sonitech whitepaper - fire sprinkler preventive maintenance

2011

www.SoniTechNDT.com Tim Frederick

Preventative Maintenance for Fire Sprinkler Systems Common fire sprinkler piping corrosion issues and preventative maintenance inspection technologies

w w w . S o n i T e c h N D T . c o m 3 0 3 - 5 5 2 - 1 0 9 9 i n f o @ S o n i T e c h N D T . c o m

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Table of Contents

Table of Contents .............………………………......................................................................................... 1

Introduction .........................................……………....................................................................................... 2

Overview of Problem ...............................………………................................................................... 2 The New Solution................................................................................................................................. 2

Fire Sprinkler Corrosion Issues ............................……………………................................................... 3

Microbiologically Influenced Corrosion (MIC) ..................................................................................... 3 Other Corrosion Concerns ……………………................................................................................... 4

SoniTech’s Cost Saving Preventative Maintenance Program...................................................... 4

Risk Mitigation ................................................................................................................................. 4 What is Preventative Maintenance .....................…............................................................................. 5

Non-Invasive Inspection Technologies................................................................................................ 5

Comparison of Technologies ……………………………………………………………………………… 5 The SoniTech NDT Cutting Edge Solution ………………………………………………………………… 6 Patented Guided Wave Pipe Corrosion Detection.............................................................................. 6 Conventional Ultrasonic Thickness Measurements .................................................................... 7 Alternative Inspection Techniques...................................................................................................... 7

Analysis and Reporting............................................................................................................................. 7

Return on Investment .......................................................................................................................... 8

SUMMARY REMARKS...............................................................…................................................................. 8

REFERENCES ............................................................................................…............................................... 8


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Introduction

Overview of the Age Old Problem

Corrosion of Fire Sprinkler piping can lead to potentially hazardous system malfunctions, as well as costly water damage and repair costs. In addition to “typical” corrosion issues, Microbiologically Influenced Corrosion (MIC) rapidly accelerates corrosive growth, which can quickly lead to serious problems in buildings less than five years old

1, and in a most extreme case, has been witnessed in stainless steel pipe only three

years old.

Recognizing that pipe systems are the only non-redundant system in most Mission Critical Facilities, it’s easy to see how these systems are the Achilles’ Heel of the industry. Facilities commonly incorporate redundant systems such as backup servers, backup power supplies, and multiple connections to the internet, but have only one pipe system with one layer of pipe protecting their business assets.

As the “red headed stepchild” in Mission Critical Facility Management, inspections for MIC and Corrosion are often overlooked until expensive problems such as damaging leaks occur or the corrosion is so prevalent that large areas of the entire Fire Sprinkler system have to be replaced. This corrective after-the-fact maintenance approach is a costly reactive strategy. The usual task of the maintenance team in this scenario is to effect repairs as soon as possible, oftentimes outside normal business hours, raising expenses even further. Costs associated with corrective maintenance include repair costs (replacement components, labor, and consumables), logistical expenses, lost production, and lost sales.

The New Solution

SoniTech NDT believes that an ounce of prevention equals a pound of cure, which is why our non-destructive service detects and maps potential for failure BEFORE significant damage occurs, when mitigation costs and logistics are at a minimum…all with little to no interruption to daily operations.

A proactive approach to fire sprinkler maintenance is available using completely noninvasive technologies that form the basis of a Preventative Maintenance approach. This new 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 treat or schedule replacement of localized sections of the system in the most economical fashion, on your schedule, and before leaks or operational failures occur.

Figure 1. Typical Sections of an inspected Fire Sprinkler System


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Fire Sprinkler Corrosion Issues The most common Fire Sprinkler Pipes are engineered and constructed using steel pipes sized according to specific hydraulic requirements, typically ranging from 1.0 inch diameter to 10.0 inch diameter pipes in Schedule 5, 10 or 40.

There are numerous types of corrosive reactions that can occur with steel, and while there are various methods for combating or trying to slow the corrosive activity, nothing stops it completely. One may think corrosion in Wet fire sprinkler systems will not be a problem IF all of the air is removed from the system, but that is not true, especially if MIC is present in the water supply. Even a small amount of trapped air or oxygen dissolved into the water can cause the onset of corrosive activity, even in a galvanized or chemically treated system.

