A storage tank holds liquid at atmospheric pressure. A pressure vessel holds it at 0.6 MPa, 1.6 MPa or 4.0 MPa-and the penalty for error is not leakage, it is rupture. Zhongneng Huajian's pressure vessel and vessel-head product line is the "high-pressure sibling" of its tank business, and many chemical EPC buyers do not realize the same Shandong shop rolls shell plates and presses dished ends under one roof.
What ZN makes in this category
Horizontal/vertical pressure vessels: air receivers, nitrogen buffers, separator vessels, surge drums
Reactors and process columns (low-to-medium pressure, custom internals)
Dished ends / vessel heads: ellipsoidal 2:1, hemispherical, torispherical, flat flange heads
Skid packages: vessel + pump + instrument panel + pipe rack on one base
Code and document stack
Design per ASME VIII Div.1 or GB/T 150 / JB 4732
WPS/PQR to ASME Sec. IX or NB/T 47014
RT/UT/MT/PT mapped to ASME V or JB/T 4730
Hydrostatic test to 1.3 × MAWP, pneumatic only when water test is unsafe
Mill cert, impact test (if low-temp service), PWHT record, nameplate with U-stamp-equivalent data (for non-ASME-shop projects, GB150 nameplate)
Why this matters for tank buyers
A fuel depot or chemical tank farm rarely needs only atmospheric tanks. It also needs:
Instrument air receiver (horizontal pressure vessel)
Glycol surge drum
Desalination high-pressure permeate buffer
Nitrogen blanket supply vessel
If the tank vendor cannot make vessels, the buyer manages two factories, two MDR formats, two NDT philosophies. ZN bundles them: same job-number logic, same English dossier, same supervisor on site.
Dished head detail most buyers ignore
A 2:1 ellipsoidal head is not "a cap." Its crown radius, knuckle radius and straight flange length change the stress distribution at the shell-to-head junction. ZN controls:
Plate crown centered on press to avoid asymmetric thinning
Straight flange ≥ 25 mm for nozzle reinforcement continuity
Surface roughness on food/pharma heads Ra ≤ 0.8 µm
Magnetic particle on head-to-shell seam before hydrostatic test
FAQ snippet
"Is a pressure vessel just a thick storage tank?" No. A storage tank is designed for liquid head and wind/seismic; a pressure vessel is designed for hoop stress from internal pressure, with formal code stamping, relief device calculation and periodic inspection regime.
ZN's Special Equipment Manufacturing License (TS2237U26-2029 / TS3837J54-2029) covers the vessel family alongside tanks, so a chemical EPC can issue one PO for "3 atmospheric tanks + 2 separators + 40 dished heads."
