Durable Dished Ends For Corrosion Resistance In Petrochemical And Industrial Applications
A torispherical head is a common, cost-effective pressure vessel end design that features a spherical cap (crown) connected to the cylindrical shell by a smaller-radius curved section (knuckle), followed by a straight flange.
Durable Dished Ends For Corrosion Resistance In Petrochemical And Industrial Applications
A torispherical head is a common, cost-effective pressure vessel end design that features a spherical cap (crown) connected to the cylindrical shell by a smaller-radius curved section (knuckle), followed by a straight flange. this geometry offers a balance of structural strength for moderate pressures, ease of manufacturing, and a compact, space-saving profile compared to a full hemisphere.
Torispherical heads, also known as Klopper heads or dished ends, are essential components for sealing pressure vessels and boilers, offering robust corrosion resistance and structural reliability. These heads are critical for boiler pipeline protection and erosion/corrosion resistance in industries such as petrochemical, power generation, chemical processing, and oil and gas.
Compliant with standards like DIN 28011, ASME UG-32, and EN 13445, torispherical heads feature a crown radius (typically equal to the vessel diameter) and a knuckle radius (6-10% of the diameter), providing cost-effective stress distribution. They are available in sizes up to 72″ (DN1800), with wall thicknesses up to 200 mm, and are made from materials such as carbon steel (HII, P265GH), stainless steel (304, 316L, 1.4541, 1.4571), or alloy steel (15Mo3, 13CrMo44, 10CrMo910). Surface treatments like pickling, passivation, or Fusion Bonded Epoxy (FBE) coatings enhance durability in corrosive environments.
Torispherical heads undergo rigorous testing, including chemical analysis (e.g., HII: C ≤0.16%; 316L: C ≤0.03%), tensile testing (HII: YS ≥235 MPa, TS ≥360-510 MPa; 316L: YS ≥205 MPa, TS ≥515 MPa), hydrostatic testing (up to 9.8 MPa), and nondestructive methods (radiographic, ultrasonic, PMI). With a density of ~7.85 g/cm³ for carbon steel or ~8.0 g/cm³ for stainless steel, and suitability for temperatures up to 450°C (carbon steel) or 870°C (stainless steel), these heads excel in high-pressure vessel applications like boilers, heat exchangers, and refinery systems.
The torispherical design offers a balance of cost and performance, making these heads ideal for sealing pressure vessels in corrosive and high-pressure settings, such as chemical plants, offshore platforms, and power generation facilities.
Torispherical head (or flanged and dished head), These heads have a dish with a fixed radius (r1), the size of which depends on the type of torispherical head. The transition between the cylinder and the dish is called the knuckle. The knuckle has a toroidal shape.
These heads have a dish with a fixed radius, the size of which depends on the type of torispherical head. The transition between the cylinder and the dish is called the knuckle. The knuckle has a toroidal shape.
Vessel dished ends are mostly used in storage or pressure vessels in industry. These ends, which in upright vessels are the bottom and the top, use less space than a hemisphere (which is the ideal form for pressure containments) while requiring only a slightly thicker wall.
Compared with elliptical head, due to its easier manufacturing processes, the torispherical head is often used in addition to the pressure is larger diameter pressure vessel.
With the same same design conditions with the same design pressure, design temperature and material, your calculated wall thickness under internal pressure will be approximately half of the shell thickness.
For example, if you have calculated your shell thickness under internal pressure and obtained 12 mm, your hemispherical head thickness also will be approximately 6 mm.
The inside depth of your Torispherical head will be one-half of head inside diameter (h = D/2).
You need to make a dimensional inspection on the pressure Torispherical head for any effort for the fit-up process. The dimensional inspection is done on the knuckle radius, crown radius, skirt length, depth and thickness.
