It's all relaed to : Brand manufacturer and price, quality glue used, is not same hand gluing with a Chinese glue compared to a German, French or Italian top quality more expensive PVC glues, spot on temp controll and humidity conditions at assembly line + skilled hand labor.
Premature tube seam failure could be blamed to poor quality glue, excesssive UV radiation standard now a days and overall poor tube inflation, where you need to have rigid tubes as opposed to marshmellow tube inflation, which stresses the seams & transom along. Anyway what have become unsoldered must be restored hand glued, unless you count with a welding machine at home, what a tech incongruency...
Due to GW issues, you should replace your PVC sibs if heavily used and abussed all year round at max 3 years use, will avoid mayor ungluing issues and a much better resale price, put the diffeerence and buy a new sib. Like you do with your cars....
Happy Boating
