Cleaning and Thermal Insulation of the Piping System
1) Preparation before cleaning
Before cleaning, it is necessary to select a suitable connection point, set a jumper on the system, and connect the system completely through the jumper to ensure that the cleaning liquid is in a closed circuit; a single system only has one outlet and one inlet. If the uniqueness of the entrance and exit cannot be guaranteed, a subsystem with only one entrance and exit for cleaning should be provided. The selected cleaning pump should include a bypass valve to adjust the flow rate or pressure, and the rated flow rate of the pump is greater than the flow rate of the liquid in the process of system use. The filter should use a variable precision oil return magnetic filter with a globe valve and cannot be bypassed. The cleaning medium is the working medium of the system, or the cleaning medium recommended by the equipment manufacturer. It should be compatible with the working medium of the system, and should be easy to clean and corrosion-resistant.
2) Gas cleaning of the piping system
Blow the pre-cleaned pipe system with clean and dry compressed air, and at the same time tap the pipe joints and corners with a rubber hammer to remove impurities such as welding slags attached to the pipe until no obvious iron filings are blown. Then put the sponge column matching the pipe diameter into the inlet of the piping system, and use compressed air to push the sponge column to blow from the outlet. Repeat the above steps until the surface of the blown sponge column is free of impurities.
3) Liquid cleaning of piping systems
At the beginning of cleaning, the flow rate of the liquid is controlled at 10 to 12 m/s, and a filter screen with 77 to 109 µm is used; then, gradually increased, and finally reaches the filter screen’s precision required by the system cleaning or meets the precision requirements of the equipment manufacturer. After starting cleaning, the time for the first two disassembly and inspection of the filter should not be too long. It is recommended to carry out the first disassembly and inspection for about 10 minutes. When the precision of the filter screen reaches the precision required by the manufacturer, and the cleanliness of the filter screen is similar for three consecutive times, it can be considered qualified for the time being. After marking, keep it sealed and send it to the testing center for testing. At this time, according to the requirements, the liquid washed in series is sampled before the filter. After marking, keep it sealed and send it to the testing center for testing.
Heat insulation of piping systems
In order to reduce energy loss and prevent the physical state change of the medium in the pipe due to the heat exchange with the outside world, some of the surfaces of the pipe system need to be wrapped with cotton for heat insulation. This work should be carried out under the condition that the accessories have been restored after the series washing of the piping system is completed. The thermal insulation structure is generally divided into a thermal insulation layer and a protective layer. When the thermal insulation layer is laid, the joints should be well sealed; the filling should be even, and the binding should be firm. For piping systems with multiple layers of heat insulation, the longitudinal and circumferential joints must be staggered from the previous layer. For the longitudinal weldings at the two adjacent ends of the semi-tubular heat insulation layer, the longitudinal welding seam needs to be staggered, and an 18-gauge galvanized annealed steel wire is bundled at an interval of 200 mm. The wire used for tying is to be taut; the excess wire ends are cut, and the wire ends are bent inside the insulation. The protective layer is generally glass fiber cloth. If necessary, it can be painted twice. After the protective layer is constructed, tightness and firmness must be ensured, and the appearance should be beautiful. The exposed pipelines in open-air spaces and cabins frequently visited by personnel shall be covered with stainless steel sheets of 0.5 mm outside the glass fiber cloth. The blind rivets are fastened at intervals of 200 to 250 mm according to the actual position on site.
Before cleaning, it is necessary to select a suitable connection point, set a jumper on the system, and connect the system completely through the jumper to ensure that the cleaning liquid is in a closed circuit; a single system only has one outlet and one inlet. If the uniqueness of the entrance and exit cannot be guaranteed, a subsystem with only one entrance and exit for cleaning should be provided. The selected cleaning pump should include a bypass valve to adjust the flow rate or pressure, and the rated flow rate of the pump is greater than the flow rate of the liquid in the process of system use. The filter should use a variable precision oil return magnetic filter with a globe valve and cannot be bypassed. The cleaning medium is the working medium of the system, or the cleaning medium recommended by the equipment manufacturer. It should be compatible with the working medium of the system, and should be easy to clean and corrosion-resistant.
2) Gas cleaning of the piping system
Blow the pre-cleaned pipe system with clean and dry compressed air, and at the same time tap the pipe joints and corners with a rubber hammer to remove impurities such as welding slags attached to the pipe until no obvious iron filings are blown. Then put the sponge column matching the pipe diameter into the inlet of the piping system, and use compressed air to push the sponge column to blow from the outlet. Repeat the above steps until the surface of the blown sponge column is free of impurities.
3) Liquid cleaning of piping systems
At the beginning of cleaning, the flow rate of the liquid is controlled at 10 to 12 m/s, and a filter screen with 77 to 109 µm is used; then, gradually increased, and finally reaches the filter screen’s precision required by the system cleaning or meets the precision requirements of the equipment manufacturer. After starting cleaning, the time for the first two disassembly and inspection of the filter should not be too long. It is recommended to carry out the first disassembly and inspection for about 10 minutes. When the precision of the filter screen reaches the precision required by the manufacturer, and the cleanliness of the filter screen is similar for three consecutive times, it can be considered qualified for the time being. After marking, keep it sealed and send it to the testing center for testing. At this time, according to the requirements, the liquid washed in series is sampled before the filter. After marking, keep it sealed and send it to the testing center for testing.
Heat insulation of piping systems
In order to reduce energy loss and prevent the physical state change of the medium in the pipe due to the heat exchange with the outside world, some of the surfaces of the pipe system need to be wrapped with cotton for heat insulation. This work should be carried out under the condition that the accessories have been restored after the series washing of the piping system is completed. The thermal insulation structure is generally divided into a thermal insulation layer and a protective layer. When the thermal insulation layer is laid, the joints should be well sealed; the filling should be even, and the binding should be firm. For piping systems with multiple layers of heat insulation, the longitudinal and circumferential joints must be staggered from the previous layer. For the longitudinal weldings at the two adjacent ends of the semi-tubular heat insulation layer, the longitudinal welding seam needs to be staggered, and an 18-gauge galvanized annealed steel wire is bundled at an interval of 200 mm. The wire used for tying is to be taut; the excess wire ends are cut, and the wire ends are bent inside the insulation. The protective layer is generally glass fiber cloth. If necessary, it can be painted twice. After the protective layer is constructed, tightness and firmness must be ensured, and the appearance should be beautiful. The exposed pipelines in open-air spaces and cabins frequently visited by personnel shall be covered with stainless steel sheets of 0.5 mm outside the glass fiber cloth. The blind rivets are fastened at intervals of 200 to 250 mm according to the actual position on site.
