Innovative Development of Composite Pipe JoiningIFitting Technology for Advanced Composite Pipe Systems
Authors: Lea Richard H. , Stubblefield Michael A. 
Published: October 2008

Introduction

The domestic oil industry is vital to the American economy because of its dependence on hydrocarbons as a primary fuel source for industry and defense. As the oil industry has extended its exploration into deeper water, weight-sensitive floating platforms have replaced stationary, bottom-founded structures. The cost penalty for weight on Tension Leg Platforms, (TLP's), is in the USS5-1OILB, (USS2.25-4.50/kg.). Hence, considerable economic incentives exist to reduce the dead weight of topside facilities. Composite piping has been identified as a technology that could provide significant impact. On the Shell MARS TLP, it is estimated that the use of composite pipe for merely the firewater ring main and drain systems reduced the topside weight by 160,000 Ib.(72.576/kg.). With a design life of over 20 years and with an installed cost of approximately one-third that of 90/10 copper-nickel pipe. it is easy to comprehend the economic advantages composite piping can offer facility engineers. Corrosion data on composite pipe composed of epoxy and isopolyester resins used in sea water service applications dates back to the 1950's. Composite pipe is as light as aluminum, has better resistance to erosion than copper-nickel pipe and fouling in quiet seawater can be controlled by marine electrolytic chlorinators which are commercially available. In stagnant water fire tests conducted in accordance with API 607, considered by many the most severe case scenario. composite pipe outperforms copper-nickel pipe. Composite pipe systems have been in use in the Chemical Process Industries in the United States for over 40 years. Composite pipe has replaced titanium pipe in the Caustic-Chlorine Industry and stainless steel pipe in the Pulp and Paper and Phosphoric Acid Industries. The question one should ask is why has it taken so long for the Offshore Oil & Gas Industry to recognize the merits of composite pipe. What technical barriers must be conquered for composite pipe systems to gain acceptance in the relatively mild corrosion service of sea water at ambient temperatures?

Major Challenges Facing Composite Pipe Industry Prior to Acceptance in the Offshore Oil & Gas Industry

There is a need for industry performance guidelines to govern design, assembly and installation of composite piping systems. Fire endurance and smoke toxicity issues are important to risk assessment personnel. But standards, improperly applied often become a straight jacket for future product development and false insurance for uninformed engineers and contractors. In many major oil companies the responsibility for the implementation of composite materials falls under the corrosion engineer or metallurgist, whose very name implies the study of metals at the atomic level. Most mechanical and piping engineers responsible for detail design do not understand the unique mechanical characteristics of composite materials and the design flexibility available. The ability to design for "FITNESS FOR PURPOSE" is one of the major advantages of composite pipe systems. Engineers and material scientists are well versed in the behavior of and use of isotropic materials, such as most alloy metals and pure polymers. but do not comprehend the complex directional characteristics of anisotropic materials, such as wood, human bone and all fiber reinforced materials. Isotropic materials have identical mechanical physical. thermal and electrical properties in every direction. In general. isotropic materials are mathematical approximations to the true situation.