scope:

In the construction of a flexible pipe, an inner polymeric pressure sheath is the only layer which seals the conveyed fluid within the pipe structure. Therefore, its integrity is crucial to safe and reliable operation. Polyamide 11 (PA-11) is the most commonly used pressure sheath material (1), other options being polyvinylidene fluoride and polyethylene.

This document provides comprehensive guidance on materials and pipe issues regarding the use and operation of PA-11 in flexible pipe applications, typically in production and gas handling applications up to 100°C.

The document concentrates on the use of PA-11 in the internal sheath of flexible pipes, although similar considerations may also apply to other uses of PA-11 within flexibles, e.g., anti-wear layers, intermediate sheathes and outer sheathes.

The collective goal of this document is to prevent failure of the internal pressure sheath, as a result of ageing and associated loss of mechanical properties, by determining and disseminating the necessary scientific and practical information. API Specification 17J and Recommended Practice 17B (2,3) contain only limited information with respect to these phenomena, and this report supplements and updates the data in the Third Edition of API RP 17B (3) .

PA-11 is also used in umbilicals. However, the exposure temperatures are frequently lower than production temperatures. In cases of higher temperature exposure, the information contained in this document applies.