This also safeguards the pipes against rust and corrosion, extending their lifespan and reducing maintenance requirements This also safeguards the pipes against rust and corrosion, extending their lifespan and reducing maintenance requirementsfiberglass pipe insulation fittings.molded frp gratings are manufactured in a one piece construction which results in a bi-directionally strong product. This allows openings for piping or cables in the grating of up to 10” without any additional support required (may vary depending on grating depth and location of opening). During the molded manufacturing process, the continuous fiberglass rovings are completely covered in a high percentage of resin, 65% by volume. With this high resin content, molded gratings are the most chemically resistant gratings offered and are often used in caustic chemical environments without hesitation.