Page 13 - Reliability and Maintainability of In service Pipelines

2 Reliability and Maintainability of In-Service Pipelines

Chapter Outline
1.1 Background 2
1.2 Scopes of Pipeline Reliability Analysis 4
1.3 Types of Pipelines 5
1.3.1 Metallic Pipelines 8
1.3.2 Nonmetallic Pipes 11
1.4 Design of Buried Pipelines 15
1.5 Loads and Stresses on Pipelines 22
1.5.1 Loads on Pipelines 22
1.5.2 Stress in Buried Pipelines 25
1.6 Deterioration of Pipes 28
1.6.1 Deterioration of Concrete Pipes 29
1.6.2 Deterioration of Ferrous Pipes 36
1.6.3 Deterioration of Plastic Pipes 42
1.6.4 Deterioration of Other Types of Pipes 44
References 45
Further Reading 48

1.1 Background

Pipelines are widely used engineering structures for the collection, conveyance,
and distribution of fluid in different areas from rural and urban regions to marine
areas. Most of the time, pipelines are placed underground, surcharged by soil
weight and traffic loads. Evidently, underground pipelines are required to resist
the influence of the external loads (soil and traffic), internal fluid pressure, as
well as environmental loads. Buried pipelines are subject to chemical and
mechanical loading in their environment of service and these stresses cause fail-
ure that is costly to repair.
In many cases underground pipelines are required to withstand particular envi-
ronmental hazards. Corrosion of pipe material is the most common form of pipe-
line deterioration and should be considered in both strength and serviceability
analysis of buried pipes (Ahammed and Melchers, 1997; Sharma et al., 2008).
According to “The World Factbook” (2010), the United States has approxi-
mately 800,000 km and Russia has 252,000 km of pipes transporting products like
crude oil, natural gas, and petroleum products. The statistics for the United
Kingdom and Australia are 20,000 and 32,000 km, respectively. More than half
of the US oil and gas pipeline network is over 40 years old and corrosion has
caused 23% and 39% of failures of oil and gas pipelines, respectively (Anon,
2002).