The lap joint stub end is a core matching pipe fitting for industrial pipeline loose flange connection systems. It is mainly used together with slip-on loose flanges. One end is butt-welded and fixed to the pipe, and the other end is flange
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Lap joint stub ends are also called lap joint stub ends, loose flange rings, and belong to steel butt welding pipe fittings. One end is a standard butt welding bevel, welded and fixed to the pipe; the other end is stamped and precision-turned to form a flat flanged sealing surface, which is pressed together with a loose flange to achieve a detachable sealed connection. This structure allows the flange to rotate, making bolt hole alignment more flexible, and making on-site installation and later maintenance easier. Compared with using stainless steel or alloy flanges for the entire pipeline, lap joint stub ends only use corrosion-resistant material in the part that contacts the medium, while the flange can be made of ordinary carbon steel, significantly reducing material costs. We implement standards such as ASME B16.9, MSS SP43, GB/T12459, and our products are used in pipeline systems for petrochemical, power station thermal, ship and marine, pharmaceutical clean, environmental water treatment, and other industries. For specific diameters, wall thicknesses, materials, and pressure ratings, please contact us to confirm.
| Product Name | Stub End |
| Product Categories | Flanges & Stub Ends |
| Customization | Our factory has comprehensive high-end non-standard customization capabilities for lap joint stub ends, and can precisely match customization needs for various special sizes, special wall thicknesses, special materials, and extreme working conditions. Specification customization supports DN15–DN1200 arbitrary non-standard diameters, non-standard wall thicknesses, extended straight pipe sections, and widened flanged sealing surfaces, adapting to the connection dimensions of niche imported equipment and special pipeline renovation projects. Process customization can produce long pattern, short pattern thickened and reinforced versions, mirror-finish precision-turned sealing surfaces, and high-precision precision-machined styles, meeting the supporting requirements of high-end clean pipelines and high-pressure precision equipment. Material customization can undertake customization of special alloys such as 2205, 2507 duplex steel, 15CrMo alloy steel, C70600 copper-nickel alloy, Hastelloy, Inconel, etc., adapting to high-temperature, high-pressure, sea |
| MOQ | To adapt to the diversified procurement needs of foreign trade cross-border trial orders, sporadic engineering replenishment, batch supporting for equipment factories, and overseas warehousing stockpiling, our factory has set relaxed and flexible tiered minimum order quantity standards for lap joint stub ends, greatly lowering the threshold for cooperation with global customers. For conventional DN20–DN300 mainstream standard diameters, conventional wall thicknesses, and general-material in-stock models, the MOQ is as low as 1 piece, supporting overseas samples |
| Lead Time | Our factory has a dedicated stamping and precision machining production line for lap joint stub ends and a constant-temperature dust-proof finished product warehouse. Order production capacity is sufficient and scheduling is stable, precisely matching foreign trade shipping rhythms and domestic and international engineering delivery schedules. For conventional carbon steel and 304/316 stainless steel standard in-stock specifications, after payment confirmation, precision inspection, protective packaging, and ultra-fast outbound shipment are completed within 24–48 hours. Within 1000 pieces |
| Packaging | Our factory's lap joint stub ends use protective packaging dedicated to high-end foreign trade pipe fittings, specifically protecting the flanged sealing end face and welding bevel, preventing transportation collisions, wear, and rust, and adapting to long-distance logistics such as ocean shipping, international air freight, and cross-border land transport. Each individual product is wrapped independently in anti-static PE film, and the precision flanged end face is equipped with dedicated protective gaskets and bevel protective sleeves, strictly preventing scratches, collisions, and deformation of the high-precision sealing surface. Products are neatly packed by specification into thickened export cartons, with high-strength moisture-proof desiccant built in, effectively resisting oxidation and rust caused by high humidity and salt spray environments during sea transport. The outer layer of the carton is wrapped with waterproof stretch film for all-round reinforcement. Bulk full-order goods are uniformly stacked on fumigation-free solid wood pallets and secured tightly with high-strength strapping, preventing displacement due to transportation bumps and carton damage. All |
| Reference Price | Inquiry |
| Structure Type | Long pattern (LP), short pattern (SP); can be confirmed according to project requirements |
The lap joint stub end is a core pipe fitting in a lap joint flange connection system. One end is butt-welded to the pipe, and the other end is flanged to form a sealing surface, which cooperates with the lap joint flange to achieve a detachable connection. The flange can rotate, allowing flexible alignment of bolt holes, making it suitable for pipelines with limited on-site space or requiring frequent maintenance. Our lap joint stub ends are integrally formed by hot stamping of seamless steel pipes, with no splicing welds. The flanged end face is CNC finish-turned with high flatness. The products comply with standards such as ASME B16.9, MSS SP43, GB/T12459, etc., and are used in industrial pipelines for petrochemical, power station thermal, marine offshore, pharmaceutical clean, and environmental water treatment applications.
