Fatigue and Ultimate Limit State of Grouted Tubular Joints

A joint industry project commenced in 1993 to develop a design manual for tubular joints, which are strengthened or repaired through chord grout filling. This project was carried out in two phases and was completed in the late 1990’s. The project comprised the conduct of over 200 SCF and ultimate load tests on large scale as-welded and grouted tubular joints. In addition to the testing programme, studies on offshore deployment were carried out to ensure that complete chord grout filling was achievable for all practical scenarios. The primary reason for carrying out this project is the industry-wide recognition that chord grout filling represents an extremely cost-effective and mechanically efficient method to strengthen or repair tubular joints. Further, it has been recognised that double-skin joints (e.g. pile through leg with annulus grout-filled) are often present in structures and the enhanced strength and fatigue characteristics as a result could be exploited to permit more efficient new platform designs or better estimation of joint performance for existing installations. Although API RP2A [1] and ISO [2] recommendations permit the use of grouted joints, little guidance is provided. The guidance that is provided is based on public domain data and engineering principles. This project was carried out to generate a substantial amount of new data/information, leading to the creation of a detail design manual for grouted joints [3,4].