The ASTM A516 Gr.70 Elliptical Head is a formed pressure vessel closure engineered for moderate- and lower-temperature service applications. Manufactured from carbon steel pressure vessel plate, this 2:1 semi-ellipsoidal head delivers uniform stress distribution through its continuous curvature transition from the dish to the straight flange, minimizing discontinuity stresses at the shell junction.
Yuhong Group Co., Ltd. supplies this component to the oil, gas, chemical, petrochemical, heat exchanger, and boiler industries, with comprehensive supporting capabilities for tube bundles, U-tubes, heat exchanger tubes, finned tubes, tubesheets, baffles, and other pressure vessel components.
| Element | Percentage (%) | Element | Percentage (%) |
|---|---|---|---|
| C | 0.10-0.22 | Cu | ≤0.30 |
| Si | ≤0.60 | Ni | ≤0.30 |
| Mn | 1.00-1.70 | Mo | ≤0.08 |
| P | ≤0.030 | Nb | ≤0.01 |
| S | ≤0.030 | Ti | ≤0.03 |
| Al | ≥0.020 (min) | V | ≤0.02 |
| Cr | ≤0.30 |
Reference: ASTM A516/A516M Standard Specification
The elliptical head requires precise hot or cold forming processes, with thickness reduction (thinning rate) as a critical control parameter. For hot-formed heads, thermal contraction after forming directly affects the final inner diameter—studies indicate contraction can reach approximately 6mm on a 1200mm diameter head, necessitating dimensional compensation in die design. The maximum allowable thinning rate per industry practice is 10%.
| Test Method | Application |
|---|---|
| Ultrasonic Testing (UT) | Lamination detection in raw plate material |
| Radiographic Testing (RT) | 100% weld seam examination (for segmented heads) |
| Liquid Penetrant Examination (PT) | Surface defect detection after forming |
| Magnetic Particle Inspection (MPI) | Ferromagnetic material surface/crack detection |
| Dimensional Inspection | Inner diameter tolerance, roundness, straight flange height, and overall depth verification |
Third-party inspection services (ABS, GL, DNV, PED, CCS) available per project requirements.
Yuhong Group provides integrated supply for complete pressure vessel and heat exchanger assemblies, including:
| Standard | Equivalent Grade |
|---|---|
| ASME | SA516 Grade 70 |
| British Standard | BS1501-224-490A/B |
| European Norm | EN10028 P355GH |
Dimensional range: Thickness 3mm -150mm, diameter up to 260" as formed
| Industry | Equipment/Service |
|---|---|
| Oil & Gas | Pressure vessels, separators, storage tanks |
| Petrochemical | Reactors, distillation columns, accumulators |
| Chemical Processing | Mixing vessels, high-pressure reactors |
| Power Generation | Boilers, deaerators, feedwater heaters |
| Heat Transfer | Shell & tube heat exchanger end closures |
The mechanical and chemical properties are identical. ASME "acquires" ASTM specifications and assigns an "S" prefix (A516 becomes SA516) for use in ASME Boiler and Pressure Vessel Code construction.
For electric arc welding of thicker plates (typically >25mm), preheating may be necessary due to the higher carbon content (up to 0.28%) of Grade 70 compared to lower grades.
It provides the optimal balance—lower stress concentration than torispherical heads, less material than hemispherical heads, and continuity of curvature that minimizes edge discontinuity stresses at the shell junction.
