Aug 10, 2012
Liquid gaskets said to outperform traditional materialsBack
Africa|Castings|Components|gasket|Henkel|Henkel South Africa|Industrial|Loctite|Paper|Petroleum|Screen|Systems|Technology|Water|Africa|Adhesives Supplier|Chemicals|Manufacturing|Metal|Metal Surfaces|Metal-to-metal Contact|Product|Products|Rubber|Sealed Steel Casing|Silicone Products|Steel|Systems|Anaerobic Technology
Speciality chemicals and adhesives supplier Henkel South Africa, which is also the manufacturer of the Loctite brand of sealants, maintains that liquid gaskets produce seals that create better results than traditional materials.
To ensure the integrity of a seal between two bolted flanges, it is necessary to have some form of gasket between the mating surfaces that will remain intact and leak-free in often extreme and varying conditions over a prolonged time.
In a test where a sealed steel casing was subjected to torsional stresses, a number of significant differences between various sealing methods were noted, reports Henkel.
In particular, conventional solid gaskets showed leaks after 150 000 cycles, whereas seals made with an anaerobic product con- tinued to show reliability beyond 250 000 cycles.
Further, in the conventional gasket, the tension of the bolt dropped by 25% within just a few thousand cycles.
There are three typical types of gaskets: conventional precut compression gaskets, formed-in-place (FIP) liquid gaskets and cured-in-place (CIP) gaskets.
Although a well-used and traditional method of sealing joints, these gaskets do present some significant and practical disadvantages, says Henkel.
For example, conventional gaskets require an initial compressive load to deform it into the irregularities of the mating surfaces, which, over time, is a major cause of gasket failure.
This occurs when the gasket loses its elastic properties and becomes less resilient. The load on the gasket and relative motion causes a general decrease in the gasket thickness, resulting in a bolt clamp load loss that can cause it to leak.
FIP Liquid Gaskets
Two types of sealants are available for FIP gasketing jobs: anaerobics for rigid joints, such as Loctite 510 and Loctite 518; and special silicone products for applications requiring a flexible seal, such as Loctite 5699.
Further, no retightening of the bolts is required and no allowance is needed for gasket thickness, reports Henkel.
Meanwhile, anaerobic sealants provide high shear strength that stops movement to eliminate bolt loosening and fretting and to increase the assembly’s structural strength.
Anaerobic sealants also allow relaxation of surface finish and flatness tolerances that enable scratches and scored surfaces to be sealed without rectification.
Anaerobic gasket materials only cure in the absence of air when trapped between metal surfaces. This enables it to offer extensive on-part life when exposed to the atmosphere, making multiple application methods possible and reducing the problems associated with the use of volatile or moisture-cured materials on production lines, notes Henkel.
Further, the anaerobic technology enables excess material to be wiped from exterior surfaces or flushed away from interior faces maintaining free, unblocked internal passages and channels.
An advantage of cured anaerobic gaskets is its resistance to petroleum-based fuels, lubricating oils, water-glycol mixtures and most other industrial chemicals.U
nlike precut compression gaskets that are difficult to automatically position on the parts, anaerobic gaskets can be automatically dispensed by robotic dispensers, screen printing or stencil printing systems.
Further, anaerobic gasket products reduce inventory costs, as one container of an anaerobic can be used for flanges of varying sizes and shapes. Precut gaskets can only be used on specific flanges.
They are applied as a fluid in precise beads to one of the surfaces and are cured before use, either by ultraviolet light, heat cure, two-part mix or moisture curing.
Once the bead is cured, an elastomeric material is formed that adheres to the surface. Sealing is achieved through compression of the cured gasket during assembly of the parts.
The advantages of these gaskets include automatic application, serviceability, labour savings, improved quality, reduced inventory and flexible manufacturing.
Meanwhile, Henkel states that flanges, such as pressed steel parts and thin castings with widely spaced bolts, can be considered as flexible, have inconsistent clamp pressure and may move under pressure or dynamic loading.
Sealant manufacturers offer special silicones, formulated to meet all of the requirements of a gasket for flexible joints. Such products provide high elongation to compensate for any micromovement, as well as long-term adhesion to most substrates.
It is important to consider the nature of the surfaces involved in a gasketed assembly.
For example, the original substrate used for the component may be metal – but for operational reasons the part has been painted. It is not a metal-to-metal contact that needs to be sealed but rather a metal-to-paint or paint-to-paint configuration.
