CB* 3348-1988 Technical requirements for the assembly of shell-type auxiliary boilers for marine use CB*3348-1988 Standard download and decompression password: www.bzxz.net

(Original standard) CB 3348-1988 Technical conditions for the assembly of shell-type auxiliary boilers for ships. CB
National Technical Committee for Ship Standardization Professional Standard CB*3348-88
Technical conditions for the assembly of shell-type auxiliary boilers for ships
Published on November 19, 1988
National Technical Committee for Ship Standardization
Implementation on May 1, 1989
National Technical Committee for Ship Standardization Professional Standard Technical conditions for the assembly of shell-type auxiliary boilers for ships
Subject content and scope of application
This standard specifies the technical requirements and inspection rules for the assembly of auxiliary boilers for ships. CB*3348-88
Classification number: U41
This standard applies to shell-type marine auxiliary boilers (including exhaust gas boilers) with a medium whose design pressure is not more than 2.45MPa (25kgf/cm2) and whose temperature is saturated temperature.
2 Reference standards
GB11038
GB11037
CB*3347
Technical conditions for welding pressure components of marine auxiliary boilersHydraulic test methods for marine auxiliary boilers and pressure vesselsTechnical requirements for painting, insulation and packaging of marine auxiliary boilersDimensions and deviations of expansion tube holes of boilers
JB1622
3 Technical requirements
The pressure components and non-pressure components of the boiler can only be assembled after passing the inspection. 3.1 Each
3.2 The welding technical conditions for the assembly of the boiler body shall comply with the provisions of GB11038. 3.3 For fillet welds directly exposed to flame radiation or flue gas erosion with a temperature greater than 800°C (unless otherwise approved), the form shall be as specified in Figure 1. The rounding radius of the plate edge shall not be less than 0.58, the surface roughness Ra<25um, and there shall be no notches perpendicular to the weld. <3
The minimum angle in Figure 1a shall be connected with the maximum radius R=10mm, and the maximum angle shall be connected with the minimum radius R=.5mm. 3.4 During the assembly of the main body, the components shall be assembled naturally and shall not be assembled by force to avoid assembly stress. Approved by the National Technical Committee for Ship Standardization on November 19, 1988 and implemented on May 1, 1989
CB*3348-88
3.5 When welding after the components are assembled, measures shall be taken to prevent deformation. 3.6 After the boiler is assembled and positioned, the deviation values ​​of the spacing of the full tube plate, the center of the tube hole, and the center of the furnace hole shall comply with the provisions of Table 1. Table 1
Tube sheet spacing L
.1 000
1000~2000
>2 000
Spacing deviation △L
After the main body is assembled, the flatness of the tube sheet shall not exceed the requirements of Table 2. Table 2
Nominal inner diameter
Plate surface
1000-1500
3.8 The smoke tube and the tube sheet are connected by welding. Deviation of center line of tube hole
1 500~1800
Deviation of center line of furnace
>1800~2200
>2 200
3.8.1 When the tube end is exposed to flame or the flue gas temperature is greater than 800℃, the smoke tube must be pre-expanded before welding, and slightly expanded after welding to eliminate the barrier between the tube end and the tube hole wall. The length of the tube end protruding from the tube sheet shall not exceed the height of its welding angle, see Figure 2a. 3.8.2 When the tube end is not exposed to flame or the flue gas temperature is less than 800℃, the length of the tube end protruding from the tube sheet shall not exceed the height of its welding angle by 3mm, see Figure 2b.
Welding angle equal deer
3.9 The furnace tube and the tube sheet are expanded.
3.9.1 The tube ends of the furnace tubes shall be annealed, and the annealing length shall not be less than 100mm. 3.9.2 Before the tubes are expanded, the outer surface of the tube ends shall be evenly polished to a metallic luster. The polishing length shall be greater than 2 times the thickness of the tube sheet and not less than 50mm. After polishing, there shall be no defects such as peeling, dents, interlayers, cracks and longitudinal grooves. 3.9.3 The expansion rate should generally be controlled within the range of 1%~2.1%. The expansion rate is calculated according to the following formula: 2
Wherein: H
-Expansion rate, %;
CB*3348—88
d,-The measured inner diameter of the tube after expansion, mm; d2-The measured inner diameter of the tube before expansion, mm; d,-d2-4
d3-The measured diameter of the tube hole before expansion, mm; 4-The difference between the measured diameter of the tube hole before expansion and the measured outer diameter of the tube, mm. 3.9.4 Before expansion, all dirt and rust in the tube holes should be cleaned up. During the expansion process, dirt or oil should be prevented from entering the expansion surface. The transition from the expanded part to the unexpanded part should be uniform and smooth. 3.9.5 The length of the tube end extending out of the tube sheet before expansion shall comply with the provisions of JB1622. 3.9.6 The plate edge taper angle of the bell mouth of the tube end shall not be less than 30°, and shall begin to tilt 0 to 2 mm from the point where it extends into the tube sheet hole. There shall be a clear boundary from the expanded part to the bell mouth part, but there shall be no obvious cut, see Figure 3a. 3.9.7 When the flue gas temperature at the expansion mouth is greater than 800°C, the expanded tube is 90° plate edge, the edge of the flange is close to the tube sheet, the maximum gap shall not exceed 0.4mm, and the gap length shall not exceed 20% of the tube circumference, see Figure 3b. >30*
3.9.8 When the tube is expanded in a tube hole that is not perpendicular to the tube sheet, see Figure 4, the effective length of the tube attached to the tube hole shall not be less than 13mm.
