H2S and CO2 gases are used in corrosion tests that are related to the oil and gas industry pipeline applications. H2S and CO2 are byproducts obtained during oil and gas drilling processes. Both the gases can cause severe corrosion damages for the carbon steels used as pipeline construction materials. There are a few testing standards that are applied to simulate the corrosion phenomena taking place in H2S and CO2 containing environments.
Both the H2S and CO2 are dangerous gases for human beings. H2S Long-term Exposure Limit (LTEL) and Short-term Exposure Limit (STEL) values are 5.0 ppm and 10 ppm in the European Union member countries. The corresponding limits are 20 ppm and 50 ppm in USA. At H2S concentrations above 1000 ppm, a single inhalation may result in instantaneous unconsciousness and further death.
CO2 itself is not poisonous but the high CO2 concentration is often linked with oxygen deprivation that leads to headaches, fatigue and in extreme cases convulsions, coma and death.
Many kinds of testing cells are used in H2S and CO2 containing corrosion tests in various temperatures and pressures. There are usually both the gaseous and the liquid phases present in a testing cell. Gases are bubbled through the liquid phase. The dissolved gas concentration in the liquid phase depends on the partial pressure of gas and temperature. The gases are led to the neutralisation during the bubbling or at latest after ending of a test.
Two HIC testing cells and H2S neutralisation containers installed in a draft cabinet.
It is obvious that the testing cell gas will be released in the surrounding space in case the testing cell has a leakage. It is evident that a gas leakage releases a lot of H2S / CO2 in air. A liquid leakage is also dangerous as the testing liquid can also have considerable amount of dissolved gases. They will also be released in the environment with a somewhat slower kinetics than from the gas phase.
H2S + CO2 corrosion tests are always performed in draft cabinets. The testing laboratory, the gas cylinder cabinets and even the draft cabinets have wall mounted H2S and CO2 sensors that are connected to a laboratory gas sensor monitoring device. The monitoring device reads the gas sensors, controls the ventilation fan, alarm beacon and horn and gas feeding operations.
Typically, there is no H2S in Cormet’s H2S laboratory during the operation. The most critical phases are the test starting and especially the testing cell opening after a test. It is certainly possible that there are leakages during the normal operation but that is rare.
Cormet’s gas monitoring systems have normally 5 ppm and 10 ppm H2S alarm limits. If the H2S concentration exceeds 5 ppm in air, the beacons will flash and the ventilation will accelerate to the maximum speed. At 10 ppm H2S concentration, the alarm horns will start and the H2S feeding valve in the gas cylinder cabinet will be switched off. The CO2 levels 0.4 vol-% and 0.8 vol-% will cause the same effects.
H2S and CO2 sensors attached on the container laboratory wall.
Due to the risks related to the poisonous gases, the H2S + CO2 laboratories are normally located separately from the other laboratories. Even in case of the reasonable worst case scenario, one should not be able to smell H2S in the close-by lab rooms. The human nose is sensitive for H2S smell. Even a small trace of H2S causes anxiety among the co-workers. Therefore, the H2S lab should have separate inlet air and ventilation lines.
Cormet builds H2S + CO2 laboratories in existing buildings and in containers.
One has to pay attention to the isolation of the lab room if the lab is built in an existing building. The make-up air supply and AC capacity must be adequately high because the laboratory ventilation fan will be running continuously. The outlet air duct must be separated from house's ventilation infrastructure.
The lab container concept is a simple method to isolate the H2S + CO2 laboratory from the other laboratories. A laboratory container is a 40 feet high ceiling container that is thermally isolated and further instrumented. The container space will be divided typically in about 3 meter long control room and 9 meter long laboratory room.
Cormet's H2S / CO2 container lab installed in Saudi Arabia.
The laboratory room includes the corrosion testing instruments built in draft cabinets, a draft cabinet for H2S titration, working tables, storage cabinets, a waste water container and a ventilation system with a high waste gas pipe on the container roof. The gas cylinders will be located in the separate cabinets outside of the lab container.
A view from the laboratory room.
The control room contains the gas monitoring device, the electrical cabinet, testing device electronics and space for Operators.
A typical control room of a container laboratory with a glass panel door showing the laboratory space.
The laboratory container installation time is very short. The Operator can start the production right after Cormet’s engineers have given the testing and safety procedure training. A special attention is paid to the Operator safety, the minimization of the H2S leakages and the every-day laboratory maintenance and hygiene. Various kinds of after-sales services will be available.