The most widespread application of polymers in structural applications is their use as pipe material for e.g., gas distribution systems. Pipes have a design lifetime of typically 50 years, which rules out real-time lifetime assessment methods. Here, an engineering approach is presented, which makes it possible to predict long-term ductile failure of loaded glassy polymers based on short-term tests. The approach is based upon the hypothesis that failure is governed by accumulation of plastic deformation up to a critical strain. A pressure-modified Eyring relation is employed to calculate the accumulation of plastic strain for any simple loading geometry. It is demonstrated that the approach can produce accurate quantitative time-to-failure predictions for loaded PC specimens and uPVC pipe segments.