Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.
We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.
Gayle, Margot, Look, David, and Waite, John. Metals in America’s Historic Buildings: Uses and Preservation Treatments. Washington, DC: National Park Service, .
Zahner, L. William. Architectural Metal Surfaces. New York: Wiley .
Iron is a dark grey metal and is the major constituent of a range of materials including wrought iron, cast iron, carbonized iron (carbon steel) and steel, each of which has its own unique properties. Iron was first used as a material for tools and weapons. Its uses have since grown to include items for domestic use to architectural building components. The presence of iron in a feature may be detected with a magnet.
Wrought iron differs from cast iron and steel in that it contains less carbon. The three metals are ranked as follows in terms of their carbon content:
Wrought iron: Contains the smallest amount of carbon (less than .035%).
Steel: Contains a moderate amount of carbon (between .06% and 2%).
Cast Iron: Contains the largest amount of carbon (between 2% and 4%).
Soft.
Ductile.
Magnetic.
Strong - high elasticity and tensile strength.
Malleable - can be heated and reheated and worked into various shapes.
Becomes stronger the more it is worked.
Suitable for members in tension or compression (whereas cast iron is suitable for members in compression only).
Stage 1: Preparation of puddled iron.
Pig iron was first smelted in blast furnaces and subjected to a reducing condition when it apparently ‘boiled’.
The boiling iron was worked continuously by the iron puddler and more impurities were removed from the iron, making the iron stiffer.
The iron was boiled until virtually no carbon remained, leaving a pasty mass of iron. This was evident when the carbon monoxide would stop bubbling through the iron.
The iron was then formed into balls to be molded.
Stage 2: Iron balls were hammered with a shingling hammer, to expel surplus slag or cinder (shingled).
Shingling was completed in minutes and the finished product was a bloom of approximately 5 inches x 5 inches x 3 feet.
The bloom, still at bright red heat, was then passed through rolling mills, becoming more elongated and thinner in section after each pass, and finished as puddled iron bar.
Stage 3: The bars were reheated and reworked as required to achieve the desired grades.
This stage increased the ductility and tensile strength of the puddled iron.
The more times the metal was reheated and reworked, the stronger were its mechanical properties.
Historical uses during the seventeenth and eighteenth centuries were typically decorative and included:
Fences, gates and railings.
Balconies.
Porches and verandas.
Canopies.
Roof cresting.
Lamps.
Grilles.
Hardware.
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Historical uses during the nineteenth century were more structural and included:
Nails.
Iron cramps (i.e. to secure masonry veneer building frames).
Structural members in tension such as tie rods, bulb-tees and I-beams. The standard sections of wrought iron included bar iron, angle irons, T irons, channel iron (half H iron), rolled girder iron (rolled joist iron, beam iron, I iron, or H iron), various special sections (sash bar, beading iron, cross iron, quadrant iron), iron bars, rivet iron, chain iron, horseshoe iron, nail iron, plate iron, coated iron (tin or lead), and corrugated sheet iron (generally galvanized).
Note: By the end of the nineteenth century, the use of wrought iron for structural purposes had been superseded by steel.
Problems may be classified into two broad categories: 1) Natural or inherent problems based on the characteristics of the material and the conditions of the exposure, and 2) Vandalism and human- induced problems.
Although there is some overlap between the two categories, the inherent material deterioration problems generally occur gradually over long periods of time, at predictable rates and require appropriate routine or preventive maintenance to control. Conversely, many human induced problems, (especially vandalism), are random in occurrence; can produce catastrophic results; are difficult to prevent, and require emergency action to mitigate. Some human induced problems, however, are predictable and occur routinely.
Chemical corrosion can attack decorative and structural wrought iron features in several ways:
Uniform Attack: Corrosion attacks the metal surface evenly.
Pitting: Attacks the metal surface in selected areas.
Selective Attack: When a metal is not homogenous throughout, certain areas may be attacked in preference to others.
Stress corrosion cracking: Attacks areas in a metal which were stressed during metal working and were later exposed to a corrosive environment. Old, hand wrought iron items are more likely to be affected than are machine rolled wrought iron pieces.
Rust: Probably the most common form of chemical corrosion of wrought iron. It occurs when unprotected metal is exposed to oxygen in the atmosphere in the presence of moisture. Moisture can be in the form of normal humidity, rain, dew, condensation, etc. Other gases, such as carbon dioxide, sulfur compounds, soot and fly ash will exacerbate the corrosion of the iron, as will airborne salts.
Galvanic (or Electro-Chemical) Corrosion: Galvanic corrosion occurs when two dissimilar metals are in contact with one another and an electrolyte, such as rainwater, condensation, dew, fog, etc. is present. Such a reaction will cause one or the other of the metals to corrode. In the case of wrought iron, direct contact with copper or zinc, and to a lesser extent galvanized iron or steel, will cause galvanic corrosion.
