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Guy Anchor Shaft Corrosion. Guard anchors against rusting with Cathodic Protection Systems anodes.

To protect your guyed tower, we recommend an anchor shaft excavation inspection for all guyed towers which are more than a few years old if they have not had a corrosion protection system. (CPS).

Since 99% of anchor shaft corrosion & shaft failures normally occurs in the lowest 1′ of the anchor shaft, it is prudent to carefully excavate & inspect the entire length of each anchor shaft. Installing our high quality Cathodic Protection System (CPS) ensures the safety, security & life expectancy to your guy wire tower structures. Our cathodic protection systems have proven they can last over 30 years when used in conjunction with a resilient anchor shaft protective coating.

    $550. GPT-CPS-1 anchor protection kit for towers up to 12″ wide with 3 guy anchors. 3 anodes in the kit.
    $1,090. GPT-CPS-2 anchor protection kit for towers 13″ to 30″ wide with 3 guy anchors. 6 anodes in the kit.
    $1,630. GPT-CPS-3 anchor protection kit for towers 31″ to 42″ wide with 3 guy anchors. 9 anodes in the kit.
    $2,100. GPT-CPS-4 anchor protection kit for towers 43″ to 60″ wide with 3 guy anchors. 12 anodes in the kit.

Great Plains Towers Guy Anchor Shaft excavation inspection methodology:

  • While holding back the guy anchor heads entire guy wire tension load with a suitable safe temporary anchorage system, excavate down & along “one” side of the anchor shaft down to the concrete anchor deadman block. Use a hand shovel to manually clear away & knock down the soil from the opposite side of the anchor shaft. Extremely important safety note: In the eventuality of a guy anchor block moving or the guy anchor shaft failing & parting while being excavated it is imperative to supply & utilize an excessively strong temporary anchorage system behind the anchor & fasten it to the guy anchor shaft fanplate assembly which will be capable of withstanding the impact load of an entire failed guy anchor shaft system & all of its guy wire tensions & their total potential tension energy if a violent anchor shaft exit motion occurs.
  • After securing soils from caving into the open hole, clean soil away from the exposed anchor shaft down to bare metal, use a measuring device to check for metal loss & photograph document the entire clean bare anchor shaft utilizing the cameras flash option to include photos of where the anchor shaft enters the concrete anchor deadman block.
  • If an anchor shafts cross sectional mass measurement is still 100% of new & if there is no sign of corrosion, then proceed to the next inspection step. If anchor shaft metal is missing due to corrosion, a new replacement anchor shaft may be required. Consult with us or a professional structural engineer.
  • Install our correct size corrosion protection system (CPS) to guard against corrosion at each guy anchor shaft location per the illustrations on the right side of this paragraph.
  • Coat the entire bare, dry clean guy anchor shaft where it is exposed to the soils with an impervious coating layer of any of the following sealants; flexible aqua sealant tape, pipeline tape wrap, epoxy or fibered roofing tar coating which greatly extends the cathodic protection operating systems life. Do not apply cold galvanize paint to the bare guy anchor shaft before coating with a protective coating.
  • Before backfilling soils, always photo-document all of the workmanship utilizing the flash option to ensure photo clarity of bottom of the normally dark excavated hole.
  • Backfill & compact the excavated soil materials every several inches. Add additional compactable soil into the excavation while backfilling if necessary to ensure there is a slight rise earth mound & not a depression above each guy anchor location.
  • Important: Always remove all copper coated ground rods from within 20′ of the guy wire anchor shafts, since copper ground rods sacrificially carry away the steel anchor shaft molecules through the soil. Replace all copper ground rods with hot dip galvanized ground rods.
  • Test & document each anode -DC voltage meter reading or its current flow meter reading of the anode wire at each guy anchor with a digital DC volt meter or Ammeter as part of every annual tower inspection to ensure that the hi-potential magnesium anodes are sacrificially depleting themselves & protecting every guy anchor shaft. Outside electrical influences such as potential stray current or voltage sources may sacrificially deplete an anchor shaft. That sacrificial influence action may be from a nearby: pipeline compressor station, electrical substations, electrical transformers, broadcast facilities or other “active” or “rectified” cathodic protection systems.
  • The following is a purchasing guide to which size Cathodic Protection System (CPS) kit is recommended for your different width guyed towers:


Note: If a guyed tower has six guy anchor shaft locations, order “double” the amount of above listed CPS kits.
 

