Loose flanges (slip-on flanges), featuring flexible installation, easy centering, compensation for minor pipeline deviations, and labor-saving disassembly for maintenance, are a common pipeline connection method for ultraviolet (UV) disinfectors. They are core-adapted to working conditions such as large on-site pipeline deviations, frequent disassembly and maintenance, butt joint of pipelines with different materials, and large-caliber/high-pressure operations, and are particularly suitable for the on-site construction characteristics of secondary water supply and sewage treatment in the water treatment industry. The following are the specific applicable scenarios, selection basis, and a clear adaptation boundary with fixed flanges.
I. Core Applicable Scenarios (Prioritize Loose Flange Connections)
1. Severe installation deviations in on-site pipelines that make precise centering difficult
This is the most core application scenario for loose flanges. Affected by civil engineering and pre-phase pipeline laying, on-site construction is prone to pipeline coaxiality deviation, slight angular offset, and uneven axial clearance (e.g., pump room renovation, butt joint of old pipelines with new equipment). The loose sleeve structure of loose flanges allows fine position adjustment within a certain range, enabling precise butt joint between the disinfector and on-site pipelines without re-cutting or welding pipelines. This avoids stress on equipment interfaces and seal failure caused by rigid connection, and reduces the workload of on-site secondary construction.
2. Working conditions requiring frequent disassembly, cleaning and maintenance of the disinfector
The core maintenance work of UV disinfectors includes quartz sleeve cleaning, lamp tube replacement and internal overhaul, which requires regular disassembly of inlet and outlet pipelines. Loose flange connections allow separation of pipelines and equipment only by loosening bolts. Compared with welding and fixed flanges (with high disassembly requirements), they are more convenient and efficient to disassemble, and are suitable for all scenarios requiring daily maintenance, especially:
Sewage treatment scenarios (poor water quality, easy scaling of sleeves, and high cleaning frequency);
Small UV disinfectors without automatic cleaning function (requiring regular manual disassembly and cleaning);
Compact spaces in secondary water supply pump rooms (insufficient operating space for complex disassembly).
3. Butt joint scenarios of pipelines with different materials
When the inlet and outlet of the UV disinfector need to be connected to pipelines of different materials (e.g., stainless steel pipelines of the disinfector body → on-site carbon steel/UPVC pipelines, stainless steel pipelines → cast iron pipelines), loose flanges can adapt to the butt joint requirements of pipelines with different materials by replacing matching gaskets (e.g., nitrile rubber, fluororubber). At the same time, they avoid stress generated by pipelines during heating/cooling due to different thermal expansion coefficients of materials, which may damage equipment interfaces or seals.
4. Water treatment working conditions with large caliber and medium-high pressure
Applicable to UV disinfectors with a large caliber of DN80 and above (e.g., channel/tubular disinfectors in sewage treatment plants, large-scale secondary water supply pressurization systems) and pipeline systems with a working pressure of ≥0.6MPa:
Large-caliber pipelines: The centering difficulty of loose flanges is much lower than that of fixed flanges, making on-site installation more efficient and avoiding concentricity errors in rigid connection of large-caliber pipelines;
Medium-high pressure: The sealing structure of loose flanges (matched with high-pressure gaskets) can ensure sealing reliability, and at the same time disperse the impact of pipeline pressure on the equipment body, suitable for municipal sewage main pipelines and high-pressure pipelines for high-rise secondary water supply.
5. On-site construction scenarios without welding/ hot work conditions
Such as high-rise building pump rooms, underground enclosed spaces, and flammable and explosive areas (e.g., sewage treatment stations in chemical parks), where welding and hot work are prohibited on-site. Loose flanges adopt a bolt connection type, which can be directly assembled on-site without hot work, complying with safe construction specifications, and avoiding fire risks and pipeline deformation caused by hot work.
6. Working conditions requiring capacity expansion, transformation and equipment relocation in the later stage
If the project has requirements for pipeline capacity expansion, disinfector relocation, and equipment upgrade and replacement in the later stage, loose flange connections enable quick disassembly and re-butt joint without damaging the original pipelines, greatly reducing the transformation cost and construction period. They are suitable for projects with later adjustment requirements such as newly built water plants and park supporting water treatment facilities.
