St. Johns River Shipyard's welding machine is 15 years old, fully depreciated, and has no salvage value

Question:

St. Johns River Shipyard's welding machine is 15 years old, fully depreciated, and has no . However, even though it is old, it is still functional as originally designed and can be used for quite a while longer. A new welder will cost $182,500 and have an estimated life of 8 years with no . The new welder will be much more efficient, however, and this enhanced efficiency will increase earnings before depreciation from $27,000 to $74,000 per year. The new machine will be depreciated over its 5-year MACRS recovery period, so the applicable depreciation rates are 20.00%, 32.00%, 19.20%, 11.52%, 11.52%, and 5.76%. The applicable corporate tax rate is 40%, and the firm's WACC is 12%. Should the old welder be replaced by the new one?
Salvage Value
Salvage value is the estimated book value of an asset after depreciation is complete, based on what a company expects to receive in exchange for the asset at the end of its useful life. As such, an asset’s estimated salvage value is an important...