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Infrastructure In Decline

The scenario is unfortunately all too familiar. A concerned phone call describing widespread pipe corrosion or failure, even though every standard and industry accepted action had been taken to avoid such event.

In many instances, additional precautions such as automatic water filtration systems, extensive chemical feed controls, and chemical / corrosion monitoring had been implemented. For some others, third party corrosion consultants monitored every fine aspect of the water treatment program. Yet for many, none of their actions made any difference and failures still occurred.

While lacking, inadequate, or poorly administered and maintained chemical water treatment programs clearly exist in many examples, the majority of corrosion problems develop despite evidence that corrosion control had been a high priority item. In reality, chemical water treatment companies and their representatives have a strong underlying interest to provide the finest service possible for every client – thereby extending their contract past just the first year.

Results, however, are often far different than originally planned, with the destruction of virtually new piping systems a growing occurrence we are unfortunately introduced to on a near monthly basis.

• Results Decades Ago

We return to 1982 and our entrance into the corrosion control field when pipe corrosion at even the highest threat areas of open condenser water and process water piping systems was an almost non-issue. For closed piping systems, such as chilled water, reheat, hot water heating, or secondary systems, corrosion problems simply didn’t exist. And no one would even consider that corrosion could develop at a fire sprinkler system. Copper pipe was considered immune to corrosion, and galvanized steel pipe was expected to last almost forever.

Water treatment just 45 years ago was often nothing more than a roughly measured scoop of chemical inhibitor dumped into the cooling tower pan or by-pass feeder on a daily or weekly basis, or often – when remembered. Biocides were similarly hand fed, or added only after the cooling tower fill turned green.

A precision feed pump on a 24 hour cycle timer was the first major improvement in chemical treatment. Water meter usage based dosaging and conductivity based automated blowdown control equipment was just beginning to be implemented in the early 1980’s. Corrosion coupons were generally regarded as unnecessary, as was water filtration.

In short, pipe corrosion and its impact to building operations was often as far down the ladder of concern as was even possible.

• A Historical Perspective

Our 38 plus year involvement in the field of corrosion control and monitoring has produced undisputable hard proof to the far higher levels of corrosion activity common today. With over 1,075 ultrasonic piping investigations of properties dating from 1.5 years old, back to the year 1865, we have accumulated a massive volume of hard data. In fact, well over 3.4 million wall thickness measurements addressing over 2,795 piping systems support this opinion beyond debate.

Past ultrasonic investigations have documented older closed piping systems from the 1950’s, having no history of chemical treatment whatsoever, with still high and uniform wall thickness near new ASTM factory specifications. Oldest condenser water installations from the 1940’s have still been found at near new extra heavy specifications. In the case of one installation where the outdoor steel cooling tower pipe was never even painted, its ASTM stamp from 1947, exposed to the elements and cooling tower overspray for more than 62 years, was still intact and easy to read.

In one of our oldest investigations, testing identified the original galvanized steel domestic water pipe at a 1896 New York City property only now nearing retirement. For another New York City high rise office building built in 1959, we identified its 24 in. condenser water risers at 0.500 in. – still at its original ASTM thickness specification 56 years later. Incredibly, we have even documented a fire sprinkler system installed in San Francisco in 1907, right after the great earthquake and fire, in near new condition.

The caliper measurement at left showing a 0.534 in. wall thickness is not that of a new pipe installation, but of unpainted and uninsulated roof level condenser water pipe installed in 1933, operated for 30 years, and then cut, abandoned, and left open to rain, snow, and the atmosphere for another 52 years! Not even its cut edge has corroded.

For building properties where we have identified the installation of Bethlehem Steel pipe, outstanding results are virtually guaranteed regardless of the level of chemical protection or maintenance provided. Single pipe steam heating systems from 1906, using Bethlehem Steel pipe, have been assessed with still another 250 years of service life available.

Wrought iron pipe, (removed from manufacture in 1965), with its distinctive cross hatch markings, is extremely tough and naturally corrosion resistant. For virtually any building services application where it has been installed, from condenser water to chill water to fire sprinkler, 100 years of service can often be expected.

