Gas distribution systems: efficient, safe and cost effective

Gas distribution systems are often considered a utility. Like a plant's electrical grid, it is often assumed that a gas distribution system will always work properly. Because these systems occur throughout the plant, no single department has exclusive responsibility for system optimization. For plant managers, other pressing operational issues usually take priority.

What is a gas distribution system?

A gas distribution system consists of a network of pipes, regulators and other components that transport gas from its source to a desired user point. Often, gas distribution systems have several purposes:

1. Access point to gas supply: Gas distribution systems create a connection between the gas source and the user point so that users have access to the gas they need.

2. Source pressure reduction: They reduce the high pressure of gas from the source to a stable and controllable pressure for various applications.

3. Gas supply without interruption: Gas distribution systems provide a continuous supply of gases, which is essential for critical processes.
   
   
4. Transport of various types of gases: These systems can handle reactive, toxic, corrosive or high-value gases, depending on the specific requirements.
   

Risks associated with gas distribution systems

Poorly functioning gas distribution systems pose risks. Examples include:

• Worker safety: Gases that escape can cause injuries to nearby workers, even if the gas itself is not dangerous.

• Equipment damage:
  Excessive pressure can cause damage to equipment, resulting in process downtime and the need for costly repairs or replacements.

• Hazardous gases:
  In cases where the system transports hazardous, toxic or flammable gases, any undetected leak can pose a significant risk to both workers and equipment.

Cost considerations

Even small gas leaks that seem harmless can eventually lead to significant costs. For example:

• Unidentified leaks of nitrogen (costs an average of a few cents in euros per^{cubic meter}) resulting in tens of thousands of dollars in losses per year.
• Leaks of more expensive gases, such as helium (with prices of tens of euros per^m3), can increase costs even faster.

At a leading chemical company, Swagelok discovered opportunities to unify the design of gas panels.

Important subsystems for gas distribution systems

A primary function of gas distribution systems is to reduce pressure from a supply source and deliver gas at a stable pressure to a user point with minimal interruption. This can be achieved by building gas distribution systems with four main subsystems:

• inlet connection from the source, supply of the gas
• primary gas pressure control
• automatic changeover
• user point

The source inlet connects the high-pressure gas source to the gas distribution system. Building the inlet requires appropriate cylinder connections, hoses, piping, filters, and vent connections. Some gas panels may not have a standard source inlet- always check the components and that the panels use the correct cylinder connector. Certain heights of pressure and/or hazardous gases (including oxygen) also require the use of special hoses.

The primary gas pressure control panel provides the initial pressure drop and provides that the medium is delivered at the proper flow rate to the next stage of the system. Pressure reduction is achieved using a single pressure regulator or by control with a dual pressure regulator. Determining exactly the correct inlet and delivery pressures is complex. It is important to consider the differences between the various media, for example ammonia which can be bottled around 8 bar and for nitrogen that is at 300 bar.

The automatic switchover panel switches from one gas source to another to ensure uninterrupted supply to user points where constant supply is required. This is accomplished through small differential pressures between two pressure regulators, allowing the system to continue operating when the first gas source is switched. The use of an automatic changeover panel prevents waste and ensures that you get as much gas as possible from each bottle. The system is safer to use and requires less labor and fewer personnel.

The user point provides the critical final stage of control. Usually equipped with a pressure regulator, pressure gauge and valve, these subsystems provide operators with a convenient and accurate method of adjusting pressure. When varying line pressure between the primary gas pressure control and the point-of-use is acceptable, a single-stage pressure regulator can be used to reduce cost and complexity.

Design and assembly of gas distribution systems.

Correct component selection, solid design and assembly, and ongoing maintenance are essential to the long-term reliability of gas distribution systems.

Component selection

Improper component selection is a common cause of unsafe or costly gas systems. Because there are a wide range of general industrial fittings, valves, regulators and other components available on the market, it can be difficult to make the right selections.

For example, choosing the right pressure regulator depends on a few key characteristics. The right regulator will:

• Be able to handle the pressures of your system
• Provide the proper flow capacity (Cv) to meet your needs at the point of use
• Be made of compatible materials that will not corrode or otherwise degrade during regular use (which applies to all components in the system)

System design

Thoughtful system design is also critical to ensure that all components work together to ensure optimal system efficiency and safety. Ideally, your subsystems should contain as few threaded connections as possible to minimize the risk of leaks. In addition, it is recommended that you choose a design that is user-friendly and allows for easy maintenance. Gas panels with clearly marked controls can simplify operation and reduce the risk of user error.

In addition to individual subsystems, it is essential that the overall system design be tailored to the specific goals and needs of your gas distribution system. This is true during the construction of new systems or when modifying existing ones. Making consistent, thoughtful choices when it comes to design, component selection and can contribute to an even safer and more efficient system.

Assembly and installation

Errors during system assembly and installation can lead to undesirable safety consequences. Improper assembly combined with insufficient testing prior to pressurization can affect not only the long-term performance of the system, but also the safety of operators and bystanders. Lack of training on gas and fluid systems is a major cause of assembly and installation problems.
Once installation is complete, it is important that operators are also properly trained to use and maintain the systems.

Watch the video below and discover the benefits of holding an evaluation of your current gas distribution system.

Maintenance

Gas panels that are easier to maintain obviously give a time advantage. Panels designed with essential components such as regulators on the front, rather than on the back, can make them easier to access when filter changes or other maintenance tasks are required.

Better accessibility to controllers can lead to:

Time savings of 30 minutes to 2 hours, depending on circumstances

Cost savings of thousands of dollars

Expertise

If you need help designing, building and assembling new gas distribution systems or evaluating existing systems, gas and fluid systems specialists can help. Choosing pre-designed, fully tested, standardized subsystems that are available will also minimize your techs' time. Suppliers can also add features or make modifications to meet your requirements.

An outside evaluation can help identify opportunities for system improvements, inform controller selection, and guide the design and assembly of engineering solutions. An expert familiar with specific gas delivery challenges can also offer suggestions for how existing systems can be modified to meet new requirements.

Although often overlooked, gas delivery is a critical component of the safe, efficient and economical operation of your facility. Therefore, your gas distribution system deserves careful attention.

Are you interested in improvement opportunities for your gas distribution system? Contact us and discover the various options