Never use tools to tighten fittings into the acrylic ports. Gaskets should do the sealing work, not thread pressure. Use Soft Gaskets/Risers:
Hot cracking occurs at elevated temperatures when a material is in a "mushy" state—partially liquid and partially solid—during solidification. This phenomenon is especially common in high-stress areas like the fillet (FLT) of a weld. flt cracks hot