Big storage tanks like above-ground storage tanks, underground storage tanks or pressure vessels are a crucial component for various industries. Commercial storage tanks are designed for storing a variety of products like chemicals, fuels, vapours, gases, and whatnot. If storage tanks are not checked and maintained properly, it could lead to catastrophic results like leakage, contamination, explosion, and environmental hazards. Most above-ground storage tanks must undergo API 653 tank inspection services. API inspection is conducted by an experienced professional with proper inspection training.
Understanding API-653 Storage tank Inspection
American Petroleum Institute writes and maintains the inspection code for API-653 storage tank. The code has sections with details like inspection intervals, requirements for the API inspection services, and results. The code further delves into vessel repairing and its process. The inspection reports must be documented and maintained throughout the life of the vessel. Storage tank inspection can be categorized into Out-of-service vessel inspection and In-service vessel inspection.
Out of service storage tank inspection
Out-of-service storage tank inspections are also called off-stream assessments, and it is done in 10 years interval. Depending on the condition of the vessel, inspectors could require opening and cleaning of the vessel.
Inspections performed while examining Out-of-service inspection.
- Visual Inspections:
Visual Inspection is a common type of non-destructive tank testing method. In VT, the inspectors perform a visual inspection of the storage tank’s internal and external parts. Tank inspections are highly specialized processes, and thus, only certified professionals can conduct the assessment. API-150 inspectors undergo inspection training courses similar to the API 653 training course. The inspectors go through a visual checklist to assess the condition of the tank’s foundation, heads, nozzles, ancillary equipment, pressure relief valves, and shell.
- Ultrasonic Thickness Testing:
Ultrasonic Thickness Testing, or UTT, is another non-destructive tank testing carried out by a certified UT Inspector. Internal and external shells, heads, and nozzles of the pressure tanks are assessed while performing the ultrasonic thickness test.
Inspectors may suggest other inspections like Magnetic Particle based on the results of initial assessments.
The final report contains the complete results of various tests and recommendations based on them. The report also mentions short and long-term corrosion rates and the remaining lifespan of the tank. The client reviews the documents to determine if the pressure tank is fit to be used further.
In-Service Storage tank Testing
Inspection of storage tanks that are still in service is often called on-stream tank testing. In-service storage tanks are required to be examined every five years.
Certified professionals usually carry out Non-destructive external visual inspection to assess the condition of the tank’s foundation, shell, heads, and nozzles.
Besides this, Ultrasonic Thickness Test is performed to evaluate the condition of the tank’s external shell, heads, and nozzles.
Once the inspection is over, a complete report is prepared that contains the examination and recommendations results.