Why are pressure vessels important in chemical processing?
Why are pressure vessels important in chemical processing?
Definition: A pressure vessel in chemical processing is a closed container designed to hold gases, liquids, or powder/liquid mixtures at pressures significantly different from ambient — from vacuum (<0.1 bar absolute) to high pressure (>10 bar) — and is critical for reactions, storage, distillation, and containment of hazardous substances. HECHT integrates pressure vessel-compatible interfaces (flanged connections, pressure-rated flex hoses) into powder handling systems for chemical processes operating under PED 2014/68/EU and ATEX 2014/34/EU, enabling contained transfer between vessels at 0.1–10 bar differential pressure.
Key points
- PED 2014/68/EU classification: Pressure vessels above 0.5 bar × volume >1 liter fall under the Pressure Equipment Directive — category I to IV based on fluid hazard and PS × V product; Category III/IV vessels require notified body (NoBo) inspection and CE marking with DNVGL, TÜV, or Lloyd register.
- Process integration: Powder handling systems connecting to pressure vessels must be pressure-rated to the same level — HECHT flexible connections, rotary valves, and discharge valves are rated to match vessel operating pressure (up to 10 bar) and tested to 1.5× design pressure per PED Article 19.
- ATEX compliance in chemical reactors: Chemical reactors with organic solvents or flammable gases are classified ATEX Zone 0/1 internally — all powder feeding and discharge equipment must be ATEX cat. 1G/2G certified for gas zones and ATEX cat. 1D/2D for powder zones at inlet/outlet.
- Material compatibility: Chemical vessels handling acids, bases, or oxidizing agents require Hastelloy C22, titanium, or glass-lined internals — HECHT supplies powder handling interfaces in corrosion-resistant materials with material certificates per EN 10204 3.1 and positive material identification (PMI).
- Pressure relief and safety interlocks: PED requires pressure relief devices (safety valves, rupture discs) on all vessels above design pressure limits — HECHT powder handling connections are designed with pressure equalization vents and safety interlocks to prevent over-pressurization during powder charging.
Related HECHT solutions: Powder handling & transport | Pharma containment | Test & Trial Centre
Frequently Asked Questions about pressure vessels in chemical processing
What European regulations apply to pressure vessels used in chemical processing?
The primary regulation is PED 2014/68/EU (Pressure Equipment Directive), mandatory for pressure vessels above 0.5 bar operating pressure. Additional regulations: ATEX 2014/34/EU if the vessel contains flammable media, Seveso III Directive (2012/18/EU) for large hazardous chemical inventories, and REACH Regulation (EC 1907/2006) for chemical substances. HECHT designs powder handling interfaces to pressure vessels with full PED compliance documentation and CE marking as part of the delivery package.
How do you safely add powders to a pressurized chemical reactor?
Powder addition to pressurized reactors requires: (1) Pressure-rated charging valve (rotary valve or double flap valve rated to reactor pressure), (2) Pressure equalization step before opening the charging port (to prevent powder blow-back), (3) Contained transfer from bag or IBC via pressure-rated flexible connector, (4) N₂ purging if the reactor contains flammable or reactive atmosphere. HECHT designs complete reactor charging systems from powder storage to reactor inlet, with all components PED- and ATEX-certified and pressure tested to 1.5× design pressure.
What is the difference between a pressure vessel and a storage tank for chemical powders?
A pressure vessel operates above 0.5 bar gauge and is subject to PED 2014/68/EU — designed to withstand internal pressure with wall thickness calculated per EN 13445 or ASME VIII. A storage tank typically operates at atmospheric pressure or slight overpressure (<0.5 bar) and falls under the Simple Pressure Vessels Directive (SPVD) or no directive at all. For powder handling, most intermediate storage is at atmospheric pressure; reactor charging and pneumatic conveying involve pressure differentials that bring vessels under PED scope. HECHT advises on the correct regulatory classification for each vessel in your process.
Author: Joost van Velzen | Date: May 22, 2026 | Hecht Technology B.V.
Related reading
- Pressure Vessels Guide
- How Does a Pressure Vessel Work
- How Is Pressure Vessel Safety Ensured
- All HECHT Products