Loose flange LJ
LJ loose flange is a split-type movable pipe connection fitting, used in combination with a loose flange plate and a flanged short piece; the short piece is welded and fixed to the pipe, and the flange plate can rotate freely. It is mainly used for pipe docking, equipment port connections, anti-corrosion pipeline connections, and piping systems that require frequent disassembly and maintenance. The flange plate does not directly contact the conveyed medium; only the flanged short piece contacts the fluid, making it highly suitable for conveying corrosive media, seawater, and acid-base fluids. It is widely used in chemical anti-corrosion pipelines, water treatment and environmental protection pipelines, clean pipelines for food and pharmaceuticals, ship seawater pipelines, and municipal water supply and drainage projects. It is suitable for pipeline scenarios involving minor misalignment adjustment, difficulty in aligning bolt holes, and the need for repeated disassembly, assembly, and maintenance, and is a core supporting connection component of anti-corrosion industrial piping systems.
Inquiry
- The biggest core advantage of LJ loose flange is cost saving and anti-corrosion, flexible installation, and zero alignment error. The split structure can realize the combination of "carbon steel flange plate + stainless steel short pipe",
- No need for all-stainless steel tube
- greatly reducing the raw material cost of high-end anti-corrosion projects. The flange plate rotates freely 360°,
- perfectly solving the problems of misaligned pipe holes and installation misalignment,
- greatly improving construction efficiency. It is formed by integral forging process,
Detailed Introduction
Loose flange LJ (code LJ) adopts a two-piece structure: the stub end is fixed to the pipe by butt welding, and the movable flange ring is loosely fitted on the outer ring, capable of 360-degree rotation, relying on bolts and gaskets to complete the sealed connection. This design keeps the flange ring from directly contacting the conveyed medium, so in corrosive pipelines, only the stub end needs to use stainless steel or special alloy, while the flange ring can use carbon steel, which can significantly reduce material costs. At the same time, the flange ring can rotate freely, solving the problem of difficult bolt hole alignment on site, making installation and maintenance more convenient. The product complies with standards such as ASME B16.5, GB/T9120-9122, HG/T20592, etc., covering DN15-DN600 (NPS1/2"-24"), pressure ratings Class150-600LB, PN6-PN40, suitable for low and medium pressure working conditions such as chemicals, water treatment, food and pharmaceuticals, ship seawater pipelines, etc. Guojie provides full-size stock and customization services, supports mixed-batch purchasing, and comes with comprehensive after-sales service.
- Split-type structure, the flange ring does not contact the medium, carbon steel flange can be paired with stainless steel stub end, greatly saving precious metal costs
- The flange ring can rotate freely 360 degrees, easily solving the bolt hole alignment problem and improving installation efficiency
- Integral forging process, stable structure, reliable sealing performance, suitable for low and medium pressure anti-corrosion pipelines
- Disassembly and assembly require no pipe cutting, later inspection and maintenance are convenient, reducing operation and maintenance costs
- Complies with mainstream standards such as ASME, GB, HG, etc., diameter DN15-DN600, pressure Class150-600LB/PN6-PN40
- Supports non-standard customization, free combination of materials and sealing face forms, and provides export packaging and fast delivery
| Product Name | Loose Flange LJ |
| Product Category | Contact Us to Confirm |
| Standard | ASME B16.5, GB/T9120, HG/T20592, EN1092-1; nominal diameter: DN15-DN600 (NPS1/2″-24″); pressure rating: Class150/300/600LB, PN6-PN40; structural form: butt welding ring, flat welding ring, lap joint stub end combined type; sealing face: RF, FF, customizable MFM/TG; process: integral forging, precision turning, non-destructive testing; connection method: stub end butt welding + flange bolt fastening; working temperature: carbon steel -20℃~425℃, stainless steel -196℃~600℃; suitable media: seawater, acid and alkali, sewage, room temperature fluids. All parameters strictly benchmark against international standards, |
