SO hubbed slip-on flanges are mainly used for detachable sealed connections between pipe and pipe, pipe and valve, and pipe and equipment in industrial piping systems. During construction, the steel pipe is inserted into the flange bore and fixed by double-sided fillet welds on both the upper and lower sides, relying on the flange plate, sealing gasket, and bolts and nuts to achieve fastening and sealing. The hubbed structure effectively disperses pipeline stress and reduces the risk of weld cracking, and can be used for process pipelines with slight vibration and pressure fluctuations. It mainly conveys media such as clean water, circulating water, compressed air, ordinary oil products, low-pressure steam, and neutral process fluids. It is widely used in chemical, thermal, HVAC, municipal, and electromechanical installation projects, for pipe network connections, valve fixing, equipment nozzle connections, and sectional maintenance connections. Between plate slip-on flanges and butt-welding flanges, it is a cost-effective choice for conventional medium-pressure working conditions.

Slip-on flange with neck SO

Reference Price

Inquiry

The biggest advantage of SO hubbed slip-on flanges is the hubbed reinforcement structure, high strength, resistance to deformation, and excellent cost-effectiveness. Forged and integrally formed
Tapered neck transition structure effectively distributes pipe stress
Reduces the probability of weld fatigue cracking
the overall rigidity far exceeds that of ordinary plate-type slip-on flanges. The product has a flat end face, precise bolt holes, high perpendicularity, and stable sealing performance
and can withstand pressure fluctuations and slight pipeline vibration. Welding uses a simple fillet welding process

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Detailed Introduction

Weld neck flange (SO) is a detachable sealing component used in industrial piping systems to connect pipe to pipe, valves, or equipment. Its body has a short tapered neck; the pipe is inserted into the flange bore and then secured by fillet welding. This structure effectively disperses pipe stress and reduces the risk of weld cracking, and its overall rigidity and fatigue resistance are superior to those of slip-on flanges. The product complies with HG/T20592 (European standard PN system) and ASME B16.5 (American standard Class system) standards, and the sealing face can be provided in RF raised face, MFM male-female face, TG tongue-and-groove face, and other types. Materials cover carbon steel, alloy steel, and stainless steel, and pressure ratings cover PN10 to PN100 as well as Class150 to Class600. Weld neck flanges are suitable for medium-temperature and medium-pressure working conditions, and are not suitable for pipelines with extremely high temperature and high pressure or severe alternating loads. They achieve a good balance between installation convenience and structural strength, and are a commonly used flange type in industrial piping projects. We provide stock in multiple specifications and materials, and support non-standard customization. Welcome to contact us for detailed parameters and quotations.

Neck-reinforced structure, high strength, deformation resistance, superior to slip-on flanges
Tapered neck transition disperses stress and reduces the risk of weld fatigue cracking
Fillet welding process, simple construction, fast installation speed, low labor cost
Flat sealing face, precise bolt holes, stable sealing effect
Diverse materials: carbon steel, alloy steel, stainless steel, adapting to different media
Support non-standard customization and OEM contract manufacturing, meeting special engineering needs

Product Name	Slip-On Flange SO
Categories	Contact Us to Confirm
Customization	Our factory has mature non-standard customization and OEM contract manufacturing capabilities for SO weld neck flanges, and can meet various differentiated engineering needs. We support customization of flanges with special non-standard hole diameters, special hole spacing, non-standard thickness, and special pressure ratings. We can customize special materials such as carbon steel, alloy steel, 304, 316L, and duplex steel, adapting to special working conditions such as low temperature, anti-corrosion, and medium temperature. We support precision machining customization of RF, MFM, and TG sealing faces of all types, and can carry out mold production according to American standard, European standard, and non-standard drawings. We support laser marking of LOGO, batch number, specifications, and standard OEM branding, and can customize special anti-rust packaging for foreign trade and engineering supporting documents. With high customization precision, stable processes, and a 100% qualification rate, we can undertake various high-end non-standard customization orders at home and abroad.
MOQ	Our factory's SO hubbed slip-on flanges support flexible and diverse procurement modes, suitable for sample orders, urgent replenishment orders, engineering bulk orders, and foreign trade full-container orders. For conventional DN15-DN600 in-stock specifications, the minimum order quantity is 1 piece, supporting scattered replenishment at construction sites, maintenance and renovation, sample submission for inspection, and small-scale pipe network construction procurement, with no procurement threshold. For conventional engineering bulk procurement, the MOQ is 50 pieces for batch orders, and you can enjoy
Lead Time	This factory has fully automatic forging, CNC turning, and precision machining production lines, with sufficient production capacity and stable delivery times for SO hubbed slip-on flanges. DN15-DN600 conventional PN16/PN25/PN40 carbon steel stock specifications are shipped quickly within 24 hours, meeting the needs of construction sites for emergency replenishment and rush schedules. Conventional medium and large diameters, stainless steel, PN63/PN100 high pressure
Packaging	SO hubbed slip-on flanges are packaged with industrial-standard anti-rust protective packaging, suitable for domestic engineering transportation and international sea freight export. The products are sprayed with anti-rust oil before leaving the factory to prevent oxidation, rusting, corrosion, and discoloration during long-distance transportation. Small-diameter flanges are individually wrapped with protective film and sorted into thickened cardboard boxes, marked with specifications, pressure, material, and standard information. Medium and large-diameter flanges are wrapped in multiple layers of waterproof stretch film and woven bags, and fixed and packed with solid wood pallets to avoid collisions, sealing surface scratches, and flange deformation. Each batch is accompanied by a product certificate of conformity, material report, flaw detection inspection report, and factory inspection documents. The outer packaging is moisture-proof, shock-proof, pressure-resistant, and rust-proof, capable of withstanding long-distance land transportation and stacked storage in container sea freight, effectively reducing the transportation damage rate and meeting high-standard shipping packaging requirements at home and abroad.
Reference Price	Inquiry
Standard	HG/T20592 (PN Series), ASME B16.5 (Class Series)

