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Dished Heads Component – Machinery and Equipment Manufacturing

Component Specifications

Definition

Dished heads, also known as dished ends or tank heads, are hemispherical or elliptical domed components that seal the ends of cylindrical pressure vessels, shells, and tanks. They are engineered to provide structural integrity under internal pressure by distributing stress uniformly across the surface, reducing stress concentrations compared to flat ends. Common types include hemispherical, elliptical (2:1 ratio), torispherical (dished and flanged), and conical heads, each optimized for specific pressure ratings, volume requirements, and manufacturing considerations. They are critical in industries handling gases, liquids, or processes requiring contained pressure.

Working Principle

Dished heads operate on the principle of membrane stress theory, where internal pressure creates tensile stresses that are evenly distributed across the curved surface. The curvature allows the head to resist pressure by converting radial forces into hoop and meridional stresses, minimizing bending moments. This design reduces material thickness requirements compared to flat ends and enhances fatigue resistance. Under pressure, the head deflects slightly, with stress highest at the crown and transitioning smoothly to the cylindrical shell via a knuckle region (in torispherical heads) to prevent abrupt stress changes.

Materials

Materials include carbon steel (e.g., SA-516 Gr. 70), stainless steel (e.g., 304/316L), aluminum alloys, nickel alloys, and clad materials for corrosion resistance. Selection depends on pressure, temperature, corrosion environment, and industry standards. Thickness is calculated per ASME codes, typically ranging from 3 mm to 50 mm based on diameter and pressure.

Technical Parameters

Diameter 100 mm to 6000 mm
Thickness 3 mm to 50 mm
Surface Finish Ra ≤ 3.2 μm for hygienic applications
Pressure Rating Up to 100 bar (standard)
Temperature Range -50°C to 400°C

Standards

ISO 9095, DIN 28011, ASME BPVC Section VIII, EN 13445

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Dished Heads.

Parent Products

This component is used in the following industrial products

Vessel/Shell

The structural housing that contains and protects the desiccant material within a desiccant bed system.

View Product Details

Engineering Analysis

Risks & Mitigation

Stress corrosion cracking
Fatigue failure from cyclic pressure
Weld defects leading to leaks
Improper installation causing misalignment

FMEA Triads

Trigger: Material degradation due to corrosive media
Failure: Leakage or rupture under pressure
Mitigation: Use corrosion-resistant materials (e.g., stainless steel), apply protective coatings, and conduct regular inspections.

Trigger: Overpressure beyond design limits
Failure: Catastrophic deformation or burst
Mitigation: Install pressure relief valves, adhere to ASME design codes, and perform pressure testing during commissioning.

Trigger: Poor welding quality at head-to-shell joint
Failure: Crack propagation and structural failure
Mitigation: Follow qualified welding procedures, perform NDT (e.g., UT, RT), and ensure post-weld heat treatment.

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance

Diameter tolerance ±0.5%, thickness tolerance ±10% per ASME standards; surface defects limited to 0.5 mm depth.

Test Method

Hydrostatic pressure testing at 1.5x design pressure, visual inspection, ultrasonic thickness testing, and dye penetrant testing for welds.

Procurement Evaluation Criteria

Not customer reviews or live demand data. These dimensions support RFQ preparation and supplier evaluation.

Technical documentation

4/5

Manufacturing capability

4/5

Inspection readiness

5/5

Supplier transparency

3/5

These scores are example evaluation dimensions, not real customer ratings, country-specific buyer feedback, or live inquiry activity.

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Frequently Asked Questions

What are the main types of dished heads?

Common types include hemispherical (for high pressure), elliptical (2:1 ratio for balanced stress), torispherical (with knuckle for cost-effectiveness), and conical heads (for gradual transitions).

How are dished heads manufactured?

They are typically formed by hot or cold pressing, spinning, or forging steel plates, followed by welding, heat treatment, and non-destructive testing (e.g., radiography) to ensure integrity.

What factors influence dished head selection?

Key factors include pressure rating, temperature, corrosion resistance, material cost, vessel diameter, and compliance with standards like ASME or DIN.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

Data Basis

CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Dished Heads