A process for manufacturing welded titanium alloy tubes and pipes having good corrosion resistance and good mechanical properties from a titanium alloy which consists essentially, by weight, of one or more of the platinum group metals in a total amount of 0.01-0.14%, at least one of Ni and Co each in an amount of 0.1%-2.0%, not more than 0.35% of oxygen, not more than 0.30% of iron, optionally at least one of Mo, W, and V each in an amount of 0.1%-2.0%, and a balance of Ti. The process comprises preparing a slab by hot working from an ingot of the titanium alloy after heating in a temperature range of from 750.degree. C. to a temperature 200.degree. C. above the beta-transus point, hot-rolling the slab with a finishing temperature of not lower than 400.degree. C. to form a hot-rolled strip after heating in a temperature range of from 650.degree. C. to a temperature 150.degree. C. above the beta-transus point, optionally performing annealing in a temperature range of from 550.degree. C. to a temperature 20.degree. C. above the beta-transus point, and/or cold-rolling followed by such annealing, forming and welding the strip to form a tube or pipe, and optionally heat-treating the welded tube or pipe in a temperature range of from 400.degree. C. to a temperature 20.degree. C. above the beta-transus point.