UNS S31400 stainless steel was tested as a reactor material for a thermal cracking process of agricultural, silvicultural, industrial and anthropogenic resources containing HCl. This material was chosen as it offers proper corrosion resistance in hot gases besides a good price and a high availability.
Thermal insulation is used in operating facilities to conserve heat and protect against freezing amongst others. A consequence of insulating the pipe is the necessity to manage the introduced threat of corrosion under insulation (CUI). For CUI to occur water and oxygen must enter and migrate through the insulation to reach the external surface of the pipe. The water transport characteristics are dependent on several factors such as type of insulation type of jacketing pipe operating temperature external weather water entry/leakage rate and cyclic service. In hot piping there are competing water transport characteristics as in water vapor moves outwards away from the pipe as water enters into insulation. Knowing the water transport and the parameters that influence the time of wetness at the metal surface helps in understanding conditions favoring CUI.The use of transient hygrothermal models for moisture control is well established in the building insulation design codes and standards. The building designs naturally shed the liquid water to minimize entry and facilitate breathing of vapor so that moisture doesn’t accumulate within building. Several building industry hygrothermal models have been developed and are available for commercial use. One such commercial model has been used to understand water transport in a CUI application. The case study involves evaluation of piping and pipeline installed with a closed cell polyurethane insulation. The hygrothermal model provided insights on the parameters influencing the time of wetness and the ease of water escaping the pipe-insulation-jacketing system. Additional results comparing different insulations are also presented.Key words: Corrosion under insulation water transport hygrothermal models building industry polyurethane insulation
The corrosive fluids transportation inside carbon steel pipelines is critical due to internal corrosion. To avoid failures barrier corrosion protection techniques are applied by insulating the inner metal wall of the pipe. However when the tubes are welded together the inner coating is damaged by the heat generated during the welding process. As a result the ends of the tubes are uncoated and consequently subjected to corrosion. There are solutions to this problem but all have some kind of inconvenience either by the cost of implementation or the difficulty of application. This work aims to present the results of the tests of the application of an alternative technique: zinc thermally sprayed as sacrificial anode for internal protection of welded joints.
Corrosion in the field manifests over a large timescale so when considering material choices in the design of aerospace systems and subsystems use is often made of accelerated tests such as ASTM B117 salt spray chamber test to rank the possible materials. Even these ‘accelerated’ tests take more than 1000 hours and despite their widespread use are often criticized as a design trade tool since the test environments are considerably different to the expected field environment running the risk of either hiding true corrosion processes or simply being unrealistically challenging for the materials under test.The corrosion community has expended substantial effort in trying to make the tests ‘more realistic’ but in doing so there is considerable debate about whether the tools employed to accelerate the corrosion (thermal cycling high salt concentrations UV exposure etc) actually introduce other corrosion processes that are not even present in the eventual targeted field of operation for the device under test.Computational techniques hold a great deal of promise as a way to understand the effects of different service environments but if the simulations cannot even discern between say an ASTM B117 test and an atmospheric exposure then the simulation results would be of questionable value.The processes involved in corrosion are many and complex however one key parameter is the electrolyte film thickness which will clearly be different whether inside a chamber at high humidity with a continuous supply of sprayed saltwater compared to exposure on a beach where diurnal cycles result in a very thin electrolyte of varying salt concentrations except of course when it is raining!To help designers quickly assess corrosion risk and choose appropriate materials Corrdesa have already developed an electrochemical database of modern alloys and coatings. This has been extended by deconvoluting the polarization data to accurately account for the impact of the actual electrolyte thickness on the oxygen reduction reaction.In this paper using fluid shell elements in a free surface flow formulation we actually predict the variable electrolyte film thickness in a CFD (Computational Fluid Dynamics) code for a given environmental condition on different test specimens and geometries. The appropriate polarization data for the local electrolyte thickness is then implemented with User Functions in a potential model framework. In this way the galvanic corrosion is simulated for a test device with a more realistic and variable film thickness.The result is that we can dial different test conditions into the simulation such as whether we wish to simulate chamber results or field results cyclic salt fog cyclic humidity (or both).Keywords: Computational Corrosion Analysis Galvanic corrosion prediction FEA corrosion prediction polarization data potential model fluid shell elements CFD
Understanding environmental conditions experienced during shipping (both domestic and export) and/or storage is critical when determining the most effective corrosion control system for metal components. Temperature and humidity sensors were used to help understand the conditions within industrial packaging applications during different overseas shipping routes and during warehouse storage. The effect of secondary packaging (i.e. polyethylene film) on temperature and humidity within a package was also evaluated. The scope of this paper is to compile and analyze the data and utilizing it to help develop the best corrosion prevention strategies.Key words: Sensor corrosion control packaging overseas shipping