During the past few years, end users in the power generation industry have considered specifying pumps according to American Petroleum Institute (API) standards. The standards, according to the API website, “are designed to assist industry professionals improve the efficiency and cost-effectiveness of their operations, comply with legislative and regulatory requirements, safeguard health, and protect the environment.” Typically, the standards require a more robust equipment design.
The API Standard 676 is a purchase specification used for rotary positive displacement pumps. Like all API standards, 676 was developed to establish a minimum standard for process pumps in mission-critical applications.
In power generation, these applications include fuel injection, fuel transfer or booster services. The standard helps ensure the integrity of the pump’s envelope during an emergency, such as a fire. The most recent version of API Standard 676 (Third Edition, November 2009) specifically states that “... in auxiliary services (for example, lube oil systems), manufacturer’s standard with demonstrated experience is acceptable.” In most cases, API 676 is applied only when handling fuel.
The standard must be relevant to service needs. Alone, it cannot be applied to the overall operation. The purchaser must specify certain details and required features. More than 70 bulleted paragraphs require either a decision by or more information from the purchaser.
A completed data sheet should also be supplied to the vendor. The purchaser should complete the following sections: operating conditions; detailed fluid data; site and utility data; API Standard 682 data sheets for mechanical seals; driver detail; quality assurance inspection; piping and appurtenance details; instrumentation requirements; preparation and paint; and baseplate detail.
The manufacturer’s sales engineer can assist in completing the data sheets by evaluating the trade-offs and ensuring a complete specification is furnished to the vendor. The cost of the pump will vary depending on user input.
The pump manufacturer should also work with the motor and turbine manufacturers to ensure compatibility. The modifications generally do not involve performance ratings. The pump will still operate at the same pressure ratings. The modifications typically include steel casings, upgraded mechanical seals, bolts and other hardware.
The 676 standard focuses primarily on the pump’s external envelope, where safety is a key concern. The customized pump may be of a higher-quality construction than a standard pump. For example, a pump adhering to the standard may employ a steel case and cover instead of cast iron. In case of fire, the cold water used to extinguish the flames could crack a cast-iron case and lead to dangerous leakage. A steel case, on the other hand, could prevent cracks and leaks with the help of hard mechanical seal faces.
The standard can require more stringent and detailed documentation. The API specification requires certified material test reports, performance curves and a certificate of compliance.
Customizing pumps to a standard may include additional costs, but these costs depend on decisions made by the end user. As selections are made within the standard, costs must necessarily increase because of the requirements for more rugged materials and expanded testing. The best method for managing the cost is that the purchaser ensures that the comments and answers to the bulleted paragraphs within the standard are necessary to the service.
Purchasing several pumps built to the standard rather than a single pump creates an economy of scale, so end users should consider future ramifications when initiating the purchase order. The additional lead time that may be necessary should be factored into the project schedule.
A pump built to API Standard 676 is not an off-the-shelf product. The manufacturer and customer must have a dialogue to make sure the pump is built to the standard. Choosing a manufacturer that has built pumps to API Standard 676 for the oil and gas industry is a plus.
The API does not have an enforcement team. Documentation must assure customers that the pumps meet the standard. On-site inspectors hired by the end user can determine whether or not the manufacturer followed the specification’s requirements.
At new and existing power plants, safety is paramount. API Standard 676, along with all API standards, can offer an added level of safety to power generation applications.