Research On Fitness-for-service Of Subsea Repair Clamp For Subsea Pipeline With Pitting Corrosion

Pitting corrosion(pit)is the beginning of many forms of corrosion damage,and pitting corrosion perforation is one of the forms of corrosion damage.Subsea repair clamp is the main method to repair this form of damage.However,subsea repair clamp method is subject to pipeline defects which constraint with ECA technology.In the existing domestic and international standards,there is no stipulation of subsea pipeline’s damage defect.when the geometrical scale of defect is satisfied,the subsea repair clamp method can be used.It is necessary to research the fitness-for-service of subsea repair clamp method.When research on collapse pressure technology,this paper studies collapse characters of subsea pipeline within pitting corrosion perforation.The collapse pressure formula is deduced by theoretical derivation.Based on the deducted theoretical formula and finite element numerical simulation method,it is concluded that there is a link between the geometrical characteristics of the pitting corrosion perforated diameter and the influence coefficient of collapse pressure.Using the finite element numerical simulation method,this paper obtains the relationship between circumferential seal pressure which provided by the clamp’s circumferential bolt group and the collapse pressure of subsea pipeline.With increase of limited collapse pressure,the circumferential seal pressure can be take greater value.The engineering critical assessment technology is used to assess the key geometric quantities of the subsea repair clamp,and the recommended values for the key dimensions of the clamp are given.The engineering critical assessment technology is used to assess pitting corrosion perforation defects of subsea pipeline.The ECA evaluation results can be used to evaluate fitness-for-service assessment of subsea repair clamp.When research on sealing technology.According to the basic theory of constitutive relation of rubber hyper elasticity model and finite element numerical simulation method.This paper research on the static seal of axial sealing and obtain contact stress curve along the real path distance.