Lap Joint Flange | Professional Non-Standard Custom Manufacturer
Lap joint flange, commonly known as loose flange, is a movable pipe connection fitting composed of a loose flange ring and a lap joint stub end. The flange can rotate freely for alignment without direct contact with the conveying medium. As a professional flange manufacturer based in Cangzhou, we specialize in producing standard lap joint flanges compliant with Chinese, American, German and Japanese standards. We also undertake customized non-standard lap joint flanges with large diameters, thickened walls, special bolt pitches and corrosion-resistant structures. We support drawing-based and sample-based customization with direct factory supply.
1. Structural Characteristics of Lap Joint Flange
The most prominent feature of the lap joint flange is weld-free sealing surface and free rotation. The complete structure consists of a lapped pipe end and a movable flange ring. The medium is completely borne by the stub end, while the flange ring only undertakes compression and fixation without contacting or corroding the internal fluid. During installation, the bolt hole position can be adjusted freely, effectively solving on-site pipe misalignment and angle deviation and greatly simplifying construction work.
Manufactured by integral forging, lap joint flanges feature flat surface, high toughness, excellent compression resistance and stable deformation resistance. Compared with ordinary welded flanges, lap joint flanges allow repeated disassembly and convenient maintenance and replacement without pipe cutting. They are highly suitable for piping systems requiring frequent inspection and disassembly, and serve as ideal matching fittings for corrosive pipelines and non-ferrous metal pipelines.
2. Common Materials and Specifications
We customize lap joint flanges with different materials according to pipeline media, corrosion degree and pressure conditions, fully adapting to complex working conditions such as weak acid, weak alkali, seawater and chemical corrosion:
- Carbon Steel Lap Joint Flange: 20#, Q235B, A105, 16Mn. Featuring high structural strength and cost performance, it is widely used in conventional water supply and drainage, ventilation and atmospheric oil and gas pipelines.
- Stainless Steel Lap Joint Flange: 304, 316L, 321, 2205 duplex steel. With outstanding acid, alkali and salt spray corrosion resistance, it is extensively applied in chemical, pharmaceutical, sewage treatment and seawater desalination pipelines.
- Non-ferrous Metal Matching Flange: Applicable for matching titanium, copper and aluminum alloy lapped pipes, perfectly adapting to special anti-corrosion pipeline projects.
Specification coverage: Conventional sizes DN15-DN3000 and customized large-diameter products; Pressure grades include PN10, PN16, PN25, PN40, PN64 and mainstream medium and low-pressure grades such as American standard Class150 and Class300.
3. Implementation Standards and Sealing Types
All our lap joint flanges are produced in strict accordance with domestic and international industry standards, suitable for domestic engineering projects and export orders. Core applicable standards include GB/T9122, HG/T20592, ASME B16.5, EN1092, JIS B2220 and more.
A full range of customizable sealing faces are available, mainly including RF (Raised Face) and FF (Full Face). The seal is realized by compressing gaskets through the lapped end face. Compatible with rubber gaskets, PTFE gaskets and spiral wound metal gaskets, it delivers stable sealing performance and convenient daily maintenance.
4. Working Conditions and Application Scope
With excellent corrosion resistance, flexible disassembly and easy on-site alignment, lap joint flanges feature economical cost and stable performance. They are mainly used for corrosive medium pipelines, non-ferrous metal pipelines, frequently disassembled pipelines and difficult on-site alignment projects:
- Chemical industry: Pipelines for acid and alkali corrosive media and supporting piping systems for chemical reaction equipment
- Environmental water treatment: Anti-corrosion pipelines for sewage treatment, seawater desalination and saltwater transportation
- Special pipelines: Connection of stainless steel, titanium, aluminum, copper and other non-ferrous metal pipelines
- Municipal engineering: Conveyance pipelines for corrosive sewage, industrial wastewater and chemical park media
- Equipment matching: Detachable tank interfaces and process pipelines requiring regular inspection and maintenance
5. Our Production and Customization Advantages
Equipped with complete production lines covering forging, CNC machining, precision polishing and quality inspection, we satisfy bulk wholesale of standard products and non-standard customized demands for various engineering projects:
1. Mature and stable technology: Integrally forged blanks and precision CNC turning ensure flat flange surface, accurate roundness and high symmetry of bolt holes, enabling easy on-site alignment and zero sealing deviation.
2. Powerful non-standard customization: We can customize lap joint flanges with large diameters, thickened walls, special shapes, exclusive bolt pitches and special pressure grades. No mold opening is required, and both small trial orders and large-scale engineering orders are acceptable.
3. Strict and traceable quality inspection: Each batch of products is equipped with material certificates and factory inspection reports. Dimension re-inspection and non-destructive testing are available on demand to meet the requirements of domestic project acceptance and export customs clearance.
4. High cost performance and stable delivery: Direct factory production ensures controllable quality. Sufficient stock for conventional specifications and stable production cycle for customized products will not delay project progress.
6. Common Purchasing FAQs
Q: What is the difference between lap joint flange and ordinary welded flange?
A: Lap joint flanges do not contact conveying media, support free rotation and require no end welding. They are easy to disassemble and maintain with better corrosion resistance, ideal for corrosive working conditions and non-ferrous metal pipelines. Ordinary welded flanges are fixed and non-rotatable, only suitable for conventional working conditions.
Q: Can you produce non-standard large-diameter lap joint flanges?
A: Yes, we support full-range non-standard customization. Lap joint flanges with extra-large diameters, thickened and widened structures, special pressure grades and special hole pitches can be precisely produced according to customer drawings.
Q: Can you provide complete acceptance documents?
A: We provide free complete documents including product certificates, material test reports, dimension inspection reports and NDT reports to support project acceptance and export customs clearance.
Inquiry & Cooperation
Whether you need in-stock standard lap joint flanges or custom non-standard loose flanges for engineering projects, simply provide your drawings, dimensions, materials and pressure parameters. Our technical team will verify specifications and calculate costs for free, and provide accurate quotations promptly. We welcome long-term cooperation with engineering companies, trading enterprises and terminal manufacturers worldwide.