Applications

Process pipeline connections for industries such as chemical, petrochemical, power, and metallurgy
Civil and industrial pipelines such as factory water supply and drainage, central air-conditioning circulating water, and heating pipe networks
Inlet and outlet flange connections for equipment such as pumps, valves, heat exchangers, etc.
Pipeline network connection in municipal industrial pipelines and mechanical and electrical installation engineering
Foreign trade export projects, used for overseas engineering contracting and bulk procurement

Overview

Key Features

- Neck-reinforced structure, high strength, deformation-resistant, superior to plate-type flat welding flanges - Conical neck transition disperses stress, reducing the risk of weld fatigue cracking - Fillet welding process, simple construction, fast installation speed, low labor cost - Flat sealing surface, precise bolt holes, stable sealing effect - Diverse materials: carbon steel, alloy steel, stainless steel, adapting to different media - Supports non-standard customization and OEM contract manufacturing, meeting special engineering needs

Applications

- Process pipeline connections in chemical, petrochemical, power, metallurgy and other industries - Civil and industrial pipelines such as factory water supply and drainage, central air conditioning circulating water, heating pipe networks - Inlet and outlet flange connections for equipment such as water pumps, valves, heat exchangers - Pipe network connections in municipal industrial pipelines and mechanical and electrical installation projects - Foreign trade export projects, used for overseas engineering contracting and bulk procurement

Specifications

Product name: Slip-on flanges with neck SO Product classification: Please contact us to confirm Customization capability: Our factory has mature non-standard customization and OEM contract manufacturing capabilities for SO slip-on flanges with neck, capable of meeting various differentiated engineering needs. Supports customization of special non-standard hole diameters, special hole spacing, non-standard thickness, and special pressure rating flanges. Can customize special materials such as carbon steel, alloy steel, 304, 316L, duplex steel, etc., adapting to special working conditions of low temperature, anti-corrosion, and medium temperature. Supports precision machining customization of RF, MFM, TG various sealing surfaces, and can produce molds according to American standards, European standards, and non-standard drawings. Supports laser marking of LOGO, batch number, specifications, standard OEM contract manufacturing, and can customize special anti-rust packaging for foreign trade and engineering supporting documents. High customization precision, stable process, 100% qualification rate, capable of undertaking various high-end non-standard customization orders at home and abroad. Minimum order quantity: Our factory's SO slip-on flanges with neck support flexible and diverse procurement modes, adapting to sample orders, urgent replenishment orders, engineering bulk orders, and foreign trade full-container orders. Conventional DN15-DN600 in-stock specifications have a minimum order of 1 piece, supporting sporadic replenishment at construction sites, maintenance and renovation, sample submission for inspection, and small-scale pipe network construction procurement, with no procurement threshold. Conventional engineering bulk procurement MOQ is 50 pieces for batch orders, can enjoy Delivery cycle: Our factory has fully automatic forging, CNC turning, and precision machining production lines, SO slip-on flanges with neck have sufficient production capacity and stable delivery times. DN15-DN600 conventional PN16/PN25/PN40 carbon steel in-stock specifications ship quickly within 24 hours, meeting urgent replenishment at construction sites and rush schedule needs.Conventional medium and large diameters, stainless steel, PN63/PN100 high pressure Packaging method: SO slip-on flanges with neck use industrial standard anti-rust protective packaging, suitable for domestic engineering transportation and international sea freight export. Products are sprayed with anti-rust oil before leaving the factory, preventing oxidation, rusting, corrosion and discoloration during long-distance transportation. Small-diameter flanges are individually wrapped with protective film, classified and packed into thickened cartons, marked with specifications, pressure, material, and standard information. Medium and large diameter flanges are wrapped in multiple layers of waterproof stretch film and woven bags, fixed and packed with solid wood pallets, avoiding collisions, sealing surface scratches, and flange deformation. Each batch is accompanied by product certificates, material reports, flaw detection inspection reports, and factory inspection documents. The outer packaging is moisture-proof, shock-proof, pressure-resistant, and anti-rust, capable of withstanding long-distance land transportation and container sea freight stacked storage, effectively reducing transportation damage rate, meeting domestic and international high-standard shipping packaging requirements. Reference price: Inquiry Execution standards: HG/T20592 (PN series), ASME B16.5 (Class series)

