Sports Light Pole Inspection & Assessment

Sports lighting poles, as with any man-made structure, require periodic inspection and maintenance during their service life. Without proper maintenance, the deteriorating effects of the environment over time can reduce the functional life of a sports pole and in some cases, cause pole collapse. Corrosion, an unusually strong wind event, metal fatigue due to prolonged, wind-induced vibrations, or an overloading of the structure may damage a pole and lead to a catastrophic failure.  To protect people and property, Matco Services, recommends pole owners perform regular inspections of all pole structures to ensure (1) the welds that attach the base plate to the pole shaft are crack free, (2) the surface does not exhibit corrosion, (3) and nuts/bolts are checked checked to ensure they are snug.

Contributing Factors to Loss of Service Life:

Consistent winds, severe storm events, industrial and maritime environments, peeling paint, and improper base plate grouting can all accelerate pole fatigue and structural corrosion, dramatically shortening pole life.  These occurrences are briefly described in the following section.

Fatigue Failure: Although rare, wind-induced vibration can cause a pole to crack and fail over time.  This phenomenon is referred to as “vortex shedding.”   Vortex shedding occurs when there is uneven wind induced air flow that results in movement of the upper portions of perpendicular structures, as shown diagrams A and B, below.

As there are conditions that will cause vortex shedding to occur to a greater degree, such as strong vibration over time or strong gusts of wind, routine inspections are recommended.  The heat affected zone (HAZ) or weld area connecting the base plate to the pole shaft or the pole shaft to arm members are particularly susceptible to cracking caused by vortex shedding.

Left, a horizontal crack above the heat affected zone / weld area is shown.  Right, a vertical crack in the weld area is shown.

As there is only a small window of time when the cracks are both large enough to detect, and small enough to not yet cause catastrophic failures routine inspections are highly recommended.

Left, a sports lighting pole that was installed on a 3’ concrete pier collapsed.  Right, the base of the structure was sent to determine root cause and mode of failure.

Corrosion on sports lighting poles, high mast poles and other metal structures intended for outdoor use is directly related to the atmospheric and soil conditions present for each structure as well as to the materials of manufacturing and the quality of these materials.   Internal corrosion due to the presence or entrapment of corrosive water (electrolyte) or external corrosion due to corrosive atmospheric and environmental conditions are both forms of corrosion commonly observed on these structures.   The following photographs show a pole collapse due to corrosion and metal loss.

Routine Inspections are Recommended:

Due to the importance of reliability and safety, we recommend annual inspections by Matco Services ASNT or NACE non-destructive technicians.  These qualified technicians specialize in the various non-destructive test (NDT) methods that can be used to detect cracking that is not readily available by visual inspection.  Among the most common forms of NDT used to identify cracking on these structures are:

• Dye-penetrant testing is one method Matco Services has at its disposal to verify pole integrity. A special dye is applied to the pole base exposing internal cracks the average maintenance technician would never discover.
• Magnetic particle testing is another test which may be used to reveal virtually invisible external and internal cracks. By employing non-destructive inspection techniques, offering expert analysis and delivering documented reports, our NACE-certified pole inspectors can determine the current-state condition of every pole inspected.

These forms of inspections can identify subsurface cracks and internal corrosion not readily apparent to an outside visual observation of the pole. Tests such as these are useful in detecting hairline cracks, internal corrosion and other structural integrity issues which can be difficult to detect through basic visual inspection techniques.   NACE-certified pole inspectors can determine the current-state condition of every pole inspected.

Matco Services also recommends a NDT inspection be performed periodically as a part of an inspection and maintenance program in areas where pole fatigue risk factors have a history or become apparent.   Property owners and facility managers are informed, pole-by-pole, whether the risk of structural failure is low, moderate or high.  From this position of knowledge, those responsible for safety can assess risk and take appropriate actions, as they deem necessary, to safeguard against pole failures.

Inspection Frequency:  Frequency of inspection depends on many risk factors including geographical location, site location, the age of the structure, and information collected from the initial inspection.  Inspection should always occur immediately after a major wind event.

Matco Services recommends a Pole Condition Audit be performed at least every ninety days and with greater frequency if risk factors warrant. A follow-up Nondestructive Testing inspection is recommended for pole sites where suspect areas of concern have been discovered through the visual inspection of the Pole Condition Audit.

Pole Condition Audits performed by knowledgeable maintenance personnel should consist of a visual observation of the pole condition and include the following inspection procedures:

1. Visual observation for any cracks to the pole base or shaft. For example, the area directly above the base weld is an important area to check for cracks. If any cracks are observed, contact your contractor or Matco Services immediately.

2. Visual observation for loose anchor bolt nuts. Check to ensure anchor bolt nuts are tight on both the top and bottom side of the base plate. If the nuts are loose, snug the bottom leveling nut and then tighten the top nut by the Turn-of-the-Nut Method. For more information on the Turn-of-the-Nut Method, please refer to the following website:

www.nucor-fastener.com/Files/PDFs/TechDataSheets/TDS_012_Turn-of-Nut_Installation.pdf

3. Visual observation for corrosion should note areas where the paint, galvanizing or any other decorative/protective coating has been damaged or is no longer intact. Poles with diminished protective coatings should be promptly repaired with a suitable protective coating material. If facility maintenance personnel detect a noticeable loss of steel due to corrosion, or if holes in the shaft become visible, consult with your contractor or the pole manufacturer immediately. Grouting at the base of the poles is not recommended, as grouting will entrap internal moisture and weaken structural integrity by facilitating internal corrosion. Existing poles with grouting should be addressed immediately; remove all grout and perform an inspection utilizing a NDT technician to check for internal corrosion. Significant rust staining on the foundation may also be an indicator of internal corrosion.

