WASHERS

The basic purpose of washers when used with cladding are to provide a larger bearing surface when transferring wind forces from the cladding via the fasteners to the supporting structure on pierced-fix cladding systems. Washer are also used to enhance the anchoring power of fasteners used to attach flashings. The size, thickness and shape determine the ultimate performance of a washer. As with fasteners washers need to have corrosion resistant properties or coatings at least equal to those of the cladding. In addition to resisting the design wind loading they have to be sufficiently robust to withstand the mechanical forces of installation.

Traditionally washers were punched from 0.58 or 0.80mm Z275 hot-dipped galvanised carbon steel, aluminium or stainless steel onto which a neoprene rubber sealing gasket was bonded. Currently bonded washers available in the market range from aluminium alloy domes with hard plastic grommets (most hardware outlets) through 0.4mm slightly domed steel with a nominal hot-dipped galvanised coating and wafer thin EVA or so called EPDM gasket (which are easily dished during installation) to quality aluminium and stainless with electro negative EPDM gaskets.

Washers made from too thin a material provide virtually no benefit and have a tendency to dish at the first resistance when being installed resulting in ponding around the head of the fastener and formation of a crevice corrosion cell. Invariably the dish is transferred to the top of the rib of the cladding thereby forming an additional larger pond and possible crevice corrosion cell if the gasket is of dubious quality, Figure-1 & 2.

Figure 1 – Screw
Figure 2 – Washer

Such washers can have a ruinous effect on translucent cladding. We recommend the use of saddle washers with translucent materials. A way of avoiding these problems is to use flanged head fasteners where the washer is incorporated as part of the head, Figure-3.  

Figure 3

Effective performance of the gasket is dependent on the material used being capable of maintaining its elasticity over a temperature of -10° to 110°C, be UV resistant and  impervious to moisture. Additionally it should have hardness of Shore-A 30-90 and have a maximum electrical conductance of 0.5×10-6 ampere. The thickness of the gasket should not be less than 2.0mm. the most suitable material for gaskets is EPDM rubber.

What is overlooked by the majority of suppliers is the mismatch between the corrosion resistance of metallic coatings on the fasteners, washers and cladding which can result in bi-metal corrosion. Another factor that can have a major impact on corrosion is the inclusion of electroactive carbon in the gasket.

It is important to remember that the performance of most types of washers is dependent upon the use of the proper fastener installation equipment and care being exercised by the installer not to under or over tighten fasteners, Figure-3 refers.  

Please visit our website www.samcra.co.za for other articles and papers on subjects pertaining to cladding.      

STEASA Engages with TRADE

The Steel Tube Export Association of South Africa (STEASA) recently had a meeting with TRADE (an acronym for TRAde and DEvelopment) which is a research and advisory division at the North-West University (Potchefstroom Campus) specialising in international trade and economic development. We discussed an array of issues all related to global trade and specifically their model of identifying realistic export opportunities which could be tailored for steel tubes and pipes.  

Their research is geared towards export promotion and economic development. From identifying new and high-potential export opportunities, to uncovering the keys to greater competitiveness and inward investment flows. All areas of great concern to economic policymakers and decision-makers in business.

At the heart of TRADE’s research programmes is its international TRADE-DSM® (Decision Support Model) which is used to identify realistic export opportunities for countries, provinces and industry sectors in the form of high-potential product-market combinations. Complementing the TRADEDSM® is the TRADE-DSM Navigator®, a powerful, interactive computer-based application which interprets the results of the TRADE-DSM® in a user-friendly way.

TRADE is also a chair of the WTO (World Trade Organisation) Chairs Programme. The WTO Chairs Programme (WCP) aims to enhance people’s knowledge and understanding of the multilateral trading system by awarding research Chairs to selected universities and research institutions. In 2014, Prof Wilma Viviers, director of the TRADE, was awarded a WTO Chair (1 of 7 recipients worldwide to receive the honour that year), heralding the start of an international partnership.

STEASA in collaboration with Trade Advisory intend to host a trade and investment seminar in September 2018 that focuses on current global trade developments, with a keen focus on the opportunities in steel tube and pipes and the pitfalls that these trade developments present.

                                                             WWW.STEASA.COM           

Allied Steelrode’s LT20 tube laser: Imagination is the only limitation

Allied Steelrode’s LT20 tube laser: Imagination is the only limitation

  • High-speed, versatile five axis 3D tube laser creates dynamic new processing and pre-fabrication possibilities

While many companies these days may claim to be innovators, true innovation is rare. However, for South Africa’s leading steel processor and supplier, Allied Steelrode, innovation is in the lifeblood of the company and part of their organisational ethos.

