This standard specifies the manufacturing and acceptance requirements for spiral finned tubes that are formed by winding tubes and steel strips and welded by high-frequency resistance welding. This standard applies to spiral finned tubes (hereinafter referred to as finned tubes) for boiler heating surfaces with a rated steam pressure not exceeding 3.82MPa. JB/T 6512-1992 Technical conditions for manufacturing high-frequency resistance welded spiral finned tubes for boilers JB/T6512-1992 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
High-frequency resistance welded spiral finned tubes for boilers
Manufacturing technical conditions
1 Subject content and scope of application
JB/T6512-92
This standard specifies the manufacturing and acceptance requirements for spiral finned tubes formed by winding tubes and steel strips and using high-frequency resistance welding. This standard applies to spiral finned tubes (hereinafter referred to as finned tubes) for boiler heating surfaces with a rated steam pressure not exceeding 3.82MPa. 2 Reference standards
Boiler raw materials factory inspection
JB3375
GB3087
GB5310
GB3522
GB4239
JB1611
JB1613
JB1612
Seamless steel pipes for low and medium pressure boilers
Seamless steel pipes for high pressure boilers
High quality carbon structural steel cold rolled steel Strip
Stainless steel cold-rolled steel strip
Technical conditions for boiler tube manufacturing
Technical conditions for welding of pressure-bearing components of boiler
Technical conditions for boiler water pressure test
JB/T1615Technical conditions for boiler painting and packaging3 Technical requirements
3.1 Materials
3.1.1 The selection of materials for tubes and steel strips for manufacturing finned tubes shall comply with the provisions of the design drawings and relevant technical documents, and the material substitution shall be handled in accordance with the regulations.
3.1.2 The tubes must be inspected by the inspection department in accordance with the relevant provisions of JB3375. They shall not be put into production without inspection or unqualified inspection. 3.1.3 Requirements for tube materials
3.1.3.1 The tube material shall comply with the provisions of GB3087 and GB5310, and the surface shall be smooth without defects such as wrinkles and pits. 3.1.3.2 Before welding, the welded surface of the pipe should be cleaned of rust, scale, paint (grease) coating, and other defects that affect the welding quality.
Requirements for steel strip materials
Steel strip materials should comply with the provisions of GB3522 and GB4239. The surface should be bright and free of wrinkles, and the edges should be free of obvious burrs, nicks, cracks and other defects.
For steel strips processed by the manufacturer, the width dimension deviation of the steel strip should not exceed ±0.6mm. 3.1.4.2 Before welding the steel strip, the welded surface should be cleaned of rust, scale, paint (grease) coating, and other defects that affect the welding quality.
3.1.4.3Steel strip materials should be delivered in coils. In the delivery state, carbon steel should be in annealing state, and alloy steel should be heat treated. 3.1.5Alloy steel pipes and steel strips should be spectrally analyzed one by one before welding. Approved by the Ministry of Machinery and Electronics Industry of the People's Republic of China on December 21, 1992, and implemented on May 1, 1993
3.2 Splicing of fins and steel strips
JB/T6512-92
3.2.1 When the length of the welded finned tube is not more than 7m, splicing is generally not allowed; when it is more than 7m, one welded joint is allowed, and the raised part of the weld surface should be ground to be flush with the tube surface. The requirements for pipe butt joints should comply with the provisions of JB1611. 3.2.2 The pot strip of the welded finned tube is allowed to be spliced, and the spliced ​​weld should be ground flat after welding. The weld should not have defects that affect the welding quality after appearance inspection. If necessary, the weld and heat-affected zone should be locally heat treated according to the material properties. 3.3 Finned tube size deviation
3.3.1 The deviation of the outer diameter d of the finned tube should not be greater than ±1.5mm (see Figure 1). The fins of the finned tube should be perpendicular to the tube surface, and the pitch angle α of the fins should not exceed 8 (see Figure 1). 3. 3-2bZxz.net
3.3.3 The average value of the fin pitch t deviation within any 10 pitches should not exceed ±0.5mm, the total deviation of the fin part of the finned tube should not exceed ±10mm, and the deviation of the number of fins should not exceed ±1.5%. 3.3.4 The straightness of the finned tube should not exceed 1.0mm per meter, and the total length should not exceed 10mm. 3.4 Welding of finned tubes
3.4.1 The welding of the tube and the steel strip must be subject to the process assessment of high-frequency resistance welding in accordance with relevant regulations, and can only be produced after passing the process. 3.4.2
Record.
