I have frozen water pipes and a lot of heat going on them but nothing is working can I use a welder?

ok I have had frozen water for the last 7 days we have been working on defrosting the pipes non stop we have 3 electric heaters going one turbo heater plus heat tape and we have water coming from the ground pipe in to the hot water heater but we can not get any water past that any Sugestions I am desperate for help some one has told me about using a welder to send a current through the pipes is that safe? can it be done?