Safety, service and security

The full version of this article can be read in the May 2011 edition of Hydrocarbon Engineering.

Protecting the integrity of gas throughout the supply chain, from manufacture to end user, is an ongoing challenge, particularly as gases and gas mixtures become increasingly sophisticated to meet needs across the full spectrum of contemporary global industry.

Gas molecules are continually in motion, filling every corner of every space and capable of flowing through minute gaps. Gases stored within a container or in a gas supply system are constantly seeking ways to escape; simultaneously other gases present in the atmosphere have the ability to migrate into the container or system. Unintended gas mixtures and contamination could adversely affect production processes, damage the environment, cause safety risks or be harmful to human health.

Specialty gases applications are of particular concern. These are extremely sensitive high purity gases, often intentionally containing very low levels of trace components (in some cases as low as parts per trillion), which are used in equipment calibration and gas analysis. These trace components are easily compromised by a reaction with contaminant gases.

In response, leading gas manufacturers have developed increasingly hi tech cylinders, valves, regulators and supply systems, developed from new generation materials, to ensure that gas products remain pure and uncontaminated throughout their life cycle. This mitigates threats to the environment and human life, avoiding the exposure of all parties to the high cost of integrity failure.

Moving gas

When the intention is to deliver gas out of a cylinder, regulators are required to control pressure and valves to direct the flow rate. These are separate tasks and generally need multiple devices to achieve this successfully. Moving a gas or a gas mixture from a cylinder to the site of use requires a range of valves, regulators, piping and sometimes the inclusion of other gases and procedures, such as purge techniques, to achieve the correct result.

Speciality application

Specialty gases are extremely high purity gases which can also be toxic or corrosive. Storing, handling and using these gases correctly is critical, thus there is a huge focus on the leak integrity of supply systems. In these applications, diaphragm valves are considered ‘best in class’ as process flow regulation devices, because they employ a flexible diaphragm to effectively control a process flow line either partially or completely as needed in order to regulate the transport of the gas stream and eliminate the possibility of contamination. ‘Leak free’ connections between these valves and other piping components are often achieved using national pipe tapered (NPT) thread.

Conclusion

Essentially, a gas supply system is only as good as its weakest component: all components should be of compatible quality, as this is the only way gas users can guarantee the safety and purity of the products they use. Ideally, the gas that leaves the cylinder should be exactly the same as the gas that emerges at the point of use. Choosing a high quality valve for a system is pointless if the regulator incorporated is sub standard. The system must be designed to be appropriate for the application, including valves, regulators and piping, while the installation process remains important. Furthermore, the right connections must be selected and once the system is commissioned, it must be tested for pressure integrity and gas purity before the installer certifies the system as safe and ready for use.

The full version of this article can be read in the May 2011 edition of Hydrocarbon Engineering.

Read the article online at: https://www.hydrocarbonengineering.com/gas-processing/27042011/how_the_safety_quality_and_integrity_of_gas_supply_depends_on_equipment_competency/