A tyre plant is a press hall with a vulcaniser problem
Tyre retreading takes a worn casing, applies new tread rubber, and cures it under heat and pressure. The curing is the defining operation: it needs presses, it needs heat, and it needs time.
Presses are heavy and they are anchored
A vulcanising press is a substantial machine with a rigid frame and a large clamping force. The force is contained within the press, but the mass and the vibration reach the floor.
The floor therefore needs to be designed for the press footprints and anchorages rather than for a general industrial load. Where presses are added over time, as they usually are in retreading, the slab should be designed for a future press as well as the first one.
Heat comes from the presses and from the boiler
Curing is done with steam or electric heat. Steam means a boiler, and a boiler means a separate room with its own fire separation and its own ventilation.
Putting the boiler in a corner of the press hall is common and it is a mistake: the press hall then inherits the boiler's fire load and its heat, and the boiler loses the separation it should have had.
Rubber dust is fine, black and persistent
Buffing and skiving produce fine rubber dust. It is black, it is light, and it settles on every surface in the building including the roof structure.
It is also combustible. The combination of a fine combustible dust, a heat source and a building full of rubber stock is the reason retread plants burn: the hazard is not the press, it is the accumulation.
From the building's point of view, the responses are cleanable surfaces, extraction at the machines, and relief venting where a dust assessment calls for it.
The stock is the fire load
Casings waiting for process and finished tyres waiting for dispatch are both large volumes of rubber. Stored vertically on racks they occupy a lot of height and a lot of floor, and they burn intensely.
Separating the stock from the press hall with a wall, or putting it in a separate structure, is the same argument as in any other plant that stores its own fuel. The cost of the wall is small against the exposure.
What I want before drawings
- The press schedule with masses, footprints and anchorage requirements.
- Whether curing is by steam or electricity, and where the heat source sits.
- The buffing and skiving locations and the dust extraction concept.
- The casing and finished-tyre storage volumes and whether they are separated.
- Whether the plant expects to add presses later.
- The wind speed for the site in km/h from the applicable local code, not a round number.
Retread plants grow by adding machines, which means the building should be designed for the plant it will become rather than the plant it starts as. A clear bay and a heavier slab are cheaper at the start than at any later point.
Written by Johnny Joe, who advises owners and project managers in Africa and South America on steel buildings. If this decision is live on a project, send the layout and the constraint that worries you and I will tell you what it changes.
Related: a process with its own boiler · crane rails in a production hall · fine dust that settles everywhere · separating a fire load