Figure 2. Corrosion in Fire Sprinkler Pipe

Microbiologically Influenced Corrosion (MIC)

MIC is the term used for corrosion influenced by microbes in water. The primary concern is that the influence of these microbes is often at an extremely accelerated rate of corrosion, destroying perfectly good pipe in just a few years. MIC is not caused by a single microbe, but is attributed to many different microbes that react with metal pipe, even in chemically treated systems. MIC is often categorized by common characteristics such as byproducts (i.e., sludge and tubercules) or the compounds they affect (i.e. sulfur oxidizing). In general, all MIC microbes fall into one of two groups based upon their oxygen requirements; one being aerobic (requires oxygen and thrives in dry pipe systems), and the other being anaerobic (requires little or no oxygen and thrives in wet pipe systems).

Microbiologically induced corrosion becomes problematic when steels are in constant contact with nearly neutral water that has a pH between 4 and 9 and a temperature between 50° and 122°F (10° and 50°C) and is more pronounced if the water is stagnant or slow-moving, such as in fire sprinkler systems

Although there have been regions of the United States, such as the Phoenix and Las Vegas areas, 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 have been received from throughout the entire United States and also from abroad

1.

Figure 3. MIC Nodules in both Dry and Wet Fire Sprinkler Systems

MIC frequently occurs concurrently with other corrosion mechanisms, thriving in small crevices such as joints and micro pits, and is difficult to distinguish from other forms of corrosion. 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.


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Other Corrosive Concerns

In a dry or pre-action system, water often collects in low spots in the piping after the pipe is periodically flushed (per NFPA requirements for Dry systems

2). Humidity in the air can also condense into pools within

the pipe system. As the water collects and sits in the pipe, corrosion can begin to rapidly eat through the wall thickness, which is of particular concern dry systems due to the thinner schedule pipes they typically employ.

Wet systems can have similar issues, particularly when poor installation or angled ceilings leave high spots where air pockets and dissolved oxygen can collect, leaving a ripe environment for corrosion to develop.

Figure 4. Wall Loss and Pitting in Fire Sprinkler System Piping

SoniTech’s Cost Saving Preventative Maintenance Program

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

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 in some degree, but several types of facilities heavily rely on the sprinkler system to extinguish or slow the spread of fire. These include highly populated buildings (i.e. airports, convention centers, stadiums), distribution hubs, ships at sea, correctional facilities, manufacturing plants, and power plants (fossil fuel and especially nuclear).

The potential of fire sprinkler leaks may not seem especially risky or life threatening, but for facilities housing sensitive inventory (food processing, paper goods, etc) or sensitive electronics and equipment (clean rooms, data centers, telecommunications facilities, etc), even a minor leak can produce potentially catastrophic financial losses.

Figure 5. Leaks in Mission Critical Facilities like Data Centers, Clean Rooms, Hospitals, Distribution Centers, and Manufacturing Plants could be disastrous


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What is Preventative Maintenance?

Preventative Maintenance refers to care and servicing by personnel for the purpose of maintaining equipment and facilities in satisfactory operating condition by providing for systematic inspection, detection, and correction of incipient failures either before they occur or before they develop into major defects.

3 Maintenance can either be performed according to fixed preventive schedules or when a certain change in

characteristics is noted, much like putting new tires on your car every 80k miles regardless of condition or when they show wear/damage. Periodically inspecting fire sprinkler systems for the presence of MIC or Corrosion allows the facility manager to accurately monitor the condition of the system, treat systems at the onset of corrosion to extend pipe life, or schedule localized replacement of bad pipe and significantly reduce the risk and costs associated with corrective maintenance.

Non-invasive, Ultrasonic Inspection Technologies

All Ultrasonic Inspection Methods are NOT the same

Do you think you know Ultrasound? Several “flavors” of Ultrasonic Testing are available today, including one cutting edge highly effective method.

