The Challenge of Elastomer Seals for Blowout Preventer BOP and Wellhead/Christmas Trees under High Temperature

Abstract

It is critically important for elastomer sealing components in blowout preventers (BOP) and wellheads to meet the pressure and temperature rating requirements under the newly released American Petroleum Institute (API) standards, API 16A (fourth edition) and API 6A (twenty-first edition) respectively. Extrusion resistance under high pressure and high temperature is one of the most critical challenge for the elastomer sealing components to meet the above API standards. This challenge is related to the basic properties of elastomer materials and mechanical design of the sealing components. This paper outlines how a simple and low-cost approach was developed to evaluate extrusion resistance of elastomer sealing components, and the correlation between critical tear pressure and extrusion gap of the two elastomers seals was evaluated using a power law equation. This correlation revealed that the above challenges of elastomer sealing components for BOPs and wellheads/Christmas trees is related to the weak strength of elastomers under high temperature and large clearances (extrusion gap) in current designs. New materials and/or new mechanical design to overcome such a challenge were also provided and discussed in this paper. The paper will help practicing engineers understand the challenge of material selection, mechanical design, and API testing as well as better understand the capability and limitation of sealing components for blowout preventors and wellhead applications under high pressure and/or high temperature (HPHT).