GPT2_V1
GPT2_V2
GPT2_V3
 
 
Growing list of collapsed towers due to unprotected & corroded guyed tower anchor shafts
NAME YEAR SIZE TYPE DURATION
Hazen ND 1990 250′ tall Two-way radio tower 25 year old tower site.
Valley City ND 1995 300′ tall FM tower 4 year old tower site.
Langdon ND 1990 350′ tall Cable TV tower 25 year old tower site.
Drake ND 1999 200′ tall Microwave tower 30 year old tower site.
Grand Forks ND 1991 500′ tall Cable TV tower 20 year old tower site.
Valley City ND 1998 300′ tall Microwave tower 15 year old tower site.
Devils Lake ND 1988 300′ tall Cable TV tower 20 year old tower site.
Aberdeen SD 1981 300′ tall TV Brdcst & studio 30 year old tower site.
Colfax ND 1980 300′ tall Microwave tower 15 year old tower site.
Grand Forks ND 2007 180′ tall Two way radio tower 7 year old tower site.
Britton SD 2008 400′ tall Cable TV tower 20 year old tower site.
Vermillion SD 2003 280′ tall Cellular tower 12 year old tower site.
Portland ND 2001 180′ tall Cable TV tower 8 year old tower site.
Toronto SD 1980 220′ tall Two way radio tower 25 year old tower site.
Toronto SD 1995 400′ tall Microwave tower 15 year old tower site.
Toronto SD 1998 400′ tall Microwave tower 18 year old tower site.
Moorhead MN 2008 300′ tall Cellular tower 11 year old tower site.
Austin MN 2012 440′ tall TV broadcast 33 year old tower site.
Woonsocket SD 2013 480′ tall Cellular/Microwave 20 year old tower site.
Mitchell SD 2014 300′ tall FM Broadcast 7 year old tower site.

Each of our high potential magnesium anodes has the following physical properties:

  1. 45 LB anode package overall dimensions: 29″ long X 6.5″ in diameter.
  2. Backfill material in each anode package: 75% Gypsum, 20% Bentonite, 5% Sodium Sulfate.
  3. Connecting core wire is 20′ long, 8 gauge stranded copper, heavily jacketed with HMWPE coating.
  4. 17 lb Magnesium anode “core”. Material consists of:
    • Magnesium / High quality 98.839 %.
    • Aluminum 0.01 % maximum.
    • Manganese 1.0 % maximum.
    • Copper 0.02 % maximum.
    • Silicon 0.05 % maximum.
    • Iron 0.03 % maximum.
    • Nickel 0.01 % maximum.
    • Other each 0.05 % maximum.

The following is our procedure for measuring a CPS / cathodic protection system at each anchor fan plate location:
Temporarily disconnect the anode wire connection clamp from the guy wire anchor shaft or its fan plate, Using a volt meter, test for the DC voltage present between the anchor fan plate & the anode wire connector.
Finding a DC voltage reading between the anode wire & the anchor in excess of -1.15 volts is a good sacrificial CPS.
A DC voltage reading of less then -.90VDC is too low & may be a sign of a dormant, disconnected or depleted CPS which requires additional high quality anodes added to the anode bed to bolster the DC voltage until voltage achieved is upwards of -1.15VDC or higher.
Contact us for additional anodes since low anode voltages may not be preventing anchor shaft corrosion or if you have questions.

 

How Can We Help You?

Contact us with any questions - info@greatplainstowers.com 

We would be happy to answer your questions and set up a meeting with you.

 Great Plains Towers
                  126 Sixth Street West
                  West Fargo, North Dakota 58078
 
701 282 2236 ,  800 853 2236
 
 
 
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