A. The equivalency is based on loading specified by ANSI 05.1 for each wood pole class, and then modified by a ratio of overload factors for wood and steel NESC (ANSI C2-2017).
A. Wood naturally deteriorates with age. Wood poles are subject to rot, fungus and decay, as well as attack by insects and woodpeckers, all of which will reduce structural strength. In most utility applications, the "normal" life of a wood pole is approximately 30 years. Steel, on the other hand, has a much longer life span, especially when corrosion is kept in check. Galvanizing is an effective deterrent to corrosion for above-ground applications and many below-grade applications. There are other high-performance coatings that have been developed for below-grade protection when soil conditions warrant it. These coatings, in conjunction with galvanizing, can extend the lifespan of steel considerably.
A. The U.S. Department of Agriculture (USDA) Rural Utility Services (RUS) does not approve material. They have a listing of approved suppliers of material. Valmont Utility is on the list as an approved supplier of steel poles. Rural Electrification Administration (REA) co-ops that have used steel distribution poles have indicated in their work plans they are being used "to gain experience and to look to the future." The application of steel distribution poles may require conditional approval for use on RUS funded projects.
A. Structurally, steel distribution poles can be used just like their wood counterparts. In addition, since steel poles are conductive, they offer an added benefit of being an efficient path to ground, which may replace the ground wire used on wood poles. The hardware currently used on wood poles usually works well with steel poles, but consideration should be given to line reliability issues, such as BIL.
A. Valmont Utility provides one grounding device at the ground line as a standard for all distribution poles. It is very easy to add additional ground nut devices (i.e., at the transformer location) during fabrication, should the utility indicate such a need. Our standard is a ½-inch diameter threaded insert. This detail will also accept the grounding stud used with transformers. Additional threaded inserts can also be added in the field by the utility at the time of pole installation, should they be required.
A. Because steel poles are round and approximately the same diameter as their wood counterparts, any transformers currently mounted on wood poles should be able to be mounted on steel.
A. The same safety procedures and precautions currently being used for wood poles should be used for steel poles in this type of application. Steel poles are conductive and wood poles are generally considered to be conductive during hot line insertion.
A. Steel distribution poles would need to be guyed if the wood pole it is replacing would have been guyed. The steel pole can be guyed just as you would a wood pole using the same hardware. By using a stronger class steel pole, though, it may be possible to eliminate the need for guys altogether.
A. Steel poles can be guyed using the same hardware currently used for wood poles. Permanent attachments such as vangs can be welded into the poles for attaching guys but this will increase the delivery times and pole costs. The use of your current hardware and construction standards means no additional changes have to be done to enable a utility to start using steel distribution poles. Valmont Utility is happy to work with you regarding any specific hardware questions you may have.
A. The preferred method of lifting the poles is to use nylon slings. While a galvanized pole is very tough and abrasion resistant, it is not recommended that chains be used when handling them. During storage in the material yard blocking should be used to keep the poles off the ground and to separate each layer just as you currently are doing with your wood poles.
A. A tag is attached to the pole with the manufacturer's name, pole height and class stamped on it. If the utility wishes to tag the poles with other information they can easily add a tag using self-tapping screws, pop rivets or adhesives.
A. There is no standard for the number of holes in a Valmont Utility pole. The utility may specify the number and location of holes they would like, and Valmont Utility will provide holes during fabrication. Additional holes can also be field-drilled, should they be required.
A. Holes can easily be drilled using either a hole saw or stepped "Christmas Tree" style of bit. The Rota broach works best, since it requires less force or energy to drill a hole. Twist drill bits are not as easy to use, since they use more energy to drill a hole. Drill speed should be limited to 300 rpm or less.
A. When required, Valmont Utility offers a 100% solids polyurethane coating for below-grade protection. This product replaces traditional coal tar epoxies and has been successfully used in the transmission industry. The requirement for below-grade protection needs to be determined by the utility, as it depends on a number of factors, such as how well drained the soil is and the corrosion potential in the soil. Experience with galvanized ground rods, lighting poles or transmission/substation structures in the area can be helpful in determining coating requirements.
A. Valmont Utility does not recommend shrink wrap as a barrier coating due to the possibility of water wicking into the gaps between the wrap and the pole. Valmont Utility offers two factory applied barrier coatings for below-grade protection. First is a spray-on polyurethane coating, discussed above. The second is a steel groundsleeve.
A. A variety of finishes are available with steel, including galvanized, paint over galvanized (powder coat or liquid), dulled and darkened galvanizing and weathering steel. Below-grade coatings are available for direct embedded poles. Click here for additional coatings information.
A. In short, if your desired BIL or critical flashover voltage calculations include the insulating properties of the wood pole, then the results will be different with a steel pole. The differences can either be overcome by using different hardware (i.e., larger insulators, bigger air gap, fiberglass material change) or by evaluating the BIL of the steel installation and how it supports your overall reliability goals. Valmont Utility is happy to work with you regarding your particular construction approach and how it might affect overall system performance.
