This study examines the types of hydrogen leaks that can support combustion and the effects on stainless steel of long term hydrogen flame exposure. Experimental and analytical work is presented. Hydrogen diffusion flames burning on round burners were observed. Measurements included limits of quenching, blowoff, and piloted ignition for burners with diameters of 0.36 - 1.78 mm. Results are compared to measurements for methane and propane. A dimensionless crack parameter was identified to correlate the quenching limit measurements. Flow rates of 0.019 - 40 mg/s for hydrogen, 0.12 - 64 mg/s for methane, and 0.03 - 220 mg/s for propane were studied. Limits of spontaneous ignition are identified using an analytical model.