Applications – Warehouses

• Systems Overview

As the expansion of massive warehouses continues to grow, so does the need to ensure the remain safe and operational.  While plumbing is still necessary for such facilities, the most extensive and critical piping system throughout these buildings is the fire suppression system.  Commonly, these facilities are not cooled by HVAC systems and therefore no threat would be present.   The fire sprinkler system not only provides life safety to building occupants, but also to the massive inventory stored within.

• Common Vulnerabilities

  • • HVAC

Commonly, warehouses do not have centralized heating and cooling systems.  Exhaust fans on the roof may assist in cooling the building during warm summer months, with localized electric or gas heaters providing warmth in the winter.

If present, heating and cooling systems provide hot and cold water to large air handling units which maintain the temperature and humidity of warehouses.  Unlike residential buildings which have an extensive layout which runs throughout tenant spaces providing individual levels of comfort, warehouses typically have limited and larger diameter mains which supply centralized air handling units which serve a vast area.  Lesser concern is commonly shown for the larger diameter chill water systems which are typically typically installed at warehouse facilities as long as a successful water treatment program has been implemented.  However, these chill water systems commonly suffer much greater external wall loss due to insulation failure and moisture condensation.  Hot water heating systems are typically shown to be in better condition than the chill water, as long as an effective chemical treatment program has been implemented since the additional external corrosion threat does not exist.

• • • Fire Sprinkler

The functioning of a fire sprinkler system relies as much upon internal corrosion conditions of the piping as much as it does its prompt activation.  Highest oxygen content and greater water movement at the building inlet is a common source of fire pipe deterioration, followed by other locations which experience fresh water movement.  For warehouses which are required to have the piping run parallel to the roof, specific areas of weakness exist anywhere air may remain trapped during system filling, modifications and testing.  Since these systems are filled from bottom to top, it is common for air to remain trapped at the top of the system.  It is common for vent lines to not be properly installed or operated.  This air boundary then caused very aggressive corrosion activity in localized areas, which may not represent the condition of the system as a whole.

Dry fire sprinkler systems are installed at areas where freeze protection may be an issue, or where valuable electronic inventory may be stored in fear of a leak from an above wet fire sprinkler line.  These dry fire sprinkler systems have the greatest vulnerability to corrosion simply due to the fact that they are never ever “dry.”  Along with some water content, they contain an abundance of oxygen which then creates an ideal environment for corrosion activity to occur.

A further vulnerability to all more recently installed fire sprinkler systems is movement toward  thinner materials such as Schedule 10 of 7 pipe, and even threaded thinwall schedule 10 pipe.  The use of galvanized steel pipe, which was once considered the answer to the entire fire pipe corrosion problem, can actually advance system failure due to its declining quality.  Combined, significantly greater threat exists to a piping system which was considered for almost a century as being immune to the corrosion.

• Pipe Related Issues

We consider pipe material quality as the most significant factor related to system longevity.  Our ultrasonic investigations have proven noticeable differences between the far superior quality of all pipe manufactured decades ago against what is available today, and we commonly identify better results at 60 year old examples of original pipe in comparison to pipe recently been installed into the very same system.  Retaining original pipe which is still in good condition throughout aging building properties is a significant benefit to building owners today.

In addition to a greater vulnerability to all forms of corrosion, most pipe is manufactured not to the wall thickness specified by ASTM, but to the minimum thickness allowed by ASTM, or typically 12.5% less.  This has a lesser impact against larger diameter welded pipe, and far great impact against both thinwall pipe as well as threaded pipe installations.

• Top Failure Locations

HVAC

• • • • • Small diameter chill water
        • Dissimilar metal connections

Fire Sprinkler

• • • • • Building inlet
        • Areas of greatest water movement
        • Dry fire sprinkler systems
        • Thin-wall Schedule 10, 7, or 5
        • Air-bound pipe sections

• Testing Priorities

With the specific vulnerabilities defined above, areas of priority for testing can be easily established.

• • • Any areas of the fire sprinkler system which may remain air-bound.
    • Thinwall schedule 10, 7, or 5 pipe, especially at dry fire systems.

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