SUMMARY A description is given of the design and installation of several wet welded repairs made to appurtenances on 2 North Sea jackets. Details are given of the mechanical properties obtained for welds made in both the tank and offshore. Fatigue specimens were also prepared offshore and subsequently tested in 4 point bending. An S-N curve is developed and compared to data available for welds made in air. INTRODUCTION Underwater repairs in the North Sea have traditionally been made by either hyperbaric welding or installation of mechanical/grouted clamps. However, in the Gulf of Mexico wet welding has also been used successfully. Since several areas of secondary structural significance required repair on the Claymore platform's catholic protection system it was decided to make repairs by wet welding provided it were demonstrated that adequate mechanical properties could be developed from such welds. The completion of these repairs. Would permit evaluation of both the performance and cost of wet welds in a North Sea application versus other methods of repair. During the course of this repair work, further defects were discovered to appurtenances on the nearby Piper platform. The scope of repair work was therefore extended to cover these items. BACKGROUND The Piper and Claymore fields are situated some 100 miles north east of Aberdeen in Blocks 15/17 and 14/19 in the UK sector of the North Sea. The Piper field was discovered in January 1973 followed by Claymore in May 1974. The Piper Platform is a 36 slot drilling and production facility located in 474 ft (144.475 m) water depth. It was launched in June 1975 and initial production was achieved in December 1976. Complete details of the installation are given in a paper by Duvivier and Henstock (1). The Claymore platform is a 36 slot drilling and production facility located in 360 ft (108.728 m) water depth. The jacket is conceptually similar to the Piper structure except for the removal of one bay of framing to accommodate the different water depth. The jacket was launched in June 1976 and first production was achieved in November 1977. DESCRIPTION OF THE CLAYMORE PLATFORM REPAIRS INTRODUCTION Corrosion protection of the underwater sections of the jacket was originally provide, by an impressed current cathodic protection system. 55 anodes were distributed over the jacket terminating at various levels. Cables to these anodes were run in pipes to the surface, where they terminated in junction boxes at the first level of jacket framing above water. Cabling was then routed from these junction boxes to the power supply located within the topside modules. The pipes or "anode risers" carrying the cable were welded to the jacket at each structural member (either horizontal or diagonal) which they passed. This connection consisted of a cruciform plate fillet welded on both the jacket member and "riser" sides (see Figure- 1) There were 377 such connections distributed over the depth of the jacket.