Air Products’ former chairman Hap Wagner may have raised eyebrows a couple of decades ago when he declared that, “Nothing is more important than safety, not production, not profits.”
Today all of the major gas producers have adopted a similar stance regarding workplace safety and all have well established safety procedures which outline safe working practices.
Protective clothing is provided to all employees who require it, to ensure their safety at work. Guidelines are issued to increase safety awareness among the whole work force.
Management and safety representatives are highly committed to the achievement of safe operational practices and these efforts are reflected in the performance statistics reported by the industry.
Gas industry responsibility
Considerable time and effort has gone into identifying the root causes of workplace accidents and these can be sorted into two categories: technical failures and human error.
The frequency of accidents attributed to technical failure has been reduced by engineering and organisational improvements, to the point where accidents caused by human error appear to be prevalent.
In the gases industry, accidents can and unfortunately do occur at all stages of the manufacturing process, maintenance and distribution. According to Inter-Governmental Conference (IGC) statistics for the European Union (EU), about 30% of all reported lost time accidents take place in cylinder filling stations. The routine, low skilled and some might say uninteresting nature of cylinder filling tasks increases the difficulty of making workers more interested in, and motivated towards, safety in their working environment.
Analysis of records and statistics clearly indicates that newly hired employees are the most likely to be involved in accidents but does not explain why. Obviously new recruits are unfamiliar with the work environment, the hazards of the materials to be handled, the equipment used and the safe working procedures. It is a fundamental responsibility of management to ensure that recruits are quickly and safely integrated into the workforce.
Despite the reality of recurring accidents, people persist in the belief that that they personally will continue to escape being involved. This attitude can be extremely difficult to change and often frustrates well intentioned efforts to improve safety performance. Effective training programmes help to create relations of trust which are beneficial to the safety awareness of all employees.
A useful document entitled ‘SAFETY TRAINING OF EMPLOYEES’ was published by the European Industrial Gases Association (EIGA) in 2008, which attempts to clarify the following aspects of employee safety training:
*Which topics must be included in the training?
*Which key messages should be delivered as part of each topic?
*How should a consistent training schedule be arranged?
This document deals mainly with the common industrial gases, namely oxygen, nitrogen, hydrogen, argon, carbon dioxide and acetylene. It also deals with basic safety rules, the use of hand tools and portable power tools, chemicals and solvents, safe procedures and safety instructions related to the use of fork lift trucks, electricity, fluid pressure, fire and protective devices, cylinders handling, and more.
Although the publication is primarily directed at the training of new employees, it also addresses the retraining of experienced employees. This document aims to help the plant manager select the proper safety training material when making the first contact with the new employee before he starts work, or could be used to write a training programme for an existing employee who is being transferred to a new job – or just to periodically refresh employees’ knowledge on basic safety rules and practices.
Gas users responsibility
Compressed gases present a unique hazard because, depending on the particular gas, there is a potential for simultaneous exposure to both mechanical and chemical hazards.
The catastrophic failure of a high pressure cylinder is possibly the most feared type of gas related accident and is characterised by extreme violence and extensive property damage. Serious personal injury or death very often results, depending on the proximity of personnel to the explosion site.
The quality standards applied during the manufacture of modern high pressure cylinders and responsible filling practices implemented by the gases industry have virtually eliminated any possibility of cylinders being ruptured by normal use, even when in service under extreme climactic conditions. Maintaining this safety standard over the expected lifespan of steel high pressure cylinders depends on their effective inspection and testing at specified intervals. Standard filling procedures also include certain critical safety checks.
The risk of cylinders being weakened by internal corrosion depends on the quality of gas being filled and also on the ingress of contamination or moisture at any point in the cycle of usage. While in most cases gas cylinders are the property of the gas supply company who also retains responsibility for their safety.
Customers and users of high pressure gas do, however, have an important role in minimising the risk of premature cylinder failure.
The following four steps are recommended to reduce the risks associated with contaminated cylinders:
1. Reverse flow protection devices should be installed to prevent backflow of gases or liquids into gas handling equipment or cylinders.
2. Cylinder valves should be closed before cylinders are completely empty, to maintain a minimum residual pressure of 150kPa.
3. Ensure that cylinders are never connected to a system of higher pressure than the rated cylinder pressure.
4. Cylinders exposed to any contaminant (even air) should be clearly marked and the risk reported to the supplier.
New valves maintain integrity
Internal corrosion is named as the cause of at least 30% of the cylinder related incidents recorded in EIGA’s ‘Failed Cylinder Database’ – indicating that a practical solution to this problem is long overdue.
Residual Pressure Valves (RPV’s) that prevent the possibility of back contamination by maintaining positive pressure in the cylinder are a practical alternative that maintain gas quality and reduce the need for internal cylinder maintenance. They are gaining popularity especially for medical gases, food grade gases and for applications where cylinder corrosion is a particular problem.
The introduction of directives like the GMP for medical gases and the proposed directive for food gases is contributing to the demand for RPV’s. Currently there are two types in use:
1. Type A prevents complete evacuation of the cylinder by maintaining a small residual pressure.
2. Type B also serves this function, but includes an integrated non-return valve to prevent the back flow of fluids from a higher pressure source.
New modes of supply
New supply options are now offered by gas suppliers in many industrial markets that complement the traditional high-pressure cylinder or bulk liquid supply, including liquid cylinders, portable cryogenic tanks and mini-bulk liquid deliveries.
In addition, certain applications such as laser cutting require the installation of pressure boosting systems and high pressure buffer storage tanks.
While these new supply modes definitely provide convenience and improved operational efficiency, they also introduce unfamiliar equipment to the customer’s site and without appropriate training this can represent a safety hazard. Operators that are accustomed to receiving gas supply in cylinders are likely to be unaware of the properties of cryogenic liquids and require training to understand pressure building vaporisers and pressure relief devices.
Information is the key
It is vitally important that throughout the cycle of gas usage, starting with the production, packaging, transport, storage and continuing to the end-use application, responsibility for gas safety must be clearly assigned to appropriately trained personnel.
Training should include the associated hazards of the materials, necessary safety precautions, personal protective equipment (PPE) and emergency response procedures. Appropriate material safety data sheets (MSDS’s) or other gas supplier product information shall be made accessible to industrial gas users.
It’s clear that the responsibility for safety spans the entire chain of both the gases business and the personnel, with information and an approach of prevention largely key to this. The sharing of knowledge and, ultimately, the harmonisation of standards and legislation is a cause our gases industry continues to promote and strive towards.