Safety Alerts 9

Compressors

• HP Gas Injection compressor head developed was low. Unable to inject gas. Third stage FT error resulted in anti-surge valve NOT opening under low/no flow. Blocked outlet heat generation and temperature rise resulted in HC gas release that auto-ignited. Process gas reached via dry gas seal Compressor - GT common Lube Tank, that exploded. Compressor tripped and plant blowndown. Emergency Lube oil pump continued running added fuel to fire

• Compressor Outlet Pipe: Vibrations let a bolt cut thru Hydrogen piping, leading to leaks

• Compressor vibration resulted in crack of large shrinkage cavities in discharge thermowell. Leak

• Poor recycle/ suction pressure control, in a LP compressor led to air suck-in and explosion

• Lightning strike: Black DCS Screen. Induced high voltage impacted C2+ plant compressor control devices. Excessive recycle / PSV chattering cracked weldolets in flare lines. Root cause: Poor grounding of cables to control room

• C2= Plant: Pneumatically assisted NRV in Cracked Gas Compressor line failed. VCE. Similar. C3 Refrigeration system compressor discharge line, in another C2= Plant

• C2= Plant. Cracked Gas Compressor. HP Stage 2” balance line (balances impeller thrust force) had cracks. Assumed due to long-term fatigue. Accelerometer tests showed natural frequency resonance at a small window of compressor operating speeds. Fixed with suitable supports. Include auxiliary piping also in design reviews as is done for main lines

• Isolation: After maintenance, isolation blinds were removed. Ethylene leaked thru the isolation valves into the compressor and the ethylene-air mixture ignited. WWW

• Process gas with return seal oil can cause lube oil tank explosion when breather is clogged or unable to cope

Dehydration

• Small bore: Glycol Pump discharge ½" SS tubing upstream tower SDV broke. Glycol, condensate, and gas sprayed onto the glycol reboiler and ignited

Sweetening

• HC separated in Rich DEA Surge Drum routed to unit Flare KOD. Pumped from KOD to Lean Amine Tank instead of Slop Tank, leading to HC accumulation in tank. Tank HAC (Hazardous Area Classification) didn’t factor it. Tank drained by a vacuum truck using an unearthed non-conducting hose. Explosion

• Pyrophoric Fire: Wet spent metallic parts with water on opening a column/ tank in H2S service

Piping

• Piping failure is the cause of about 50% of leaks. Fatigue and/or inadequate flexibility. WWW

• Erosion: Downstream of Test Sep LCV led to large hydrocarbon release. Avoid bends immediately after an LCV/PCV, min 20D. Proppants / sand in the fluid can accelerate corrosion. If the downstream separator is elevated to provide pump NPSH, install a check valve at its inlet, to prevent its emptying

• Similar, thinning/hole observed in Cold Box piping bend, downstream of a liquid methane LV - flashing and cavitation

• Erosion-Corrosion: Wash water injected in Deethanizer feed. Water at gas velocity thinned downstream piping elbow. Gas release and explosion. Avoid bends immediately after such injection point. Liquid injection: consider spray nozzle, gas as atomizing fluid. Inspect downstream bends regularly. Similar case. See Refinery/ FCC

• Similar, cold VGO injected via a quill into hot VGO+H2 downstream of HX preheat train. Distance to downstream elbow was only 2D, instead of 10D. Piping and elbow failure and fire. Inspect downstream bends and its trunnion piping support regularly

• LP Production header: 10’ long corrosion rupture, below a demulsifier injection point without injection quill. The quill would have introduced the chemical into the middle of the flowing stream, avoiding localized corrosion. Check injection points

• Low Temperature Embrittlement, due to poor mixing of LT fluid into warm fluid. Keep minimum distance upstream of mixing point in HT line for HT/LT spec break

• Low Temperature Embrittlement: While service temperature may suit CS, auto-refrigeration on loss of pressure - venting/ blowdown can bring down metal temperature. MDMT issues

• Brittle fracture of CS piping during hydrotest as a result of manufacturers reducing Manganese to lower limit of piping codes - A106/A53 pipes + A105 flanges + A234 fittings. Ask for “Mn:C ratio > 5 and grain size <7”

• Brittle fracture: Threaded 3” cast iron Y strainer installed in a welded SS piping failed. Likely thermal expansion. 4,500 kg iso-butylene released. VCE

• Bellows: Fail due to poor installation or when not designed to applicable operating conditions. A bellow not designed for steam out failed. WWW

• Poor Isolation: Pump PSV removed but inlet was not blind flanged. Condensate discharge and fire

• Poor Isolation: Cyclohexane leak and explosion. Earlier blamed on temporary patch up piping by plant personnel, without a design review. Now understood as caused by fugitive water into reactor that vaporized suddenly with a pressure surge. Follow Management of Change procedures

• Poor Isolation: Attempt to cut a 30m vertical line from CDU fractionator to Naphtha Stripper resulted in naphtha release due to a passing valve across LCV. Ignited by fractionator bottom bare area running above naphtha auto ignition temperature