Hemispherical (spherical) pipe cap
Hemispherical spherical pipe caps are mainly used for sealing and plugging the ends of pressure pipelines and for sealing the ends of pressure vessel equipment. They belong to permanent pressure-bearing plugging pipe fittings, different fro
Inquiry
- The biggest advantage of hemispherical spherical pipe caps is uniform spherical stress distribution
- Compared with elliptical and dished heads
- Thinner wall thickness required under the same pressure conditions
- Effectively saves raw material costs
- the pressure-bearing performance is the best in the industry. The standard HHA model with straight edge eliminates stress concentration at the welded part
Detailed Introduction
Hemispherical pipe caps are also called spherical pipe caps, hemispherical heads, and hemispherical end caps, and belong to the large category of convex pipe caps/heads, with the English terms being Hemispherical pipe cap / Hemispherical head. They are composed of a standard hemispherical shell plus a straight edge section (welding groove), with a cross-section that is a standard semicircle, and the spherical curvature radius is equal to the inner diameter of the cylinder. Among all convex pipe caps, hemispherical pipe caps have the optimal stress conditions, the most uniform stress distribution, the minimum required wall thickness under the same working pressure, and the strongest pressure-bearing performance, making them suitable for high-pressure and ultra-high-pressure working conditions. The product uses welded connection and belongs to permanent sealing accessories, different from removable blind plates. We provide multiple materials such as carbon steel, stainless steel, heat-resistant alloy steel, duplex steel, and titanium alloy, and support customization of non-standard sizes, special wall thicknesses, special groove forms, and surface treatments, and can assist in selection according to customer drawings or working condition parameters.
- The spherical stress distribution is uniform, and under the same pressure conditions the required wall thickness is thinner than that of elliptical and dished pipe caps, resulting in high material utilization.
- The HHA standard structure with straight edge can eliminate stress concentration at the welding site and is suitable for the severe working conditions of pressure vessels.
- The inner wall has a smooth transition with no dead corners, and the medium flows smoothly; the sanitary-grade polished version can be used for aseptic production in food and pharmaceutical industries.
- Supports nominal diameters DN15‑DN6000, pressure ratings PN10‑PN420 and American standard Class150‑Class2500.
- Can customize carbon steel, stainless steel, heat-resistant alloy steel, duplex steel, titanium alloy, and special alloys such as Hastelloy and Monel.
- The MOQ for standard in-stock specifications is as low as 1 piece, and sample procurement is supported; non-standard customization starts from 1 piece.
| Product Name | Hemispherical (Spherical) Pipe Cap |
| Product Categories | Contact Us to Confirm |
| Nominal diameter DN range DN15‑DN6000, supports non-standard oversized diameter customization; pressure rating PN10‑PN420, American standard Class150‑Class2500; wall thickness covers SCH5‑SCH160, XXS extra-thick, and the wall thickness must match the connecting pipeline cylinder. The structure is divided into HHA standard hemisphere with straight edge, and no-flanging | 20#、Q345B carbon steel, 304, 316L, 321 stainless steel, 15CrMo, 12Cr1MoVG heat-resistant alloy steel, 2205/2507 duplex steel, TA1/TA2 titanium alloy. Executive standards GB/T25198‑2023, GB/T12459, ASME B16.9. Working temperature varies from ‑196℃ to 600℃ depending on material. Forming processes are divided into integral stamping, spinning, and segmental welding; surface treatment includes sandblasting, pickling and passivation, and mirror polishing. Weld requirements: welded products can undergo RT radiographic testing and UT ultrasonic testing. The spherical curvature radius R is equal to the cylinder inner diameter; the straight edge section height follows national standard requirements; welding grooves are machined according to pipeline standards, wall thickness |
