Mechanical Integrity - Facilities Maintenance

Corrosion of a piping system can lead to potentially hazardous system malfunctions, as well as costly water damage and repair costs.

Firewater / Facility Maintenance

Overview of Problem

Corrosion of a piping system can lead to potentially hazardous system malfunctions, as well as costly water damage and repair costs. Corrosion and especially Microbiologically Induced Corrosion (MIC) can rapidly accelerate corrosive growth leading to these problems even in buildings less than five years old. Unfortunately, inspections for MIC and Generalized Corrosion are often overlooked until expensive problems, damaging leaks occur or the corrosion is so prevalent that large areas of the entire piping system have to be replaced. This corrective maintenance approach is a retro-active strategy. The task of the maintenance team in the retro active scenario, is usually to effect repairs as soon as possible, which infers that costs will be higher and involve the additional costs.

The Alternative to Failure

The proactive approach to infrastructure maintenance is available using completely non-invasive, ultrasonic and radiation based technologies that form the basis of a predictive maintenance approach. This approach provides a cost-effective means of detecting the presence and monitoring progression of corrosion and creating a digital record of the system state that can be used to schedule replacement of localized sections of the system before leaks or major operation failures occur.

Pristine looking piping like the items shown in these pictures, in service for less than five years, had circuit failures, because of water quality?

Problems Identification – Dead Leg Situation

There are numerous types of corrosive reactions that can occur with steel and various methods for combating or trying to slow the corrosive activity. Corrosion in piping systems is not usually a problem "If" all of the air is removed from the system after filling the system with water unless MIC is present. However even a small amount trapped air can cause the onset of corrosive activity. from the system after filling the system with water unless MIC is present. However even a small amount trapped air can cause the onset of corrosive activity.

Microbiologically Induced Corrosion (MIC)

MIC is the term used for corrosion influenced by microbes in the water. The primary concern is that the influence of these microbes provides an extremely accelerated rate of corrosion. MIC is not caused by a single microbe, but is attributed to many different microbes. These are often categorized by common characteristics such as by-products (i.e., sludge producing) or compounds they effect (i.e. sulfur oxidizing). In a general sense, they all fall into one of two groups based upon their oxygen requirements; one being aerobic (requires oxygen) such as sulfur oxidizing bacteria, and the other being anaerobic, (requires little or no oxygen), such as sulfate reducing bacteria [2].

Although there have been regions of the United States, such as the Phoenix, Arizona area, where a large number of MIC cases have been reported and documented, there is presently no indication that MIC is confined to any specific geographical area. Reports of MIC attack have been received from throughout the United States and also from abroad [1].

MIC almost always occurs concurrently with other corrosion mechanisms, and it is virtually impossible to separate them. This is in part due to the fact that microbes help create conditions under which other corrosion mechanisms can occur, such as crevice corrosion, pitting, and under-deposit corrosion [1].

Solution: Mechanical Integrity's Predictive Maintenance Program

Problems - Dry Riser System:

In a Dry system, water often collects in low spots in the piping after the pipe is periodically flushed (per NFPA [National Fire Protection Association] requirements for Dry systems). As the water sits in the bottom of the pipe, MIC can begin to rapidly eat through the wall thickness, as most Dry systems incorporate thinner Schedule 5 or Schedule 10 pipe thickness.

Mechanical Integrity Inc. has developed a comprehensive inspection service and predictive maintenance program for facility managers and building owners. The basis of this program is a completely non-invasive, inspection technique that provides a quick and accurate measurement of internal pipe corrosion and MIC. Systems software permanently stores the analyzed results and ties the measurements to copies of the facilities blueprints.

Routine Predictive Maintenance

Predictive maintenance refers to maintenance based on the actual condition of a component. Maintenance is not performed according to fixed preventive schedules but rather when a certain change in characteristics is noted. Periodically inspecting piping systems for the presence of MIC or Corrosion allows the facility manager to accurately monitor the condition of the system, schedule localized replacement and significantly reduce the risk and costs associated with corrective maintenance.

Using the non-invasive, inspection techniques, a cost-effective predictive maintenance program can be implemented to detect the presence and the

Investigative Non Destructive Technologies

Mechanical Integrity Inc. uses a wide variety of ultrasonic inspection technologies can be used to quickly detect and monitor the level of corrosion and MIC in piping infrastructure system.

Long Range Ultrasonics (GUL)is a global inspection technique capable of inspecting up to 200' of pipe from a single location. Guided Waves are used to saturate the complete cross section of the pipe being tested looking to detect any changes in the material such as internal and external corrosion. Guided Wave is capable of inspecting under insulation and around elbows looking for material loss type defects. The test can be performed without disrupting any piping process and does not require liquid couplant.

There are three system components; a transducer ring (attached to pipe), a Wavemaker (UT sound generator), and a laptop computer with Wavepro collection and analysis software.

Localized Guided Wave signatures for undamaged pipe have been stored in software for all of the possible pipe diameters and schedules for both Wet and Dry systems. The measured signature collected during inspection is compared to the stored calibration signals. The more corrosion (presence of nodules attached to the interior of the pipe and amount of wall thinning) the more the received signal is affected.

Conventional Ultrasonic Thickness Measurements

Any areas of pipe that show indications of corrosion are investigated further with highly accurate wall thickness measurements made around the circumference of the pipe.

MII Real Time Radiography requires a short set up time, and has fast exposures using Constant Potential X-Ray Technology Real Time image display and analysis. Digital imaging allows immediate image manipulation and colorization. The capabilities of imaging through insulation of pipe, elbows and valves. The data is digitally stored so future manipulation is easy with no need to re-shoot an area. This also eliminates extensive stacks of xray film. There is NO need for barricading or personnel evacuation and other special precautions used with conventional x-ray.

The complete system

Work completed with minimum local disturbance due to highly focused radiation source.

Leaks above Data Centers like these could be disastrous

Corrosion Mapping is one of the more common inspections performed today. It provides reliable information about the remaining wall and ID geometries of equipment and piping to engineers and inspectors, who use the information to establish corrosion rates, equipment longevity, and maintenance and repair cycles.

Risk Mitigation

The risk of MIC or Corrosion in fire sprinkler piping can be broken into two general categories: (1) loss of life or property damage caused by fire that spreads due to an operational failure; and (2) significant property damage caused by a leak from corrosive pitting. Almost any facility that is required to have a fire sprinkler system is subject to the first risk, but several types of facilities rely on the sprinkler system to extinguish or slow the spread of fire more so than other structures. These include military and commercial ships at sea, correctional facilities, petroleum refineries, chemical plants, power plants (oil, coal, and especially nuclear).

Return on Investment

The potential of leaks may not seem especially risky, but for facilities that house sensitive electronics and equipment such as clean rooms and computer data centers a single small leak can produce potentially catastrophic financial losses. Calculating the Return on Investment in a predictive maintenance program for MIC and corrosion in the fire sprinkler piping requires assessing the risk of either type of system failure, estimating the potential cost of such a failure, estimating the cost of a corrective maintenance approach once a problem is discovered. Once these costs are estimated they need to be weighed against the cost of inspecting the system using a non-invasive, ultrasonic technique and monitoring the level of corrosion at suitable intervals for the associated level of risk.

The inspections proposed in this document are non-intrusive.
The work can be performed while daily operations continue.
The cost of no inspection on inventory and lost time can be extreme.