Healing, and Welding

Through diffusion, the cracks in a polymer can be healed, and two different parts of a polymer can be rejoined or welded together. In the following, we shall discuss briefly the application of the reptation model for the study of the healing and welding processes. 

Figure 1-18. Instead of replacing the eye-bolls, new studs were welded in place of the threaded portions. They were made brittle by the heal and failed in use. Fortunately the chain prevented the lid from going into orbit.

Hold the steel tube in a vise, heal the end and bend it, Hacksaw a curve for the nose and another for the shoe. Remove the waste, pound the shoe up around the nose and weld the nose and shoe together. Drill two A-in. holes, in alignment with the holes in the standard skid, to attach the new skid to the mill. 

Total interpenetration of chains (X approaches Rg) is not necessary to achieve complete strength when M > M and x < 7). However, a word of caution while complete strength may be obtained in terms of critical fracture measures such as G c and A lc, the durability, measured in sub-critical fracture terms, such as the fatigue crack propagation rate da/AN, may be very far from its fully healed state at r. We have shown that while the weld toughness A lc increases linearly with interdiffusion depth X as K f. X, the fatigue crack propagation behavior of partially healed welds behaves as [1]... 

Stress relieve carbon and chrome steel welds and cold bends in amine service regardless of service temperature. For all concentrations of carbonate solutions and in concentrations of caustic up to 30 percent stress relieve for service temperatures above 140 F (60 C). For 30 to 50 percent caustic, the service temperature where stress relief is required decreased from 140 >F(60°C) to 118T (4B C). Welded tubing does not require heal treatment in addition to that required by the ASTM specifications. Rolled tube-to-tube sheet joints do not require stress relief. 

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