Jun 17, 2011
Hot dip galvanising of fasteners to be reviewedBack
Construction|Engineering|Cleaning|Education|Eskom|Petrochemicals|Power|PROJECT|Projects|Sasol|Africa|Mining|Petrochemicals|Power Generation|Steel|Bob Wilmot|Infrastructure|Power|Corrosion Protection
© Reuse this
The current standard practice when hot dip galvanising grades 4.8 and 8.8 fasteners is to apply South African National Standard 121, or SANS 121 (ISO 1461: 2009), specifications and test methods.
SANS 10094 Annex B Edition 4.1 represents the current specification for hot dip galvanising of high-strength components greater than 1 000 MPa, such as grade 10.9 friction grip fasteners.
During 2010, the South African Bureau of Standards (SABS) circulated a Draft South African Standard that will adopt ISO 14399 as a replacement standard for fasteners.
SANS 14399 consists of ten parts for high-strength structural bolt and nut assemblies. The specifications are highly detailed and include greater controls and test procedures.
The effect of the proposed specifications on the hot dip galvanising of high-tensile fasteners, greater than 1 000 MPa, will be the replacement of SANS 10094 with SANS/ISO 10684 titled ‘Fasteners – Hot dip galvanised coatings’.
The current hot dip galvanising cleaning practice involves the pickling of high-strength fasteners in hydrochloric acid. This practice has the remote possibility of causing hydrogen embrittlement of the components.
ISO 10684 allows for both limited acid pickling as well as mechanical cleaning. However, Wilmot says local modifications are being planned to eliminate acid pickling and only allow mechanical cleaning. Implementation of this cleaning process will ensure the total elimination of the potential for hydrogen embrittlement.
Although the standard is still under discussion, Wilmot is confident that the SABS is committed to approving the new specifications, owing to the bureau’s tendency to lean towards adopting ISO specifications and implementing these without modification.
He feels this could have a positive impact on the industry, as it would ensure better quality control, give fastener manufacturers increased responsibility at all levels and extend fastener application.
“Manufacturers will have greater input throughout the entire production process, from checking the quality of the input material to ensuring that galvanising is done according to specification,” Wilmot adds.
Meanwhile, Wilmot tells Engineering News, State-owned power utility Eskom’s build programme to expand its power generation capacity is driving local enquiries about galvanising procedures.
“These are major projects that require not only enormous numbers of fasteners, but also fasteners that have a long life and low life- cycle cost,” he explains.
Following a peak in 2007/8, the industry’s growth fell by between 8% and 10% owing to the economic downturn, after which it stabilised. But growth resumed in the 2009/10 financial year.
“During the last financial year we recorded 4% growth and we are going to conservatively project a further 3% to 4% improvement over the next financial year,” he notes.
However, the total growth of the industry depends on the number of major projects that are on offer.
“Some of our members have been busy with Eskom’s build programme and its associated infrastructure, such as the development of the Grootegeluk colliery. Further, the demand for galvanised fasteners in the mining industry has been fairly static; however, we hope to see growth in the platinum industry that will translate to an increase in demand for fasteners.
“Many platinum projects were put on hold but we believe that the economy has now reached a point where these projects will be resumed. This represents significant growth,” says Wilmot.
Continued growth in the coal-mining industry, not only associated with Eskom, but also with exports and petrochemicals company Sasol, augurs well for future growth.
“The export of commodities, such as coal, platinum and iron-ore, has increased. This has spin-off benefits for the galvanised fastener industry,” he adds.
Wilmot says it is important for engineers and their clients to distinguish and understand the difference between hot dip galvanised and zinc electroplated fasteners.
“Hot dip galvanised fasteners should be referred to as such and not simply as galvanised fasteners, as this could be, and is, confused with zinc electroplated components.
“From a corrosion protection point of view, hot dip galvanised fasteners have much better durability and service life, as the process produces a thicker coating,” he adds.
Hot dip galvanising coating thicknesses normally range between 60 µm and 70 µm, whereas zinc electroplating thicknesses are between 6 µm and 10 µm.
“It sometimes appears that fasteners, which are in reality a highly technically important piece of equipment, do not receive the attention they deserve. Damage or shortages in supplies tend to be caused by end-users visiting the nearest hardware shop to purchase readily available fasteners, which, in most cases, consist of zinc electroplated fasteners,” he says.
