CB/T 3708-1995 Technical requirements for repair of marine screw pumps
Some standard content:
Shipbuilding Industry Standard of the People's Republic of China
CB/T3708-1995
Technical Requirements for Repair of Marine Screw Pumps
Published on December 19, 1995
Published by China State Shipbuilding Corporation
Implemented on August 1, 1996
Shanghai Shipbuilding Industry Standard of the People's Republic of China
Technical Requirements for Repair of Marine Screw Pumps
1 Subject Content and Scope of Application
CB/T_3708-1995
Classification Number: R32
This standard specifies the inspection, repair, test and acceptance requirements for marine electric screw pumps (hereinafter referred to as screws). This standard applies to twin-screw pumps and three-screw pumps with a discharge pressure of less than 10MPa for liquids such as fuel, lubricating oil and hydraulic oil. It can also be used as a reference for screw pumps of other types or for conveying water and chemical media. 2 Reference standards
GB4323 Elastic sleeve pin coupling
GB11035 Marine electric twin-screw pump
CB/T3668 Technical requirements for brush plating nickel and copper 3 InspectionbZxz.net
3.1 Scope of inspection
3.1.1 For small-scale repairs, only the parts that are clearly specified by the shipowner for repair shall be disassembled and inspected. 3.1.2 For projects that require repair of the entire machine or major parts, a pre-repair test should be carried out first, followed by a disassembly inspection. 3.2 Pre-repair test
3.2.1 The pre-repair test can be carried out in any of the following ways: sailing with the ship, pre-repair sea trial or pre-repair mooring test. 3.2.2 During the test, the system to which the screw pump belongs should be in a stable operating state and reach the rated load or the maximum load that can be tolerated. During the test, observe and test the technical status of the screw pump before repair, including the following contents; a.
Parameters;
Test the speed, voltage and current of the motor. Test the discharge pressure, suction height, flow rate and medium temperature of the screw pump. b. Test the working condition of the bypass safety valve and test the starting pressure of the bypass safety valve; c. Test the heating, leakage, vibration and noise of the relative motion and matching working parts such as the pump housing, screw, transmission gear, bearing, sealing device and coupling;
d. For the mechanical failures and abnormal phenomena raised by the ship, and the abnormal phenomena found in the pre-repair test, key tests must be carried out, and the relevant technical parameters and operating conditions must be tested in detail and recorded. 3.3 Disassembly inspection
3.3.1 Disassemble all parts of the pump group according to the process regulations. 3.3.2 Use effective cleaning methods such as manual brushes, shovels or cleaning solvents to thoroughly clean the parts. 3.3.3 Carry out the following inspections on the wear, mechanical damage and corrosion of parts: b. Check whether the pump body has cracks or severe corrosion. If necessary, conduct a water pressure test at 1.5 times the working pressure to check for leakage; b. Measure the precise dimensions of the shaft diameter or hole diameter of the screw and pump body bushing, screw shaft and bearing bushing, transmission gear inner diameter, bushing outer diameter, rolling bearing inner and outer diameter, etc., determine the actual dimensional deviation and shape and position error and calculate the actual fit clearance. Then determine the repair scope according to the provisions of Table 1 and Table 2;
c. Measure the screw side clearance, transmission gear meshing clearance and driven screw axial thrust clearance; China Shipbuilding Industry Corporation approved on December 19, 1995 and implemented on August 1, 1996
CB/T3708-1995
d. For the main force-bearing parts, such as screws, transmission gears, couplings, etc., they should be carefully checked for cracks, serious deformation or other defects: for mechanical seals, bypass safety valves, thrust pads, rolling bearings and bases, their defects such as damage, mechanical damage, and deformation should be checked.
4.1 Principles for determining the repair plan for parts
4.1.1 When the repair standards are specified in the original technical documents provided with the machine, they should be followed. If there are no provisions in the random data or the original provisions cannot be found, repairs can be carried out in accordance with the provisions of Table 1 or Table 2. 4.1.2 After the parts have been inspected or repaired, the measured fit clearance or form and position errors shall be compared with the provisions of Table 1 or Table 2 to determine the repair plan.
