A gas pipe system encompasses a network of pipes and other related equipment used to transport and distribute gas to end-users. Gas pipe systems can carry various types of gases like natural and industrial gases for instance.
Types of Gas Pipe Systems
There are different types of gas pipe systems varying with factors like design, application, and gas being transported. Common types of gas piping systems include:
Natural Gas Distribution System
This gas pipe system delivers natural gas for applications such as heating, cooking, and electricity generation. Natural gas pipelines typically serve industrial, residential and commercial customers.
Industrial Gas Pipe Systems
Transports the different gases utilized in industrial processes such as nitrogen, helium, oxygen, hydrogen and argon. They are designed to meet the pressure requirements and specific purity of industrial applications.
Medical Gas Systems
Provide gases used in various medical operations such as oxygen and nitrous oxide to healthcare facilities. These are utilized in patient care like respiratory therapy and life support as well as surgeries.
Materials Used For Gas Pipe System
The choice of materials for gas pipe systems is crucial as it directly impacts durability, system efficiency, and safety. The material selected is dependent on factors like the gas type being transported and the operating conditions.
Some of the materials used for gas pipe systems include:
PVC (Polyvinyl Chloride)
PVC is a plastic-type known for its versatility and chemical resistance. When used for gas pipe systems, it is possible to fashion different sizes to accommodate different pressures. The standard color code for PVC gas pipes is yellow making it easily distinguishable.
Advantages
- Corrosion Resistance: PVC is highly resistant to corrosion eliminating the risk of degradation suitable for both indoor and outdoor piping systems.
- Lightweight: Gas pipes made from this material are lightweight simplifying handling and easy to transport and install.
- Cost-Effective: The cost of manufacturing PVC pipes is low making this a cost-effective option when setting up large-scale systems.
- Ease of Installation: PVC gas pipes are relatively easy to install. They can be joined using solvent cement, which creates strong, leak-resistant connections.
- Low Friction Loss: Since the PVC pipes have a smooth interior, there’s minimal friction loss which allows for efficient flow of gas.
- Durable: You can expect an extended service life when using PVC pipes typically over fifty years when installed and maintained properly.
Limitations
- Temperature and UV Sensitive: Very low temperatures may hamper the integrity of PVC pipes making them brittle. Additionally, sustained exposure to UV radiation degrades PVC pipes.
- Pressure Limitations: Where the gas pipe system is meant for high-pressure gas distribution, PVC gas pipes may not be ideal given their low capacity.
- Fire Hazard: PVC material can catch fire and burn easily, putting piping systems using PVC at risk of fires. This warrants the use of safety measures.
Polyethylene (PE)
Polyethylene gas pipes can utilize either high-density polyethylene (HDPE) or medium-density polyethylene (MDPE). HDPE finds more common use given that it is a high-density polymer with corrosion resistance, excellent strength, and durability. It also displays a high strength-to-weight ratio.
While MDPE is a lower-density polymer compared to HDPE, it offers good flexibility and crack resistance. It finds most use in residential gas pipe systems where they are used for underground gas lines.
Polyethylene gas piping offers the following advantages:
- Corrosion Resistance: Pipe systems made from PE are highly resistant to corrosion conducive for underground use not ideal for metal pipes.
- Flexible: Installing PE pipes is uncomplicated when facing challenges like uneven terrain thanks to their flexibility. This reduces the need for multiple joints and fittings which works against leakages.
- Wide Range of Pressure Ratings: Gas pipe systems using HDPE/MDPE are available in various pressure ratings to suit applications requirements. They can serve both low-pressure systems like residential applications to high-pressure systems like industrial installations.
- Lightweight: Polyethylene pipes are significantly lighter than metal alternatives. This makes their handling and transportation less cumbersome reducing labor and transportation costs.
- Leak Resistant: When you properly fuse polyethylene pipes, the resulting joints are secure and leak-resistant. This enhances overall reliability and safety of the gas pipe system.
- Fusion Welding: PE pipes are usually joined by using heat fusion techniques which create a strong, homogeneous joint ensuring system integrity.
- Durable: With proper installation and maintenance PE gas pipes have a long service life. As a result, there’s less need for frequent replacements and maintenance.
Limitations
- Temperature Sensitive: PE pipes are susceptible to very low temperatures where they become brittle making installation in extremely cold environments untenable.
- UV Degradation: Sustained exposure of pipes using PE to ultraviolet (UV) radiation, can degrade the material especially when installed above ground.
- Mechanical Strength: While it demonstrates high tensile strength, this piping material is not mechanically robust like say, steel. As such, it can be mechanically damaged during installation or excavation activities when care is not taken.
- Limited Fire Resistance: Polyethylene is combustible making it vulnerable to fires and thus damage. Fire safety measures are therefore required during installation.
- Pressure De-rating: High temperatures necessitate pressure de-rating in PE gas pipe systems hampering their pressure capacity.
Hot-Dip Galvanized Steel
These gas pipes are steel pipes coated with a zinc layer via hot-dipping process. The galvanization process provides several benefits when used in gas distribution systems particularly in outdoor and underground applications.
Advantages
- Corrosion Resistance: The hot-dip galvanization process creates a protective zinc layer over the steel surface significantly enhancing corrosion resistance.
- Longevity: Hot-dip galvanized steel gas pipes have an extended service life given proper installation and maintenance.
- Strength and Durability: Galvanized steel pipes display high tensile strength and durability exemplified by their mechanical stress resistance. This property is particularly useful for gas piping done underground.
- Wide Range of Sizes and Pressure Ratings: Gas pipe systems built with galvanized steel can be made to different sizes capable of accommodating diverse pressure ratings.
- Fire Resistance: Galvanized steel does not easily catch fire and can be less aggravating in case of a fire break out.