The expansion of the pipe should not have the following defects:
CB*3348-88
The inner surface of the pipe end is rough, peeling, notched, cracked, etc.; a.
The pipe end has a crack after the flange is turned;
The edge has a fine crack longer than 2mm after the 90° flange is turned. c.
3.9.10 If the water pressure test fails, it can be re-expanded. The number of re-expansion times shall not exceed two times, but it shall still meet the requirements for expansion. 3.10 For bolted connections, the bolts shall not be subjected to excessive stress when tightening, such as hitting the wrench handle or using other methods to increase the wrench arm. The maximum wrench size allowed for threaded connectors of various diameters is shown in Table 3. Table 3
Thread diameter
Wrench length
Cover.
12，14
The sealing gasket between flanges must be coated with paint to prevent gasket and flange from sticking. When removing the gasket with smooth surface, the sealing surfaces of the manhole and hand hole shall not be damaged. The surface roughness R, <12.5um, may have slight circumferential notches, but no radial notches. 3.12
The internal accessories of the boiler should be reliably fixed and adapt to the expansion of the boiler. 3.13bZxz.net
3.14The lifting lugs and supports welded on the boiler body must be added with double plates. And 1 to 2 vent holes of not less than 6mm are set at appropriate positions on the double plates. The sharp corners of the double plates should have a rounded transition of not less than the plate thickness. 3.15All welded double plates and seat plates on the boiler shell should fit tightly with the boiler shell. 3.16Allowable deviation of flange on the boiler shell.
3.16.1The verticality 4h of the center line of the flange plane on the boiler shell butt pipe should not be greater than 2mm. The deviation Ae of the center position of the flange bolt hole: when the flange outer diameter is not greater than 100mm, it should not be greater than 1mm; when the flange outer diameter is greater than 100mm but not greater than 200mm, it should not be greater than 2mm; when the flange outer diameter is greater than 200mm, it should not be greater than 3mm. The deviation △H of the flange height H should not be greater than ±2mm, see Figure 5.
3.16.2 Water level gauge flange deviation, see Figure 6. Aa<±1.5mm, Ab<±1mm, △c<1mm, Ad<1mm4
CB*3348-88
3.16.3 The verticality 4f of the pipe joint on the boiler shell to the boiler shell is not greater than 1.5mm, see Figure 7. Figure 7
3.17 After the main body is assembled, the straightness of the boiler shell within each meter of length should not exceed 1.5mm, and the total length should not exceed 7mm. 3.18 After the boiler body is assembled, the deviation of the total length L shall not exceed +15mm, see Figure 8. L+
3.19· The interior of the boiler body should be cleaned in time during the assembly process. 3.20 After the boiler body is assembled, the shell surface is concave. When the depth is within 0.5~1mm, it should be smoothly transitioned; when it exceeds 1mm, it should be welded and smoothed, and when the protrusion height exceeds 1mm, it should be repaired and ground. CB*3348-88
3.21 The smoke box door and the smoke box frame should be reliably sealed, and the hinged smoke box switch should be flexible. 3.22 Paint and insulation packaging shall be carried out after passing the inspection of 4.1; 4.2; 4.3; 4.4. The paint and insulation packaging of the boiler body shall comply with the provisions of CB*3347. 4 Inspection rules
4.1 The inspection department shall conduct inspection according to the drawings and the provisions of this technical condition. 4.2 The welds should be inspected according to the provisions of GB11038. 4.3 The hydraulic test shall be carried out in accordance with the provisions of GB11037. 4.4 After the boiler body has passed the inspection, the mark shall be printed in accordance with the requirements of GB11038 and the parts specified by the ship inspection department. Additional remarks:
This standard was proposed by the 603rd Institute of China State Shipbuilding Corporation. This standard is under the jurisdiction of the 704th Institute of the 7th Research Institute of China State Shipbuilding Corporation. This standard was drafted by Qingdao Marine Boiler Factory and Qingdao Branch of the Ship Inspection Bureau. The 603rd Institute, Shazhou Marine Boiler Factory and Nanjing Branch of the Ship Inspection Bureau participated. The main drafters of this standard are Zhang Qing, Zhang Zhongbo, Zhong Chongxin, Jing Guohua and Ji Sui.
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