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Views: 0 Author: Site Editor Publish Time: 2026-07-27 Origin: Site
In industrial processing, oil and gas refining, chemical manufacturing, food and dairy processing, and power generation, pressure vessels and storage tanks must withstand extreme internal pressures, vacuum conditions, severe thermal cycling, and corrosive environments. The structural foundation of these systems rests on the integrity of their end closures: spun tank heads (also designated as tank ends, dished heads, or vessel covers).
Forming heavy-gauge tank heads via cold or hot CNC metal spinning—often integrated with flanging and dish-pressing operations—offers significant structural advantages over multi-piece stamped or welded fabrications. Spinning flows heavy metal plate into a seamless, monolithic pressure barrier, aligning the metal’s crystalline grain structure along the radial contour of the dish and knuckle. This process eliminates structural weld seams across high-stress radii, dramatically improving fatigue life, hoop strength, and pressure containment reliability.
At HS Metal Spinning, we operate as a full-service OEM manufacturing partner specializing in precision CNC-spun tank heads and vessel ends. By managing every stage of production under one roof—from mill-certified plate procurement and high-tonnage dished-and-flanged spinning to multi-axis 3D laser weld prep, non-destructive testing (NDT), and heat treatment—we deliver code-compliant tank heads engineered for demanding pressure vessel applications.
Selecting the correct tank head geometry requires balancing internal design pressure (P), allowable material stress (S), wall thickness economy (t), and vessel volumetric efficiency. We spin tank heads across four primary geometric classifications governed by ASME Section VIII, Division 1 and EN 13445 standards.
The dish depth is equal to one-fourth of the inside diameter (D/4), and the knuckle radius is equal to 0.17D.
This profile offers optimal stress distribution under high internal pressures. Its geometry matches the hoop strength of a seamless cylindrical shell of equal thickness, allowing engineers to minimize plate thickness without sacrificing pressure ratings.
High-pressure boilers, gas storage spheres, chemical reactors, and oil/gas separators operating under ASME Code requirements.
Features a fixed crown radius (R ≈ D) combined with a tight toroidal knuckle radius (r ≈ 0.06D).
Torispherical heads are economical to form and widely used for moderate-pressure applications. While requiring a slightly thicker starting plate than semi-ellipsoidal heads to handle localized bending stresses at the knuckle, they provide a reliable, cost-effective pressure closure.
Atmospheric storage tanks, water treatment vessels, food and beverage mixing tanks, and pharmaceutical storage.
Formed as a complete half-sphere, where the depth equals half the inside diameter (D/2).
The hemispherical geometry is the ultimate pressure-resistant shape. It distributes internal pressure uniformly in all directions, allowing for a 50% reduction in nominal wall thickness compared to a cylindrical shell under identical operating conditions.
Extreme high-pressure gas storage, aerospace propellant tanks, and deep-submergence pressure hulls.
Ranging from shallow dished discs to steep conical bottom hoppers (30° to 60° apex angles) and flat flanged end caps.
Optimized for material drainage, solids discharge, or tight space constraints where maximum volumetric capacity is prioritized over high-pressure performance.
Dry bulk hoppers, mixing silos, bottom discharge vessels, and low-pressure fluid reservoirs.
Manufacturing large-diameter tank heads from thick stainless or carbon steel plate demands immense hydraulic tonnage, precise thermal management, and multi-pass CNC roller paths.
Performed at ambient temperatures on high-purity carbon steel, stainless steel, or aluminum plate. Heavy dual-roller CNC positioners cold-flow the metal over precision mandrels. Cold working significantly increases yield strength through strain hardening, producing an extremely tough, scratch-resistant surface.
For ultra-heavy structural plate or hard-to-form alloys (such as high-nickel steels or titanium), the circular blank is preheated in temperature-controlled furnaces to 900℃ - 1100℃. Hot spinning lowers the material’s yield strength, allowing hydraulic rollers to form massive wall sections without micro-fracturing or structural tearing.
After forming the central dish radius, the outer rim is flanged to create a straight cylindrical skirt (SF).
Machining or spinning a uniform straight skirt (25 mm to 100+ mm in length) ensures clean alignment with the main cylindrical tank shell during fit-up.
Using multi-axis CNC live tooling or 3D fiber lasers, we cut precision weld preparation profiles—including single-V, double-V, or J-grooves—directly onto the skirt edge. This enables automated Submerged Arc Welding (SAW) or TIG welding on downstream tank assembly lines.
We source certified, pressure-vessel-grade plate directly from tier-one steel mills, ensuring full chemical heat-number traceability and compliance with global codes.
Low-carbon austenitic stainless steels essential for sanitary dairy, food processing, pharmaceutical, and general chemical storage.
Delivers twice the mechanical yield strength of standard austenitic grades along with superior resistance to chloride stress-corrosion cracking, making it ideal for offshore oil platforms and desalination plants.
Standard carbon steel plates for moderate- and lower-temperature pressure vessels requiring excellent notch toughness and weldability.
High-temperature alloy steel engineered for petroleum refining and power generation boilers operating under elevated thermal conditions.
Lightweight, cryogenic-grade alloys ideal for LNG transport tankers and fuel storage.
Formed for extreme corrosive environments, such as chemical processing and marine scrubbers.
Pressure vessel components require rigorous non-destructive testing (NDT) to ensure zero internal flaws, uniform wall thickness, and precise profile geometry prior to vessel assembly.
Metal spinning naturally stretches the blank along the knuckle radius. Our quality control team uses ultrasonic thickness gauges across a dense grid of inspection points to confirm that post-forming wall thickness meets or exceeds minimum design requirements (tmin).
We scan finished tank heads against 3D CAD models to verify crown radius, knuckle curvature, and total indicator runout (TIR) on the straight skirt.
Applied to the critical knuckle region and weld-prep bevels to verify 100% freedom from surface micro-fissures or micro-tears.
For heads formed from multi-blank welded plates, full-length X-ray inspection confirms complete weld seam integrity before spinning.
Severe cold working induces internal residual stresses. We perform full solution annealing on stainless steels or stress-relieving heat treatments on carbon steels in automated furnaces to restore ductility and corrosion resistance.
From technical drawing evaluation to final shipment, our tank head OEM production follows a structured five-step workflow.
Calculating starting plate diameter (Dblank), accounting for knuckle stretch allowance, and performing finite element analysis (FEA) on thinning rates.
Approved DFM report, thickness calculation chart, and material blank specification.
Sourcing pressure-vessel-certified plate with EN 10204 3.1 Mill Test Reports (MTRs) and conducting baseline ultrasonic plate testing.
Certified MTRs matching heat numbers and baseline material test certificates.
Forming the central dish profile, cold or hot spinning the toroidal knuckle, and rolling the straight skirt on multi-axis CNC forming cells.
In-process dimensional logs and forming parameter reports.
3D laser-cutting weld prep bevels, running liquid penetrant inspections (PT), and stress-relieving heat treatment in atmosphere-controlled furnaces.
NDT inspection logs, heat treatment time/temperature charts, and FAIR documentation.
Applying anti-corrosion coatings, installing edge protection on weld bevels, and mounting tank heads on custom steel transport saddles or ISPM 15 plywood crates.
Final Certificate of Conformance (CoC) and pre-shipment quality verification media.
Sourcing custom spun tank heads from a dedicated OEM partner ensures your pressure vessels meet international mechanical standards while optimizing raw material utilization. By combining high-tonnage multi-axis CNC spinning, integrated edge beveling, rigorous NDT inspection, and complete heat treatment capabilities under one roof, HS Metal Spinning delivers reliable, installation-ready vessel ends engineered for demanding industrial environments.