Founded through a merger of Allied Chemical and Steel Pty Ltd and Steelrode Pty six years ago, Allied Steelrode has grown exponentially, supplying high volume merchants and end-users with – amongst other product offerings – bulk coils, slit strip, flat steel, steel pressings, standard sheets, and the entire structural steel portfolio of products.

L – R: Arun Chadha, CEO and Warne Rippon, Executive Director of Allied Steelrode.

In 2014, Allied Steelrode’s Executive Director Warne Rippon and CEO Arun Chadha recognised the structural, architectural and mechanical advantages inherent in tubular steel. This material is lighter and more cost-effective than conventional ‘I’ beams and, when welded together, offers far greater strength. By cutting specially shaped openings in steel tube, sections can be interlocked and then welded with far greater ease.

“For example, we produced the components for a pre-fabricated steel building which had a specialised agricultural application. Once processed by the LT20, the components were taken to site and, with a perfect fit ensured, were rapidly assembled,” explains Rippon.

“There are many other companies in agriculture, mining, and construction who could use this service to their advantage,” he emphasises.

“The sky really is the limit. Our LT20 Jumbo opens up a completely new range of design possibilities for architects and structural designers. Now – thanks to this technology – many more beautiful and innovative tubular structures can be designed, as the only limitation is the bounds of architects’ own imaginations.

As such, we look forward to seeing tubular steel featuring increasingly in our daily lives, such as in the design and construction of shopping malls, airports and sports stadiums,” he enthuses.

The application of the LT20 is very diverse. It can process tube for architectural and agricultural applications; and meet the requirements of the heavy transportation, construction, mining, automotive power generation, shipbuilding and petrochemical industries, amongst others.

As a long-term investment, and to broaden its offering to the southern African steel construction and manufacturing sectors, Allied Steelrode purchased the BLM Adige LT20 Jumbo tube laser in the fourth quarter of 2015. This revolutionary machine was commissioned at the end of January 2016 and by mid-March 2016 was in production.

“Worldwide, tube laser cutting is a comparatively new innovation in the steel processing industry,” explains Rippon.

Before tube laser, processing tubular steel involved time-consuming sawing and drilling. Now, with tube laser, it is possible to cut even the most complex geometries in steel tube. The LT20, for example, can process tubes ranging in section from 75mm to 508mm and in lengths of up to 18 metres.

“Unlike many other lasers which can only cut up to 8mm wall thicknesses, the LT20 can cut up to 16mm thick tube walls,” adds Chadha.

The hugely versatile five axis laser cutting system is ideal for three dimensional parts, bent, hydro-formed or pre-assembled tubes or flat and pressed sheets. In addition, the superior edge quality produced by the LT20 frequently eliminates time-consuming post-processing steps, when compared to conventional processing technologies.

As the machine produces a finished component in a single cycle, there are no problems with storing semi-finished work, a factor which streamlines and increases productivity.

The LT20 will cut round, square and rectangular section tubes as well as open structural sections whether they are mild steel, high-strength steel, stainless steel, aluminium, alloys, brass or copper. It is possible to economically produce anything from a one-off prototype to a production run of thousands in a fraction of the time that was previously required.

The tube laser is fully automated and requires minimal operator intervention. With extended production runs, this guarantees absolute product consistency and faster turnaround times.

For example, recently, Allied Steelrode processed the tubular steel sections of a two storey 100-ton parking garage.

“We cut the steel preparation time from what would have taken three weeks to a mere eight days,” Chadha explains.

An additional motivation for the purchase of the LT20 was that, in 2015, Allied Steelrode won the contract to supply the complex structural steel for the iLanga and Kathu solar power projects in the Northern Cape.

Apart from the major investment in the LT20, Allied Steelrode has imported and commissioned South Africa’s only dedicated steel stretcher leveller  in a purpose-built factory in Midvaal, with a second more powerful one – suitable for very high-tensile strength steel –  already purchased and due to be commissioned in the first quarter of 2018.

“Major investments of capital equipment of this nature are very much long-term ‘votes of confidence’ and game-changing value-adds in the partnership which we have with our customers – and the industry as a whole,” explains Rippon.