The welding of finned tubes should be carried out by high-frequency resistance welding specialists, strictly follow the welding process regulations, and make the operation of finned tubes in accordance with the regulations. The welds between the tubes and steel strips of the finned tubes should be good, and the length of the local unfused line of the weld should not be greater than the diameter of the tube and the number of local unfused places of the weld. There should be no more than 2 places per meter of tube length, otherwise repair welding should be carried out. 50mm.
The defects of high-frequency resistance welds on finned tubes are allowed to be repaired by qualified welders using manual electric welding according to the qualified welding process. 3.4.5 The finned tubes made of alloy steel should be subjected to stress relief heat treatment after welding. 3.5 The distance between the end of the finned tube and the fin should be not less than 50mm. 3.6 The starting and ending ends of the fins of the finned tube should be cut off from the radial direction, and the sharp corners of the ends should be removed. 3.7
The manufacture of the light tube part of the finned tube shall comply with the relevant provisions of JB1611. Inspection and acceptance
The finned tube shall be inspected and accepted according to the drawings and the provisions of this standard. Before the formal production of finned tubes, welding test pieces shall be prepared and formal production shall be carried out only after they have passed the inspection. Inspection items of welding test pieces
Appearance inspection
The deviations of the fin pitch and outer diameter, fin number and other deviations of the finned tube shall comply with the provisions of this standard and drawings. The tube and steel strip of the finned tube are well fused. Physical and chemical inspection
The pull-off test of the sample of the welding test piece shall be carried out according to the provisions of Figure 2, and the pull-off strength value shall not be less than 196MPa; b.
JB/T6512—92
The weld of the steel strip of the pipe shall be inspected by metallographic (coarse phase method) to evaluate the fusion rate of the weld, and the fusion rate shall not be less than 80%. The calculation formula of fusion rate is as follows:
Fusion rate two
Steel strip fusion thickness
Nominal thickness of steel strip
×100%
4.4 The size of the welding test piece should be able to meet the needs of making macro inspection and physical and chemical test samples. 4.5 If a welding test sample fails in a certain item, double samples of the unqualified items should be taken from the original welded test piece for retest. If it still fails, the finned tube represented by the test piece is unqualified. 4.6 When producing warped tubes, welding test pieces should be made once per shift, and the test items shall be in accordance with the provisions of Article 4.3.2 a. After welding, the finned tube and its welded test piece should be printed with a steel stamp of the operator code. 4.7
4.8 After the finned tube is made, it should be subjected to a water pressure test one by one, and the water pressure test requirements should comply with the provisions of JB1612. The inspection department shall conduct a comprehensive inspection of each batch of finned tubes according to the drawings and the provisions of this standard, mark them after they pass the inspection, and list the main 4.9
inspection items in the product quality certificate of the furnace. Marking, painting and packaging
5.1 After the finned tubes pass the inspection, they shall be coated with anti-rust oil or paint, and the part drawing number or number shall be marked on the tube end. 5.2 The paint packaging of finned tubes shall comply with the provisions of JB/T1615. The packaging shall be in a sturdy box-type packaging, and the finned tubes shall be kept with sufficient spacing or cushioned, and shall be relatively fixed. Additional remarks:
This standard was proposed and managed by Hangzhou Waste Heat Boiler Research Institute. This standard was drafted by Hangzhou Boiler Factory. The drafters of this standard were Qin Yegu and Jinping.
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