The alloy steel lap joint stub ends we produce cover materials including 12Cr1MoV, 15CrMo, Cr5Mo, Cr9Mo, P11, P12, P22, P91, P92 and other chrome-molybdenum heat-resistant alloy steels, and are manufactured according to GB/T12459, ASME B16.9, and MSS SP43 standards. The products are divided into two structures: LP long type (Type A) and SP short type (Type B). The forming processes include integrated stamping, seamless pipe precision machining, and large-diameter plate rolling, with a diameter range of DN15–DN3000. One end is a standard butt welding bevel for homogeneous fusion welding with the pipeline; the other end is formed by hot pressing or CNC turning into a flat lap joint surface, which, combined with a loose flange, can rotate freely for alignment, solving problems such as on-site misalignment during butt jointing of high-temperature pipelines, fixed equipment nozzles, and difficult installation in confined spaces. It is suitable for scenarios such as thermal power main steam pipelines, reheat steam pipe networks, high-temperature pipelines of supercritical units, petrochemical hydrogen-facing reaction pipelines, and high-pressure boiler supporting pipelines.
Overview
Alloy steel lap joint stub ends are a type of special pipe fitting used for lap joint connections in high-temperature and high-pressure pipelines. One end is a standard butt welding bevel, which is homogeneously welded with alloy steel pipes to ensure matching weld metal and consistent high-temperature mechanical properties; the other end undergoes hot-press forming or CNC precision turning to form a flat and dense lap joint sealing surface, which can rotate 360° freely for alignment when used with a loose flange. This structure mainly solves problems such as on-site misalignment during butt jointing of high-temperature pipelines, fixed equipment nozzles, difficult installation in confined spaces, and sealing failure caused by high-temperature deformation. The materials of the lap joint stub ends we produce cover 12Cr1MoV, 15CrMo, Cr5Mo, Cr9Mo, P11, P12, P22, P91, P92 and other chromium-molybdenum heat-resistant alloy steels, manufactured according to GB/T12459, ASME B16.9, and MSS SP43 standards, with a diameter range of DN15–DN3000, divided into two structures: LP long type and SP short type.
Key Features
The chromium-molybdenum alloy elements give the pipe fitting a slower rate of high-temperature strength decay in environments of 450℃–650℃, allowing it to withstand pressure for long periods without easily developing softening deformation or cracking and leakage. The product undergoes normalizing and tempering heat treatment to eliminate processing stress, has a uniform metallographic structure, and has good resistance to cold-hot alternating and start-stop fatigue. Structurally, the LP long type separates the welding heat zone from the sealing surface, making it suitable for main steam high-pressure main pipe networks; the SP short type is more economical and lightweight, suitable for installation positions with compact space. The butt welding end is homogeneously welded with the pipeline, and the lap joint end can rotate for alignment with a loose flange, making installation and maintenance disassembly and assembly relatively convenient. In terms of material selection, 15CrMo and P11 are suitable for medium-temperature working conditions, 12Cr1MoV and P22 are the main materials for power stations, Cr5Mo and Cr9Mo are suitable for hydrogen-contacting desulfurization environments, and P91 and P92 are used for ultra-high-temperature and ultra-high-pressure units above 600℃.
Applications
In the power and thermal power sector, it is suitable for main steam pipelines of thermal power plants, reheated steam pipe networks, high-temperature pipelines of supercritical and ultra-supercritical units, high-pressure pipelines at boiler inlets and outlets, and high-temperature auxiliary pipe networks of power stations. In the petrochemical and refining sector, it is used for crude oil heating devices, hydrogen-contacting reaction pipelines, high-temperature sulfur-containing medium transportation, external pipelines of heating furnaces, and continuous high-temperature process pipe networks. In the industrial special equipment sector, it is suitable for high-pressure boiler supporting pipelines, high-temperature circulating pipelines of thermal units, and high-temperature heat exchange equipment connections, etc. In addition, scenarios such as old power station pipe network renovation, connection to imported high-temperature equipment, and non-standard parameters of special process pipelines can also be customized according to drawings or technical agreements. It should be noted that this product is designed for high-temperature, high-pressure, and hydrogen-contacting working conditions, and is not suitable for normal-temperature corrosive working conditions.
Specifications
Materials cover the full series of chromium-molybdenum heat-resistant alloy steels: 12Cr1MoV, 15CrMo, Cr5Mo, Cr9Mo, P11, P12, P22, P91, P92. Structures are divided into LP long type (Type A) and SP short type (Type B). Diameter range is DN15–DN3000, and forming processes include integrated stamping, precision turning of seamless pipe, and rolling and welding of large-diameter plates. The implemented standards are GB/T12459, ASME B16.9, and MSS SP43. Customization is supported for non-standard diameters, non-conventional straight pipe lengths, widened and thickened sealing surfaces, and special wall thicknesses. For the minimum order quantity and delivery cycle corresponding to specific specifications, please contact us to confirm.
