Your production facility is no different from many in the business.
Despite your equipment running effectively for years, it will experience performance and reliability issues. Often times, the equipment can still operate when problems arise, although its safety and reliability may be in question.
While inspecting the system, you discover vibration has developed within the structure containing a pump and heat exchangers. A suspected tube leak is causing cavitation conditions in the pump.
At this point, the cause is unclear, as it could be tube vibration in the exchanger or a net positive suction head problem in the pump. It appears to only occur at the higher loads, however, you have run at higher loads previously without incident. Fouling conditions in the exchanger can affect the temperature to process to the pump. This is commonly overlooked and addressed at the next scheduled shutdown.
You recognize that operational standards have come under increased scrutiny over the years, and you are accountable for ensuring that your facility is safe and environmentally friendly. Prioritizing process safety management, you evaluate your next steps. You must determine whether this system is "fit for service" (FFS) until the next shutdown. It is not known whether the root cause of the problem involves static or rotating equipment.
There are guidelines and methodologies to address whether equipment is FFS for continued operation. API Recommended Practice 579 Fitness For Service involves "quantitative engineering evaluations that are performed to demonstrate the structural integrity of an in-service component containing a flaw or damage." This code is an excellent document for static equipment. Methodology and approach for rotating equipment is on a case-by-case basis with the intention to satisfy all applicable codes and standards.
In general, there are two important things to remember for all FFS work: no analysis or solution can be more accurate than the input data given, and nothing beats experience.
For static equipment, our company considers API 579 a good resource. We recognize that the defect or flaw must be carefully characterized by a qualified professional. Many times, individuals charge forward in an FFS without properly identifying the details of the flaw or defect.
It is important to note that an FFS is not merely a "stopgap" measure to keep the equipment running, but is an engineering evaluation of its current status that determines its remaining life based on the conditions analyzed. FFS is a methodology to characterize flaws and defects and address them in such a way so as to meet code conditions. It is important to note that FFS should not be viewed as a shortcut or workaround to effective and thorough process safety management.
A proper FFS frequently involves the following considerations:
- Process and operations assessment - Steady state, upset, startup and any transients that the equipment may experience.
- Condition assessment - Flaws, defects and conditions are characterized by qualified personnel. This is a critical step because the failure to identify the actual condition of the operations may render all other assessments inaccurate.
-FFS
1. Static
a. Determine the appropriate level of analysis.
b. See that applicable code conditions are met.
2. Rotating
a. Characterize the equipment condition.
b. Risk assessment.
c. Analysis. This may include hand calculations and structural simulations.
- HAZOP - Include a review of the FFS.
- Recycle the above steps.
- Process, mechanical, materials, controls, and operations must sign off.
- Implementation with a feedback loop on equipment.
The main aspect of FFS is that it is not a "cookie cutter" approach, and each problem should be evaluated for its unique conditions. Finally, all FFS work should be directed and approved by a qualified professional engineer.
KnightHawk is your one-stop resource for FFS. We have performed many Level 3 API 579 analyses for static equipment. We also have performed FFS on rotating equipment in order to keep operations running safely and smoothly. Our staff constitutes a formidable team for those challenging problems.
For more information, visit www.knighthawk.com or call (281) 282-9200.