| Customization | Hemispherical spherical pipe caps possess strong all-dimensional customization capability, support non-standard size customization, can customize non-national-standard diameters and special wall thicknesses, including thickened and thinned non-standard wall thickness products, adapting to special equipment cylinders. Materials can be customized as carbon steel, various stainless steels, heat-resistant alloy steel, 2205/2507 duplex steel, titanium alloys TA1, TA2, Hastelloy, Monel and other special alloys. In terms of structure, HHA with straight edge, non-flanged spherical crown can be customized, special straight edge heights can be customized, special welding groove forms can be customized, and 1:3 edge reduction transition is performed for products with large wall thickness differences. Surface treatment can be customized as sandblasting, pickling and passivation, internal and external mirror polishing, meeting food and pharmaceutical sanitary working conditions. Large diameters can be customized by segmental welding, with heat treatment performed as needed to eliminate welding stress. Can |
| MOQ | Hemispherical spherical pipe caps are divided into stock standard parts and non-standard customized parts, with differences in MOQ minimum order quantity. For standard stock specifications, carbon steel and ordinary stainless steel DN50‑DN600 HHA hemispherical pipe caps with straight edge, the MOQ is as low as 1 piece, and sample procurement can be supported, facilitating customer sample testing and small project rush repair supplementary orders. Small-diameter DN15‑DN45 standard pipe fittings, stock |
| Lead Time | Hemispherical spherical pipe cap delivery time is divided into stock and customized orders. For conventional standard stock specifications, carbon steel and 304 stainless steel DN50‑DN600 integrally stamped HHA hemispherical pipe caps, the warehouse has inventory, and after order payment confirmation, inspection, packaging and shipment are completed in 1‑3 working days, suitable for emergency repair projects. Standard non-stock conventional specifications, ordinary carbon steel, stainless steel integral |
| Packaging | Hemispherical spherical pipe caps implement graded packaging according to specification size and material grade. For small-diameter DN15‑DN200 finished pipe fittings, stainless steel and alloy products are surface-wrapped with plastic protective film to prevent bumps and scratches, loaded into moisture-proof and waterproof woven bags, then placed into plywood wooden boxes, with foam and pearl cotton filled inside the box for fixation and isolation, avoiding spherical deformation and scratches caused by transportation bumps. For medium and large diameter DN200 and above carbon steel and stainless steel pipe caps, the spherical surface is covered with protective plastic film, and plastic protective caps are installed at the pipe mouth groove positions, with key protection of welding grooves from impact damage; large pieces are fixed with wooden frame supports, rubber buffer pads are placed at the bottom, and partitions are set between multiple products to prevent mutual friction and collision during transportation. Export orders use IPPC fumigation heat treatment export wooden boxes, fully |
| Reference Price | Inquiry |
Applications
- Petrochemical hydrogenation units, oil and gas gathering and transportation high-pressure pipeline end plugging, bearing oil, gas and corrosive chemical fluid media
- Thermal power boilers, high-pressure heaters, nuclear power auxiliary pressure-bearing cavity ends, adapting to high-temperature and high-pressure steam media
- High-pressure gas storage tanks, hydraulic accumulators, pressure test chambers and other energy equipment, bearing continuous internal high pressure
- Food and pharmaceutical fermentation tanks, sterile reaction tanks, ingredient tank body ends, sanitary mirror-polished inner walls are not prone to material residue
- Terminal sealing of seawater medium pipelines for marine vessels, and supporting manufacturing of seawater treatment equipment
Product Overview
Hemispherical pipe cap is also called spherical pipe cap, hemispherical head, hemispherical end cap, and belongs to the convex pipe cap/head category; in English it is Hemispherical pipe cap / Hemispherical head. It is a pipe fitting used for closing and sealing the end of pipelines in piping and pressure vessel systems, with a function equivalent to a plug or blind plug; most are connected by welding and belong to permanent sealing fittings, different from removable blind flanges. The structure consists of a standard hemispherical shell plus a straight edge section (welding bevel), with a standard semicircular cross-section, and the spherical surface curvature radius is equal to the cylinder inner diameter. Among all convex pipe caps, the hemispherical pipe cap has the optimal stress conditions and the most uniform stress distribution; under the same working pressure conditions, the required wall thickness is the smallest, material utilization is high, and pressure-bearing performance is the strongest, making it suitable for high-pressure and ultra-high-pressure working conditions.
