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|Insulated Panel Systems or Composite Sandwich Panels are used in a variety of applications from Industrial and Commercial Coolstores to Agricultural and Architectural Buildings, Sport Centers, Commercial Premises, Warehouses and Factories, Offices, Exhibition Space and Convention Centers around the world.|
|People can spend millions of dollars on building Insulated Panel Coolstores to house their produce for the export market, those products need to be kept in a controlled environment. By attaching height safety products or systems that can cause damage to those Insulated Panels can cost you millions in export sales through loss of that controlled environment.|
Metal Insulated Sandwich Panels
The Metal Insulated Sandwich Panel is a lightweight panel system incorporating an expanded foam core with factory 0.55 laminated outer steel covers in a flat or trapezoidal profile manufactured to act as a roof systems which can have a minimum pitch of 3 degrees. Unlike single skin metal roof profiles, the strength of panel construction permits exceptional spans requiring fewer structural supports.
When designing any height safety anchor points or systems that are attached to Metal Insulated Sandwich Panels, extreme care must be taken to protect the core and the outer skin of the Insulated Panel from damage.
The main anchor body is made up of three components: a mounting plate which is 10mm thick mild steel, a 30mm mild steel stem which can vary in height to control the type of absorption that may be required to reduce excess loading on the panel, and a 10mm diameter mild steel bar welded to the top of the stem to form the eye. This eye also absorbs energy.
All Insulated Sandwich Panel Anchors are manufactured using 250 grade mild steel. The welding of all height safety anchors is carried out using the Welding certification Procedure AS/NZS 2980:2007
Kulorthene Series ABCITE® thermoplastic powder coatings have been developed specifically for enhanced long term corrosion protection, high impact strength and excellent exterior weathering.
Coating Benefits include
Exceptional resistance against salt spray,humidity, most common chemicals, acids, and alkalis. Abcite® coatings have high elongation properties, excellent mechanical resistance, are solvent free, have excellent substrate adhesion without the need for primers, superior chip resistance, and will provide superior substrate protection even to sub zero temperatures.
(View coating system)
To fully protect the Insulated Panel from the dynamic force generated from a fall-arrested load, the Insulated Panel needs to be sandwiched between the main mounting plate of the height safety anchor on the outside of the building (see photo 1) and the height safety anchor backing plate is placed on the underside of the Insulated Panel. (see photo 2)
Before attaching the mounting and backing plates we recommend applying Sikaflex 11FC white sealant to the under sides of the anchor to act as a gasket, sealant and an adhesive. (see photo 3) The bonding strength of the Sikaflex 11FC is 50kgs per 1 millimeter square. By using both methods, bolts and Sikaflex 11FC, we are able to spread the loading over a much greater area to protect the Insulated Panel from point loading from a single bolt or fixing which can damage the Insulated Panel.
The system we use is the same system the Insulated Panel manufactures have designed to attach the Insulated Panel to the building structure. (see dia 1)
Attachment of the anchor consists of
All tests that were carried out on this product included a safety factor of x 2
There are two types of testing required under the AS/NZS:5532.2013 Standards for anchor points, they are
A. Dynamic testing
B. Static testing.
NB: The maximum safe stopping force that can be placed on the human body caused by a fall is 6kN or 600kgs. Safetor Insulated Panel
anchors start absorbing energy at around 3.8kN to 4kN or 380-400kgs, this brings us well under the maximum safe stopping force.
Some structural engineers have told me that the Safetor mild steel structural anchors don't work because they yield at under the 15kN or 1500kgs. While they do yield at under 15kN or 1500kgs, it is largely due to the elasticity of the low grade mild steel we use. As the bar bends the yield lowers because it is going through a bending process and the energy is being absorbed by the bending action, when it reaches a certain point in the bend the yield starts to rise again and well exceeds the yield for anchor points. In the strongest direction the anchor has failed at 5000kgs or 50kN and in the weakest direction the anchor has failed at 4000kgs or 40kN.
Surface Anchor Testing on roofing material
There are a many types of height safety surface mounted anchors designed for fall-arrest and lifelines that are in use on buildings today, these anchors are attached to roofing material using rivets, screws or bolts. The most common of these anchors are manufactured using a 4mm stainless steel mounting plate with no form of backing plate. The tests we had carried out using a riveted type system alerting us to the fact that this type of system is not safe for use as a fill-arrest anchorage devices.
Point loading on cladding
Point load: A load used in a testing regime as a measure of the ability of roof or wall cladding to support a person with a bag of tools, at mid span. (1.1kN)
A point load is often the most severe of the imposed loads which is calculated at 112 kgs = 1.1 kN. As required by AS/NZS 1170.1 the point load is taken as 1.1 kN over an area of 100 mm diameter in the case of a superimposed load, such as anchor points, the area of contact if the load is not directly attached to the structure. A point load on a roof is always positive or downward (+).
Roof and wall cladding is required to comply with the requirements of the NZBC clauses B1, B2, E2, E3, and also with AS/NZS 1170.
Von-Mises Stress Loading
Von Mises stress is considered to be a safe haven for design engineers, using this information an engineer can say if his design will fail if the maximum value of Von Mises stress induced in the material is more than the strength of the material. This works well, especially when the material is ductile in nature.
In 2015 I engaged BVT Engineering Professional Services in Christchurch New Zealand to carry out the Von-Mises stress analysis test on a surface mounted anchor. (view full report)
It was evident in the Von-Mises Stress test that a 4mm stainless steel base plate has enough flexibility to direct the loading away from all the fixings working as one to a small number of fixings depending on the direction of loading, this creates greater point loading on the sandwich panels. By using a 270mm or greater in diameter bonded anchor, manufactured from 10mm mild steel plate with a 4mm backing plate that is also attached using 4 x M12 bolts, the load is then spread over a much greater area and removes point loading at the equation altogether.
Sandwich panels can be damaged by using:
Material Testing Laboratory in Auckland New Zealand have carry out a number of static tests for me on roofing iron. The tests carried out by MTL are shown below in photos 10a, 10b and 10c you will note the roofing completely failed in photos 10b and 10c.
Static test results on roof material
The static test results on single skin roofing material are related to photos 10a,10b & 10c. The testing material used in this test was: 2 x 0.55 and 2 x 0.40 Galvanised Corrugated Iron roof sheets, 14 x 7.70 Olympic Bulb-Tite rivets complete with EPDM washer with weather tight seal and 2 x 50 x 400 x 4mm flat mild steel.
Static test photos 10b and 10c show that the roofing iron failed at the last rivet, in the dynamic testing the surface mounted anchors again failed at the last very rivet as seen in photos 11b and 11c. Failure always occurs at the very last rivet because the bulk of the loading is transferred to the end rivet. Because a hole has been drilled in the roofing iron to accommodate the rivets this creates a week point in the roofing iron were the tearing of the material begins.
|Lifelines on Panels