Fiberglass composite pipe example

At the 2013 Offshore Technology Conference, Joie L. Folkers of National Oilwell Varco Fiber Glass Systems presented a paper illustrating the difficulties associated with prescriptive rules (Folkers 2013). He used the example of fiberglass-composite pipe. The following is extracted from his presentation. 

As with any new, unfamiliar piping material, standards were set very conservatively in order to mitigate risk of improper use of the material, resulting in failures with consequences potentially ranging from inconvenient releases to loss of life. Traces of equivalency to steel can be found in the requirements, as that was the incumbent material in most cases, despite its limited service life in corrosive seawater applications. 

20 years later, with a significant history of use, suooess, mistakes, corrections and evolved preference for the material, it is reasonable to take a new look at the performance requirements and modify them to more accurately reflect the real life, worst-case scenarios. 

An example of need to re-examine the requirements is illustrated in the conduct of a Level 1 fire endurance test. In this test, a pipe spool is placed inside a furnace with no fluid inside (other than N2 gas at 0.7 bar) and subjected to a hydrocarbon fire temperature curve ranging from 945°C after 5 minutes up to 1100°C after a period of 60 minutes. This exposure would exceed the structural strength of steel and is extremely more severe than any plastic pipe could endure without significant amounts of passive fire protection. The purpose of this test is to assure that there would be no loss of integrity (that) may cause outflow of flammable fluid and worsen the fire situation.  

---

Example 2.4 Estimation of heat flow through a composite wall with constant thermal conductivities A pipe with an outside diameter of 10 cm and a length of 110 m is carrying hot fluid. The pipe is insulated with 0.5 cm thick silica foam and 10 cm thick fiberglass. The pipe wall is at 120°C and the outside surface of the fiberglass is at 30°C. Estimate the heat flow in the radial direction of the pipe. The thermal conductivities of silica foam and fiberglass are 0.055 and 0.0485 W/(m K), respectively. 

Other civil engineering examples of polymers and composites are geotechnical fabric for soils, polymer natural gas pipe, fiberglass reinforcing-bar (re-bar), composite I-beams, as well as the aforementioned decking for bridges. 

---