Mechanical or physical deterioration:
Fatigue: Failure of metal that has been repeatedly stressed beyond its elastic limit.
Wrought iron is generally fatigue resistant because it is so tough. It will deform considerably, within its elastic limit, without failure.
Even if past overloading has caused deformation, wrought iron fixings will usually continue to function.
Defects in the wrought iron itself, or stress points can cause a feature to fracture.
Heat: Usually in the form of fire, will cause wrought iron features to become plastic, distort, and fail.
Distortion: Permanent deformation or failure may occur when a metal is overloaded beyond its yield point because of increased live or dead loads, thermal stresses, or structural modifications altering a stress regime.
Connection failure:
Chemical and mechanical processes can breakdown or reduce the effectiveness of structural metal fixings such as bolts, rivets, and pins.
Stress failure is often a contributor to breakdown situations. Iron water traps are particularly susceptible.
Traveler reimbursement is based on the location of the work activities and not the accommodations, unless lodging is not available at the work activity, then the agency may authorize the rate where lodging is obtained.
Unless otherwise specified, the per diem locality is defined as "all locations within, or entirely surrounded by, the corporate limits of the key city, including independent entities located within those boundaries."
Per diem localities with county definitions shall include"all locations within, or entirely surrounded by, the corporate limits of the key city as well as the boundaries of the listed counties, including independent entities located within the boundaries of the key city and the listed counties (unless otherwise listed separately)."
When a military installation or Government - related facility(whether or not specifically named) is located partially within more than one city or county boundary, the applicable per diem rate for the entire installation or facility is the higher of the rates which apply to the cities and / or counties, even though part(s) of such activities may be located outside the defined per diem locality.
The reasons for a high security fence vary across the board. It may be to keep people out, keep people in, protect assets from tampering, etc. However, trying to pick the best security fence can be difficult when faced with a multitude of options between iron, steel, aluminum, wood, vinyl and chain link fence. Of all those options, an iron fence is going to be your best bet. Let’s go over the reasons why you should choose iron for your security fence.
This is one of the best attributes of iron fence for security. The inherent nature and strength of iron and steel vs other materials means that trying to break through is going to be more difficult. Chain link can easily be cut. Aluminum is a lighter metal that bends easier and can be broken. Vinyl can easily be cracked and broken through. Wood slats can be pried off. To cut through an iron fence, you are going to need to bring some heavy-duty tools. Simple kicking and batting at it is not going to make an opening. You can also weld the entire iron fence together to the posts for an extremely strong and secure fence. This goes double if you utilize a heavier-duty iron fence like our Signature grade fence.
The open construction of an iron fence with its rails spaced fairly far up to 4ft or 5ft apart on 5ft and 6ft tall fence panels means that even if someone jumps up and grabs the top, trying to swing a leg that high is going to be difficult. The pickets have a fairly small contact patch for shoes to really get traction. In addition, if you go with something like our Classic style iron fence with the finial tips on top, that makes climbing over more difficult as well. Wood fences can be climbed easier with being able to get foot traction on the boards. Same on vinyl. Chain link is the worst since those small openings provide lots of hand and foothold spots to climb the fence.
The welded construction of an iron fence means that the panel is one solid piece that cannot be taken apart or broken easily. Even the weak spot on an iron fence where the bracket connects to the post can be welded for a single joined unit with no separate parts. Having a solid fence like that makes quiet entry almost impossible. Aluminum fence can be unscrewed and the pickets slid out. Wood slats can be pried back. Vinyl can be easily broken or peeled. Chain link can quietly be snipped with cutters.
While some people think that obstructing the view onto your property is a good security measure, it can actually backfire. Its still easy to see through wood slats or privacy sheets and even cheap drones can be used to get a view over a fence line. Having an open design fence like an iron fence (and aluminum too) where there is about a 4in air gap means that if someone does get in the property, they have nowhere to hide. On something like a wood or vinyl fence, once they are in they can no longer be seen from the street and it gives them a guarded hiding spot from view outside of the property. The openings in an iron fence means that getting through the fence does not equal guarded cover for an intruder.
This one is a bit more opinion based (and I may be a bit biased), but an iron fence can act as a security fence without being an eyesore. As a matter of fact, iron fence often helps increase a home’s curb appeal with a more upscale look. A chain link fence may act as a barrier, but it is going to look horrible in front of a nicer home. Wood fence can look nice when its new, but with time its going to grey out, get water/ mold streaking or need staining to keep it looking nice. Vinyl fence can also go from nice to grime covered in a short period of time without constant washing. The wood and vinyl options will also block the view of the home which can ruin curb appeal and give a more ‘prison yard’ feel with taller fences.
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Contact us to discuss your requirements of wrought iron components. Our experienced sales team can help you identify the options that best suit your needs.