Recommended Use Galapagos or ductile iron bypass collars, are used to install household connections, in PVC or STEEL pipes, are used in water pipes and other fluids. They are composed of two pieces of ductile iron ASTM A – 536, with zinc-sealed tortilleria, hot-dip galvanized or stainless steel and elastomeric packaging, which guarantees a long service life, its derivation is an NPT thread.