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 When Pipe Corrosion At A Fire

Protection System Can Cost Lives

  Corrosion, once it has been identified ata fire protection system, is typically viewedexclusively in terms of the cost for pipereplacement. By the time it is finally realized,years of deterioration have often occurred.

  With repair, corrosion remediation, and

the removal of rust deposits a difficult andoften unlikely to succeed option, partial or complete fire pipe replacement is often theonly alternative - at tremendous expenseand inconvenience.

Greater Problems Today

  The incidence of corrosion problems atfire piping, virtually unheard of 25 years ago,has now become an every day issue.

 Approximately 30% of our involvement incorrosion and ultrasonic pipe testing todayrelates to failures at fire protection systems.

  With some of the oldest fire protectionpiping at near 80 years still in excellent condi-

tion, and capable of providing many decadesof additional service, there are clearly factorsrelated to more recent installations which areresponsible for today’s more advanced fail-ures.

  The predominant use of thin wall sched-ule 10 pipe, more corrosion susceptiblesteels, poor quality galvanizing, insufficientgrade, and seamed pipe are the primaryphysical influences often associated withpremature fire system failure. Installing thinwall schedule 10 pipe rather than schedule 40not only halves its wall thickness, but canreduce service life by 500%.

  Dry sprinkler systems, now morefrequently installed, are associated withsome of the most advanced and completepiping failures we have documented. A drysystem presents inherently greater threatdue to the fact that inadequate grade alwaysallows water and moisture to remain withinthe lines - the source of dramatically higher corrosion losses. In reality, it is never “dry.”

  Frequent testing, flushing, and drainingrequirements regularly bring into every firesystem abundant fresh oxygenated water toraise corrosion levels. With corrosion againststeel pipe directly related to available oxygen,the potential benefits of such test procedures

to confirm the operation of key systemcomponents has ironically resulted in thepremature destruction of the fire piping itself.

  Flushing procedures to clear a fireprotection system of accumulated iron oxide

rust and debris are of extremely limited effec-tiveness in such a widespread network of horizontal dead-end and often air-boundpiping - thereby allowing most rust product toremain behind. This photograph of a 4 in.main fire distribution line, regularly drainedand flushed, easily proves such argument.

  And if the above factors are not a suffi-cient detriment to fire protection systems inthemselves, add the more recent threat of microbiologically influenced corrosion, or MIC. Where even a severe general corrosioncondition may take 10 years to produce aleak, microbes in the water supply can literallyeat and dissolve their way through 6 in.

schedule 10 steel fire pipe in under one year.  Unquestionably, multiple forces existagainst modern fire protection systems toproduce threats and concerns still not widelyunderstood nor recognized within the fireprotection and building operations industries.

Different Consequences

  The similarity between a corrosionproblem at a fire protection system and other HVAC or plumbing related piping systemsends with the economic cost of replacementand interference with regular building opera-tions.

  A relatively small corrosion-inducedpipe failure at a high rise commercial officebuilding can easily exceed $1 million in justwater damage alone. Replacement of acondenser cooling or domestic water systemfor a 40 story high rise office building canmean an unexpected expenditure exceeding$10 million.

  The failure to provide sufficient coolingwater to the mainframe computers of a major financial institution are estimated at millionsof dollars per minute of downtime. Hugeeconomic losses indeed, but rarely doessuch corrosion-related failure result in theloss of life.

  Corrosion at a fire sprinkler system,however, directly impacts the life blood of thefire protection system itself - water, andnegates the central purpose of every other single piece of equipment designed andinstalled into the fire system. Fire sensors,alarms, pumps, control panels, actuatingvalves, sprinkler heads, and standpipeconnections are all designed with theprimary interest to move abundant water tothe source of the fire as quickly as possible.

  Water pressure, flow rate, sprinkler head location and density, orifice size,discharge times for dry pre-action systems,and every other conceivable aspect of a fire

protection system are precisely defined byNFPA Chapter 13.

