
After heat treatment, each alloy tube should undergo a metallographic examination. The actual grain size of the alloy should not be coarser than grade 4, and the grade difference among tubes from the same heat number should not exceed 2 grades.
Conduct hardness testing on 46 pairs of heat-treated pipe fittings to ensure that the hardness value of any part of the pipe fitting does not exceed the range required by the standard.
After heat treatment, the oxide scale on the inner and outer surfaces of the 47 pipe fittings should be removed by sandblasting until the metallic luster of the material is visible. Scratches, pits, and other defects on the surface of the material should be polished smooth using tools such as grinding wheels. The local thickness of the polished pipe fittings should not be less than the minimum wall thickness required by the design.
48. Fill in the heat treatment records according to the pipe fitting numbers and identifications, and rewrite the incomplete identifications on the surface of the pipe fittings and on the flow cards. 5. Bevel processing
The beveling of high-pressure pipe fittings is carried out using mechanical cutting methods. Our company has over 20 sets of machining equipment, including various lathe power heads, which can process various thick-walled pipe fittings according to the requirements of DL869 Technical Code for Fossil Fuel Power Plants GD87 Typical Design Manual for Steam and Water Piping Components and Parts of Fossil Fuel Power Plants, DLT6951999 Steel Butt Welding Pipe Fittings for Power Stations, as well as the double V-type or U-type bevels and internal and external bevels required by the bidder. The company is fully capable of processing according to the bevels and technical requirements provided by the bidder, ensuring that the pipe fittings are easy to operate and maintain during the process.
After the pipe fittings are beveled, the inspectors shall inspect and accept the overall dimensions of the pipe fittings according to the paper requirements. Products with unqualified geometric dimensions shall be reworked until they meet the design dimensions.
six
The work related to pipe fittings such as "tee joints" and "elbows" is carried out by welders with many years of experience. Appropriate process evaluations are conducted according to requirements, mechanical property tests are performed on the welds, and production is guided by suitable process specifications. Qualified process evaluations are adopted for the process, which comply with the provisions of Volume IX of the ASME Boiler and Pressure Vessel Code and brazing process evaluations. Welders are also assessed and qualified accordingly. If the welding project undertaken by a welder during the process does not match the project for which the welder passed the examination, it cannot be carried out. During the process, the quality assurance engineer stipulates monitoring and measurement for hold and witness points of the procedure to ensure that no issues arise in this critical process. Strict control is exercised over parameters such as interlayer temperature, preheating temperature, and pass number for alloy materials, and careful interlayer cleaning is performed. Tempering treatment is carried out immediately after welding to ensure that the joint performance meets the specification requirements.
The process is strictly carried out in accordance with the "Process Guidance Card" formulated by the company, and care is taken to avoid issues such as unwelded air holes, slag inclusions, cracks, undercutting, etc.
The post-weld heat treatment for pipe fittings can be conducted in resistance furnaces or oil-fired furnaces, or alternatively, in far-infrared heating furnaces, to ensure that the joints possess mechanical properties and other technical indicators similar to those of the base material.
The welds of 64 welded pipe fittings shall undergo 100% radiographic or ultrasonic inspection, and shall meet the requirements of Level I for ultrasonic inspection and Level X for radiographic inspection according to the 47302005 standard.
7 Inspection
All high-pressure pipe fittings undergo various inspections before leaving the factory, in accordance with standards such as DL869 and DL5031. According to ASME B311, all inspections are conducted by qualified inspectors recognized by the Technical Supervision Bureau.
Perform magnetic particle MT testing on the outer surface of the 72-degree high-pressure three-way elbow reducers, conduct ultrasonic thickness measurement and flaw detection on the outer arc side of the elbow, the shoulder of the three-way elbow, and the reducing parts of the reducers, and perform radiographic or ultrasonic flaw detection on the welds of the pipe fittings. Before machining forged three-way elbows or elbows, conduct ultrasonic testing on the billets.
