Frequency of inspections

Define inspection interval (Daily, Monthly, Annual, 5-year). Inspection data is to be reviewed by an Authorized Inspector to evaluate for any changes in inspection intervals. The Minimum allowable wall thickness must be determined from (U1A Form), design data, data plate, operational procedures, or engineering evaluation. Typically this is in accord with ASME B&PV Code.

The average and minimum thickness can be determined from the UT data, plus any pitting depths. Compare MRT with time interval to determine corrosion rate. Use the original construction date for first inspection. The time between inspections can be determined by using corrosion rates to calculate time until reaching MAWT. For safety use current, average and worst-case rates

Methods of inspection

Visual Testing (VT) - Physical inspect the vessel, either interior or exterior, evaluating for: Corrosion activity, Leakage, Weld conditions, Appurtenance Conditions: Relief valves, Piping / venting, Control equipment, alarms, etc.

Ultrasonic Testing (UT) - Use Ultrasonic Thickness (UT) Gauging equipment to determine remaining wall thickness. With the establishment of repeatable wall thickness locations (TML) wall thickness data is used to assess a pattern of wall loss over time. Proper calibration of the UT equipment is vital for continued accuracy and data integrity. Data is to be recorded in a manner that comparisons over time can be established.

Other inspection methods may include; Remote Visual Testing (RVT), Penetrant Testing (PT), Magnetic Particle Testing (MT), Radiographic Testing (RT).

Documentation

Without proper documentation all inspection work is of limited use. A file for each piece of equipment needs to be established. Documentation can be simplified by developing a form for each type of equipment and inspection i.e. short-term and annually are typical.

All inspection forms and data archived in their respective files.

Access selection can also play a key role in effectiveness, safety, and cost in the overall API Inspection Program. Traditional methods of access such as scaffolding and can be very costly to erect at all inspection locations, and at times exceeds budgets which reduces the scope of the inspection program. Another way is to inspect areas accessible by ladders and landings which is more restrictive to the inspection scope. Limiting the API inspection scope can leave suspect areas as potential failures and possibly causing serious issues for the environment, safety, life and cost to the facility not to include potential legal fees and regulatory fines.

A safe and cost effective alternative access method that will facilitate effective API Inspection Programs is Rope Access. Rope Access techniques and procedures provides for safe and quick access to the most difficult and costly, at height locations to inspect on facility equipment i.e. vessels, columns, pipe racks. Rope Access can be utilized internal or external of vessels. Multi-disciplined Rope Access Technicians can perform insulation removal, facilitate inspection or perform the inspections, perform remedial actions and re-insulate without expensive scaffolding cost, while leaving more money in the budget for a comprehensive API Inspection Program.