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Designed-in Safety

Issue 11 and Volume 112.

Comprehensive review of potential hazards and operational safety designed into power plants is becoming more common.

By: James Brown, PE, PMP, and Michael Martin, CEP, Fluor

As design engineers and architects, we have a tremendous opportunity to improve the quality of life in the communities in which we work and live. Engineers are able to take the theoretical and sometimes abstract principles of science and apply them to make the world a better place. However, with this opportunity come the responsibility and the challenge to ensure the designs we develop, while furthering one aspect of our quality of life, do not do so at the expense of another or cause undue harm to individuals implementing or applying the design. This provides an opportunity to take sustainable actions: providing designs that are safe and environmentally responsible to current and future generations.

It is common practice at Fluor to perform a formal HAZards and OPerability Review (HAZOP) during the design phase of many projects in the chemicals, petroleum and mining industries. The HAZOP process identifies hazards and operability problems through a methodical and formal procedure.

For the U.S. power industry, however, the use of a formal HAZOP review has not been widely used unless the power plant was part of a large refinery or chemical plant. This may largely be attributed to the relatively minor changes in the core fossil-fueled power industry process system cycles. While the rigorous, nodal analysis of a formal HAZOP may not be warranted for the power industry, it is clear that with the use of varying water treatment and flue gas treatment process chemicals, varying fuel supplies, varying advancements in metallurgy and varying plant layouts, some type of review focused on addressing health, safety and environmental (HSE) issues is needed.

Fluor Power has adopted a process hazard analysis (PHA) review to be conducted on all new power plants and plant betterment projects such as selective catalytic reduction and scrubber projects for which the company has design responsibility. Since its adoption, this work practice has been applied to Fluor’s design of Newmont’s 242 MW coal-fired TS Power Plant, Luminant’s 2×750 MW supercritical coal-fired Oak Grove Power Plant and numerous Fluor betterment projects. Furthermore, this review concept can be applied to any new generation facility or existing plant modification project.

Drivers for Developing PHA Review

With the recent resurgence of the power market worldwide, it is essential for engineers and designers to take a fresh look at the way their design products affect HSE aspects of new projects. Market expansion and growth in the energy and chemicals sector have also placed tremendous pressure on the ability to gain and retain experienced technical resources. This pressure has been seen by all engineering, procurement, construction and commissioning (EPCC) companies in all business lines (horizontally) and through the supply chain (vertically) for equipment and material providers.

In addition, the so-called impending “crew change,” as baby boomer technical experience leaves the industry, could further affect the design experience being applied to new generation projects. The PHA review provides a forum to ensure knowledge sharing with respect to HSE issues.

For the U.S. market, the proliferation of low sulfur Western coals represents just one example of how a complete new set of potential HSE issues has been introduced, the result of this fuel’s high volatility and self-combustive nature. In addition, the next wave of generation facilities is introducing new control system architectures. Digital bus technologies are now being used for safety instrumentation as opposed to the traditional hard wire control systems. Environmental legislation and clean air requirements have required power generation facilities to store, transport and use a varied new list of onsite plant chemicals and materials. With all these technological advancements and new processes come potential HSE issues that must be addressed.

Track Record

Prior to adopting this practice, Fluor Power reviewed safety aspects of their designs for power facilities during piping and instrumentation diagram (P&ID) reviews, supplier document reviews and 3-D model reviews of projects. Fluor’s experience in other industries has provided insight into the benefits a focused HSE design review can provide to new projects.

Fluor adopted the PHA review as standard design practice to determine if engineered safety of a design and verification of safety instrumentation are adequate. Consequences considered include employee safety, loss of plant equipment, loss of production, liability, insurability, public safety and environmental impacts. The PHA further provides a framework for prioritizing and mitigating risks. The PHA review is not as methodical a review as a formal HAZOP review, which could take months to complete. Instead, the PHA review is a more general analysis focusing on the hazards and taking a critical view on how the designed systems work together to ensure protection of HSE.

The focus here is the Phase 3 PHA Review, which includes HSE personnel and other participants outside the project team. Preparation for the PHA Review (Phase 3) begins weeks prior to the actual review session. Team composition is important so that the team’s experiential knowledge of the processes involved ensures thorough examination of the possible outcomes. Typically, the HSE director delegates that to an engineering manager who is from a different project. This approach ensures the design is reviewed by an experienced individual outside of the project design team who can guide the team in an objective manner. In some cases, the client’s operations team or owner’s engineer participates depending on contractual structure and client interest.

Key leaders from the project team also participate. After appointing a facilitator, PHA review planning begins with a kickoff meeting. Several days are planned for the PHA Review of a large EPCC project such as Newmont’s TSPP or Luminant’s Oak Grove Power Plant, or as little as half a day for a betterment project. The schedule will be highly dependent upon the scope of work, chemicals anticipated to be used and involvement expected from the design team and owner’s team. The format of the PHA Review is a participative, informal “roundtable” review of the potential plant hazards with the facilitator directing the team through topical discussions.