In those circumstances, an anaerobic that relies on a metal surface in the absence of air to initiate the cure is inappropriate. However, a silicone – even if a rigid joint is involved – is the correct choice.
Edited by: Chanel de Bruyn
Creamer Media Senior Deputy Editor Online
To subscribe email firstname.lastname@example.org or click here
To advertise email email@example.com or click here
Other Seals, Gaskets and Sealing Mechanisms News
Ready-mix concrete supplier a.b.e. Construction Chemicals’ durajoint flexband joint bandage system offers a solution for waterproofing expansion and construction joints, including critical joint areas with high or frequent movement, says the company’s concrete repair...
International packaging and paper group Mondi is replacing the quench-to-drain flushing and lubricating systems of the mechanical seals at its Richards Bay mill with a continuous loop water management design supplied by mechanical seals and support system company...
Updated 3 hours ago The Department of Human Settlements (DHS) has approved 101 “catalytic” public–private partnership (PPP) projects, valued at around R340-billion – more than half of which would be sourced from the private sector – that would mobilise and coordinate private-sector...
Updated 3 hours ago By 2050, agricultural productivity in Africa has the potential to increase by 70%, through technological innovation leveraged by the Internet of Things (IoT). This would meet the continent’s growing food demand which, based on population growth, is set to grow by...
Updated 3 hours ago Branded food, home and personal care products manufacturer Tiger Brands expects to report earnings per share (EPS) of between R10.23 and R10.65 for the six months ended March 31, a 23% to 28% improvement on the EPS of 832c reported for the six months to March 2015....
Recent Research Reports
Automotive 2016: A review of South Africa's automotive sector (PDF Report)
Creamer Media’s Automotive 2016 Report provides an overview of South Africa’s automotive industry over the past 12 months. The report provides insight into local demand and production, vehicle imports and exports, investment and competitiveness in the sector, as well...
Energy Roundup – April 2016 (PDF Report)
The April 2016 roundup covers activities across South Africa for March 2016 and includes details of a North Gauteng High Court Judge’s dismissal of a court application to postpone the 9.4% electricity tariff increase, which the National Energy Regulator of South...
Electricity 2016: A review of South Africa's electricity sector (PDF Report)
Creamer Media’s Electricity 2016 report provides an overview of South Africa’s electricity sector, focusing on State-owned power utility Eskom and independent power producers, electricity planning, transmission, distribution and the theft thereof, besides other issues.
Energy Roundup – March 2016 (PDF Report)
The March 2016 roundup covers activities across South Africa for February 2016 and includes details of the Department of Energy’s plans to announce the preferred bidders for the first tranche of the coal independent power producer procurement programme; the Council...
Steel 2016: A review of South Africa's steel sector (PDF Report)
Creamer Media’s Steel 2016 Report examines South Africa’s steel industry over the past 12 months. The report provides insight into the global steel market and and particularly into South South Africa’s steel sector, including production and consumption, main...
Construction 2016: A review of South Africa's construction industry (PDF Report)
Creamer Media’s Construction 2016 Report examines South Africa’s construction industry over the past 12 months. The report provides insight into the business environment; key participants; local demand; geographic diversification; corporate activity; black economic...
This Week's Magazine
The two spent-fuel pools at Eskom’s 1 800 MW Koeberg nuclear power station, in the Western Cape, will be full by 2018, increasing the urgency on the State-owned utility to begin pursuing alternative storage options. Koeberg has, over the past 32 years, accumulated a...
South Africa lacks the skills necessary to implement the government’s plan to build 9.6 GWe of new nuclear energy capacity, warns nuclear-qualified Quality Strategies International CEO David Crawford. “Apart from the concern about the affordability of the programme,...
Cybersecurity multinational Check Point has released its latest 700-series cybersecurity systems for small businesses, which draw on its international threat intelligence to provide up-to-date cybersecurity, says Check Point South Africa country manager Doros...
Daimler Trucks and Buses Southern Africa (DTBSA) saw a marked slip in new-vehicle sales in 2015 compared with 2014, with sales dropping from 5 897 units to 5 300 units. The decline came as the South African new truck and bus market declined from 31 558 units in 2014...
Group of 20 (G-20) economies threatened to penalise havens that don’t share information on their banking clients after the leak of the Panama Papers provoked a global uproar over tax evasion. The G-20 will consider “defensive measures” against financial centers and...