| Customization | Our factory possesses full-dimensional LJ loose flange non-standard customization capabilities, and can customize special large-diameter, non-standard wall thickness, irregular hole spacing, and special eccentric structure loose flanges. Supports free pairing of different material flange plates and stub ends, achieving special combination customization of carbon steel with stainless steel and duplex steel. Can perform special sealing surface machining, sandblasting and rust removal, hot-dip galvanizing, epoxy anti-corrosion, and acid and alkali resistant coating treatment. Can reverse-customize irregular loose flanges according to customer drawings, samples, and engineering parameters. Supports laser marking, LOGO engraving, OEM production, and exclusive packaging customization. Can produce low-temperature steel, duplex steel, nickel-based alloy and other high-end special products, adapting to overseas high-end anti-corrosion engineering and special equipment customization needs. |
| MOQ | Our factory's LJ loose flanges adopt an ultra-low flexible minimum order mode. The MOQ for conventional standard in-stock specifications is as low as 1 piece, meeting the needs of sample testing, equipment repair, engineering material replenishment, and small-order trial orders. Commonly used carbon steel and stainless steel conventional DN25-DN200, Class150/300, PN16/PN25 specifications on the market support scattered purchasing, mixed batches of multiple specifications, and combined |
| Lead Time | Conventional national standard and American standard in-stock LJ loose flanges have sufficient inventory. Commonly used specifications can be shipped quickly within 24 hours, efficiently solving customers' urgent order and replenishment needs. The production lead time for standard batch conventional orders is 3-7 working days, with stable and efficient shipment. The lead time for ordinary non-standard orders involving size changes, hole changes, and sealing surface changes is 7-10 working days. Large-diameter extra-large specifications, duplex steel special materials, special |
| Packaging | Our factory's LJ loose flanges adopt standardized multi-layer protective packaging for foreign trade export, strictly ensuring the safety of long-distance sea and land transportation. The flange sealing surface is pasted with anti-scratch and anti-dust protective film to prevent collisions, scratches, oxidation, and rust; each piece is individually wrapped with thickened bubble film to avoid friction damage between products. Conventional specifications are classified and packed into high-strength export cartons. Large-volume full orders are packed using fumigated solid wood pallets, reinforced overall with steel straps, with a stable structure that is not easy to scatter. The outer box is clearly printed with product model, standard, material, specification, pressure, quantity, batch, and export shipping marks. Supports customer-customized neutral packaging, LOGO OEM, exclusive shipping marks, and custom packaging boxes, fully complying with export commodity inspection, customs clearance, and overseas warehousing standardized packaging requirements. |
| Reference Price | Inquiry |
Applications
- Chemical acid and alkali transportation pipelines: used to connect corrosive medium pipelines, carbon steel flange + stainless steel stub end combination reduces cost
- Water treatment and environmental protection engineering: suitable for sewage, seawater desalination and other pipeline systems, corrosion-resistant and easy to disassemble and maintain
- Food and pharmaceutical clean pipelines: stub ends are made of stainless steel, meeting hygiene requirements, and the flange plate does not contact the medium and is easy to clean
- Ship and seawater pipelines: resistant to seawater corrosion, suitable for occasions with frequent maintenance
- Equipment interface and pipeline modification: resolving on-site installation deviations and the problem of difficult bolt hole alignment
Overview
The lap joint flange LJ is a two-piece pipe connection consisting of a loose flange plate and a stub end. The stub end is butt-welded and fixed to the pipe, while the flange plate is loosely fitted over the outer ring of the stub end and can rotate freely. This design prevents the flange plate from directly contacting the conveyed medium; therefore, in corrosive pipelines, only the stub end needs to be made of stainless steel or special alloy, while the flange plate can use carbon steel, thereby greatly reducing material costs. At the same time, the rotatability of the flange plate solves the problem of difficult on-site bolt hole alignment, making installation and maintenance more convenient. The product is suitable for medium- and low-pressure, normal-temperature industrial pipelines, and is especially suitable for scenarios such as chemical anti-corrosion, water treatment, food and pharmaceutical, and ship seawater pipelines.