Chemicals

At the beginning of the PHA review, the facilitator leads the team through a summary of the material safety data sheets (MSDS) of the chemicals and materials utilized on site, highlighting the following items from the MSDS:

  • Recommendations on first-aid measures
  • NFPA 704 Hazard Rating System designations
  • Incompatibilities with other materials
  • Environmental containment/spill response requirement
  • Fire-fighting recommendations
  • Special storage and ventilation requirements.

    Review of these chemical/material characteristics provides the background for many areas to be covered in the review, including containment/storage requirements, safety shower / eyewash requirements and P&ID reviews.

    With a clear understanding of the chemicals and materials used at the plant, the PHA review team begins a review of the handling, storage and containment of these chemicals. The team reviews storage design, including fixed onsite tankage or portable bulk containers. The unloading of the chemical is also analyzed, be it truck unloading, rail or bulk container supply. The team reviews provisions required in the design for containing a potential spill/leak or catastrophic failure of the storage container and means of personnel egress. The team reviews how rain water or washdown water in the containment is processed. In addition, the team reviews how fire-fighting water in the containment area is managed during emergencies.

    Following review of the chemicals and materials and their storage and handling, the PHA review facilitator leads review of the location of the safety shower (SS)/ eyewash (EW) stations. At Fluor Power, each SS/EW location is reviewed in the plant’s 3-D design model. This method affords the team easy access to review locations at various angles and take measurements as required to determine required length of travel from various hazards.

    The guidelines that the PHA review team uses during this discussion are provided by Occupational Safety and Health Administration (OSHA) 29 CFR 1910.151 (c) and ANSI Z358.1 and include 1) travel distance limitations (< 25 feet), 2) pressure and flow requirements, 3) unobstructed access and 4) appropriate signage.

    Plant Systems Review

    The PHA facilitator then leads the review team through select P&IDs for potential hazards associated with the process, equipment and facility operations. These P&IDs have been determined prior to the review by the facilitator to be worthy of team review due to the material handled or the magnitude of a potential HSE catastrophe in the system.

    Typically, the process engineering team lead provides a brief overview of the system purpose and background on design features. The facilitator then leads discussions with the team to analyze the system for potential hazards that could be experienced in operations or maintenance of the system. A safety checklist is used by the team to initiate discussion of potential issues and operating scenarios that should be reviewed.

    The PHA review team facilitator then directs the team through the potential electrical, instrumentation and controls hazards in the power plant design. In addition to general electrical operations/equipment hazards checklist, the team reviews the electrical hazardous classification areas. NEC Article 500-2 requires areas where fire or explosion hazards may exist to be classified based on the properties of the flammable material (class and group) and the likelihood that a combustible concentration is present (division). The Electrical Hazardous Classification documents reviewed by the team include the hazardous classification specification, hazardous classification area drawings, and any supplier hazardous classification drawings. Typical areas for review in a power facility include coal handling and storage areas, hydrogen areas, natural gas areas, wet cell battery rooms and others.

    Upon completion of the PHA Review, the HSE director and engineering manager determines disposition of any potential hazards that may need to be evaluated after the review to determine if any action is warranted. True safety errors that are identified in design must be corrected regardless of how they might rank in the assessment. The proposed approach is similar to the approach that might be typical in a formal HAZOP review. It should be noted that this risk assessment methodology is provided as an illustration of the framework that may be used. The actual values and ranking scheme should be determined by the entity employing the evaluation matrix.

    After deciding the severity and likelihood values, a risk ranking is determined and interpreted. Color-coded areas depict the overall risk categories that require a PHA review recommendation to eliminate the hazard, improve mitigation or reduce frequency of occurrence. If the matrix indicates deficiencies in the design such that a “risk ranking” of 10 or higher is determined, then recommendations must be provided to eliminate the hazard. The recommendations may include upgrades to the basic process control, critical alarms or containment equipment. A ranking of nine or lower is acceptable and a recommendation is not required; however, one may be provided to enhance the safety or operability of the system.

    The results of the assessment are distributed to the project team and assignments for implementation or corrective action are given for those items resulting in an undesirable or unacceptable risk ranking. A timeframe for implementation of the corrective actions is defined in the summary report.

    The power sector has plenty of reasons to establish a systematic, focused approach to evaluate HSE impacts for new power plant and betterment projects during the design phase. Critical HSE issues must be acknowledged and addressed to support sustainable design. The PHA review is a pre-emptive methodology to minimize these risk factors. The PHA practice introduced in this article or a similar process would be beneficial to the power industry to adopt as a standard execution procedure for new power generation facilities and plant betterment projects.

    Authors: James Brown, PE, PMP, is director of engineering for Fluor Power’s solid-fueled projects business line. He holds a mechanical engineering degree from Clemson University, an MBA degree from Queens University and has more than 19 years of experience in management, design and engineering of coal and gas-fired power facilities.

    Michael Martin, CEP, is director of health, safety and environmental for Fluor Power, providing HSE engineering and environmental coordination and project management to solid fuel, betterment and gas turbine projects. He is a certified environmental professional (environmental documentation), holds a bachelor’s degree from the University of South Florida and has more than 30 years of experience in environmental management of power plant facilities.