All pipe fittings shall undergo magnetic particle inspection within 100mm of the groove, ensuring that no cracks or other defects caused during the cutting process appear at the groove.
74 Surface quality. The inner and outer surfaces of the pipe fittings are not allowed to have cracks, shrinkage cavities, slag, sand adhesion, folds, solder skips, cold-lap, etc. The surface should be smooth, without sharp scratches, and the depression should not exceed 15mm. The maximum size of the depression should not be greater than 5% of the pipe circumference and not greater than 40mm. The weld surface must be free of cracks, pores, arc craters, and splashes, and must not have undercutting. The inner corners of the tees should have a smooth transition. All pipe fittings undergo a 100% surface appearance inspection. Cracks, sharp corners, pits, etc. on the surface of the pipe fittings are polished with a grinding machine, and the polished areas are subjected to magnetic particle inspection until the thickness of the polished pipe fittings is not less than the designed minimum thickness.
For pipe fittings with special requirements from customers, the following tests should also be conducted:
751 Hydrostatic Test: All pipe fittings can undergo a hydrostatic test along with the system. The pressure for the hydrostatic test should be 15 times the design pressure, and the duration should not be less than 10 minutes. If the quality certification documents are complete, the pipe fittings leaving the factory may not undergo a hydrostatic test.
752 Actual Grain Size: The actual grain size of finished pipe fittings should not be coarser than Grade 4, and the grade difference for fittings from the same heat number should not exceed 2 grades. The grain size inspection shall be conducted according to the methods specified in YBT514893 or ASTM E11295, with one inspection for each heat number + each heat treatment batch.
753 Microstructure: The manufacturer shall conduct microstructure inspection and provide microstructure photos in accordance with the relevant provisions of GBT1329891 or corresponding international standards. The inspection frequency is once per heat number + size, diameter, wall thickness + heat treatment batch. 8 Packaging and Marking
The exterior of the pipes needs to be coated with anti-rust primer. The exterior should be painted with different colors of paint according to different pipes, ensuring even application without bubbles, wrinkles, or peeling. The grooves should be treated with a special anti-rust agent. Small forged pipe fittings or important pipe fittings should be packed in wooden boxes, while large pipe fittings are generally packed in nude. All pipe fittings should have their ends protected firmly with rubber plastic rings to prevent damage to the fittings. Ensure that the final shipped products are free of any cracks, scratches, stretch marks, cold-lap, sand inclusion, laminations, slag inclusions, etc. The pressure, temperature, material, caliber, and other specifications of the pipe fittings should be marked on the visible part of the pipe fitting product. The steel seal should be made of low-stress steel.
9. Shipping
The shipment of pipe fittings should be arranged according to the actual situation, selecting a qualified transportation method. Generally, domestic pipe fittings are transported by truck. During transportation by truck, it is required to use high-strength soft packing belts to firmly tie the pipe fittings to the vehicle body. During driving, they must not collide or rub against other pipe fittings, and rain and moisture prevention measures should be taken. When shipping pipe fittings, the delivery status of alloy steel pipe fittings is: normalizing + tempering; the delivery status of carbon steel pipe fittings is: normalizing.
10 Technical documents available
Before delivery, various quality records, reports, and technical documents of the product are reviewed according to regulations and can be examined by the owner before delivery. The documents submitted with the goods include: quality assurance certificate, design parameters and design drawings of machined parts, inspection reports of pipe fittings, including A raw material re-inspection report; B radiographic inspection report; C heat treatment report; D ultrasonic inspection report; E magnetic particle inspection report; F dye penetrant inspection report; G geometric dimension inspection report; H various reports negotiated with the user, including material and weight of pipe fittings, as well as other documents.
The factory configuration of pipelines involves the following tasks:
Pipeline design
1. Design the direction of the pipeline and the relative distance between the position of the pipeline circumferential weld and the platform hole. The relative position of the bent pipe, straight pipe section, hanging block, various hole connections, pipe sockets, factory welds, and construction site welds.
