MAXIMUM WORKING LOAD (M.W.L.)
Maximum Working Load (M.W.L.) is the maximum static and/or dynamic load at which the product will still function without excessive friction, distortion, wear or permanent deformation of components. Above this load, bearing systems may fail, moving parts may seize and stainless steel or plastic components may begin to bend, stretch or otherwise deform. Maximum working loads should never exceed half of the breaking load and should never be exceeded in use.
BREAKING LOAD (B.L.)
Breaking Load (B.L.) is the load at, or around which, a major failure can be expected to occur to some part of the product's structure when new. Plastic components may split, rivets may give way, shackles may break, and other metallic components may fracture. Stated values for Breaking Load refer to a test load situation representative of a product’s typical use and applications. Load situation and circumstances of actual use may vary, affecting the load at which a major failure may occur. No product should be used at more than half of the stated Breaking Load, so as to provide a minimum safety factor of two (2).
FACTOR OF SAFETY
An appropriate factor of safety should be applied to Breaking Load figures to suit each application before choosing or specifying a particular product. For many industrial and safety related applications, and for some yachting applications, a factor of safety greater than two (2) should be used or may be required by law or other regulations. It is the customer’s responsibility to ensure that an appropriate factor of safety is used, and it should allow for factors including but not limited to safety implications, service life, fatigue (as may be caused by wave action, wind stresses or repetitive cyclical loading), type of load (e.g. cyclic, shock, rotational speed), orientation of load, environment (e.g. exposure to ultraviolet light, corrosion and stress corrosion). Note that a ‘safe working load’ is not specified as this is dependent on the factor of safety, which must be determined by the user relative to each application.
The useful life of any product is determined by the above factors and must be assessed in each application, and thus no guarantee can be provided for product life, load capacity or any other factor due to the variability in usage. In some jurisdictions government regulations require the replacement of rigging components within certain periods of time, usually every three to five years. You must ascertain whether any such regulations affect you. While every precaution is taken in the product design and manufacturing processes to minimise the effects of corrosion and stress corrosion, there are also preventative as well as corrective treatments that can be carried out after installation. Contact your local representative for further assistance and advice.
STAINLESS STEEL CONSIDERATIONS
Stainless steel generally has good natural corrosion resistance in common uses but can still suffer degradation and discoloration if subject to certain environmental, physical conditions or lack of suitable maintenance schedule and servicing. In general, clean and smooth surfaces are preferred to rough finishes to encourage a protective oxide layer to be maintained and enable stainless steel to remain bright. Specifying the cleaning & maintenance of stainless steel surfaces by regular washing to avoid staining and dirt marks is highly recommended, especially when used in more severe environments. Natural rain can often be sufficient to remove basic contaminants but more frequent scheduled cleaning may be required when products are used in inner urban and more aggressive environments. Technical advice on appropriate cleaning techniques for specific situations is available from specialist cleaning firms. Stainless steel representative associations are another good contact to consult for the most up to date advice. Information on material grades, selection, specification, end usage and other topics is also available from these organizations.
Stainless Steel Specialist Websites of Interest:
- Australian Stainless Steel Development Association
- Specialty Steel Industry of North America
- British Stainless Steel Association
CARE & USE OF THREADED PRODUCTS
Ronstan produces and supplies many threaded items. All are made to the relevant thread standard and gauging processes.
Stainless steel is a material which when used in male / female threaded elements and loaded with an applied torque can “Gall” or “cold weld”. This occurs when the stainless steel oxide surface film breaks down as a result of direct metal to metal contact. Solid-phase welding takes place (whereby material is transferred from one surface to another via contact pick-up). The symptoms of galling include thread surface damage and permanent seizure of the thread. Galling can be minimized with the use of dissimilar metals. Other Ronstan products uses brass alloys on turnbuckle ranges and use of brass nuts for the load carrying nuts as used in cable systems. If using stainless steel male / female threaded systems, use of high pressure lubrication compound is required to help reduce the possibility of thread seizure. Care using these lubricated products is required to ensure threads stay clean during installation / service. Suitable clean up of lubricants after installation is required to avoid staining and grime build up.
Protection of threads during transport & in preparation for installation must be done to avoid any thread damage. Keeping threads wrapped until final installation is recommended. Threads must be clean of burrs, dirt, coarse grime or sand to help reduce the possibility of thread seizure and ensure the correct functionality of the product. Use of a secondary tensioning system for pre-stressing tension members on-site may be required to achieve the desired tension forces and avoid thread or product damage.
CLEANING AND MAINTENANCE OF STAINLESS STEEL
Ronstan recommends regular inspection of stainless steel products to ensure they remain free of contaminants that may cause discolouration or staining.
Depending on the type of finish on the material, site conditions, concentration of airborne contaminants and exposure to rain stainless steel may exhibit discolouration. Cleaning with a mild detergent, warm water and a soft cloth may assist with removal of discolouration.
In cases of severe build-up of grime, a domestic grade nylon or synthetic scouring pad can be used in conjunction with warm soapy water to clean stainless steel components, however abrasive pads should not be used on chrome or nickel plated components.
Under no circumstances should steel pads of any description be used in the cleaning process, Stainless steel can be contaminated by pick-up of carbon steel residue from these steel pads and this will cause corrosion.
PRODUCT INFORMATION AMENDMENTS
All catalogue information is subject to specification changes during a product’s life-cycle. Any alterations will be posted on the website - www.ronstan.com, which should be considered the most up to date source of product information.