Ultra-High Pressure Gauge Selection in Petrochemical Plants: Case Study for Reactors and High-Pressure Piping

A high-pressure polyethylene plant required reliable pressure monitoring for a 280 MPa reactor and 30–60 MPa transfer piping. Standard pressure gauges failed repeatedly due to pointer flutter, Bourdon tube fatigue, leakage, and housing rupture.

·High pulsation from reciprocating compressors (shock peaks >1.5× working pressure).

·Process temperature up to 180°C, with hydrogen and trace H₂S.

·Zone 1 classified area requiring Ex d / Ex ia certification.

·Absolute zero-leakage requirement on high-pressure connections.

3. Dedicated Gauge Solution

·Wetted parts: Inconel X-750 Bourdon tube, 316L or Hastelloy C-276 fittings — resistant to hydrogen embrittlement and sulfide corrosion.

·Ranges: 0–400 MPa for reactor; 0–100 MPa for piping, working point at 60–70% of full scale.

·Vibration & pulsation control: Silicone-oil-filled case, stainless steel pulsation damper, and restrictor to attenuate shock.

·High-temperature isolation: Cooling coil or remote diaphragm seal with capillary line to keep gauge temperature below 80°C.

·Connection & sealing: High-pressure cone-and-ferrule type (M20×1.5 or 9/16″-18UNF) with metal gasket.

·Safety features: Ex d IIC T6 flameproof enclosure, blow-out back, and optional electric contact for overpressure alarm.   

 4.Customized thread size      

     Will make NPT  , G , BSPP or UNF thread .(Especially for the ultra-high pressure, it is 9/16" UNF.)                                                 

5. Results

·12 months continuous operation with zero leakage or gauge failure.

·Maintenance parts consumption reduced by 80%.

·Pressure fluctuation reduced from ±5 MPa to ±1 MPa.

·Reactor conversion efficiency improved by 1.2% through stable pressure control.

Ultra-high pressure gauge selection in petrochemical service must integrate wetted materials, range selection, pulsation damping, heat dissipation, and explosion-proof certification. This solution provides a proven reference for procurement managers and distributors serving high-pressure reactor and piping systems.