  The frictional loss of water based uponthe internal surface resistance of new pipethe flow resistance of each fitting, valve, and

elbow, and most importantly, predictions oflow rate based upon inside pipe diameterdefine a fire protection system that isexpected to supply the required volume owater to every point of the system ondemand.

  Assumption is made by everyone thathe fire protection system, as designed andinstalled, will be in similar physical conditionwhen called upon in a real fire emergency -whether that call is tomorrow or decadesaway.

Corrosion’s Terrifying Impact 

  Internal pipe corrosion, however, influ

ences every aspect of a fire protectionsystem - from interfering with the propeoperation of individual equipment components, to constricting inside pipe diameteand reducing flow. In its most severe formcorrosion may produce through wall penetration and / or sufficient internal rust deposits toclog the smallest branch lines and sprinkleheads entirely.

  Is there even the slightest possibility thathe huge volume of loose rust shown in theabove 4 in. main, after being forced into thebelow 1-¼ in. branch line of the same firesystem, would allow any water through thesmaller orifice of a ½ in. sprinkler head?

Obviously not. And yet this condition

remained unknown for years until multipleleaks prompted an ultrasonic investigationThis fire system, as most, was assumedfunctional because regularly prescribedtesting and flushing indicated acceptableresults. In fact, no fire protection existed!

Unstoppable Loss

  Corrosion is an unstoppable force onature seeking to revert steel back to its original form of iron ore. It is extremely difficult tocontrol for even HVAC systems having thebenefit of constant circulation and the dailyaddition of chemical inhibitors and high-techelectronic monitoring.

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  But unlike HVAC systems, which aretypically designed with a corrosion factor taking into account lost heat transfer effi-ciency due to deposit buildup and reducedwall thickness due to corrosion, no suchconsideration for fire protection systemsexists. Fire piping is installed with the unrea-sonable expectation that no significant corro-sion will occur to impact system performance.

Material Weakness

  Ultimately, the service life of a fire sprin-

kler system is a question of pipe quality, wallthickness, and its inherent corrosion resis-tance, verses the corrosive potential of thelocal water supply and water flow.

  Seamed pipe, and pipe of some foreignmanufacture, almost always suggests thepotential for greater corrosion activity beforethe system is even filled. The use of thin wallschedule 10 pipe simply doubles the potentialnegative effect of any individual physicalweakness or corrosion condition.

  Galvanized pipe, still viewed as the solu-tion to the corrosion of carbon steel andwidely used in dry fire systems, rests its effec-tiveness at providing long service life entirelyupon the quality of the zinc protective finish.

  Where the galvanized finish holds,corrosion activity is prevented. Where it fails,however, the entire corrosive potential in thatarea then focuses its attack upon one or moresmall areas to pro-duce deep localizedpitting and penetrationbest described ashaving been produceby a drill bit.

  Nearly impossible to evaluate for futureservice life prior to installation, the use of galvanized pipe often means a hopeful

expectation of corrosion-free operation, butwith the more likely result of more advancedfailure over carbon steel. Combining multiplefactors such as poor quality galvanizedseamed pipe in a dry fire system with inade-quate pitch virtually guarantees a corrosionproblem that will render it totally worthless inunder 10 years, and often sooner.

  Pipe quality is still generally unques-tioned as long as it meets the ASTM specifi-cations. Local water quality, which can varygreatly in terms of its chemical propertiessuch as hardness, pH, conductance, alkalin-ity, chlorine content, and of course MIC, isstarting to be considered in estimating future

corrosion problems at fire pipe.

  Any such planning, however, is likely far less than required to fully address the poten-tial impact of corrosion which can evolve froma very wide variety of sources.

Inherent Threat 

  For most building owners / operators,such inherent corrosion threat remainsgenerally unrecognized. Signing off on theinstallation of a new fire protection systemimplies decades of useful service life, and asystem which has the necessary safeguardsthrough design, technology, maintenance,

and inspection to ensure its effective opera-tion if ever called into service.

  Fire protection contractors install asystem design carefully defined down to boltsize and the spacing distance between pipehangers. Fire protection consultants andengineers follow well thought out andfrequently improved guidelines in designingan automatic and very effective response to awide range of potential fire threats.

