A hydrogen reformer furnace at a refinery was shutdown for maintenance to remove and cap the inlet and outlet headers of some radiant tubes that had previously developed hot spots and been isolated by externally pinching them off at the inlet. A decision was made to leave steam in the steam-generating circuit during this maintenance operation to prevent freezing. After maintenance was complete, the startup procedure required the furnace to be first heated up to 350°C (662°F) prior to introducing 4136 kPa (600 psig) steam into the radiant tubes. Just after the 4136 kPa (600 psig) startup steam was introduced into the reformer furnace inlet, the control room alarm journal reported an extreme positive pressure spike at the same time a single loud bang was reported by the operations view more
An explosion occurred within the hydrogen processing system of a chemical plant that produces sodium chlorate for bleaching pulp and paper. The chemical process utilizes electrolytic cells and is pH-dependent. Hydrogen is produced as a byproduct and is utilized as a fuel.
At the time of the incident, the plant was at an abnormal operating level of 25% capacity. A non-routine maintenance operation to repair high-pH liquid piping was in progress. To assist, operations personnel rerouted the high-pH liquid stream to the plant sump. However, in doing this, the liquid eventually made its way back into the electrolytic process by design. Ultimately this created the root cause of the explosive condition in that the pH of the electrolytic process increased faster than the computer- view more
Overview: A pipe end containing fuel oil corroded at the outlet of a heat exchanger on the outlet side of a desulfurization reactor. The corroded pipe end leaked hydrogen gas, which exploded, causing oil to leak from the heat exchanger. The leaking oil developed into an oil fire, and the damage spread. The causes of the pipe end corrosion include the following:
There was a high concentration of corrosive substances in the process injection water.
The concentration of corrosive substances increased due to re-molding the heat exchangers.
The shape of the pipe cap was dead end piping.
Incident: During normal operations at a fuel oil refinery, a pipe end in a desulfurization unit developed a hydrogen leak, which led to an explosion. The pipe end was located on view more
Hydrogen leaked from the outlet piping of a hydrogen heating furnace at a fuel oil desulfurization cracking unit during normal refinery operation. The leaking hydrogen caused a localized fire. Dilution water for cleaning polythionic acid collected in the drain nozzle after a turnaround shutdown. The chlorine concentration in this dilution water was high because its concentration in the industrial water was originally high. The chlorine in the industrial water was concentrated by the high temperature, after the plant was restarted, and stress corrosion cracking occurred. Hydrogen leaked and was ignited by static electricity or heat.
A fire occurred at the fuel oil desulfurization cracking unit of a refinery 257 hours after startup of the plant, view more
A technician was welding a cable suspended over a stainless steel H2 instrument line. During the welding process, two holes were accidentally burned through the hydrogen tubing. The operator heard a hissing sound and closed the valve, but the hydrogen had already ignited and it burned his hand while he was feeling for a leak.
A short during welding caused the pinholes in the tubing containing the gaseous H2.
A facility experienced a major fire in its Resid Hydrotreater Unit (RHU) that caused millions of dollars in property damage. One employee sustained a minor injury during the emergency unit shutdown and there were no fatalities.
The RHU incident investigation determined that an 8-inch diameter carbon steel elbow inadvertently installed in a high-pressure, high-temperature hydrogen line ruptured after operating for only 3 months. The escaping hydrogen gas from the ruptured elbow quickly ignited.
This incident occurred after a maintenance contractor accidentally replaced an alloy steel elbow with a carbon steel elbow during a scheduled heat exchanger overhaul. The alloy steel elbow was resistant to high-temperature hydrogen attack (HTHA), but the carbon steel elbow was not. view more
A rupture occurred in a 24-inch gas line in a reformer. The pipe contained hydrogen and carbon monoxide at a pressure of about 400 psi and a temperature of 930 °C. The ruptured section of pipe had a high-temperature alloy steel outer wall, a refractory liner, and a stainless steel inner liner. The refractory lining had been repaired several times before (including three months prior to the incident) because of localized deterioration and hot spots. The repair procedure consisted of cutting a section of pipe, re-pouring the refractory liner, and patch-welding the outer wall.
The first rupture occurred when the 42-inch-long welded section of the pipe suddenly blew out. On-site employees heard a rumble and observed a flame above the ruptured pipe. Before the torch fire at the view more