Oil and Gas
Content Chapters
Pipes and pipelines
There is more than 3.5 million km of pipeline for oil and gas transportation around the world and reportedly more than another 190,000 km in the planning or construction stage. That is about 88 times the earth’s circumference!. The replacement cost of pipelines is estimated to be around USD 640-650 per km with the lifetime of the infrastructure controlled by corrosion. In the US, the cost of corrosion has been estimated at approximately USD 7.0 billion per year! This can be further divided into capital costs ($2.7 billion), operation and maintenance costs ($3.6 billion) and failure costs ($0.7 billion). Pipelines for transportation of oil and gas are typically made of carbon steel and a significant part of the maintenance cost is associated with corrosion control. The driver for the expenditures in maintenance is to ensure safe operation. A failure can put the public in danger, create production loss and/or cause property and environmental damage. Therefore, it is of utmost importance for the pipeline infrastructure to be protected against impact, abrasion and corrosion: not only the outside of the pipes but also on the inside.
Pipeline coatings typically use either fusion bonded epoxy, 3 layer polyethylene, 3 layer polypropylene, coal tar enamel, asphalt enamel & polyurethane cement lining, concrete weight coating and/or other systems. The internal coating has to give protection against extraneous solids present in the gas or oil such as salts (e.g. Sodium and Potassium Chloride, Sulphates, carbonates), dirt, grease, etc. These fluids can travel through the pipe at speeds well over 300 km/h so the coating requirements are very high and need to protect against abrasion, impact and corrosion. The external coating of pipes needs to be durable as well. When the pipeline runs above ground it is subjected to the local atmospheric conditions. When underground, it will be subjected to soil stresses depending on the chemical composition of the soil and salinity of the water. Ideally, one coating or corrosion protective method should be suitable for every environment but in reality there are a number of corrosion mitigation techniques (e.g. corrosion protective coatings and cathodic protection) to provide adequate protection against corrosion. Approximately 90% of transmission pipeline corrosion related failures are caused by external corrosion. Internal corrosion is less of an issue for transmission pipelines.
Inhibispheres® could offer the benefit of an extra line of defence in coatings such as fusion bonded epoxy. When local damage to the coating occurs or cathodic protection is inadequate, the controlled release of a corrosion inhibitor can help to slow the corrosion process. The introduction of Inhibispheres® into a coating would extend the life of the coating and reduce the maintenance cycle.
Corrosion under insulation
Corrosion under insulation (CUI) is a common problem for pipelines, pressure vessels, tanks and heating/cooling systems. It is very common in the chemical industry where pipelines are a significant part of the makeup of production. Industrial segments suffering significantly from this type of corrosion include chemical, petrochemical, refining, offshore, marine and maritime industries. It occurs due to a moisture build-up on the surface of insulated infrastructure. It can cause a severe form of localised corrosion on metal surfaces. This severe corrosion can in turn lead to detrimental asset failures and unexpected production shutdowns resulting in increased loss of production time and potential health and safety issues for employees where safety has been compromised due to failure. Corrosion under insulation costs businesses billions of dollars in detection, repair and maintenance every year.
Pipelines are insulated to help preserve the energy used in processes that are not at room temperature (whether hotter or colder). The pipes are normally coated with a protective anti-corrosive coating at the pipe surface with an insulation layer surrounding the anti-corrosive coating and finally some form of jacketing around the insulation. The pipework being protected from corrosion under insulation is usually made up of carbon steel or low alloy steel. Insulating materials that absorb high levels of water in turn exhibit more severe corrosion under insulation. When the jacketing material is damaged, poorly installed or poorly designed, water penetration, whether through rainwater or condensation, into the insulation around the pipes can occurs. The water gathers in this annular space underneath the jacketing and inside the insulation and continues to build up till saturation. After penetrating through the insulation to the coating surface the moisture begins to initiate the corrosion under insulation at the interface of the metal pipe coating and the metal surface. This will happen if there are any defects (e.g. touch ups) in the protective coating or the coating itself is aged or damaged in some way allowing ingress and build-up of moisture.
Inhibispheres® can be used in protective coatings to help manage corrosion under insulation better. Inhibispheres can be added to pipeline coatings under insulation to help mitigate the initiation of corrosion. In the presence of this moisture build up, Inhibispheres® release their efficient organic or organometallic corrosion inhibitor payload helping to prevent corrosion at the metal surface by travelling with the water front as it passes through the coating. The addition of Inhibispheres® to a protective coating imparts greater anti-corrosive properties to that coating. The unique use of organic and organometallic inhibitors allows Inhibispheres to be used alone or in conjunction with traditional corrosion inhibitors to great effect.