SoniTech NDT’s Proprietary Traditional Traditional

Localized Guided Wave (LGW) Ultrasonic Thickness (UT) Long Range Guided Wave (GWUT)

Quantity of scans per day4 150 to 250+ 150 to 250+ 10 to 15

Area covered per scan point

10' to 20' span, full circumference pinpoint area 20' to 300' 5, full circumference

Type of data Quantitative and Qualitative Quantitative Qualitative

Level of Precision Very High Very High Moderate6

Pipe Clearance 3" x 6" section on pipe surface exposed for scan head, pipe can be near a wall or other structure

1" diameter area exposed for transducer and 1½” clearance from pipe to wall or other obstructions, at each scan point

24" wide area around entire circumference exposed, and 3" minimum clearance to walls or other obstructions

Technology Strengths

Accurately cover large areas of almost any kind of metallic pipe in a short period of time. Little to no disruption to client’s daily routine.

Highly accurate in a pinpoint area, offering wall thickness accurate to 0.003". Little to no disruption to client’s daily routine.

Efficient for long straight runs of welded pipe. Can scan runs that go underground or through walls etc. Great for corrosion under insulation

Technology Limitations Must be able to touch the pipe with scan head at each scan point. Upper temperature threshold of 200

oF

7

Easy to miss areas of wall loss. Cannot detect corrosion buildup or ice obstruction. Very time consuming to cover large areas. Must be able to touch the pipe at each scan point.

Only provides general information. Cannot scan through grooved couplings. Sensitivity diminishes with distance, bends, or pipe walls that are not pristine. Time consuming and expensive.


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SoniTech NDT’s Cutting Edge Solution

SoniTech has developed a comprehensive inspection service and Preventative Maintenance program for facility managers and building owners, derived from its unique patented scanning technology. The basis of this program is a completely portable noninvasive Ultrasonic inspection system that provides a quick and accurate representation of the interior of your pipe system, while it remains fully operational.

SoniTech will detect and map the presence of corrosion and MIC, ice plugs, air pockets trapped in a wet system, or water pockets left behind in a dry system. Sonic’s proprietary software compiles the analyzed results and develops a detailed report that ties the measurements to copies of the facility’s blueprints.

With this data, you can easily implement a cost effective Preventative Maintenance program for your Fire Sprinkler Pipe system. The density of inspection locations and the frequency of inspections can be customized for your individual requirements and should be chosen based on the risk associated with a leak or system operational failure, history of the system, and condition of the sprinkler system water supply.

To assure the greatest accuracy, SoniTech NDT collects redundant data using both Localized Guided Wave and conventional Ultrasonic Thickness Measurements to quickly, simply, and accurately detect and monitor anomalies within a fire sprinkler system.

Patented LGW Pipe Corrosion Detection

SoniTech’s unique patented Localized Guided Wave system is NFPA approved

2 and identifies areas of pipe that show

indications of internal corrosion or other issues. The scanning head is placed on the exterior of the pipe, which excites guided Ultrasonic waves that propagate the circumference of the pipe for about 8 seconds per reading.

The measured signature is then compared to that of brand new, pristine pipe that have been stored in the software for all possible pipe diameters and schedules, for both “Wet “and” Dry” systems.

Figure 7 below illustrates the clear difference between an inspection point from an area of good pipe as compared to an area of bad pipe. The upper wave represents the baseline and the lower represents the pipe condition at that point. The more corrosion (presence of nodules attached to the interior of the pipe or amount of wall thinning) the more the signal is affected.

Figure 6. Guided Wave Scan Head

Figure 7. No Corrosion (left) versus Corrosion Indication (right)


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Conventional Ultrasonic Thickness Measurements

In addition to random redundant checks, areas of pipe that show indications of corrosion with the more sensitive and efficient Localized Guided Wave signatures are investigated further with highly accurate wall thickness measurements made around the circumference of the pipe.

