Major oil and gas operating companies are progressively adopting the Human Factors Engineering Discipline (HFE) to ensure quality, safety and fit for purpose of equipment and facilities. Human factors are all those considerations that enhance or improve human performance in the workplace and negate the possibility of human error.
The Health and Safety Executive’s (HSE) Accident Prevention Advisory Unit and others have shown that human error is a major contributor in 90% of accidents, 70% of which could have been prevented by management action. An incident may involve the failure of a number of additional barriers and controls, which may include poor organisational decisions, in order for human error to have serious consequences (Human Factors Engineering in Projects, International Association of Oil and Gas Producers, August 2011).
Five factors have been identified that contribute to human performance: People, nature of work, work organisation and structure, equipment and the work environment. The aims of HFE seek to reduce the risk to health of personnel and the environment, to eliminate or reduce the consequences of human error, to increase efficiency and productivity and improve user acceptance of new facilities (HFE in projects, August 2011). This article will focus mainly on human performance in valve operations.
The UK Health and Safety at Work Act (1974) places responsibilities on people who design, manufacture or supply equipment for use at work to ensure as far as is reasonably possible that it is safe. Internationally, there is a visible shift of emphasis in safety legislation from the sole reliance of prescriptive regulations to a risk management (goal setting) approach. Responsibility should sit with the company to put in place company-specific standards and specifications to ensure that risks and hazards are minimised. In fact, most of the major operating companies now have their own HFE technical standards.
This ‘risk management’ approach can be applied to ensure processes are introduced that reduce the possibility of design-induced risks to health, personnel, process safety or environmental performance while at the same time, ensuring efficiency and productivity prevails. This approach places responsibility on owners and operators to adopt ‘best available’ technology and methodology to ensure safety.
HFE Valve Considerations
General HFE principles suggest undertaking a valve analysis to rank valves according to their importance and frequency of use. Valves should be selected, located and labelled so that they can be operated, maintained and inspected with accessibility appropriate to their service, without exposing operators to risk of injury. Equally, consideration should be made to accessibility and operational risk in established plants so that any possible on-going safety issues are alleviated.
The HFE design requirements with regard to location and orientation are mainly applicable to manual valves but also apply to motorised, mobile actuator or otherwise remotely operated valves if their expected criticality is such that they may need rapid or frequent manual intervention either to override or manually operate them, or to visually check their status.
Considerations should include the task involved – what are operators expected to do? Can they access the valve with ease, or is it located out of reach or squeezed between other equipment that could prove risky to reach and operate?
Does the valve require high levels of torque and does the opening and closing of the valve need excessive force, using prolonged repetitive motions with a static or awkward posture? Are all members of the workforce capable of undertaking this task? And does the weather (extreme heat or cold) or other environmental conditions play a role in how easily the valve can be opened/closed?
Portable Valve Actuator Case Study
At a petrochemical plant in Singapore, operators were straining themselves to open and close large valves that were not actuated. These valves were 14” 1500# gear operated gate valves and required two operators to manually open the valve; this took 20 minutes on average. HFE considerations here involved personnel safety and efficiency. The valve operation was physically demanding, labour intensive, and took a long time to complete.
To support plant operations, Smith Flow Control’s local Distributor, Triple-Max Engineering Pte, supplied EasiDrive – a portable valve actuator. Such a system is ideal for the operation of valves that require a high number of turns, or are difficult to operate because of high torque or in circumstances where climatic conditions can seriously impair operator functionality and effectiveness. One operator can open/close multiple valves with a single tool while reducing fatigue and injury risk. It complements the needs of an increasingly diverse workforce and can be used regardless of operator strength.
EasiDrive greatly improved productivity and performance at the petrochemical site. It provided users with complete control, ensuring the required torque was applied at all times and operators were kept safe, even when under pressure to respond quickly. Only one operator was needed to operate the large gate valves and the time taken was reduced from an average of twenty minutes to five. The risk of injury was alleviated and it satisfied the general aims of HFE identified by the International Association of Oil & Gas Producers.
Remote Valve Operators – Addressing Valve Accessibility
Even with non-critical valves, permanent accessibility is desirable. Operators may be required to operate hard to reach valves or faced with restricted access conditions, due to other process equipment and pipes, which can in turn make the valve hard to operate. In order to overcome such issues, dangerous or inaccessible valves can be operated through the use of a remote valve operator, which is a cost-effective safety tool for companies to remotely control valve operations from a safe distance.
Smith Flow Control’s FlexiDrive allows the user to locate a point of operation at a preferred vantage point. This could be a safe area, or in a better, ergonomic position, discouraging potentially unsafe behaviour like climbing on valves to gain access. FlexiDrive removes problems associated with confined entry points and can also be submerged into flooded pits. Its linear drive cable delivers rotary torque at distances up to 30 plus metres and can pass through walls and floors. Major operating companies such as BP, Exxon, Chevron and Shell have all used FlexiDrive to overcome issues of accessibility.
Such a remote drive system fulfils the guidelines of HFE by eliminating potentially difficult design issues in a cost-effective way. It overcomes obstructions to access and can increase operator safety from valves in potentially hazardous areas.
Even where 90% of accidents are thought to be caused by human error, some consideration should be made to the suitability of the working environment. Incidents may occur as a consequence, whether direct or indirect, of a failure to properly consider the environment as it relates to human performance. As a result, human error can be ‘design-induced’.
Design features should support critical human tasks, especially in potentially dangerous valve operations. The aims of HFE are to reduce risk to personal health and process safety and reduce the likelihood of errors occurring. The adoption of HFE best practice ensures that adequate controls are in place to reduce the possibility of injury and potential for human error.
Smith Flow Control’s drive systems are an example of a cost effective solution, complimentary to the Human Factors Engineering discipline. The drive systems alleviate possible safety concerns and can be used across an array of industries to support safe and successful valve operations.
Reference: Human Factors Engineering in Projects, International Association of Oil and Gas Producers, August 2011