Periodically observe the pole for any signs of a wind-induced vibration. Observe the pole for unusual shaft movement or sway, touch the pole to see if you can feel any vibration and listen for wires or cable rattling against the interior of the pole shaft. Notify the manufacturer if pole vibration, noise or movement is observed. A vibration-mitigation device may be required to reduce pole vibration. If vibration is allowed to continue, fatigue damage may occur to the pole, which may impact the pole’s structural integrity.

While the pole owner is responsible for determining what to observe and document at their facility, the pole owner may consider utilizing the attached checklist as part of their pole condition audit.

Sports Lighting Pole Condition Audit Checklist

(A) Mechanical

Check to ensure anchor bolt nuts are tight on both the top and bottom side of the base plate. Snug the bottom leveling nut and tighten the top nut by the Turn-of-the-Nut Method. For more information on the Turn-of-the-Nut Method, please refer to the following website:

www.nucor-fastener.com/Files/PDFs/TechDataSheets/TDS_012_Turn-of-Nut_Installation.pdf.

Visually inspect all structural welds for any signs of rust or cracking at or near the listed welds – Contact Matco Services if a crack is observed. Check the following:

• Base plate weld.
• Hand hole rim weld.

(B) Vibration

Check the pole for any signs of wind-induced vibration. Observe the pole for movement of the shaft, touch the pole to see if you can feel any vibration, and/or listen for wires or cable rattling against the inside of the pole shaft.

(C) Finish

Check the finish for any damage or rusting in the coating:

• Galvanized surface – Check the galvanized coating for any damaged areas such as nicks, scratches, scraps, cuts, or rusting. Clean damaged or rusted area and coat with a zinc-enriched paint such as ZRC^® (or equivalent) per ASTM A 780.
• Painted surface – Check the paint film for any damage areas such as nicks, scratches, scraps, cuts, or rusting. Clean damaged or rusted areas, prime, and top coat per manufacturer’s recommendation.

Engineering Solutions and Mitigation Techniques: As experienced materials and corrosion engineering experts, Matco Services' staff members are geared towards providing innovative and cost effective engineering solutions designed to meet the specific needs of our clients.  These solutions often incorporate the use of cathodic protection, application of protective coatings or tape wrappings, or the use of some other form of corrosion mitigation or early detection method.  Although Matco Services' has had the capability to carry out an assortment of these procedures for many years, we are delighted to now offer an additional scope of repair work that includes application of protective paints and coatings, structural repair and weld repair.  These repair procedures are performed by NACE certified technicians that have undergone extensive training in performing these repair procedures and corrosion mitigation techniques.

Additional can be found by clicking on either of the following links:

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www.valmontservicesgroup.com

Matco Services' Team Members - Our team includes experts in a variety of desciplines including corrosion engineering, materials engineering, mechanical engineering, paint and coatings specialists, electrochemists, chemists, Ph.D. level scientists in materials selection and design, polymer and elastomer specialists, and concrete (petrographic) specialists that often work as a team to identify a the root cause of a materials failure.  We also have a vast array of laboratory and field testing equipment that is enlisted at times when a repair or refurbishment of a structure is required. All of Matco Services' testing equipment is calibrated on a routine basis in accordance with both national and international standards, and is ready to be put to use at a moment's notice. Matco Services' staff includes a variety of experts in corrosion and materials engineering, as well as the methods used to repair and retrofit a variety of structures.  The following staff memebers of Matco Services' are part of the service offerings listed on this page.  An asterisk indicates NACE training and certification.

Dr. M. Zee (*)                 Mr. Carl Kempkes (*)

Mr. Ed Larkin                 Ms. Heather Groll (*)

Mr. Walter Gretz, P.E.    Mr. Geoff Rhodes

Mr. Sam Scheinman (*)   Mr. John McArdle (*)

Mr. Ron Hansen (*)         Mr. Gary Woita

Mr. Dan Gibson              Mr. Doug Swensen (*)

We Value Our Customers... Throughout the years we have noticed that much of our business comes from repeat customers. Our expertise and well-equipped lab can account for much of this, but we believe there is something more to it. We attribute it to the fact that we promote an open and friendly environment that is never too busy to meet your needs. At Matco Services we value your business whether you are a large corporation or a small enterprise. We will provide you with the attention you need and deserve. We invite you to visit us and get to know our staff, and share in the learning experience.

Why Choose Matco Services? As one of the premier testing, inspection, and repair firms,  Matco Services is able to provide a unique and diverse blend of services. Thousands of investigations have been performed at Matco Services, ranging from jet engines and boiler tubes, to computer components and implants that have promoted the advanced understanding of why these components fail to meet expectations.  Combined with our new repair and retrofit capabilities for a variety of structure types we are now able to offer our clients a comprehensive array of services from project start, to project finish.  As always, projects are conducted discretely so that client confidentiality is ensured.