PIPE CORROSION

The corrosion of steel piping and its related components is a continuous and virtually unstoppable process. Pipe corrosion exists as one of the most potentially damaging threats to industrial property second only to fire.

A very first step toward resolving any corrosion problem is to establish the overall condition of the piping system through a general ultrasonic investigation. Clearly identified problem areas can be further defined through the use of metallurgical analysis.

By comparing metallurgical against ultrasonic test results, it is possible to identify the extend and severity of the corrosion condition within the piping system. We will document not only the corrosion mechanism itself but also the remaining integrity of the system is critically important in order to minimize the potential damage from leaks.

With a properly performed piping evaluation, comprised of 100 or more individual ultrasonic tests per piping system, a clear and reliable determination of the piping can be produced.

From an initial set of wall thickness measurement and review of the plant history it is possible to derive valuable information regarding the present state of each location tested.

Information such as;

• - Pipe metal loss.
• - Corrosion rate.
• - Remaining pipe service.
• - Estimate retirement date.
• - Pass or fail recommendations.
• - Overall piping conditions.

Given sufficient wall thickness testing it is possible to create the comparison of;

• - Original pipe thickness v/s measured values.
• - Corrosion rate.
• - Corrosion rate vs. pipe size.
• - Corrosion rate vs. material used.
• - Corrosion rate vs. physical location.
• - Corrosion rate vs. direction.

For each and every test location a set of corrosion rate and retirement date calculation based upon the average of all 6-wall thickness values is provided. Under normal conditions such estimates provide a reliable indication of pipe conditions.

Calculations of wall loss and corrosion rate are based upon the assumption that all measured loss has taken place evenly over its time in service.

Predictions of allowable loss, remaining pipe life and retirement date show an estimate of the piping, from its current wall thickness, will reach minimum recommended wall thickness standards

Such predictions have proven tremendously valuable, recommending replacement at near failure condition, as well as saving the cost of unnecessary replacement.