• Sharp Difference To Today

We contrast such outstanding results to those commonly encountered today. Even with more advanced equipment, greater personal attention, outside consultants, and control at your fingertips at all times, at significant cost, results are often disappointing.

Problems are nationwide. Advanced corrosion activity at three separate luxury condominiums destroyed their condenser water systems in only 5-7 years. A critical $1 billion dollar computer data center lost almost 0.100 in. of pipe wall in under 3 years – almost twice the estimated 0.065 in. of wall thickness ASME estimates will occur over the entire lifetime of a typical condenser water system.

We have documented steel pipe corrosion rates under well monitored chemical treatment conditions approaching 40 MPY – actually exceeding those we have deliberately created in an ASTM salt spray corrosion test booth. Buildings have replaced their entire condenser water piping system having a 9 MPY corrosion rate, only to find their new pipe corroding away at 28 MPY. Investigations have shown many fire protection systems to not only have reached the end of their useful service life in as little as 5 years, but to have also produced enough internal iron oxide rust deposits during that time to clog the fire sprinkler heads and prevent their functioning.

In the example at right, sufficient corrosion product was created within this 8 year old parking garage “dry” fire sprinkler system to completely cover the lateral distribution branch take-off lines. Had a fire occurred, no water at all would have been delivered to the fire sprinkler heads. More than just a potential threat, people have lost their lives as a result of this most deadly form of pipe corrosion.

All piping systems are impacted to varying degree as well as to specific problem areas. The failure of schedule 40 galvanized steel pipe serving domestic water distribution is now a common occurrence – documented at one large sports facility in under 5 years, and at a newly constructed luxury hotel in under 1.5 years.

Large scale premature failures of galvanized steel piping in both domestic water and fire protection systems have actually forced many design engineers to avoid their use. Yet, that industry has remained adamant that nothing has changed in the production of galvanized steel pipe over the past 100 years.

• But Something Has Changed

Many events have occurred over the past 35 years resulting in both improvements and reductions in pipe corrosion control.

There is little genuine debate that current corrosion control chemicals are less effective under real world operating conditions than products used decades ago – the unavoidable result of government restrictions, environmental regulations, and escalating chemical costs.

At the same time, chemical feeding has become significantly more precise and reliable, with the monitoring of chemical levels, blowdown, and water treatment parameters now instantly available at your computer or smart phone. Most modern chemical feed stations will automatically maintain the chemical treatment precisely at set levels as long as the equipment is adequately maintained.

Water filtration, virtually unheard of a few decades ago, is now almost standard to larger open and closed piping systems. Although all too often inappropriately specified, incorrectly sized, and almost always installed where least effective, water filtration is now being recognized as extremely important to all HVAC piping systems, especially cooling towers.

Its benefit, however, is often minimal. In the above example at a hot water heating system, heavier rust particulates will be forced by velocity and centrifugal force to the outside wall of the 90° elbow and away from the inside wall placed filter suction inlet – a common error rendering the filter installation nearly worthless.

Full flow water filtration, which is the only effective method suitable for open cooling tower systems, is very rarely installed. Instead, very low flow sand filters competing against each other on the basis of their lowest sub-micron particle capture are selected. Highly sophisticated side stream filtration systems are installed, often improperly, and typically ignore the fact that all heavier particulates not captured on the first pass will settle to therefore never be removed.

• Piping Layout Designs

Engineering designs of condenser and process water piping systems have changed significantly; with the result of inadvertently promoting much higher corrosion levels. The interest to provide absolute redundancy as well as large scale future expansion may look good on a CAD drawing screen, but becomes a corrosion inducing nightmare due to the many dead ends and low flow zones created. Small by-pass lines at dead ends, intended to maintain water movement, are in reality useless, and provide no benefit whatsoever.

In fact, the greatest threat to most piping systems is not its corrosion rate, where even a high 5 MPY corrosion loss will still provide 50 years of service for larger schedule 40 pipe. It is instead the 10-15 times greater volume of iron oxide rust product created and then trapped within the system to produce far more severe secondary under deposit pitting at 25 MPY.