Procurement & Delivery
We set up tiered minimum order quantities, which can adapt to different procurement scenarios such as sample submission for inspection, engineering replacement parts, bulk centralized procurement, and foreign trade distribution. For conventional stamping and pipe-made specifications from DN15–DN300, heat treatment re-inspection, high-pressure precision inspection, and protective packaging are completed within 48 hours after order confirmation. The product adopts foreign-trade-grade protective packaging: each piece is fully enclosed and wrapped with PE film, the sealing surface is covered with an anti-scratch protective film, and the bevel is equipped with an anti-collision protective ring; small pieces are packed into thickened moisture-proof cartons with built-in desiccant; medium and large diameter products are wrapped on the outer layer with pearl cotton and waterproof stretch film; full-container orders are stacked on fumigation-free solid wood pallets, fastened with steel straps, and fully sealed with waterproof wrapping, suitable for ocean shipping. Customized English shipping marks, customer LOGO, and batch numbers are supported. For specific delivery times and minimum order quantities, please contact us to confirm.
Service & Support
In the pre-sales stage, we can assist with high-temperature working condition selection, heat-resistant material matching, pressure rating adaptation, and flange matching confirmation, helping to reduce selection deviations. Before leaving the factory, the product undergoes inspection steps such as alloy spectral verification, heat treatment process re-inspection, precise dimensional re-measurement, end face flatness testing, hydrostatic pressure testing, and non-destructive testing. The warranty period is 18 months. During the warranty period, problems caused by factory production quality defects are supported with free return and exchange and free replacement. After-sales service provides technical Q&A on alloy steel welding processes, heat treatment protection, and high-temperature pipe network operation and maintenance. Orders can be tracked logistically throughout the process, and we assist overseas customers with customs clearance. If you have special working conditions or non-standard requirements, you are welcome to contact us for communication and confirmation.
FAQ
What working conditions are alloy steel lap joint stub ends suitable for?
This product is specially designed for high-temperature, high-pressure, hydrogen-contacting, sulfur-containing, and thermal creep working conditions, and is suitable for thermal power main steam pipelines, reheated steam pipe networks, petrochemical and refining hydrogen-contacting pipelines, high-pressure boiler supporting pipelines, etc. It is not suitable for normal-temperature corrosive working conditions. If your working conditions involve a high temperature of 450℃–650℃ or a hydrogen-contacting environment, you are welcome to contact us to confirm the specific material and structural selection.
How to select materials for different applications?
15CrMo and P11 are suitable for medium-temperature working conditions; 12Cr1MoV and P22 are the mainstay materials for power plants, used for high-temperature heavy-duty pipelines; Cr5Mo and Cr9Mo are suitable for hydrogenation desulfurization environments; P91 and P92 are used for ultra-high-temperature and ultra-high-pressure units above 600°C. Specific selection needs to be combined with design temperature, design pressure, and medium characteristics. Please contact us to provide working condition parameters so we can assist in confirmation.
What is the difference between LP long type and SP short type?
The LP long type (Type A) has a longer straight pipe section, which can separate the welding heat zone from the lap sealing surface, making it suitable for positions with high requirements for sealing surface protection, such as main steam high-pressure main pipe networks. The SP short type (Type B) has a more compact structure and lighter weight, making it suitable for installation positions with limited space. Both structures are used with loose flanges. Which one to choose specifically needs to be determined according to pipeline layout and installation space.
How are minimum order quantity and delivery time confirmed?
We set tiered minimum order quantities, which can adapt to different scenarios such as sample submission for inspection, engineering supplementary parts, and bulk centralized procurement. For DN15–DN300 conventional stamping and pipe-made specifications, heat treatment re-inspection, high-pressure precision inspection, and protective packaging are completed within 48 hours after order confirmation. For the minimum order quantity and delivery time of specific specifications, please contact us and provide the required diameter, material, and quantity, and we will assist in confirmation as soon as possible.
Do you support non-standard customization?
Yes. We can customize non-standard diameters, non-conventional straight pipe lengths, widened and thickened sealing surfaces, and special wall thicknesses according to customer drawings, samples, or technical agreements. We can also provide process customization such as precision zero-tolerance finish turning, high-temperature quenching and tempering strengthening, and stress relief annealing. In terms of materials, we can customize the full series of chromium-molybdenum heat-resistant alloy steels such as 15CrMo, 12Cr1MoV, Cr5Mo, P22, P91, and P92. You are welcome to contact us to discuss specific customization requirements.
