Critical Applications - Oxygen service
Oxygen – essential for life yet so dangerous, poses huge potential risk when utilised in industrial processes
Minimising the risks
To ensure the safety of plant and personnel, extreme caution is required to ensure that all systems used for handling oxygen are correctly specified, designed, manufactured and maintained because the smallest error at any stage can prove catastrophic.
Although oxygen itself does not burn, it supports combustion. The more oxygen present in a system the greater the risk of fire occurring and the lower the temperature at which ignition will occur until, in its purest form, it can cause the rapid or spontaneous combustion of most materials – even metals.
Oxygen bonds with all elements in the process known as oxidation. If this process occurs rapidly fire can result. It is therefore essential that materials which will oxidise rapidly are not present in oxygen processing systems. Contaminants such as oils and greases – these could be anything from lubricants to simple residue contamination from handling components with bare hands are very capable of reacting with oxygen to cause fire and potentially an explosion.
In addition to ensuring cleanliness when working on oxygen handling systems all components, including sealing products such as compression packings, must also conform to the same levels of cleanliness – containing no potentially reactive lubricants or materials.
Developed and tested for safety
Supagraf OX, a new product launched by James Walker, is specifically designed to provide safe operation in duties involving liquid and gaseous oxygen.
It has been ignition sensitivity tested to limits 420bar at 300°C and 440bar at 60°C and certified by BAM as suitable for use in sealing applications with both liquid and gaseous oxygen.
In addition, the graphite material from which Supagraf OX is manufactured conforms to Shell MESC SPE 85/204 (Sept 2012).
The product is also listed in the Shell MESC 77/303 (2018) specification by name and is therefore exempt from the Solvent Extraction Production Test and Oxidation Production Test – saving valve manufacturers from the cost and time necessary to carry out such testing.
From yarn to finished product, manufacturing takes place under clean-room conditions before being dispatched to the customer in double sealed packaging to ensure it reaches the point of use in a clean condition.
Assuming that the product is then correctly handled and installed – (see US standard CGA G-4.1-2009 ‘Cleaning equipment for oxygen service’ 6th edition) Supagraf OX will provide safe, low emission stem sealing of valves in service with liquid or gaseous oxygen.
Tel: 01270 536 000
Published in Valve User Magazine Issue 46
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