  Every possible aspect of a fire protection

system seems to have been more thanadequately defined except to address theinevitable and unstoppable deterioration of the steel pipe by water itself.

Documented Failure

  On April 30, 1998, an electrical fireerupted in the laundry room of a nursinghome in Lamoni, Iowa. While the sprinkler heads functioned correctly, no water wasreleased due to their being totally pluggedwith heavy rust deposits.

  Fortunately, no loss of life occurred dueto the quick actions of the rescuers, but theoutcome could have easily been tragic.

Further investigation into the failure showedthat maintenance was current, and that thefire sprinkler system had been inspected andregularly tested according to NFPA Chapter 25 standards. A similar event near Philadel-phia in 2000 caused a woman’s death.

  Laboratory identification to the presenceof MIC throughout the piping system pinned acause to the Iowa fire sprinkler failure, and

raised important awareness to a seeminglynew problem. By focusing attention mostlytoward MIC and at specific geographic areasof the United States, however, the potentialfor similarly clogging sprinkler heads due torust product produced by more commongeneralized forms of corrosion, far moreprevalent, was entirely overlooked.

Not Just MIC 

  Today, severe rust found within a fireprotection system is automatically suspectedas MIC, until laboratory testing usually provesotherwise. In fact, by approximately 5 to 1,the majority of failure problems found at fire

protection piping are the result of generalizedand pitting corrosion which is present to somedegree in most fire systems. It is a worldwideconcern.

  MIC certainly accelerates pipe deterio-ration, and raises the potential to destroy afire system at phenomenal corrosion ratesexceeding 0.100 in. of steel per year. Equaland potentially greater threat exists,however, due to more slowly occurring andgradual effects of generalized corrosion over longer periods. To the building owner / oper-ator, however, the net effect is the same - withthe problem hidden entirely from view untilrevealed by the first leak.

Failure Before Fire

  Today, the economic impact and lifethreatening consequences of corrosion tofire pipe still remains generally unrecognizedand too often ignored. Indeed, no worsetime exists to discover a corrosion problemwithin a sprinkler system than during anactual fire emergency.

  Although the use of heavier pipe is oneobvious answer to longer system life, it alsohas a negative aspect as well, given tha

under corrosive conditions, a greateamount of rust product will be produced.

  Ironically for many property ownerstheir use of thin wall schedule 10 fire pipeleading to a more advanced failure, alsoprovided an earlier notification of a hiddencorrosion problem prior to an actual fire. Insuch cases, expensive pipe replacemencan be viewed as the cost of avoiding fagreater tragedy.

Major Liability

  The failure of fire protection piping afte50 years is a reasonable product of nature -corrosion, and old age. Its failure after 4

years is someone’s fault.

  Property owners reference a fire systemdesigned for long service life and towardwhich a testing and maintenance agreemenindicated no cause for concern. Installation

contractors cite a firesystem design followedexplicitly. For all thoseinvolved, defense reststhat corrosion is anatural occurrence

hidden from view, and therefore unknownand beyond their control.

  Extensive litigation often follows, with

the final cost of repair or replacement ultimately borne by the insurance companyDeath as a result of a fire sprinkler failure onlyincreases such conflict exponentially.

Changes Required

  The assumption that a fire sprinklesystem will perform as designed, 10 or moreyears after installation, may require newconsideration - regardless of the testing andmaintenance checks currently performed

 Although the overwhelming majority of fireprotection systems will function flawlesslywhen called upon, sufficient threat remainsto warrant further pro-active measures.

  With the current trend in fire protectioncontinuing toward those factors responsiblefor more advanced failures, tragedies suchas occurred in Philadelphia will increase.

  Greater recognition of this problemaided by more invasive testing and monitoring for hidden corrosion conditions, existsat the only response currently available.

CorrView International, LLCP.O. Box 8513 * Landi ng, NJ 07850

Tel: 973.770.7764www.CorrView.com * In fo@CorrView.com