Harsh winter temperatures mean heating utility systems face heavier loads, with a higher potential of overworking existing systems. Steam utility distribution systems, especially in institutional utility networks, have the potential for major system failures with the changing seasons.

With their elevated temperatures, steam system pipes expand when brought on line to serve heating loads and contract if taken off line for maintenance or off season. This expanding and contracting can cause aging infrastructure to experience failure at various points in the system, resulting in a potential loss of heating capability or need for major repairs when the system is needed the most.

An Overstressed System

As systems age, the risk of pipes, anchors or other parts failing increases. Additionally, if systems aren’t properly designed before installation, pipe layouts fail to allow for natural expansion and contraction over the course of usual system operation and seasonal loading. Piping anchors, necessary expansion loops or mechanical joints and proper pipe support infrastructure help alleviate pipe stresses by allowing the pipe to grow in a controlled manner.

Natural seasonal load changes — or the addition of new loads in an expanded system — stretches the existing system and can lead to failure points. For example, an expanding university campus may fail to upgrade the utility system to accommodate new infrastructure or loads.

Proper Maintenance for Issue Prevention

Failures in the system can usually be identified before they become widespread issues. If not found through preventative maintenance, failing mechanical joints may need replacement or require anchor redesign. Visual inspections, especially in advance of colder weather, can detect leaks or other pipe failures before steam loads increase and system criticality increases. Some examples include mechanical slip joints binding, bolt misalignment or steel bending at anchor locations, curvature in the straight sections of piping, pin hole leaks near pipe bends and many others. A detailed pipe stress model can help determine how to lay out parts in the system and solve for potential failures. A detailed pipe stress model can also be developed to model the existing system failure to show why it failed.

If issues aren’t preemptively resolved, the next course of action is fixing the failure. A team of mechanical and structural engineers conduct a field investigation to identify damage. Anchors, guides and joints are located and measured to produce a piping stress model utilized to identify a proper solution.

Crafting Precise Solutions

Once the pipe stress model is created, a solution is chosen to address the issue and drawing packages are then developed to show required piping system modifications. A new expansion joint may be installed, or the anchor may need to be redesigned to adjust for the correct forces created by the steam pushed through the pipe.

The system may also need to be reevaluated after a failure. Some systems, including many university campuses, have grown beyond what the original system design can handle. A well-rounded team of engineers can create different pathways to isolate sections of the system for easier upgrades or repair. Installing isolation valves also allows an outage to affect just one part of the facility, preventing the entire system from failing and creating a broad unplanned outage.

With winter weather fast approaching, now is the time to schedule preventive maintenance and visual inspections — before an unplanned outage or other system failure occurs.


A fast-growing Texas campus updated its utility system capacity and now operates with increased efficiency, flexibility and reliability.


Kali Wang, mechanical engineer at Burns & McDonnell, specializes in HVAC design, pipe stress and energy modeling for higher education, laboratories and energy plants. She also has experience in steam and condensate pipe stress modeling and piping design.