MOC and PHA of Ammonia Unloading Processes Case Study


The Challenge

A coal fired power plant which produces enough energy to supply 190,000 households had observed leaks from their break away anhydrous ammonia unloading connections. The client wanted to initiate a Management of Change (MOC) to replace the connections with non­break away connections. The plant uses anhydrous ammonia in its NOx scrubbing processes, a chemical that is unloaded from tanker trucks and tank railcars. The electric utility company had expanded their NOx scrubbing system in 2009.

OSHA 29 CFR 1910.119 Process Safety Management (PSM) requires that operators perform a Process Hazard Analysis (PHA) as part of the MOC when a design element is being altered. In their desire to ensure compliance with the PSM standard, the client retained ioMosaic to complete a PHA of the ammonia truck unloading process. The analysis and documentation were prepared using Process Safety Office® PHAGlobal® software.

Our Approach

A PHA is the study of the significance of hazardous situations associated with a process or activity. It uses qualitative techniques to judge risk qualitatively and to pinpoint weaknesses in the design and operation of facilities that could lead to accidents. PHAs focus on equipment, instrumentation, utilities, human factors and external events that might impact the process.

This PHA was performed using the Hazard and Operability (HAZOP) methodology without credit for the breakaway fittings in order to examine the risk of the unloading operation with/without them.

The Benefits

The ioMosaic team delivered worksheets created within PHAGlobal® software which reported the details of the hazards and their associated causes, consequences and safeguards. PHAGlobal® quickly identifies any compliance gaps and tracked action items. The client found that the risk level of the unloading process without breakaway connectors was acceptable, after reviewing the project deliverables. They were most pleased with the attention to detail and completeness that ensured their compliance with OSHA 29 CFR 1910.119.

Learn More

Our mission is to help you protect your people, your plant, your stakeholder value and our planet. To learn more about how we can help you manage risk, call us at 1.844.ioMosaic.