A thermal spray apparatus to apply coatings to external and internal surfaces in restricted areas is provided. The apparatus includes: a fuel input line; an oxidizing gas input line; coolant input and outlet; a combustion chamber that facilitates primary combustion; a diverging section that splits the primary combustion flow into two or more streams; an elbow section that redirects the combustion streams; a convergent/divergent nozzle; a convergence section that recombines the combustion streams into a single combustion stream within an injection zone of the convergent/divergent nozzle; and a feedstock injector for the injection of feedstock material for forming said coatings into said injection zone of the convergent/divergent nozzle; wherein the convergent/divergent nozzle has a nozzle throat downstream of the injection zone whereby in operation the injection pressure of the feedstock material upstream of the nozzle throat approximates the pressure of the combustion stream within the injection zone. The apparatus may also include the use of an accelerating gas.