There are a lot of operational issues, one of them is the tube skin temperature. This temperature can be monitored by the color of the tube or with other devices like optical pyrometers, etc. Try to no be above the maximum tube metal of the tube because it will damage the tube permanently.
Other issue is to keep a proper air/fuel ratio by mean of the excess air. So be carefull about the fuel content in the flue gases. Natural or forced draft?
You can start the procedure by increasing the heat inside the firebox using only the pilot burners, then if more temperature is needed a main burner can be lighted.
There are typical procedures.
Regards,
Alfredo Velasco