• Corrosion Monitoring

Where corrosion activity and system health are monitored by corrosion coupons, true pipe wall loss is typically under reported by at least 3-10 times – whether measured by 1 coupon or 3 coupon sets maintained by 3 independent corrosion consultants.

For areas of an open piping system subject to the settlement of rust and particulates, such as large diameter headers, by-pass lines, crossovers, futures, and lead lag distribution runs, corrosion coupons cannot provide any possible estimate of wall loss – thereby leaving the condition of the most vulnerable areas of every piping system totally unknown.

Without some other reliable form of corrosion monitoring, a total reliance on corrosion coupons often results in a surprise just a few years down the road due to corrosion issues which actually started to develop on day one.

• Lower Pipe Quality

Few knowledgeable individuals handling, fabricating, welding, and installing pipe over the past few decades would even question the statement that today’s pipe is of far lower quality – both physically as well as in its corrosion resistance. While foreign pipe imports to the United States were originally blamed for many system failures, we now see the same level of problems involving genuine U.S. made piping products.

Lower quality is not only common for carbon steel pipe, but to also galvanized steel, cast iron, ductile iron, and copper. Replacing galvanized steel pipe that first lasted 65 years, means a likely failure of the new pipe within only 5-10 years.

Copper pipe, which has traditionally offered almost unlimited service life, is now being produced not just undersized in its wall thickness similar to steel, but also having poor uniformity. The same ASTM stamped Type K copper pipe may be above Type L dimensions on one side, and near Type M on another. Corrosion rates traditionally at below 0.3 MPY, are now more commonly identified at near 1 MPY.

• Undersized Pipe Wall

Moving back in time just 20 years, almost all steel pipe was manufactured at or above its ASTM defined wall thickness specification. In the example of 82 year old pipe on the front page of this article, we measured 0.534 in. of wall thickness for extra heavy wrought iron pipe originally manufactured to an ASTM A72 thickness specification of 0.512 in.

In contrast to decades ago, most pipe manufactured today is undersized, and often at or very near the 12.5% lower tolerance limit allowed by ASTM. This means that the new 10 in. schedule 40 pipe intended for a new cooling tower is not 0.365 in. as stamped on its side, but often 12.5% below that dimension or in fact closer to 0.319 in. Actually, pipe stamps only defines what the wall thickness should be, not what it actually is.

In the above photo, all not yet installed new 6 in. schedule 40 cooling tower pipe for this project was documented having a wall thickness of near 0.248 in. That is 0.032 in. or 11.4% under its ASTM A53 specification. For an extremely competitive market in which steel pipe from as far away as China, Oman, Turkey, and Thailand is being supplied, manufacturers have taken full advantage of the exceptionally wide +/- 25% wall thickness tolerance which still exists from the early 1900’s.

The issue of undersized pipe is so pervasive today that we rarely ever measure new pipe manufactured at its intended ASTM thickness specification – a finding which holds true for carbon steel, cast iron, ductile iron, galvanized steel, and copper pipe. And while a 12.5% loss of pipe wall to 12 in. schedule 40 pipe is tolerable, it becomes critically threatening when similarly reduced from schedule 10 or schedule 7 thin wall fire sprinkler pipe.

• Cumulative Negative Impact

The advanced piping failures we regularly document at newer building properties are in stark contrast to virtually every older building similarly evaluated, and are becoming far more dramatic in comparison due to:

• Less Effective Chemical Treatment
• Lower Quality Pipe
• Complicated Piping Layouts
• Thinner Pipe Schedules
• Undersized Pipe Wall Thickness
• Inaccurate Corrosion Monitoring
• Ineffective Water Filtration
• “Green” Influences

Each of the many changes to the piping industry present its own threat to every building owner, developer, property manager, chief engineer, and P.E. Unfortunately, few such issues have been recognized within the industry. Or have they been recognized but ignored? In many respects, it is a “Perfect Storm” of critically interdependent issues all moving in the wrong direction. And from our perspective, reinforced often, there seems to be no interest or incentive to reverse its course, nor to even acknowledge its presence.

You can view and download our two page handout on this subject below.

© Copyright 2023 – William P. Duncan, CorrView International, LLC