Table 1 Main parts of commonly used screw pumps Repair requirements Screw pump model
Pump A-3GC50X3
Pump B3GC25×12
Three-screw pump
Pump C2HL10-40
THH4/1A
Two-screw pump
Pump DTMH100/A
Pump E2LB
Gap between active screw and pump bushing
Gap between driven screw and pump bushing
Gap between active screw and upper bearing bushing
Gap between active screw and lower bearing bushing
Gap between driven screw and lower bearing bushing
Axial clearance between upper end of driven screw
Screw Rod outer circle radial runout
Screw shaft journal degree and cylindrical degree
Screw and pump bushing degree
Screw thread meshing degree
Break rod and bearing bushing degree
Nominal size
New machine installation value
0.032~0.127
0.040~0.115
0.025~0.108
0.030~0.090
0.0080.043
0.020~0.063
0.025~0.077
0.016~0.052
0.020~0.063
0. 013~0. 043
1- 0~3+5
0. 200~ 0. 243
0.325~0.380
0.2000.250
0. 07~0. 10
0.25~ 0. 70
0.35~0.40
0.089~0.115
0.175~0.208
Use limit value
Radial runout of screw outer diameter
CB/T3708-1995
General repair requirements for three-screw pumps
Nominal shaft diameter
Roundness and cylindricity of screw bearing journal
Roundness and cylindricity of screw outer diameter
Screw and bearing Bushing distance
Screw and pump bushing distance
4.2 Pump body and pump bushing
>30~50
>50~80
>30~50
>50~80
>80~120
>50~80
>80~120
>120~180
>180~200
New machine installation value
0. 020~0.063
0.025~0.077
0.030~0.090
0. 040~0.110
0.07~0.13
0.08~0.14
0.14~0.22
0.18~0.28
Use limit value
4.2.1 When the pump body is cracked or severely corroded, it should be repaired by mature process measures such as welding, plate repair, bonding or metal buckling. If it cannot be repaired, it should be replaced. The repaired pump body should be subjected to a water pressure test of 1.5 times the working pressure, and the pressure should be maintained for 5 minutes without leakage. 4.2.2 When the pump body bushing is cracked or severely mechanically damaged, it should be replaced. If the above defects are minor, they can be repaired by scraping and grinding, and the pump can continue to be used after the defects are eliminated. 4.2.3 When the pump body bushing is obviously damaged, repair or replacement shall be determined according to Table 1 and Table 2. 4.3 Screw
4.3.1 If the threads and supporting working surfaces of the screw have slight scratches, burrs and other damage, they can be allowed to continue to be used after repair. 4.3.2
When the screw has cracks, deformation or other serious defects that cannot be repaired, it should be replaced. 4.3.3
When the shape and position error or fit clearance of the screw exceeds the use limit value specified in Table 1 or Table 2, it should be repaired or replaced. Defects on the supporting working surface of the screw can be repaired by chrome plating, brush plating or iron plating. Brush plating should comply with the provisions of CB/T3668.
4.4 Repair of bearings
4.4.1 When cracks or serious damage occur in the bearing bushing, it should be replaced. If slight damage and defects occur, it can be manually scraped and polished before continued use.
When the inner and outer diameter clearance of the bearing bushing exceeds the use limit value specified in Table 1 or Table 2, it should be repaired or replaced. When the outer circle of the bushing is loose, it can be repaired by brush plating or electroplating. 4.4.4 If one of the following conditions occurs in the rolling bearing, it should be replaced according to the original model and accuracy grade. B.
The rolling force-bearing part is obviously worn, the inner and outer circle matching surfaces of the bearing are worn and loose, and the bearing cannot be repaired. Overheating, discoloration, surface peeling or severe rust and other defects occur; b.