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Technical Requirements & Additional Services:
| Specification | Details |
|---|---|
| Standards | DIN 28011, ASME UG-32, EN 13445 |
| Type | Torispherical Head (Klopper), Welded or Seamless |
| Material | Carbon Steel (HII, P265GH), Stainless Steel (304, 316L, 1.4541, 1.4571), Alloy Steel (15Mo3, 13CrMo44, 10CrMo910) |
| Size Range | Up to 72″ (DN1800) |
| Wall Thickness | Up to 200 mm |
| Manufacturing | Cold Pressing, Hot Forming, Welded Fabrication |
| Surface Treatment | Pickling, Passivation, FBE, 3LPE |
| Testing | Chemical Analysis (HII: C ≤0.16%; 316L: C ≤0.03%), Tensile (HII: YS ≥235 MPa, TS ≥360-510 MPa; 316L: YS ≥205 MPa, TS ≥515 MPa), Hydrostatic (≥9.8 MPa), Radiographic, Ultrasonic, PMI |
| Operating Conditions | Pressure: ≥9.8 MPa, Temperature: Up to 450°C (carbon steel), 870°C (stainless steel) |
| Certifications | EN 10204/3.1, ISO 9001, ASME U-Stamp, Third-Party Inspection |
| Feature | Torispherical Head | Elliptical Head (2:1) | DIN 2617 Pipe Cap |
|---|---|---|---|
| Material | Carbon Steel (HII, P265GH), Stainless Steel (304, 316L), Alloy Steel (15Mo3, 13CrMo44) | Carbon Steel (HII, P265GH), Stainless Steel (304, 316L), Alloy Steel (15Mo3, 13CrMo44) | Carbon Steel (HII, P235GH), Stainless Steel (1.4541, 1.4571) |
| Standard | DIN 28011, ASME UG-32, EN 13445 | DIN 28011, ASME UG-32, EN 13445 | DIN 2617, EN 10253 |
| Function | Seals pressure vessels, cost-effective stress distribution | Seals pressure vessels, optimizes stress distribution | Seals pipe ends, protects against corrosion |
| Corrosion Resistance | Excellent (stainless steel), Good (carbon steel with coatings) | Excellent (stainless steel), Good (carbon steel with coatings) | Good (with coatings) |
| Erosion Resistance | Good (static application) | Excellent (static application) | Good (static application) |
| Applications | Pressure vessels, boilers, petrochemical | Pressure vessels, boilers, petrochemical | Boilers, petrochemical, chemical processing |
| Temperature Range | Up to 450°C (carbon steel), 870°C (stainless steel) | Up to 450°C (carbon steel), 870°C (stainless steel) | Up to 450°C (carbon steel) |
| Cost | Lower (cost-effective design) | Moderate to High | Moderate |
| Key Advantage | Cost-effective for vessels | Optimal stress distribution | Butt-welded for pipe sealing |
| Feature | Ellipsoidal Head | Torispherical Head |
|---|---|---|
| Curvature | Continuous & smooth | Discontinuous at knuckle |
| Stress Distribution | Even and efficient | Concentrated at knuckle |
| Wall Thickness Required | ≈ shell thickness | ≈ 1.77 × shell thickness |
| Manufacturing Complexity | Moderate to high | Lower, simpler |
| Vessel Height | Deeper profile | Shallower profile |
| Best Use | Medium to high pressure | Low to medium pressure |
| Cost & Material Use | Higher | Lower |
A curated list of long-tail keywords for elliptical heads, covering standards, materials, and industrial applications.
Note: Elliptical heads are designed for corrosion-resistant, high-pressure sealing in pressure vessels and industrial systems. Contact a certified supplier for detailed specifications.
Standards: ASME B16.9 and ASME B16.25
Description: Designed for butt welding to pipe end, providing permanent and strong connection.
Standards: ASME B16.11
Description: Fit into socket of pipe fitting and welded in place.
Thread Types: NPT and BSP configurations
Description: Feature internal or external threads for screwing onto threaded pipe ends.
Features: Flange, slotted head, knurled or faceted head options
Considerations: Length and width dimensions are critical
Design: Dome-shaped for optimal pressure distribution
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