Purchase & Delivery

Reference price: Inquiry MOQ: Our factory's SO slip-on flanges with neck support flexible and diverse procurement modes, adapting to sample orders, urgent replenishment orders, engineering bulk orders, and foreign trade full-container orders. Conventional DN15-DN600 in-stock specifications have a minimum order of 1 piece, supporting sporadic replenishment at construction sites, maintenance and renovation, sample submission for inspection, and small-scale pipe network construction procurement, with no procurement threshold. Conventional engineering bulk procurement MOQ is 50 pieces for batch orders, can enjoy Delivery time: Our factory has fully automatic forging, CNC turning, and precision machining production lines, SO slip-on flanges with neck have sufficient production capacity and stable delivery times. DN15-DN600 conventional PN16/PN25/PN40 carbon steel in-stock specifications ship quickly within 24 hours, meeting urgent replenishment at construction sites and rush schedule needs. Conventional medium and large diameters, stainless steel, PN63/PN100 high pressure Packaging description: SO slip-on flanges with neck use industrial standard anti-rust protective packaging, suitable for domestic engineering transportation and international sea freight export. Products are sprayed with anti-rust oil before leaving the factory, preventing oxidation, rusting, corrosion and discoloration during long-distance transportation. Small-diameter flanges are individually wrapped with protective film, classified and packed into thickened cartons, marked with specifications, pressure, material, and standard information. Medium and large diameter flanges are wrapped in multiple layers of waterproof stretch film and woven bags, fixed and packed with solid wood pallets, avoiding collisions, sealing surface scratches, and flange deformation. Each batch is accompanied by product certificates, material reports, flaw detection inspection reports, and factory inspection documents. The outer packaging is moisture-proof, shock-proof, pressure-resistant, and anti-rust, capable of withstanding long-distance land transportation and container sea freight stacked storage, effectively reducing transportation damage rate, meeting domestic and international high-standard shipping packaging requirements.

Service & Support

Customization capability: Our factory has mature non-standard customization and OEM contract manufacturing capabilities for SO slip-on flanges with neck, capable of meeting various differentiated engineering needs. Supports customization of special non-standard hole diameters, special hole spacing, non-standard thickness, and special pressure rating flanges. Can customize special materials such as carbon steel, alloy steel, 304, 316L, duplex steel, etc., adapting to special working conditions of low temperature, anti-corrosion, and medium temperature. Supports precision machining customization of RF, MFM, TG various sealing surfaces, and can produce molds according to American standards, European standards, and non-standard drawings. Supports laser marking of LOGO, batch number, specifications, standard OEM contract manufacturing, and can customize special anti-rust packaging for foreign trade and engineering supporting documents. High customization precision, stable process, 100% qualification rate, capable of undertaking various high-end non-standard customization orders at home and abroad. After-sales support: Our factory provides industrial-grade high-standard after-sales warranty services, all SO slip-on flanges with neck have a two-year warranty and lifetime technical consultation support. Products undergo 100% appearance fine inspection, flatness verification, hydrostatic pressure testing, and non-destructive testing before leaving the factory, eliminating defective and substandard products from leaving the factory. In case of non-human quality defects, deformation, sealing surface defects, or material inconsistency problems, free replacement and unconditional after-sales service. Products bumped, rusted, or damaged during transportation are all freely reissued, without affecting engineering progress. Provides free technical guidance on pipeline selection, flange connection, welding process, and gasket bolt matching. Supports re-issuance of qualification documents, invoicing and reconciliation, batch warranty coordination, one-on-one customer service follow-up throughout the process, rapid after-sales response, comprehensively safeguarding customers' engineering construction and procurement rights. Certification/Qualifications: Please contact us to confirm

FAQ

What is the difference between SO flanges and PL flanges?

SO hubbed slip-on flanges have a short neck structure, offering higher strength, resistance to vibration, and resistance to deformation, making them suitable for medium-pressure and slight-vibration working conditions; while PL plate-type slip-on flanges have a flat plate structure and are suitable for atmospheric-pressure and low-pressure working conditions.

What is the difference between SO flanges and WN butt-welding flanges?

SO flanges use fillet welding connections, offering simple installation and high cost-effectiveness; WN butt-welding flanges have a high-neck butt-welding structure and are suitable for high-temperature, high-pressure, and high-risk pipelines.

What are the commonly used pressure ratings for hubbed slip-on flanges?

In engineering, European-standard PN16, PN25, and PN40, and American-standard Class150 and Class300 are commonly used. The specific choice can be made according to your pipeline design pressure.

Can hubbed slip-on flanges be used in chemical pipelines?

Yes. They are fully compatible with conventional chemical medium-pressure process pipelines, provide stable sealing, and can pass acceptance inspections.

Do you support foreign trade export?

Supported. Our products have complete standards and full qualifications, can be exported globally, and support mixed-container or full-container shipments.

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