Increasing Levels Of Threat
How Curiosity And Due Diligence Can Re-Direct An Ultrasonic Investigation Into Entirely New Areas
Concerns to the condition of their condenser water piping system prompt an ultrasonic investigation at an assisted living home. Facility management reports abnormally high rust deposits in the strainers and cooling tower pans, and is concerned to the condition of relatively new pipe of only 8-9 years old. Although corrosion coupons are reporting low corrosion rates, visual evidence suggests otherwise.
Our ultrasonic testing identifies higher than normal corrosion activity and deep pitting in some areas. Pipe wall thickness is still acceptable even though it has suffered a large loss. We question the maintenance of the chemical water treatment program and find that the original provider failed to chemically cleanout the pipe and provide treatment for the first 4-6 months – an issue commonly identified as the starting point of most severe corrosion problems. Although a new water treatment company has taken over and is far more consciencous, we learn that that they never chemically cleaned the condenser water system of the original rust product – a deficiency which would have prevented effective chemical corrosion control and allowed higher pitting.
With this new knowledge we recommend performing some exploratory testing at the closed chill water piping given that a similar deficiency in water treatment likely existed for both systems. Ultrasonic testing immediately identifies extermely low but uniform wall thickness in contrast to the schedule 40 piping specified for installation. Following our investigation of various sections of chill water pipe throughout the facility, we find only low but uniform wall thickness which correlates to the installation of thin wall schedule 10 pipe. For their 8 in. chill water mains expected to have a schedule 40 wall thickness of 0.322 in., we measure wall thickness values of near 0.175 in. and just below the 0.188 in. ASTM specification for new schedule 10 pipe.
Irrefutable proof is gained to show that the contractor substituted thinner pipe into the chill water system, which now dramatically increases the need to maintain low corrosion rates to their minimum possible limit. We report to the facility manager that a suspicion of one piping problem has revealed two.
As the investigation continues to define the condition of now the condenser water and chill water systems, we notice new pipe installed at the fire sprinkler system. Multiple sections of new black pipe are observed intermixed with the original red painted fire sprinkler pipe – obvious evidence of a prior piping failure. Questions to the engineering department reveal that the facility is experiencing frequent leaks at their dry fire system which serve the attic area and top resident floor. Although all other fire sprinkler piping covering the lower floors is wet, the attic level pipe is dry due to the winter freezing threat. The top floor of the facility is fed downward from this attic space – thereby requiring a dry system as well.
As we have documented extensively in past investigations, we express to the engineering department that dry fire systems are “dry” in name only, and leave sufficient water behind during each test cycle to greatly accelerate corrosion activity. Water typically remains at the lower 1/3 or more of the pipe, covered by abundant air and oxygen which then generates extensive rust deposits. A pipe failure at a dry fire system, therefore, rates far greater concern than just to the repair costs, water damage, and inconvenience to the facility, and has the potential to render the entire fire line totally inoperable.
Spot testing near the dry valve produces a severe wall loss easily explaining prior failures. In discussion with the maintenance personnel, we find that failures have also occurred within the attic space, but that they have no knowledge to the interior conditions of the pipe which failed due to their having been removed by different fire protection contractors. Multiple examples of attic pipe have been replaced over time, but no concern to its condition or potential threat from internal deposits has been conveyed to anyone at the facility. Increasing the level of threat to the facility, we further learn that the top floor protected by the dry fire system is for assisted living tenants having fully functioning kitchens with stoves.
We contact the facility manager and express our very serious concern to this situation. Although our original focus was to the condition of the condenser water piping, we impress upon the manager that corrosion at a fire sprinkler system carries far greater potential consequences and should be addressed at this time. With only one day of field testing budgeted, we express far greater concern to the condition of the attic fire sprinkler pipe, and suggest it would be to the interest of the facility to abandon further investigation of the condenser water and chill water systems to focus instead at this new issue. We also offer to spend a few additional hours on site at no additional charge.
Testing identifies thin wall schedule 10 fire pipe as would be expected today for an wet or dry fire sprinkler system. Black ASTM A135 carbon steel pipe is installed. Ultrasonic testing immediately identifies very severe wall loss and low measurements representing more than a 60% wall loss along the bottom half of the pipe. Beginning at the main 5 in. supply line, we measure extremely low wall thickness well below minimum acceptable standards. A far greater concern is raised to the volume of iron oxide rust products which are likely trapped within this piping system. With the greatest wall loss at the beginning of the supply line due to a greater movement of fresh water, we can anticipate that any downstream fire sprinkler head calling for water would likely receive instead some portion of the lose rust carried from all the fire pipe before it.
We raise a significant concern to the property manager that should a fire exist at the top floor of this nursing home, the rust in the pipe may prevent functioning of the fire sprinkler heads. The very high deterioration of the main 5 in. and 4 in. pipe strongly suggests that a fire covered by any downstream piping would likely not receive any water through the sprinkler heads. Complete replacement of both dry fire systems covering the attic space and below 4th floor tenant space is required as soon as possible. We recommend bringing mobile firefighting capability to the 4th floor while the replacement of the dry fire sprikler systems are planned and executed. We also recommend removing specific examples of pipe to confirm the volume of internal rust deposits which we suspect exist.
A far more limited report is provided to the facility covering the condenser water system due to re-direction of our investigative resources to the chill water and fire sprinkler systems, but provides enough evidence to plan changes and reduce the corrosion activity. Recommendations are made to install side stream bag filtration to the chill water system and to greatly elevate corrosion inhibitor levels.
More than six months later we are contacted by the fire contractor who replaced the fire system and are informed that when the 5 in. pipe was opened for visual inspection, it was almost entirely clogged with rust and thick mud. The overwhelming consensus in following- up our recommendation to visually inspect certain areas of attic area pipe in confirmation to our ultrasonic findings is that the fire sprinkler system had zero possibility of functioning during a true fire emergency. All those involved with the visual inspection of the fire system express their deepest gratitude for CorrView having the experience to recognize such a severe problem which had been overlooked by everyone else.