Timeline to Conduct an NFPA 652 DHA for a New Facility

Meeting project deadlines for design engineering firms can be challenging for a new facility that processes combustible dust. Conducting an NFPA 652 Dust Hazard Analysis (DHA) for the Authority Having Jurisdiction (AHJ) is a compliance requirement. A DHA is a critical methodology that empowers plant owners and designers to identify combustible dust hazards, assess their risks, and recommend adequate control options, using a systematic and structured protocol. Project planning can sometimes underestimate the time required for these tasks. This article identifies critical milestones to meet compliance requirements and minimize the time necessary to accomplish these tasks using a new protocol.

Please refer to Figure 1 for a flowchart of the sequence of operations required to produce an NFPA 652 DHA report using this novel strategy.

1. Technical Dust Hazard Analysis (Phase 1)

A Technical Dust Hazard Analysis (TDHA) involves equipment and process temperature/pressure for all powders, including their health, flammability, reactivity/instability, and hazardous material properties. Once the potential hazards and possible consequences of process deviations are defined, expected combustible dust risks can be identified, and necessary mitigation can be recommended within the process's scope. A TDHA requires the following process safety information, drawings, documentation, and descriptions: 1) identification of combustible dust, 2) required documents and drawings, 3) process equipment and facility review, 4) possible flammable vapors or gases, 5) electrical classification, 6) occupancy rating, 7) ignition source control, 8) injury and damage control,  and 9) process safety information.

Conducting a Technical Dust Hazard Analysis (TDHA) at this early engineering stage allows the designer to modify the process drawings promptly to keep the project on schedule and in compliance.

2. Administrative Dust Hazard Analysis (Phase 2)

The second phase--or the Administrative Dust Hazard Analysis (ADHA)--can also be performed during pre-commissioning. The administrative requirements include 1) an ignition control program for normal and upset conditions, 2) a housekeeping program, 3) equipment inspections/preventative maintenance Program, 4) management of change program, 5) personnel protection equipment assessment (consider electrostatic and flash fire hazards) 6) annual combustible dust training program for affected personnel and contractors, 7) site emergency response plan - include local first responders and 8) management systems to comply with OSHA, NFPA, and company policies/procedures.

3. The Authority Having Jurisdiction (Phase 2)

Combustible dust requires approval from the Authority Having Jurisdiction (AHJ) for a new facility. This undertaking includes the time and information needed for the AHJ to review the client's permit and supporting documentation, including the facility's International Building Code  building occupancy rating. The report from the TDHA should be included in the AHJ's information package. Please plan for these tasks and develop a project timeline.

4. Merging the Technical and Administrative Dust Hazard Analyses (Phase 3)

This phase is primarily a documentation and recordkeeping exercise to ensure that all aspects of the DHA, including findings and recommendations, are reported. Maintain records of training, incident reports, and changes to the process or equipment for the lifetime of the facility.

A DHA must be repeated when significant plant changes occur or at least every five years. The usual practice is for the owner to generate an action plan for each recommendation. The plan typically identifies the action item, who is responsible for follow-up, an estimated target completion date, and completion status (e.g., percent complete and date).

5. Project Management Timelines (Phase 3)

The engineering design consultant and the process owner should complete the estimated time for the DHA. The estimated timeline for testing, calculations, corrective tasks, and report writing is projected. The timeline can be visualized using a Gantt chart.

These five actions, assigned into three phases, can be helpful when undertaking a DHA for a pre-construction safety review. A documented DHA with an implementation plan and a definitive timeline will enable the owner/operator to comply with local safety codes, reduce operational risk, and complete the DHA on time with minimal rework and fewer process interruptions.     

Richard Kwasny is a senior consulting engineer at Fauske & Associates LLC. Ashok Ghose Dastidar PhD is Fellow engineer, vice president, Westinghouse Electric Co., Dust & Flammability Testing and Consulting Services – Fauske & Associates. Fauske & Associate is a subsidiary of Stone & Webster LLC. For more information, visit www.fauske.com.