LOUISVILLE, Ky.-``Look, feel and listen'' may be the best advice to retreaders for avoiding injury due to zipper ruptures in steel-cord radial truck tires. At least that's one suggestion discussed by the industry task force appointed a year ago to look into the causes of such failures.
The 13-member task force, made up of tire manufacturing and retreading industry technical experts, will report its progress and offer these and other safety recommendations during a special forum on zipper ruptures, April 5, in Louisville.
The forum is to take place from 4 to 6 p.m.-one day prior to the American Retreaders' Association's World Tire Conference & Exposition, which runs April 6-8 at the Kentucky Fair & Exposition Center in Louisville.
During the April 5 meeting, attendees will get their first look at a new Rubber Manufacturers Association wall chart suggesting ways to identify zipper-prone tires and safety procedures for mounting, inflating and inspecting them.
While the specifics of the task force's recommendations are yet to be finalized, the group has previously recommended that shop employees take special precautions when inspecting or inflating any all-steel-reinforced light or medium truck radial thought to have been run underinflated-or whose service history is not known.
A preliminary draft of the group's recommendations advises inflating the tire to no more than 20 psi and carefully inspecting it prior to retreading by:
1) Looking for tell-tale sidewall bulges and other signs of internal cord damage that could lead to dangerous sidewall ruptures;
2) Feeling the tire's sidewalls for softness and other surface irregularities indicative of internal cord damage;
3) Listening for popping, crunching and other sounds caused by the shifting or breaking of the tire's radial steel cords.
All three of the above symptoms can warn of a potential sidewall rupture that leaves behind a wound area resembling an open zipper-from which such failures take their name.
These symptoms also might become apparent to tire service workers as they install, air up or deflate such tires. But the tire service worker under such circumstances is at too much risk to undertake a similar close inspection, members of the task force have cautioned.
According to Marvin Bozarth, executive di-rector of the American Retreaders' Association and chairman of the task force, the group's recommendations likely will expand on current generally accepted safety practices for tire inflation and handling-including those of the Occupational Safety and Health Administration (OSHA).
Mr. Bozarth said current safety procedures were developed primarily to protect service workers from flying debris resulting from the explosive separation of tire-wheel assemblies.
However, these safety procedures, which make effective use of tire safety cages to keep workers from being struck by flying debris, may not provide adequate protection from the equally explosive but less predictable blast of air emanating from a zipper-type rupture, he said.
In March, the task force expects to meet with manufacturers of tire safety cages to seek their input on how workers might be better protected against zipper explosions.
Unlike that of a typical tire-wheel separation, Mr. Bozarth explained, the trajectory of the air blast resulting from a zipper rupture is almost impossible to predict and the force of the blast itself is sufficient to maim or kill.
Thus, a worker airing up the tire would be well advised to stay far enough away to escape potential injury.
This can only be accomplished, he points out, by using an extra-long air hose-something not required under existing OSHA regulations. In fact, many OSHA charts presently show the service worker standing dangerously close to the tire during inflation.
Dealers and retreaders at the meeting will view two ARA-produced videotapes showing zipper ruptures taking place inside and outside of various types of safety cages and suggesting ways retreaders and tire service workers might detect prospective zipper ruptures before they occur.
In one scene on the videos, a 30-gallon aluminum trash can-positioned where a service worker typically might be standing-is hurled 150 feet and smashed to pieces by the force of the air blast.
ARA officials say they're hoping to provide attendees with free copies of the videotapes. In addition, the RMA hopes to have ``limited quantities'' of its new wall chart available for distribution at the meeting, a spokeswoman said.
The task force was organized following a similar forum on zipper failures last year. ARA President Michael Berra of Community Tire in St. Louis, who has participated in the group's deliberations, said he's pleased with what it has accomplished thus far.
Mr. Berra said the group has formulated what he termed realistic recommendations that don't require the use of X-ray or other equipment not normally found on a tire service truck.
``Based on what's in use, I think we've got a practical set of recommendations,'' Mr. Berra said. ``And after seeing the video, the (viewer) will have some realization as to why it's important to follow safety procedures.''