“In general, what we advocate is for engineers to consider the life cycle costing for construction materials, including the appropriate corrosion control specification of fasteners, when projects are designed,” Wilmot adds.
Further, incorrect application owing to a lack of skills and training of construction personnel is another challenge with costly consequences.
“Installation of fasteners must be done correctly to ensure maximum product life and efficiency. Site assembly crews that are responsible for installation of structural steel must be educated to appreciate the importance of specified fastener assembly procedures. It often appears that end-users tend to treat fasteners as unsophisticated equipment; however, quite the opposite is true,” he explains.
“We believe that, through proper education and creating an understanding of hot dip galvanised products, end-users will appreciate and apply such components on appropriate projects.
Associated with this is motivating our hot dip galvanising members to produce high-quality products,” he concludes.
Edited by: Chanel de Bruyn© Reuse this Comment Guidelines
Other Corrosion and Tribology News
Steel products manufacturer Andrew Mentis reports that it attributes its success in the provision of flooring and handrailing solutions to its approach of prioritising consumer feedback and researching the best methods of incorporating consumers’ input into its...
Construction and installation of cathodic protection and amalgamated corrosion mitigation systems, Germiston-based Amalgamated Corrosion Engineering (ACE), recently welcomed investment group of companies Reindus Holdings as a new controlling shareholder, as part of...
Updated 15 minutes ago Corobrik has secured the Diamond Arrow Award for the fourth consecutive year after survey respondents in the construction industry rated the brick supplier ahead of the pack. Last week, PMR.africa presented the award to Corobrik after the supplier achieved the...
Updated 17 minutes ago South African producer price inflation (PPI) again surpassed expectations in March, registering growth of 8.2% year-on-year from the 7.7% recorded in February, climbing to its highest level since February 2012 on the back of rising domestic price pressures, BNP...
Recent Research Reports
Steel 2014: A review of South Africa's steel sector (PDF Report)
Creamer Media’s Steel 2014 report provides an overview of the global steel industry and particularly of South Africa’s steel sector over the past year, including details of production and consumption, as well as the country's primary carbon steel and stainless...
Projects in Progress 2014 - First Edition (PDF Report)
This publication contains insight into progress at the delayed Medupi and Kusile coal-fired projects, in Mpumalanga and Limpopo respectively, as well as at the Ingula pumped-storage scheme, which is under construction on the border between the Free State and...
Automotive 2014: A review of South Africa's automotive sector (PDF Report)
The report provides insight into the business environment, the key participants in the sector, local construction demand, geographic diversification, competition within the sector, corporate activity, skills, safety, environmental considerations and the challenges...
Construction 2014: A review of South Africa's construction sector (PDF Report)
Construction data released during 2013 hints at a halt to the decline in the industry during the last few years, with some commentators averring that the industry could be poised for recovery. However, others have urged caution, noting that the prospects for a...
Electricity 2014: A Review of South Africa's Electricity Sector (PDF Report)
This report provides an overview of the state of electricity generation and transmission in South Africa and examines electricity planning, investment in generation capacity, electricity tariffs, the role of independent power producers and demand-focused initiatives,...
Defence 2013: A review of South Africa's defence industry (PDF Report)
Creamer Media’s 2013 Defence Report examines South Africa’s defence industry, with particular focus on the key players in the sector, the innovations that have come out of the defence sector, local and export demand, South Africa’s controversial...
This Week's Magazine
The Electronic Systems Laboratory (ESL) of the Department of Electrical and Electronic Engineering at Stellenbosch University is strongly reaffirming its position as one of South Africa’s leading centres for satellite technology and expertise. It is currently...
The world’s lowest-cost diesel-electric locomotive is not made in China, but in Pretoria, at RRL Grindrod Locomotives’ newly upgraded 30 000 m2 plant. The company’s locomotive pricing is “more competitive than any other original-equipment manufacturer (OEM)...
The South African Defence Review 2012, released to the public at the end of last month (despite the year given in its title) recommends the creation of the post of Chief Defence Scientist. This official would be responsible for the management of defence technology...
AltX-listed engineering technology company Ansys has been awarded an R188-million contract by Transnet to supply integrated dashboard display systems to the freight rail utility’s locomotives. Black-owned and controlled Ansys developed the bespoke integrated system...
South Africa’s sole nuclear power station Koeberg, which is located in the Western Cape, breached a major operations milestone on April 4, which marked the thirtieth anniversary of Unit 1 having been connected to the grid. Eskom, which operates the two-unit plant,...