Access and scaffolding
Scaffold is treated as a line item to be minimised. On blasting and coating work it is the thing that decides whether the job runs to programme or bleeds days in adaptations. Here is what a scaffold designed around the work looks like.
Viram Mariv Ltd · Tema, Ghana · 7 min read
On most industrial coating projects, scaffold gets priced as a separate package, awarded to whoever is cheapest, and erected before the blasting crew arrives. Then the blasting crew arrives and discovers the platforms are too close to the steel to hold a nozzle at the right standoff, there is nothing to fix containment sheeting to, and the top lift stops a metre short of the structure.
What follows is a week of adaptations that nobody priced, on a programme that had no slack in it.
It is not just somewhere to stand. On blasting and coating work the scaffold has five jobs, and a scaffold designed for general access usually only does the first.
Blasting is efficient at a particular standoff and angle. Too close and the operator cannot work the nozzle properly and the pattern is too tight. Too far and the abrasive has lost velocity and the cut is slow.
Lift heights and platform offsets should be set so a nozzle can be held correctly across the whole face without the operator leaning out or crouching. That is a design input, and it is the one most often ignored.
If the work is being sheeted — and dry blasting near anything sensitive will be — the scaffold has to carry attachment points for the sheeting, designed in during erection rather than improvised afterwards.
It also has to carry the wind load that sheeting creates. A wrapped scaffold is a sail. In coastal Ghana that is a real structural input, not a formality, and it means more ties and more bracing than the same scaffold would need unsheeted.
Most serious scaffold failures are not about the material. They are about loading, foundation, ties and inspection — and sheeting quietly changes the loading after the design was done.
Film thickness readings have to be taken across the full coated surface. If platforms are positioned so that a third of the structure cannot be reached with a gauge, either the scaffold stays up longer than planned or the readings do not get taken.
Both outcomes cost money. The second one costs it later.
Dry blasting generates a large volume of spent abrasive that has to come down. Collection points and routes should be planned into the design, otherwise crews end up carrying bagged debris down ladders — slow, and a dropped-object risk on a live site.
Scaffold gets struck the moment the spray gun stops, and then a defect is found, or the final coat needs a touch-up, or the inspector wants readings that were never taken. Re-erecting scaffold for a half-day of remedial work is one of the most avoidable costs on these projects.
Erection and dismantling should be phased with the coating programme, with the strike held until the final coat has cured and been accepted.
Ringlock system scaffold is fast to erect, dimensionally consistent and strong. It is the default for repeatable industrial access and for anything that will be sheeted, because the geometry is predictable enough to design containment around.
Tube and coupler comes into its own where the structure is irregular and the scaffold has to be built to fit — around vessels, pipe runs and existing plant. Slower to erect, but it will go where system scaffold will not.
Birdcage and deck-out gives a full working platform across an area rather than a face. Under roofs, inside tanks, across ceilings — anywhere the whole surface needs access at once.
Suspended and hanging scaffold is for structures that cannot be founded from below: jetty soffits, tank roofs, bridge undersides. Design-critical, and never a standard configuration.
The tag at the access point matters more than people think. It is the only thing telling an operator at seven in the morning whether the scaffold he is about to climb has been inspected since the storm two nights ago.
Where the blasting contractor also erects the scaffold, several things stop being anyone's problem to argue about:
That is not an argument against specialist scaffolding firms, plenty of which are excellent. It is an argument against pricing access as an unrelated package and hoping the two designs meet in the middle.
It depends on design, height and site access. Straightforward ringlock on prepared ground goes up quickly. Tube and coupler fitted around irregular plant takes considerably longer. It should be programmed with the quotation, not estimated on the day.
For standard configurations within recognised duty classes, a standard design applies. For anything unusual — heavy loading, suspended scaffold, large sheeted areas, long spans — a specific design should be prepared and issued before erection.
The provider inspects before handover, at least every seven days, and after alterations or severe weather, with records kept. If the site requires its own inspector to countersign, that gets arranged at handover.
Yes, under the site's permit-to-work system. Tie points, exclusion zones and dropped-object control need agreeing with the plant team before erection begins, particularly where ties land on coated steel or live equipment.
Yes, if you have your own competent scaffolders. Material can be supplied on hire by the week or the project, inspected before it leaves and on return.
Viram Mariv erects and hires scaffold across Ghana from our base in Tema — ringlock and tube-and-coupler, with or without crews. Most of it supports our own blasting and coating work, which is why access gets designed around the job rather than bolted on. Send us the structure details and the duration.
Written by the Viram Mariv team. We are an industrial surface preparation and protective coating contractor based in Tema, Ghana, working across West Africa.