“Early on in our partnership, we understood the need to enhance our customers’ processes. The purchase of the LT20 was yet another significant step along this trajectory,” he concludes.

Everising’s upgraded E- and P-Series sawing machines

Everising’s upgraded E- and P-Series sawing machines: ‘cut out’ to meet customers’ sawing requirements with faster cutting times and greater functionality

11 July 2018

To maintain its enviable reputation for excellence and sophistication in sawing, the Taiwan-based Everising Machine Company continuously strives to anticipate its customers’ requirements to provide timeous and effective solutions. What the company established recently was that many customers required machines capable of cutting the larger steel sections which are now being used more frequently in manufacturing today.

In South Africa, Everising circular saws and bandsaws are available from First Cut, the foremost distributor of cutting consumables and capital equipment.

In response to its customers’ requests, Everising has upgraded its P- and E-series sawing machines so that they can now process steel sections in the 300 mm to 800 mm range. The overall aim of Everising with these upgrades is to reduce its customers’ production costs by speeding up actual cutting times.

The P-series also has a user-friendly touchscreen with easy-to-follow graphics, with all cutting parameters clearly displayed on the touchscreen controller. A bonus for operators is the self-diagnostic function which allows for immediate on-screen troubleshooting.

P-series circular saws are fitted with an accurate length index device, which is driven by a servomotor and ball screw. Hydraulic-clamped front and vertical vices hold work pieces firmly in place.

A floating shuttle device and hydraulic sorting chute speeds up production, while a scraper chain type chip conveyor ensures efficient removal of cutting debris. The speed of the blade is controlled by an inverter and is infinitely variable.

In response to its customers’ requests, Everising has upgraded its P- and E-series sawing machines so that they can now process steel sections in the 300 mm to 800 mm range.

The P-series gear transmission driver provides high efficiency and consistent cutting speed. Carbide guide pads are used to strengthen the rigidity of the saw blades, which means not only accuracy, but an extended saw blade life.

Other features include an air filter, a cutting-fluid coolant system, an air compressor, a smart bar collecting system, an air blower for tube cutting, and variable vice pressure.

Importantly, the P-series requires only one operator to set up and load the machine. Excessive rework is avoided as P-series machines give a milling cutter finish with a tolerance of 0.02mm. Remnant or scrap pieces are sorted into a separate bin. With its versatility, a P-series sawing machine could replace a number of other types of circular saws, thereby saving valuable production space.

As with the P-series, Everising’s E-series band saws are CNC-controlled and also feature advanced touchscreen control. To ensure extended machine life, E-series band saws are equipped with high efficiency gearboxes lubricated by a controlled oil-feed system. An inverter controls the variable speed of the blade, which is tensioned hydraulically. An idler wheel motion detector serves to detect blade stalls thereby preventing blade damage.

The robust electronics on the E-series ensure that downtime is minimized; while an anti-vibration roller serves to protect the blade, which is cleaned by two automatically adjusting wire brushes. An advanced quick approach device and an automatic tracking blade guide protect the machine against accidental damage.

All E-series machines are manufactured with a solid steel frame with two pre-loaded linear guides for accurate, repeatable cutting. In addition, E-series machines have a safety device to ensure that blade changes are risk-free.

A dual front and rear floating vice holds work-pieces securely in place; while an out-of-square detector detects any flaws in the operator’s setting up procedure. To ensure there is no swarf build up, E-series machines are fitted with a drainage and chip removal device.

Once a particular job has been completed, the sawing machine’s computerised control systems can produce machine utilisation analyses, so that management can monitor and optimise machine usage in a particular facility.

In South Africa, First Cut supports its Everising machines with a rapid uninterrupted supply of consumables. At present, First Cut carries an inventory of blading that is in access of 50,000 metres.

The company has a presence throughout South Africa, and is able to offer fast, reliable delivery, installation and training on the range of capital equipment it offers. The company’s well-staffed and trained service department furthermore ensures that First Cut customers experience maximum machine uptime.

A call centre is available to assist with machine-related queries, the booking of services and scheduling of maintenance.

For its part, Everising continues to improve the performance of its equipment by evaluating competitor products and responding to international demand. Based on these findings, the company invests in research and development to improve performance. As a result, ISO-accredited Everising sawing machines continue to compete extremely favourably in terms of quality and price with any other comparable manufacturer in the market.