First, integrally stamped and formed, with no splicing welds or sand holes and gas pores, dense metallographic structure, and pressure resistance and impact resistance. Second, the flanged end face is CNC finish-turned and polished, with a flat sealing surface, reducing the risk of medium leakage. Third, used with matching lap joint flanges, the flange can rotate freely, bolt holes can be aligned at any position, and construction is convenient. Fourth, only the fitting body uses corrosion-resistant material, while the flange can use ordinary carbon steel, helping reduce the overall project material cost. Fifth, supports both long pattern (LP) and short pattern (SP) structures, selectable according to working conditions. Sixth, customizable non-standard diameters, extended straight pipe sections, widened sealing surfaces, and special alloy materials.
Lap joint stub ends are used for industrial pipelines that require detachable connections, corrosion resistance, or difficult on-site alignment. In the chemical field, they are suitable for acid and alkali pipelines, oil and gas transmission pipelines, and hydrogenation unit process pipelines; in the power field, they are used for boiler auxiliary equipment pipelines, high-temperature steam branch pipelines, and desulfurization and denitrification pipelines; in the marine offshore field, they cover marine seawater pipelines and platform transmission pipelines; in the pharmaceutical and food field, they are suitable for clean transmission pipelines and pure water aseptic pipelines; in the environmental protection and new energy field, they are used for anti-corrosion pipelines for sewage treatment, cooling pipelines for new energy equipment, and waste gas treatment pipelines. They are also suitable for outdoor open-air pipelines, equipment-dense and narrow spaces, and pipelines requiring regular disassembly, assembly, and maintenance.
Conventional diameters DN20–DN300, custom diameters DN15–DN1200. Structures are divided into long pattern (LP) and short pattern (SP). Materials can be selected from carbon steel (20#, A234 WPB, 16Mn, WPL6), stainless steel (304/304L/316/316L/321/310S), duplex steel (2205/2507/254SMO), alloy steel, and special alloys. Complies with standards such as ASME B16.9, MSS SP43, GB/T12459, HG/T21635, SH/T3408, etc. Parameters such as wall thickness and pressure rating are confirmed according to project requirements. Please contact us to provide specific dimensions and quantities so we can assist with a quotation.
For conventional DN20–DN300 standard in-stock models, MOQ is as low as 1 piece, supporting trial orders and small sporadic replenishment. For conventional carbon steel and 304/316 stainless steel standard in-stock specifications, after payment confirmation, fine inspection, protective packaging, and outbound shipment are completed within 24–48 hours. Packaging uses anti-static PE film, end face protective gaskets, bevel protective sleeves, thickened export cartons with built-in moisture-proof desiccant, and an outer waterproof stretch film. Bulk goods are stacked on fumigation-free solid wood pallets. Supports printing of shipping marks, LOGO, specification models, and batch numbers as needed. For specific delivery times and logistics solutions, please contact us for confirmation.
Pre-sales support includes specification selection, material and working condition matching, pressure rating adaptation, and installation and connection scheme guidance. After-sales support includes welding process guidance, lap joint flange assembly techniques, and technical Q&A for pipeline maintenance. After order shipment, full-process logistics tracking is provided, assisting overseas customers with customs clearance and receipt. The product warranty period is 18 months. During the warranty period, quality issues caused by non-human damage are repaired or replenished free of charge. 7×24-hour online after-sales response for foreign trade. If there are factory quality defects, dimensional deviations, material non-conformity, or sealing surface defects, free returns, exchanges, and replacements are supported.
Lap joint stub ends are mainly used with slip-on flanges to achieve detachable pipeline connections. The flange can rotate freely for alignment, making installation convenient. At the same time, low-cost carbon steel flanges can be used with corrosion-resistant pipe fittings, helping to save project costs.
For high-temperature and high-pressure, severely corrosive, or important process main pipelines, LP long pattern is recommended; for low-pressure and normal-temperature, water supply and drainage, or ordinary anti-corrosion pipelines, SP short pattern can be selected. For specific selection, please contact us, and we will assist in confirming based on operating condition parameters.
We use integrated stamping and forming, and the wall thickness is implemented according to standards. The entire series supports American standard high-pressure pound-class operating conditions. The specific pressure rating and wall thickness need to be confirmed according to your project parameters. Please contact us to provide operating condition information.
Conventional materials include carbon steel, 304/316 stainless steel, duplex steel 2205/2507, etc. Customized diameters cover DN15–DN1200, and non-standard wall thickness, extended straight pipe sections, widened sealing surfaces, and special alloys can be made. Please provide drawings or samples, and we will assist in confirming.
Regular DN20–DN300 standard in-stock models have an MOQ as low as 1 piece, and trial orders are supported. Regular carbon steel and 304/316 stainless steel standard in-stock specifications are shipped out within 24–48 hours after payment confirmation. For the lead time of non-standard customizations and bulk orders, please contact us to confirm.
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