22. Design pipeline and pipeline valve equipment flow measurement devices and other groove forms, the C value or corresponding inner diameter value at the groove, and the small design wall thickness and weld coefficient at the groove.
3. Design the section opening and size requirements for various types of weld metal filling, including the requirements for the formation of the inner wall of the circumferential weld and the requirements for the excess height of the outer wall. For the design of the structural dimensions and related data of the connecting socket for thermal measurement points such as venting, the design of the connecting socket is calculated using the area compensation method, and the full penetration fillet weld of the socket is designed according to the ASMEB311 power pipeline method. For branch pipes with open holes such as valve connection seats, the calculation method of thermal connection seats cannot be simply used. In the design, the calculation method of thick walled tees should be used to calculate the groove height of each section of the branch pipe. The welding angle height of the full penetration fillet weld of each section should also be designed according to ASMEB311 power pipeline.
5 can assist the design institute in calculating the slope of the pipeline and drawing the installation paper and piping paper of the pipeline, and mark the drainage slope of the pipeline and the calculation angle of the pipe fittings during the installation of the pipeline system. For this purpose, the piping engineer of the factory should, while complying with the design, understand the actual habits and installation conditions of the construction company to perform slope cutting calculations, calculate the angle of the pipe fittings and the elevation of each node after slope cutting, and consider the impact of pipe fittings on the size of the pipes after cold tightening of the piping system.
6. The factory understands the thermal, chemical, and manufacturing requirements of the design institute, as well as the specifications and requirements of various measuring points by the manufacturing and performance debugging units, and reflects these specifications in the piping design.
According to the requirements and specifications of the pipeline installation book of the design institute, design and select accessories such as clamp blocks, support blocks, and stoppers for the support and hanger to the pipe section, and incorporate them into the piping design.
Based on the technical requirements for cold tightening and installation sequence, determine the relevant technical requirements for pipeline adjustment sections.
9. Identify each piping product according to the PID of the piping system, or label the piping products according to the KKS code of the piping system identification number. Thus achieving information and traceability management of pipeline piping products.
10 pairs of pipes are equipped with welding seams, circumferential welds, various types of fillet welds, etc., and marked with welding seam numbers according to the welding seam identification regulations. These numbers can meet the requirements of metal supervision and management and adapt to the needs of relevant metal management software. And classify these welds and indicate the factory welds and construction site welds.
Pipeline factory processing technology process pipeline
Before combining, confirm that all materials are supported by process evaluation and that there are qualified welders.
2 combinations shall be carried out according to the following document requirements:
1. Combination processing
2 Homework Guidelines
3 Process Cards
4. Material List and Surplus Material List
After the completion of the assembly of the three combinations, the special inspector and the team will check the relative position of the misalignment measuring components that match the main geometric dimensions, and the position of the attachments. Only after confirming that they meet the paper requirements and standard requirements can this process be carried out, and this process will be controlled as a stopping point in the factory.
For pipes that require preheating, electric heating should be used for preheating, and the heating width on each side should not be less than 3 times the thickness of the welded piece.
The heating rate for preheating is calculated based on a wall thickness of 25025 hours and should not exceed 300 hours. There is a recorded curve for preheating for verification.
For alloy pipes, the inner wall of the pipe should be filled with argon gas for protection and fully sealed to ensure that the oxygen content at the edge of the groove is lower than the standard requirement.
7. Weld seams shall be strictly carried out in accordance with the requirements of the process parameters on the process card. During the process, inspectors shall supervise on site, and engineers shall conduct spot checks at any time.
The shape of the fillet weld is welded into a concave cross or a 45 degree straight transition, and the welding height will take into account the allowance for non-destructive testing after polishing.
After the completion of the 9-ring weld and fillet weld, stamp the welder's steel seal and weld joint number.
For alloy welds, immediately perform argon removal treatment when the temperature drops below 100. The specific method shall comply with the process requirements and automatically record the temperature.