A. Utilities that are concerned with electrocution of raptors, or other birds of prey, have modified their distribution configuration to minimize the threat to these birds. Typically, this modification on 3-phase construction consists of dropping the cross arm, with the outside phases, 43 inches. This same construction can be used with steel poles. In addition, it may be necessary to field-apply a layer of heat shrink wrap just above the cross arm to prevent the possibility of a phase-to-ground contact. In the case of single-phase construction where a bird may sit on top of the pole, Valmont Utility can supply a special pole top cap to prevent the bird from coming in contact with the pole.
A. Our parent company Valmont Industries, Inc. (VMI) has been in business for more than 50 years and has been providing steel poles to the utility industry for more than 28 years. Our engineers are very familiar with industry requirements and are active in several industry organizations, such as IEEE and ASCE. Valmont Utility has been manufacturing poles similar to the distribution poles for more than 30 years, and has supplied several million of them throughout North America and around the world. Our multiple manufacturing locations worldwide means short delivery times and has resulted in an excellent on-time shipping record. We have a network of manufacturer representatives who are local and can answer any questions concerning the product or reply promptly to any concerns you may have regarding Valmont Utility product. We constantly invest in new equipment, so we have the latest technology for galvanizing or painting poles and related transmission, distribution and substation structures.
A. Valmont Utility can provide an optional, removable climbing safety step that fits into holes in the pole.
A. During the galvanizing process, the entire pole is immersed in the bath of molten zinc. Because the pole is immersed in both the cleaning solutions, flux and zinc, the inside surface is adequately cleaned and a layer of zinc bonds to the pole. This process protects the pole inside and out. On painted poles, only the outside of the pole can be painted. Due to their small size, there is no way to mechanically clean the inside of the pole adequately for the paint to bond to the surface. This is why non-galvanized painted steel poles need to be sealed, to prevent moisture from reaching the interior surface and causing corrosion. If paint over galvanizing is specified, there is no need to be concerned about the pole interior, as the zinc bath will provide protection.
A. Since the steel poles are designed to be equivalent to wood poles per NESC Grade B construction, they can generally be used on a one-for-one basis.
A. Steel poles weigh 1/3 to 1/2 less than comparable wood poles. (See comparison chart in the technical data section.)
A. All poles come with a welded-on bearing plate to prevent the poles from settling into the soil when a vertical load is applied. This bearing plate is sized to be similar to provide the equipment bearing pressure of an equivalent wood pole.
A. Please see the beginning of the quick reference section catalog of the Valmont Utility technical binder for ordering options and how to specify poles.
A. Typically, all the hardware you are now using will fit on a steel pole also. Click here for information on Shakespeare composite tangent crossarms, which are produced by Valmont Composites Structures.
A. The same hardware currently being used for your wood poles should work with steel poles, because they are round and of approximately the same diameter.
A. Because Valmont Utility has several manufacturing locations, standard poles can be shipped quickly after receipt of an order. This time may be reduced for emergency situations, or in stocking programs.
A. Valmont Utility steel poles are optimized by their sizing to meet their strength performance designs. Plate thicknesses range from 0.120 inches to 0.313 inches. See our Class Steel Pole Catalog in the quick reference section for actual thickness by pole size.
A. Although it may be possible if excessive force is used, Valmont Utility is not aware of this problem occurring when standard practices are followed. This includes using 4-inch square washers under the heads, or nuts, of the bolts. Also, since steel poles are dimensionally stable, and do not shrink like wood poles, there is no need to overtighten the hardware. We recommend using a turn-of-the-nut method to attach hardware.
A. The number varies depending on the size of the pole. See Valmont Utility's Distribution Pole Chart for the truckload quantity for each pole size.
A. Valmont Utility uses wood dunnage between poles to prevent them from rubbing together during shipment and damaging the finish. At your request, we can bundle the poles so they are easily lifted and moved in a group. This eliminates the need to pick each pole up separately, as in wood construction.
A. Most utilities who are using steel poles still put a gain between the arm and the pole. The gain provides a good, flat surface to mount the arm to, and due to its curved surface also provides good bearing surface to the pole. It keeps the arm from rocking on the pole. We know of utilities who have not installed gains. Utilities can use either the standard gain used on wood poles or a plastic gain that has a smooth surface both against the pole and the arm. Increasingly, braceless construction is being used where the cross arm has its own gain base. Judging by customer feedback, these cross arms work very well on steel poles.
A. Yes, two-piece poles are available. The two-piece pole utilizes a slip fit connection, similar to that used in transmission pole applications.
A. Normally twisting or turning of a steel pole is not a problem. However, should a utility feel it could occur for their application the utility could easily drill a couple of holes in the base and attach either bolts or other equipment to prevent this from occurring.