Key Selling Points
Uniform spherical stress distribution is the most prominent feature of the hemispherical pipe cap. Compared with elliptical and dished pipe caps, under the same pressure conditions the required wall thickness is thinner, which can effectively save raw material costs. The HHA standard model with straight edge can eliminate stress concentration at the welded part, adapt to the severe working conditions of pressure vessels, and has a high safety factor. The inner wall has a smooth transition with no dead corners, and the medium flows smoothly; the sanitary mirror-polished version can be used for aseptic production in food and pharmaceuticals. We provide a variety of materials including carbon steel, stainless steel, heat-resistant alloy steel, duplex steel, and titanium alloy, and support customization of non-standard sizes, special wall thicknesses, special bevel forms, and surface treatments; we can assist with model selection according to customer drawings or working condition parameters.
Applications
High-pressure and ultra-high-pressure working conditions are the core application scenarios of hemispherical pipe caps. End sealing of hydrogenation units in petrochemicals and high-pressure oil and gas gathering and transportation pipelines, with media including oil, gas, and corrosive chemical fluids. End parts of thermal power boilers, high-pressure heaters, and nuclear power auxiliary pressure-bearing cavities in the power industry, suitable for high-temperature and high-pressure steam media. High-pressure gas storage tanks, hydraulic accumulators, and pressure test chambers in the energy equipment field, bearing continuous internal high pressure. In aseptic production scenarios in food and pharmaceuticals, sanitary mirror-polished hemispherical pipe caps are used at the ends of fermentation tanks and ingredient tank bodies, and the smooth inner wall is not prone to material residue. Marine vessel piping is used for terminal sealing of seawater medium pipelines, and seawater treatment equipment manufacturing can also use them as supporting components.
Specifications
Nominal diameter DN15-DN6000, supporting non-standard extra-large diameter customization; pressure rating PN10-PN420, American standard Class150-Class2500; wall thickness covers SCH5-SCH160, XXS extra-thick, and the wall thickness needs to match the connecting pipe cylinder. The structure is divided into HHA standard hemisphere with straight edge and non-knuckle spherical cap. Material options include 20#, Q345B carbon steel, 304, 316L, 321 stainless steel, 15CrMo, 12Cr1MoVG heat-resistant alloy steel, 2205/2507 duplex steel, TA1/TA2 titanium alloy; for special alloys such as Hastelloy and Monel, please contact us for confirmation. Executive standards GB/T25198-2023, GB/T12459, ASME B16.9. The working temperature varies from -196℃ to 600℃ depending on the material; for details, please contact us for confirmation. Forming processes are divided into integral stamping, spinning, and segmental welding; surface treatments include sandblasting, pickling and passivation, and mirror polishing. Welded products can undergo RT radiographic testing and UT ultrasonic testing. The spherical curvature radius R is equal to the cylinder inner diameter; the straight edge section height follows national standard requirements; the welding bevel is machined according to pipeline standards.
Purchasing & Delivery
Hemispherical pipe caps are divided into standard stock items and non-standard customized items, and MOQ minimum order quantities differ. For standard stock specifications, carbon steel and ordinary stainless steel DN50-DN600 HHA hemispherical pipe caps with straight edge, the MOQ is as low as 1 piece, and sample procurement can be supported, making it convenient for customers to conduct sample testing and emergency repair supplementary orders for small projects. Small-diameter DN15-DN45 standard pipe fittings are in stock. Delivery time is divided into stock and customized orders: for conventional standard stock specifications, carbon steel and 304 stainless steel DN50-DN600 integrally stamped HHA hemispherical pipe caps, the warehouse keeps inventory, and after order payment is confirmed, inspection, packaging, and shipment are completed within 1-3 working days, suitable for emergency repair projects. For standard non-stock conventional specifications and non-standard customized products, please contact us for confirmation of delivery time. Packaging is carried out in graded packaging according to specification size and material grade: for small-diameter DN15-DN200 finished pipe fittings, stainless steel and alloy products are surface-wrapped with plastic protective film, placed into moisture-proof and waterproof woven bags, and then placed into plywood wooden boxes, with foam and pearl cotton filled inside the box for fixation and separation. For medium and large diameter DN200 and above carbon steel and stainless steel pipe caps, the spherical surface is covered with protective plastic film, and plastic protective caps are installed at the pipe opening bevel positions; large pieces are fixed with wooden frame supports, rubber buffer pads are placed at the bottom, and partitions are set between multiple products. Export orders use IPPC fumigation heat-treated export wooden boxes to meet customs export packaging quarantine requirements. Labels are affixed to the outside of the packaging, indicating product model, material, specification, heat number, executive standard, and quantity. For humid sea transport environments, desiccant is placed inside the wooden boxes.For special high-end customized products, separate independent packaging can be provided according to customer requirements, and the packaging plan can be negotiated and adjusted.
