Fiberglass Reinforced Plastic (FRP) Standards for Vessels

Shortly after World War II, the FRP industry expanded rapidly into many areas. Chemical tanks were first fabricated in the 1950's. A comprehensive standard was needed and in 1969 a consensus standard was issued by the National Bureau of Standards: NBS PS 15-69 "Custom Contact-Molded Reinforced-Polyester Chemical-Resistant Process Equipment."

In 1974 ASME published Section X of the Boiler and Pressure Vessel Code to ensure safe FRP pressure vessels. This code required that a test vessel be made exactly as the intended vessel, the test vessel was overpressured to destruction to demonstrate the safety of the design and fabrication of the vessel. The production could proceed. Many small vessels for air, pure water, etc. were fabricated. However, if a single tank was desired for atmospheric pressure, this code was not applicable nor economical.

After some years PS 15-69 became obsolete and new standards were generated specifically for tanks: these are ASTM D 3299 "Filament-Wound Glass-Fiber0Reinforced Thermoset Resin Chemical-Resistant Tanks" issued in 1974 and ASTMD 4097 "Contact-Molded Glass-Fiber-Reinforced Thermoset Resin Chemical-Resistant Tanks" issued in 1982. These are excellent standards. But a deficiency is that although the technical requirements are spelled out, the quality assurance procedures are not covered.

In 1981, a group under the auspices of the Materials Technology Institute of the Chemical Process Industries and the Society of Plastics Industry published the "Quality Assurance Report -RTP Corrosion-Resistant Equipment." This report was very comprehensive and covered all the necessary items to ensure safe and high-quality vessels. It was intended to provide a basis for ASME for an enforceable standard.

Thus, the RTP committee of ASME was formed and issued in 1989 the ASME RTP-1, "Reinforced Thermoset Plastic Corrosion Resistant Equipment" applicable for vessels not exceeding +/- 15 psi internal pressure. Vessels made to this standard can be stamped with the appropriate ASME stamp. The standard contains comprehensive requirements for the fabrication of FRP vessels. It covers ship certification, design, operator qualification, fabrication, inspection, and all other factors affecting the quality of FRP vessels. This standard is not part of the "code" which is required in states which mandate the ASME code for pressure vessels, but could be enacted into law as each state desires.

Also, in 1989 the ASME Section X committee revised Section X to include FRP pressure vessels without the requirement for a destructive test. This inclusion requires strict design rules, fabrication quality and an acoustic emission test to ensure that the vessel has no detectable defects.