ABSTRACT

Custom fabricated fiber reinforced plastic (FRP) pressure vessels stamped in accordance with American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code have been available since 1993. These vessels are typically used in corrosive chemical processes, providing a cost effective alternative to carbon steel or other, more exotic, metal vessels.

In today?s world, it is important that people in Industry are aware of this option. It is equally important that they have a basic understanding of what goes into their design, manufacture and testing. Armed with this knowledge, individuals should be capable of making intelligent decisions concerning equipment options affecting personnel safety, risk management and equipment life cycle costs.

INTRODUCTION

As the emphasis on safety increased during the nineteenth and twentieth centuries, so did the demand for safe boilers and pressure vessels in the industrial and transportation worlds. Fueled by the memory of catastrophes such as the Sultana incident of 1865, people began to understand the importance of material properties, proper design and manufacturing Codes.

ASME Boiler and Pressure Vessel Code which followed eventually included fiber reinforced plastic (FRP) vessels under Section X. In states where ASME Section X is recognized as a part of their Boiler and Pressure Vessel Law, FRP vessel rated for pressures above 15 PSIG must carry an ASME stamp.

HISTORY

ASME was founded in 1880, largely the result of public outcry and concern for public safety. The years that followed brought about the adoption of the first standards and Codes governing the way boilers and pressure vessels were manufactured and inspected.

ASME Section X 1 is a relatively new part of the International Boiler and Pressure Vessel Code providing methods for designing, building, inspecting and testing fiber reinforced plastic (FRP) pressure vessels. Originally, this Section only concerned itself with mass produced, identical vessels. Typically, these were simplistic cylinders, only a few inches in diameter, but rated for relatively high pressures. These vessels found their way into many filtration applications such as purified potable water processing.

Vessel designs and manufacturing methods were proven to be adequate through cyclic and destructive testing under the watchful eyes of an Authorized Inspection Agency (AIA). If an accredited manufacturer successfully tested a vessel, he was then allowed to build scores of identical vessels without further testing. Although the testing requirements were expensive, the costs could be spread over a large manufacturing volume, making the whole process practical.

As time went by, a need was realized for stamped vessels that were larger and more complex. Without large unit numbers to dilute the cost of testing, larger, one of a kind vessels were not economically feasible under the Code as it was originally written. Responding to this need, the ASME Section X subcommittee amended their Document, adding provisions for a new vessel class. Following this revision, the multiple duplicate vessels were designated as Class I and the new custom vessels became Class II.

Design of Class II vessels by a licensed professional engineer was mandatory, using material properties derived from representative lamina testing. Mandatory acoustic emission (AE) testing of completed vessels would verify design adequacy, that the tank was structurally sound and free of major manufacturing defects. As with Class I vessels, the manufacturing processes would require AIA input and inspections.

In 1993, Tankinetics, Inc. became the first composite tank manufactu

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