Service & Support
Before leaving the factory, products undergo strict appearance and dimensional sampling inspection; standard parts are accompanied by certificates of conformity and material certificates, and custom products are delivered together with flaw detection and inspection reports. After the products are shipped, logistics tracking is provided to assist in following up on the cargo transportation status. Within 7 working days after the customer receives the goods, if there are dimensional deviations, material mismatches, or welding defects not caused by human factors, upon verification with photos and unpacking records, return or exchange or free repair services will be provided. Under the premise of correct model selection, compliant welding and installation, and use within rated working conditions, quality technical support is provided for the products; damage caused by incorrect model selection, use beyond pressure or temperature limits, or improper on-site welding operations is not covered by the warranty. The technical team provides model selection support and assists customers in verifying pressure, temperature, and medium parameters to avoid model selection errors. For subsequent projects, drawing verification can be provided and installation and welding precautions can be explained. Long-term spare parts matching services are provided, and later supplementary orders are given priority in production scheduling. For export orders, assistance can be provided in organizing customs declaration documents. Technical personnel respond quickly online to customer questions and provide technical communication for complex working conditions.
FAQ
How to choose between hemispherical pipe caps and elliptical pipe caps?
For high-pressure and ultra-high-pressure working conditions, hemispherical pipe caps are preferred, as they have the best pressure-bearing performance and require thinner wall thickness under the same pressure; however, hemispherical pipe caps occupy a relatively large axial height, so elliptical pipe caps can be considered when space is limited. For specific model selection, you can contact us and we will assist in verifying pressure, temperature, and medium parameters.
Can non-flanged spherical crowns be used in pressure vessels?
Not recommended. The welded structure without straight edges has concentrated welding stress and is only used for low-pressure non-pressure-bearing partitions. Pressure vessels are required to use HHA hemispherical pipe caps with straight edges.
Are large-diameter hemispherical pipe caps integrally formed?
Those within DN600 are mostly integrally formed by spinning and stamping; large diameters of DN＞1000 are limited by equipment, and usually use segmental assembly welding, with heat treatment available as needed to eliminate welding stress, and additional inspection items such as RT radiographic testing and UT ultrasonic testing can be added. For the specific process, please contact us to confirm.
What materials and customizations are supported for hemispherical pipe caps?
We provide 20#, Q345B carbon steel, 304, 316L, 321 stainless steel, 15CrMo, 12Cr1MoVG heat-resistant alloy steel, 2205/2507 duplex steel, TA1/TA2 titanium alloy, as well as special alloys such as Hastelloy and Monel (please contact us to confirm). We support customization such as non-standard diameters, special wall thicknesses, special bevel forms, 1:3 edge-reduction transitions, segmented fabrication and welding, surface sandblasting/pickling and passivation/mirror polishing, and can perform reverse design and selection based on customer drawings, 3D models of equipment, and operating parameters.
What are the minimum order quantity and delivery time?
For standard in-stock specifications, the MOQ is as low as 1 piece, and sample purchases can be supported; for non-standard customization, the minimum production quantity starts at 1 piece. For conventional standard in-stock specifications, carbon steel and 304 stainless steel DN50-DN600 integrally cold-pressed HHA hemispherical pipe caps, after order payment is confirmed, inspection, packaging, and shipment are completed within 1-3 working days. For non-standard customization delivery times, please contact us to confirm.
Submit Inquiry
Please fill in the following information, and we will contact you as soon as possible to provide product solutions or quotes based on your needs.