Coupling Failures on Steel Mill Tables

The failure

A leading Midwest steel mill plant was constantly replacing tire couplings on runout tables. Needless to say, the amount of time required for maintenance was becoming unmanageable.

The equipment and environment

This particular hot strip mill plant produces a coiled steel rolls commonly used to form large kitchen appliances and automobiles.  Runout tables, containing hundredths of rollers, move steel slabs along the shaping process. Each roller uses a tire coupling that attached to a motor, which turns the roll.

High misalignment and a lower service factor between motor and roll can cause high failure rates on the tire couplings.  In addition, each tire coupling has several component fasteners that require tools to change the element. The design of the tire coupling makes it susceptible to corrosion from the heat, water, and slag associated with a runout table application.

The steel mill plant had a dedicated maintenance team to replace the large quantities of tire couplings every month. The high replacement part cost, increased maintenance time and resources required to maintain the tire couplings was prohibitive.

The solution

After a fact-finding visit to the hot strip mill plant, the Lovejoy Engineering Team analyzed the situation and presented an effective solution.

The team addressed three core runout table failures:

1) Tire coupling slipping

2) Heat, water, and slag damages

3) Inefficient inspection process.

The recommended solution was to replace all tire couplings with the Lovejoy’s Jaw In-Shear 6 Pin (JIS) couplings.  The Jaw In-Shear 6 Pin coupling is made up of a standard L-type jaw coupling, a radially assembled element, and stainless steel locking ring.

With its effective locking mechanism, the JIS coupling eliminated the slipping issue.  The stainless steel locking ring provided the element with protection from heat, water, and slag. Lastly, the ease of simple visual inspection and quick change-out, made the JIS the most effective solution.

In the end, failures were reduced to a minimum.  The dedicated plant maintenance team could now refocus its attention on other critical areas in the mill.  Furthermore, this solution brought in a 33% cost savings per coupling.

Reducing Coupling Downtime in Brazil

Guest Post: Doug Durham (Lovejoy, VP of International Sales)

A large multinational manufacture of household products in Brazil approached one of our distributor partners with an coupling problem. They had an array of roof mounted pumps that were exposed to all the elements of hot summer sun and torrential rain in the winter months.

These extreme climactic swings were causing the metal hubs of the original equipment couplings to rust and corrode making the coupling changes very difficult. To replace the elastomeric elements you would need to move the hubs along the shaft. This was becoming more and more difficult as time went on. 

The Lovejoy solution was to use a Jaw In-Shear style of coupling. This would allow the element to be changed without the hubs being moved. The customer was ecstatic and changed all five over the next two months. Even though the cast iron hubs of the JIS couplings were still exposed to the elements and would rust, the element and the stainless steel ring would not rust or corrode. This allows for easy replacement and limited down time. 

The maintenance manager of the facility has stated that the JIS element change takes less than 30 minutes where the old system was down for at least 24 hours. The end customer has written this up their companies best practices and will consider the JIS style coupling for all the pumps in his facility. 

On a closing note, the life he is getting from the Lovejoy JIS coupling is a minimum of three times what he was experiencing from the original OEM couplings. 

To learn more about Jaw In-Shear, you can:
- Read a blog article: Jaw In-Shear Couplings - A Straight Forward Value Add
- Visit the Lovejoy Jaw In-Shear Product Page
- Download the Lovejoy Jaw In-Shear Product Catalog
- Look up Lovejoy Jaw In-Shear Product Part Numbers

To source a Lovejoy coupling in Brazil, please visit visit Setax or a Setax approved distributor. For other parts of the world, please use Lovejoy's Find a Distributor tool.
 

About the Author: Doug Durham has several decades of power transmission engineering sales expertise. To tap into Doug's rich industry knowledge and experience, please contact him through the Lovejoy webpage and/or find a highly qualified Lovejoy distributor through Lovejoy's Find a Distributor tool.