Inspection items and execution standards after November:
Appearance quality inspection: 100 DL8692004 articles
Main dimension inspection: 100 0-10mm
Circular weld VT inspection: Ultrasonic inspection of 100 SD6783 pipeline welds
Non destructive testing of fillet welds: 100 OD4 '(1016) PT 0D>4' (1016) MT
Alloy tube fillet weld spectrum: 100 meets material requirements
After all non-destructive testing and polishing, the appearance size of the weld seam shall not be smaller than the design size. If it is smaller than the design size, it shall be repaired and re inspected. Post Weld Heat Treatment
1. Perform post weld heat treatment on the welded joint of the alloy; The weld junction of A335P2212Cr1MoV10CrMo910 is subjected to 720-750 stress relief annealing treatment after welding; Perform 585-620 stress relief annealing treatment on the welded junction after welding. Tempering treatment of welded joints and overall tempering treatment of composite components
Perform overall furnace heat treatment on the welded joints in Factory 2.
The heat treatment of the 3 welded joints shall be carried out, and the heat treatment curve shall be confirmed as qualified by the special inspection personnel and heat treatment engineer before being stored in the quality department. The inspection items and qualification standards after heat treatment are as follows:
VT inspection of circumferential welds: 100
MT inspection of fillet weld: 100 OD4 '(1016) PT 0D>4' (1016) MT
Weld hardness: 100 alloy not exceeding raw material hardness+100 and not exceeding 300, not exceeding raw material hardness+100 and not exceeding 270. UT and RT testing shall be carried out on stainless steel pipes for piping assemblies
sandblasting
All surfaces of pipe fittings and accessories will undergo sandblasting treatment
The qualified standard for surface sandblasting is that the surface must have removed at least 98% of the oxide scale and be free of impurities such as oil stains, burrs, and splashes. If there are any debris that cannot be removed by sandblasting, clean them with a grinding wheel.
Paint
The paint will use the design blue required paint, and the factory will only apply the primer.
When painting, the air temperature should not exceed 80 degrees Celsius and there should be no significant dust.
Within 8 hours after sandblasting, paint the wall of the pipe hole once.
Apply transparent paint to the areas with steel stamps and frame them with yellow paint around.
Painting is not allowed within 20mm of the groove and groove edge.
Apply anti oxidation and anti rust coating on the groove without affecting the quality.
The qualified standard for paint is: no mud, cracks, adhesion, peeling, bubbles, rust, pits, buried powder particles, etc. on the surface.
Measure the thickness of the paint film after the paint has dried, and ensure that the paint thickness meets the design requirements.
9. Some painted areas should be polished to remove them, and then the area should be repainted with the original paint.
packaging
Both ends of the pipe are sealed with blind plugs. The type of blind plug can be iron, rubber, plastic, or wood depending on the situation, but it must ensure that it has the function of protecting the groove and sealing the inner wall of the pipe.
Before sealing the pipes, a certain amount of desiccant should be added to protect the inner wall of the pipes. The desiccant should be grilled before installation.
If the three sockets have threads, they should be plugged with matching bolts to protect the threads. The remaining sockets should be plugged with wooden blocks and wrapped with tape. If the sockets are slender, protective measures should be taken to prevent damage during transportation.
For non pipeline materials, appropriate packaging measures such as box loading and shelving should be taken to ensure that they are not damaged during transportation.
identification
On the pipeline, spraying will be used to identify the unit of use, specifications, material, pipe number, flow direction, and other content of the pipe. For the convenience of on-site search, the markings will be placed diagonally opposite both ends of the pipe.
For the convenience of on-site search, the pipe number will be marked on the sealing ports at both ends of the pipe
Ship
The factory will adopt suitable transportation methods such as train, car, and mail based on the nature of the goods and the convenience of on-site delivery to ensure timely and accurate delivery of the goods to the site.
The two factories will develop a shipping plan and notify the receiving units one month in advance for them to prepare for receiving the goods. The factory will provide sufficient quality records to prove the product quality in accordance with the factory's quality assurance system and user requirements. The specific project will be clarified by both parties.