106 To use piping materials (PVC Pipe & Fittings) safety Solvent Cracking (SC) Measure SC (Solvent Cracking) is a type of stress cracking and specifically distinguished from the cracking phenomenon that occurs when solvent gives an impact inside PVC pipe. SC is caused by the existence of solvent (adhesive, preservative, etc.) It tends to occur more easily due to stress (heat stress, stress of TS connection part, bending, other external stress) and installation during low-temperature like in Winter (solvent tends to remain). When piping, implement a SC measure as explained as follows. Item Measure Adhesive Usage Apply adhesive compatible to the type of pipe thinly and evenly. Do not apply adhesive extending out from the insertion length on the pipe outer face. In particular, apply thinly and evenly to the inner face of fitting. The reference ratio of adhesive application is 7 to 3 for pipe and fitting. Wiping of Adhesive After bonding, make sure to wipe off the protruded adhesive with a cloth after inserting. During application, remove the adhesive spilled on the groove floor. Opening of pipe on both ends Fully open valve, air valve, blind flange, etc. for better ventilation and remove the solvent stream. Do not enclose them. Utilization of Prefab Method Prefabricate 2 to 4 pipes in advance, remove the solvent steam by natural ventilation and then connect the pipes. Ventilation inside Piping During curing after piping, open both ends of pipe without enclosing and remove the solvent steam. Do not enclose them. During curing, the steam can be removed more effectively by ventilating inside piping using a ventilator (low-pressure specification). Washing inside Piping During curing after piping, open both ends of pipe without enclosing and remove the solvent steam. It is more effective if you fill water all the way and wash after the adhesive is hardened (do not apply the water pressure at this time). Immediately perform this after leaving 30 minutes for the size of 50 mm or less and approximately 1 hour for the size of 65 mm or more. Expansion Measure Implement an expansion/contraction treatment to prevent the heat stress from rising due to temperature differences. Support When fixing piping, try to avoid using U-bolts as much as possible and use fixation bands with a wider width. In the case of using U-bolts, provide a cushion such as rubber to prevent piping from touching U-bolts. Be fully cautious not to tighten the fixation bands and U-bolts too much. Boom! Gas Left as bonded together No enclosing Blower Curing Tape Protection Cap Gas A接d着he剤sのive使 U用sa量ge Do not apply adhesive extending out from the gauge line. Apply thinly and evenly to the inner face of TS fitting gasket. R溶e剤mo成va分l oのf 除So去lve ＆nt 管anのd 両Op端en開in放g of Pipe on Both Ends Ventilation Washing with water Opening of pipe on both ends Sサuポppーoトrt E伸x縮pa対ns策ion Measure W接i着pi剤ngの o拭f Aきd取heりsive Provide expansion/contraction treatment to lower the heat stress. Wipe off the protruded adhesive with a cloth after inserting. Be cautious not to tighten saddle bands, U-bolts and U-bands too much.