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Pressure Vessel Safety: Complete Control Guide from Compressors to Boilers
Closed volumes working above half a bar are pressure vessels: steam and hot-oil boilers, air tanks, autoclaves and expansion tanks. This guide covers the legal intervals, the proof pressure rule, the safety valve-gauge-condensate trio and the hidden fault indicators.
Pressure vessel safety is the management of closed volumes working above atmospheric pressure — steam and hot-oil boilers, heating boilers, autoclaves, air receivers, expansion tank-hydrophore sets — through periodic examination, thickness measurement, safety-gear trials and the 1,5 times operating pressure proof test. A pressure vessel burst is rare but lethal: a thinned zone, a crack-corrosion and a dead safety valve together release the stored energy at once. Full service: pressure vessel periodic inspection.
Legal Basis and Interval
Under the Work Equipment Regulation, pressure vessel control runs at intervals not exceeding one year; the proof is at 1,5 times working pressure. Boiler Code practice sets internal examination yearly, external every two years and the hydrostatic test five-yearly. Within PED 2014/68/EU, design-production conformity and CE-stamping; in operation the valve-gauge calibration records complete the file.
The Critical Trio
| Valve | Duty | Control |
|---|---|---|
| Safety valve | Relief of excess pressure | Set-pressure calibration, relief function |
| Gauge | Makes pressure visible | Accuracy check, readability |
| Level-water gear | Prevents dry running | Indicator-float-alarm cut chain |
Hidden Fault Indicators
- Corrosion-thinning: wall below the permitted thickness by UT measurement; inside, moisture-condensate pooling accelerates the loss.
- Condensate relief: in receivers such as the air tank, a blocked bottom valve is the master driver of internal corrosion — automatic drain and daily watch save lives.
- Thermal expansion: flange-gasket leak, clamp slack; the hot-zone map is drawn by thermal camera.
- Steam side: the stuck trap produces leak plus waterhammer; condensate recovery and blowdown verification are the hidden efficiency line of the boiler.
On the boiler room side you can find type-specific proof steps on the steam boiler, hot oil boiler and boiler pages of our service tree. To merge your pressure equipment into one calendar and never miss proof-calibration-interval, build the inventory plan via our periodic inspection services.
Author: KYF Test Engineering Team • Last updated: September 2026