Secondary Fastners

When it comes to metal cladding one has to consider two types of fasteners, primary and secondary. Primary fasteners are those that anchor the cladding to the structural support members (elements) whereas secondary fasteners are generally used to attach ancillary items such as flashings and for stitching side laps. Whilst most profilers provide tables and/or details of the primary fasteners and some stitching screws there is little information pertaining to the secondary fasteners. Traditionally cladding contractors use one or other form of blind rivet (pop rivet).

What is often overlooked is that in addition to corrosion these fasteners have to withstand a variety of loading conditions such as pull-out, pull-over, vibration and differential thermal movement. In addition they are required to clamp together materials with different degrees of fragility e.g. metal and polycarbonate cladding. The fasteners used to attach flashings to the leading edges of a building are subjected to the maximum wind loading conditions imposed on the cladding. Wind load increases exponentially with height above average ground level together with proximity to or location on topographical features such as hills or adjacent to edges of cliffs etc. The roughness of the surrounding terrain, roof profile (shape) and adjacent buildings can contribute to increased wind loading.

The performance characteristics of the secondary fasteners therefore have to be proportional to the loading conditions. As a rule of thumb the bigger or more exposed a building the more robust the secondary fasteners have to be.

In addition to having the correct effective length, diameter or thread type it is important to take into account the following;

  • Pull-out strength
  • Pull-over value (can be increased by introducing a bonded washer)
  • Vibration
  • Shear induced by thermal movement on both the fastener and materials being joined
  • Susceptibility of materials to being crushed or inhibited from free differential thermal movement e.g. interface between metal and translucent materials 

Please visit our website www.samcra.co.za for other articles and papers on subjects pertaining to cladding.      

POLASA to host Open Industry meeting

The next popular POLASA Open Industry meeting will be held on Monday 16 July 2018 from 14h00  to 17h00 at the WOODMEAD JCC.  

Subjects of interest or burning questions can be tabled in an informal setting. Presentations to participants to inform and stimulate discussion will include:

  • Progress made (or not) achieving the 2017-18 Compacts – and this year’s!
  • The latest on the impact of the Designation of Powerline hardware
  • A Presentation on why ESKOM’s Specifications result in South African powerlines being more expensive that in neighbouring countries!

Please note that the venue is no longer in Aucland Park JCC but at the Johannesburg Country Club off Lincoln Street in Woodmead.

This is reached taking the Woodmead Drive turnoff from the M1 followed by Woodlands Drive and is much closer for the ESKOM people.

Members and non members of POLASA are welcome but to attend you must advise:

Kobus de Beer, POLASA Secretariat  (polasa@saisc.co.za) or (011) 726-6111

                                                               WWW.POLASA.CO.ZA

SASFA arranged the 28th LSFB industry feedback meeting

SASFA arranged the 28th LSFB industry feedback meeting as a breakfast session on 14 June 2018. After the welcoming address by David van Zyl, current Chairman of SASFA, Fred Wagenaar from the NHBRC talked through the views and expectations of the NHBRC when dealing with the engineer / competent person on a residential building site where IBT’s (Innovative Building Technologies), such as light steel frame building, are used.

John Barnard then discussed the current state of the LSF building industry, showing examples of recently completed projects.Three SASFA members, viz Andrew Dewar (SMC Construction), Uwe Schluter (MiTek) and Johan Fourie (Siteform) briefly presented some of their recently completed projects. Attendees made good use of the opportunity to network with other industry players.

                                                                                              www.sasfa.co.za

Cladding – The consequences of misalignment

One of the most overlooked factors that influence the aesthetic appearance and performance of cladding is alignment, firstly of the cladding to the supporting structure and secondly the supporting structure itself.

Other than the obvious visual appearance misalignment of the cladding to the structure generally manifests in a jagged edge where; roof cladding overhangs a gutter or side cladding overhangs masonry, connects to a flashing or the edge of the runout of bullnosed cladding. In addition it results in stepped bulges at the side lap joints within the curved portion of a bullnose which in turn impacts on the weatherproofing of the cladding. This type of misalignment presents weatherproofing difficulties at the interface with longitudinal flashings e.g. sidewall, apron and corner.           

A factor having a considerable influence on the performance of modern cladding profiles is the misalignment of the supporting structure, be it of steel or timber. Modern profiles are manufactured from high tensile materials to much closer tolerances than the generic corrugated and box (trapezoidal) rib cladding and likewise require a higher degree of accuracy in the alignment of the supporting structure to achieve optimum levels of performance. Unfortunately the tolerances for the alignment of the supporting structure have not been updated since the 1960’s. SANS 2001-CS1(structural steelwork) only addresses the alignment of the frame as a whole i.e. columns and floor beams, roof steelwork and cladding rails are not mentioned whereas SANS 10234 (the manufacture and erection of timber trusses) allows a bow in purlins of the lesser of span/100 or 30mm.

