Assessment of repair reinforcement of polyester-glass fibre pipe
Andrzej Bełzowski, Przemysław Stróżyk Politechnika Wrocławska, Wydział Mechaniczny, Wydziałowy Zakład Wytrzymałości Materiałów ul. Smoluchowskiego 25, 50-370 Wrocław, Poland
Quarterly No. 2, 2008 pages 178-184
DOI:
keywords: polymer composites, composite repair for pipework, FEM
abstract Polymer composites are subject to degradation which consists in progressive damage affecting the durability of the construction. Damage may also occur during transport and assembly. The paper deals with repairs of high-risk composite process piping systems and low-risk drainage/sewerage piping systems. The current American and international standards describe repairs of high-risk chemical resistant piping systems where the criteria for assessing constructions are highly conservative. Whereas repairs of low-risk composite piping systems (for water supply or sewerage) are seldom assessed with regard to durability. A repair of large-diameter pipes in a sewerage piping system without pressure, whose structural layers were locally damaged during assembly is discussed here. In order to restore load-bearing capacity and stiffness, a circumferential ring reinforced with fibreglass chopped strand mat (CSM) was made inside the pipe. The aim of the repair was to restore the pipe parameters for the anticipated piping system lifetime. A pipe segment with a reinforcement similar to the one which was actually used was modelled (without edge effect) in ANSYS. FEM calculations showed that the repair reinforcement restores the stiffness and load-bearing capacity of the pipe. The largest hoop strains exceeded (by 0.2%) the limit design values for high-risk chemical resistant facilities but the safety factors for similar low-risk piping systems were met. The results of numerical computations for a reconstruction of the pipe by means of a laminate reinforced with fibreglass fabric showed an increase in hoop stiffness. This means that the proposed repair method can be optimized.