Improvement of bonded flexible pipes acc. to new API Standard 17K
Authors: Antal Sándor , Nagy Tibor , Boros András 
Published: October 2008

Abstract
The American Petroleum Institute issued with effective date of March 1, 2002 the new Standard: "Specification for bonded flexible pipe" (API Spec.17K) that has a great importance for the oil companies and the producers of the flexible pipes used in the oil fields. There is another important Standard "Specification for choke and kill systems" (API Spec. 16C, issued in 1993), its revision is under preparation, the last published one has revision number 11. Both Standards contain significant new information from the experience in oil fields and test requirements, with particular attention to the safety issues. The lecture outlines the problems and explains the solutions.

Introduction
There are two types of standardized flexible pipes especially used in the offshore oil industry: unbonded and bonded flexible pipes. The unbonded flexible pipes were standardized by API Spec 17J Standard between 1994 and 1997, the bonded pipes by API Spec 17K between 1996 and 2002. There wererepresentatives of the biggest oil companies (e.g. Exxon, BP, Shell, Statoil, Texaco) among the members of both standardization committees proving the demand for both product classes. 5 rubber companies were committee members in API Spec 17K working group. Our company was the first to receive an approval for the use of the API monogram.
The applications addressed by the specification API 17K include sweet and sour service production, with products including oil gas, water and injection chemicals. This specification applies both to static and dynamic flexible pipes used as flowlines, risers, jumpers and loading hoses. The Standard can be applied to flexible pipes for pile hammer, gas flare, water supply and jetting applications and there is increasing demand in other areas.
Our lecture also deals with the Standard API Spec 16C for choke and kill applications with different technical requirements. The design of the flexible pipes used for the production and choke and kill application is similar, but not interchangeable.

Choke and kill flexible pipes.
[1] The choke and kill flexible line is a safety equipment in deep drilling work as an integral part of the blow-out preventer unit. The function of the lines become effective when kick occurs during drilling. The kick is an unexpected entry of water, gas, oil or other formation fluid into the well bore. This can happen when the pressure of the medium entering in the well bore is higher than expected. To prevent the blow out, high density mud is pumped through the kill line. The pressure of the well is adjusted by the quantity of the mud passed through the choke line. There is a C&K line (Fig.1.) as an example used on the Jack-Up rig of the Ensco Company. The hoses are API 16C hoses connected to the topside BOP stack.
The standardization of the flexible choke and kill lines is very difficult, because neither the operational conditions during kick, nor reports on accidents are published in detail. The first Standard was accepted in 1993 after about 5 years heavy discussion. New standardization activity has been launched according to the regulations at API in 1998 (the Standards have to be renewed after 5 years use).