Alternative Inspection Techniques

Some areas of pipe may be inaccessible and therefore cannot be measured using the Ultrasonic techniques described above. SoniTech can employ alternative methods for inspecting hard to reach pipe, which may include long range guided wave or a digital video borescope. Borescope should only be a used as a last resort, as it is a destructive testing method that requires system shut down and cutting into the pipe to perform the inspection. This may be appropriate for limited use in high-risk areas but is too intrusive and expensive for a general recurring inspection of an entire facility

Figure 8. Conventional Ultrasonic Thickness Measurements

Analysis and Reporting

The measurements are permanently stored for each location and a report showing the current level of corrosion can be reproduced using sprinkler system blueprints. Each scan point has a unique identifier number marked on the pipe (see Figure 1 above) which corresponds to the same number within the report. All scan points are overlaid on maps or architectural drawings (when applicable) and the report will include one full page of raw data for each scan point collected.

Figure 9. Corrosion measurements are tracked and mapped for each location


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Return on Investment

Calculating the Return on Investment with a Preventative Maintenance program versus a traditional Corrective Maintenance program for a fire sprinkler piping system is difficult at best, and requires assessing the risk of both types of system failure mentioned on page 4, and estimating the total cost of such a failure (emergency mitigation and logistical costs, lost inventory, lost equipment, lost production time, loss of key accounts/customers during down time, and of course the risk to human life). Additionally, one must factor the expense of unnecessarily replacing “good pipe” when implementing a Corrective Maintenance plan.

Once these costs are estimated they need to be weighed against the cost of a Preventative Maintenance program, which includes periodically inspecting the system using SoniTech NDT’s non-invasive Ultrasonic LGW technique, and using that data to make an informed decision as to exactly which areas, if any, are in need of immediate attention and which areas still have “good pipe”, allowing your Fire Sprinkler System to perform exactly as designed. This is a key component in an effective Reliability Centered Maintenance (RCM) program.

Studies by some of the largest and most technologically advanced companies such as General Motors and 3M have shown that average rate of return for a Preventative Maintenance program ranges from 7 to 1 to as high as 35 to 1, depending on the industry. In other words, for every $1 spent on Preventative Maintenance, a company will save anywhere from $7 to $35 versus Corrective Maintenance.

Summary Remarks

There are four general approaches to maintaining any system: (1) Predictive Maintenance; (2) Reliability Centered Maintenance (RCM); (3) Corrective Maintenance; and (4) Preventative Maintenance (staying informed as to the condition of your system and repairing only the questionable areas before they fail).

Because of the expense of replacing entire Fire Sprinkler Systems and erratic unpredictable nature of MIC and corrosion, neither Corrective Maintenance (knee jerk reaction) nor RCM (without accurate data on the condition of the inside of your pipe) are good choices.

Until recently, most facility managers and building owners had little choice but to wait for corrosive problems to arise (leaks, system failure, etc.) before implementing costly corrective maintenance in a total reactionary mode. Under these circumstances, pipe is often replaced unnecessarily (at a very high cost), or corroded pipe is left in place to cause future costly problems.

Now, with SoniTech NDT’s Preventative Maintenance Program, the presence of MIC and corrosion can be quickly identified and tracked to provide cost-effective risk mitigation for both leaks and operational failure of the system. Facility managers and building owners now have the means to create a database (see Figure 10) with the current level of corrosion and MIC in their fire sprinkler system piping and use this information to proactively schedule replacement of only the pipe deemed unacceptable, in an informed and economical manner.

Please visit www.SoniTechNDT.com for more information

References

1 FM Global Property Loss Prevention Data Sheet for Internal Corrosion in Automatic Sprinkler Systems. May 2001.

2 NFPA 25 2008 Edition Chapter 14 Section 14.2.1 and Annex D Section D.3.5

3 Wikipedia: http://en.wikipedia.org/wiki/Preventive_maintenance

4 Quantities shown for LGW and UT are typical estimates. Scan quantities can be influenced by access issues or other factors, either in a positive or negative manner

5 50’ to 100’ is typical. Actual distance covered by GWUT greatly diminishes when scanning pipe that is not pristine or scanning through bends, welds, underground, etc.

6 Cross sectional differentiation must be 10% to 25% or more to be detected, and GWUT does not penetrate into branch lines or work well around “T” fittings.

7 Surface temperature cannot exceed 200

oF, however boiler/steam pipe or other high temp process pipe can be inspected

if the system is shut down and allowed to cool

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sonitech whitepaper - fire sprinkler preventive maintenance

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