Key Features
Cost-saving and anti-corrosion: the split structure allows a carbon steel flange plate to be paired with a stainless steel stub end, without the need to use stainless steel for the entire pipe, significantly saving precious metal costs. Flexible installation: the flange plate can rotate freely 360 degrees, easily aligning bolt holes, solving installation deviation problems, and improving construction efficiency. Reliable structure: integral forging process, stable structure, uniform pressure bearing, and good sealing performance. Convenient maintenance: disassembly and assembly do not require cutting the pipe, making later inspection and replacement convenient. Complete standards: complies with mainstream standards such as ASME, GB, and HG, with precise dimensions and strong interchangeability. Customization capability: supports customization of non-standard dimensions, material combinations, and sealing surface forms to meet special engineering needs.
Applications
The lap joint flange LJ is mainly used in medium- and low-pressure, normal-temperature anti-corrosion pipelines, including chemical acid and alkali transportation, seawater desalination, sewage treatment, food and pharmaceutical clean pipelines, and ship water supply and drainage, etc. It is especially suitable for occasions requiring frequent disassembly and maintenance and where bolt hole alignment is difficult. It should be noted that due to structural limitations, it is not suitable for main process pipelines with high temperature and high pressure, severe vibration, or alternating loads; for these working conditions, WN welding neck flanges are recommended.
Specifications
The implemented standards include ASME B16.5, GB/T9120-9122, HG/T20592, and EN1092-1. The nominal diameter range covers DN15-DN600 (NPS1/2"-24"), and the pressure ratings are Class150/300/600LB and PN6-PN40. Structural forms include butt-welded ring, slip-on welded ring, and flanged stub end combination types. The sealing surface defaults to RF or FF, and MFM/TG can be customized. Material combinations are flexible; a common combination is a carbon steel flange plate with a stainless steel stub end, and the specific materials can be selected according to the working conditions. Working temperature range: carbon steel -20℃~425℃, stainless steel -196℃~600℃. All parameters are benchmarked against international standards; please contact us to confirm the specific configuration.
Purchasing & Delivery
We provide flexible minimum order quantities. The MOQ for conventional standard specifications is as low as 1 piece, and we support sample testing, repair replenishment, and small trial orders. Commonly used specifications are sufficiently stocked and can be shipped within 24 hours; bulk orders have a delivery time of 3-7 working days; non-standard customized orders have a delivery time of 7-10 working days. Packaging adopts foreign trade export standards: the sealing surface is covered with a protective film, each piece is wrapped in bubble film, and the outer box or pallet is reinforced. Neutral packaging and LOGO branding are supported. You are welcome to provide your specific requirements, and we will assist in confirming the configuration and quotation.
Service & Support
All products undergo three quality inspections before leaving the factory to ensure they are defect-free. If there are quality problems, wrong shipments, or transportation damage, we support free replacement or return and exchange. We provide product parameter sheets, dimensional drawings, and selection guidance to assist with installation and connection. For long-term cooperative customers, services such as inventory custody and partial shipments can be provided. Products enjoy a warranty under normal working conditions, and after-sales rights protection is available for non-human-caused damage. If you have any technical questions, please feel free to contact us at any time.
FAQ
What are the main advantages of the lap joint flange LJ?
The core advantage of the Loose Flange LJ is that the flange plate does not contact the medium, so carbon steel flanges can be paired with stainless steel nipples, greatly saving the cost of precious metals. At the same time, the flange plate can rotate freely, making bolt hole alignment during installation convenient, and disassembly and maintenance easier.
Can the Loose Flange LJ be used for high-pressure pipelines?
The Loose Flange LJ is mainly suitable for medium and low pressure working conditions, and is not recommended for main pipelines with high temperature and high pressure, severe vibration, or alternating loads. For high-pressure working conditions, it is recommended to use WN welding neck flanges.
Can different materials be mixed and matched?
Yes. We support carbon steel flange plates paired with stainless steel nipples, or other material combinations, which can be customized according to your working condition requirements.
Do you support samples and small-batch purchases?
Yes. The MOQ for conventional standard specifications is as low as 1 piece. You can purchase samples for testing first, and mixed batches of multiple specifications are also supported.
What certificates are required for export?
We can provide a full set of quality certificates, such as 3.1/3.2 material certificates, as well as qualifications such as CE and ISO. For specific certificate requirements, please contact us to confirm.
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