CB/T3708-1995
c. When the bearing is turned by hand, it is obviously loose, the rotation is uneven or there is an abnormal sound. 4.4.5 If there are defects such as roughening, scratches or grinding on the thrust bearing surface, it should be repaired by hand chain, sand or machining. The total runout of the working surface after repair should not exceed 0.01mm. 4.5 Shaft seal
4.5.1 The repair of mechanical sealing devices shall meet the following requirements: a. When the dynamic ring or static ring has defects such as wear or rust, it should be ground. If it is severely worn or broken, it should be replaced. After processing, the working surface roughness R, ≤ 0.2μm;
b. The working part of the shaft or sleeve is not allowed to have defects such as rust spots, burrs or scratches, and the surface roughness R, ≤ 3.2μm, and the radial runout should meet the requirements of Table 3
c. When the spring has defects such as breakage, deformation, rust, etc., it should be replaced. Table 3 Mechanical seal sleeve (or shaft) radial runout Shaft diameter
Radial runout
4.5.2 Packing seal device
4.5.2.1 After repair and disassembly, all soft packings should be replaced. >30~60
>60~80
>80~100
4.5.2.2 If the surface of the packing sleeve (or shaft) is slightly worn or scratched, it is allowed to continue to be used after polishing or sanding. In case of severe wear or mechanical damage, it should be replaced.
4.6 Elastic sleeve pin coupling
4.6.1 If the elastic ring has obvious wear, fragmentation or aging defects, it should be replaced according to the original model and specification. 4.6.2 If the elastic ring pin is rusted, deformed or loose, it should be replaced. 4.6.3 When the coupling body and the shaft neck or key are loose, the repair plan should be considered in combination with the mating parts. The clearance after repair should comply with the provisions of GB4323.
4.7 New parts
4.7.1 When parts are manufactured by professional manufacturers, they should be manufactured in accordance with the drawings and technical documents approved by the prescribed procedures, and a factory certificate of conformity should be issued.
4.7.2 The material selection, manufacturing and processing quality, and technical requirements for inspection and acceptance of self-made parts should comply with the provisions of GB11035. 5 Test and acceptance
5.1 After the screw pump is repaired, it should be tested for operation through the mooring test. 5.2 The test items include running-in adjustment test, bypass safety valve adjustment test and system effectiveness test. 5.2.1 The running-in adjustment test should be carried out at the rated speed, adjusting the opening of the discharge valve of the screw pump, and testing in the order specified in Table 4. After the running-in and adjustment test, the technical performance of the screw pump shall meet the requirements of Article 5.3. Table 4
Discharge valve fully open
1/2 rated discharge pressure
Rated discharge pressure
Test time
Test relevant technical parameters after the bearing temperature stabilizes 5.2.2 The bypass safety valve adjustment test is to gradually close the discharge valve of the pump at the rated speed, test and adjust the opening pressure of the bypass safety valve CB/T3708-1995
, the opening pressure is 1.1 to 1.15 times the rated working pressure, the test is not less than twice, and the lead seal acceptance is carried out after passing the test. 5.2.3 Cooperate with the system to carry out the effectiveness test to ensure that the system and mechanical equipment can work normally. The technical parameters and performance of the screw pump shall meet the requirements of Article 5.3.
5.3 When the screw pump is running under rated working conditions, it shall meet the following requirements: a.
The screw shall rotate easily and evenly without abnormal vibration and honking sound: The working temperature of the rolling bearing surface shall not exceed 75℃, and the temperature rise shall not exceed 35. The temperature of the stuffing box shall not exceed 70℃; the leakage of the mechanical seal shall not exceed 0.2mL/min, and the leakage of the stuffing seal shall not exceed 6mL/min. Additional remarks:
This standard was proposed by the Ship Repair Sub-Technical Committee of the National Technical Committee for Standardization of Marine Ships. This standard is under the jurisdiction of Tianjin Ship Repair Technology Research Institute. This standard was drafted by Jiangnan Shipyard. The main drafters of this standard are Yao Rongyuan and Chen Xinhua.The leakage of 2mL/min packing seal shall not exceed 6mL/min. Additional remarks:
This standard was proposed by the Ship Repair Sub-Technical Committee of the National Technical Committee for Standardization of Marine Ships. This standard is under the jurisdiction of Tianjin Ship Repair Technology Research Institute. This standard was drafted by Jiangnan Shipyard. The main drafters of this standard were Yao Rongyuan and Chen Xinhua.The leakage of 2mL/min packing seal shall not exceed 6mL/min. Additional remarks:
This standard was proposed by the Ship Repair Sub-Technical Committee of the National Technical Committee for Standardization of Marine Ships. This standard is under the jurisdiction of Tianjin Ship Repair Technology Research Institute. This standard was drafted by Jiangnan Shipyard. The main drafters of this standard were Yao Rongyuan and Chen Xinhua.
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