The introduction of thin lightweight purlins and girts coupled with insufficient sag bars has seen an increase in the amount of twist within the span between trusses and rafters, this results in the top flange not being in the same plane as the cladding and causing kinks, misaligned fasteners plus induce fold lines and oil canning. Cladding rails out of plane to adjacent rails can produce similar results and on flat roofs ponding which will have a detrimental effect on the durability of the protective coating. Excessive lateral deflection of the rails in the plane of the cladding can inhibit the thermal movement of concealed-fix profiles. Cold formed sections that are rolled outside of tolerance (flanges not at 90° to web, bowed or twisted) will produce similar results.

It is imperative that the installation of cladding does not commence until all the sag bars have been installed and supporting structure fully aligned. A difficult task when all the float in the construction programme has been eroded by other trades.

Remember the cladding envelope will reflect al the humps and bumps of the underlying support structure.     

Please visit our website www.samcra.co.za for other articles and papers on subjects pertaining to cladding.      

STEASA travels to Algiers

The Mediterranean city of Algiers opened its doors to the international world of trade and investment when it hosted its annual Algiers International Trade Fair 2018 from the 8th May until 13th May 2018 at Palais des Expositions Algiers, Algeria and was organised by SAFEX. The tradeshow event showcased a variety of products such as fashion, textiles, home textiles, automotive, construction, agriculture, food, furniture, machinery, steel fabrication, cosmetics products and lots more. STEASA took part as part of the South African pavilion to show case its members steel tube / pipe manufacturing capacities and offerings in the fields of oil & gas, petrochemicals, construction, water conveyance, energy, mining and agro processing.

The Algiers International Trade Fair is one of the most strategic platforms for foreign companies to reach Algerian buyers and consumers. The fair attracts exhibitors from the United States of America, France, Germany, Turkey and China, amongst others. This years Trade Fair had China as the guest nation of honour. STEASA had the opportunity to engage with Sonatrach, the largest Algerian and African company and the 11th largest oil consortium in the world regarding their procurement opportunities and how STEASA members can get a footprint in their oil and gas operations. Another strategic meeting organised by SA’s Economic Counsellor in Algeria was with Redmed, who are the largest service provider to the Algerian oil and gas industry and have strong ties with Sonatrach and the South African Embassy in Algeria. Their Marketing director alluded to the fact that they are open to partner with SA companies servicing the petrochemical industry (Oil Country Tubular Goods) and await any proposals.

STEASA commends the DTI for including the Algiers Trade Fair to their schedule of pavilions, The Algiers Fair, I believe will grow to be an appropriate forum for South African companies in the market-relevant sectors which have been selected for participation to promote their products and services, as well as to identify possible investment partnerships.

                                                                              www.steasa.com 

STEASA attends Wire & Tube Fair in Germany

On the 16th April 2018 to the 20th April 2018, The Steel Tube Export Association of South Africa as part of the South African pavilion took part in the Wire & Tube fair 2018 in Dusseldorf Germany. The South African pavilion consisted of 5 Tube companies, namely Robor, Delberg Engineering, Barnes Hall Longmore, Honingcraft Moser, Seascape Stainless Steel Services and STEASA as the export council. Over 1300 tube exhibitors were present and visitors surpassed 38 000.

The Wire & Tube Fair 2018 by general consensus from the many patrons that I had the pleasure of interacting with over the week, didn’t disappoint and maintained its prestige as being a renowned trade fair which is dedicated to wire and tube technologies. It brought new ideas, facilitated business deals, transactions and provided an environment for ideas and creative solutions, paving the way for product manufacturers, raw material suppliers, components and equipment manufacturers and technology innovators to gain their foothold in regional as well as international markets. The trends ranged from those that were mega, to small dynamic innovations and the reverberating sentiment was that the Wire & Tube Fair is definitely looking into the future.

STEASA had a resoundingly successful Wire and Tube Fair 2018, with over 200 visitors to our stand and plenty of steel tube and pipe international procurement enquiries after the fair from stockists that we were able to establish solid rapport with, which bodes well for long term relations and export opportunities.

                                                                                          www.steasa.com