Flare Systems and Hot Tapping - Understanding Risk is Essential

Litigation, North America

After an incident in which pyrophoric material was ignited in a flare header during a maintenance activity, a recommendation was to remove a suspected leaking valve to evaluate its integrity. The flare system was still in live service; therefore, a hot-tap and stopple procedure would be required to isolate the pressure and hydrocarbon energy. Baker & O'Brien was retained to inspect the site and submit an affidavit of opinion on the safety risk of performing the non-routine energy isolation procedure.

Flare systems in refineries and petrochemical facilities are used to safely vent and combust hydrocarbons to control unexpected pressure increases in process piping or equipment, thereby mitigating potential damage and eliminating the release of flammable materials to the atmosphere. They are also used to purge flammable gases from equipment in preparation for maintenance activities.

In a typical facility, multiple process units can be tied to common flare headers. This can result in various chemicals and hydrocarbons, such as amines, hydrogen, caustic, sulfur compounds or pyrophoric materials, entering into the flare system. Consequently, strict adherence to safety protocols and work practices to identify and mitigate risks is required when performing maintenance on flare systems.

During a maintenance activity, to install a blind in a flare line, oxygen was unknowingly introduced into the flare system that ignited pyrophoric material. A potential contributing factor to the incident was a valve that was suspected to be leaking. Therefore, it was investigated whether the suspect valve could safely be removed. One possible solution was to hot-tap and insert a stopple in the flare header. Hot-tapping is a method of making a connection to a pipe or vessel while it is still in-service. The process involves welding a connection to the pipe and then drilling into the pressure-containing portion of the pipe. Stoppling is the process of inserting a plug through the hot-tap connection into the line to stop the flow and isolate the system. Performing a hot-tap on a flare system is not a common practice and requires strict adherence to specific safety procedures. These procedures can include: (1) assuring a minimum flow through the flare header to remove heat generated by welding activities; (2) identifying potential chemicals in the system that can cause failure of the welds; and (3) assessing system pressures and temperatures to make sure they are acceptable. Before the hot-tap can be performed, all requirements of the procedure must be met.

Baker & O'Brien was retained to evaluate if performing a hot-tap and inserting a stopple could be safely performed on the flare header. Following the site visit and our evaluation of the procedure, we prepared an affidavit and provided court room testimony as to whether the hot-tap and stopple could be utilized or if the valve should be left in place.

Kevin P. Milburn

Senior Consultant, PRISM Services Manager

Petroleum Refining
Standard of Care / Accident / Incident Investigation / Litigation / Expert Witness Testimony / Operations and Maintenance / OSHA-related / Safety
North America