Limitations
- Weight: Compared to alternative gas pipe materials like plastic, galvanized steel pipes are heavier. The added weight can pose a challenge in handling and transportation increasing installation costs.
- Thermal Conductivity: The thermal conductivity of steel is relatively high, making heat loss a problem in as piping utilizing this material. Consequently, when used in cold climate regions, insulation may be used to intervene in heat loss increasing the costs of installation.
The black iron material used for gas pipe systems is typically low-carbon or mild steel with a black, iron oxide coating. This coating offers some corrosion resistance. Gas pipes made from black iron are distinguished by their wall thicknesses.
Advantages
- Strong and Durable: Black iron is a high-strength and durable material making its use for both underground and above-ground piping applications possible.
- Corrosion Resistance: While its corrosion resistance is relatively lower than galvanized steel, black iron can effectively protect against corrosion when used indoors.
- Cost-Effective: Compared to stainless steel and copper, gas pipe systems utilizing black iron are relatively affordable.
- Wide Range of Sizes: Black iron pipes are presented in various thicknesses and sizes to accommodate varied pressure ratings for specific application requirements.
Limitations
- Corrosion Susceptibility: In especially aggressive environments with high moisture exposure, the iron oxide coating can deteriorate over time resulting in corrosion.
- Weight: Gas pipes made from black iron are relatively heavy making handling and transport a little bit handful. When using such pipes with large diameters, you may need additional support structures.
- Fire Hazard: Black iron is combustible making it a potential fire hazard. Thus, they are unsuitable for distributing highly combustible gases like methane and oxygen.
Aluminum-Plastic Composite
Gas pipe systems utilizing aluminum and plastic typically consist of an aluminum layer sandwiched between plastic layers. The aluminum layer offers increased strength and rigidity in addition to impermeability to other gases enhancing durability.
Advantages
- Corrosion Resistance: Having an inner and outer plastic layer makes the pipe highly resistant to corrosion and thus degradation.
- Gas Containment: The aluminum layer prevents diffusion of gases like oxygen into the pipe and escape of gas from the pipe.
- Flexible: Aluminum-plastic composite is flexible making installation of gas piping simple especially where the terrain is uneven. This also impacts installation by reducing the need for many joints and fittings, and thus leakage.
- Lightweight: Compared to traditional metal pipes, aluminum-plastic composite pipes are lighter simplifying transportation and handling.
- Durable: Aluminum-plastic composite gas pipes can offer in excess of 50 years of service minimizing maintenance costs and need for replacements.
- Thermal Insulation: Having an aluminum layer offers some degree of thermal insulation which reduces heat loss helping maintain gas temperature.
Limitations
- UV Sensitivity: The outer plastic layer makes gas pipe systems using aluminum-plastic composite sensitive to UV radiation when exposed to direct sunlight.
- Pressure De-rating: At elevated temperatures, these pipes may have reduced pressure capacity due to their high thermal expansion rate.
Flexible Corrugated Stainless Steel
This gas piping material finds common use in natural gas pipelines and residential gas pipe systems. It features a thin-walled, flexible stainless steel tube as the core with corrugations along its length. Additionally, it has a protective outer layer fashioned from material like polymer.
The stainless steel provides strength, durability, and corrosion resistance while the corrugations offer flexibility. The outer layer protects against physical damage from UV degradation as well as other environmental factors.
Advantages
- Uncomplicated Installation: The flexibility of this material makes installation relatively simpler when compared to piping systems using rigid metal.
- Corrosion Resistant: Having stainless steel for the piping’s core makes it resistant to corrosion, keeping the system integrity intact.
- High Flow Capacity: This particular piping features a smooth interior surface minimizing resistance to gas flow. As a result, it allows for high flow rates and efficient gas distribution.
- Flexible: The corrugated design makes it possible to bend the pipes in conformity to the terrain at the point of installation.
- Lightweight: Flexile corrugated stainless steel is lightweight reducing the complexities involved in transportation and handling when dealing with heavy material.
Limitations
- Temperature Limitation: Since stainless steel has a high rate of thermal expansion, using this material is unsuitable for pipe systems in high-temperature applications.
- Maintenance: Having multiple components like the inner layer and jacket means periodic inspections are necessary to identify damage or wear.
Factors Affecting Gas Pipe System Material
When determining the material for use in your gas pipe system, you need to consider a variety of factors. Some of these are:
- Gas Type: The composition of the gas being transported determines its potential corrosive properties. As such, where the gas is corrosive, you need corrosion resistant gas piping material.
- Operating Conditions: When the piping system is used above ground, it is subject to environmental conditions like temperature and pressure. Therefore, the material used should be tolerant to the prevailing conditions.
- Application: Gas pipe systems serve different uses such as national gas pipelines and residential gas pipe systems. The former are high-pressure systems which warrants use of materials capable of supporting such pressures.
- Regulatory Requirements: There are safety and regulatory standards put forward by responsible agencies guiding gas pipe systems. These standards guide issues like piping material describing distinct or unique use of such for particular applications.
- Cost and Availability: When setting up gas pipe systems, cost is a significant factor determined by the availability of the material and ease of installation.
Components in a Gas Pipe System
A gas pipe system constitutes several components making it possible for gas transportation from the source to point of use. These components ensure the system functions safely and efficiently while maintaining the integrity of the gas supply.
Some key components in a gas pipe system are captured below:
Pipelines
A gas pipe system’s primary infrastructure is its pipelines typically fashioned from different materials like steel and plastic. Pipelines carry gas over long distances often from production facilities or processing plants to distribution points. Pipelines have different sizes and capacities depending on the volume of gas being transported.
Pipe fittings connect, control, and modify the direction or flow of gas within a pipeline network. These fittings come in various types, shapes, and sizes and include the following:
- Elbows: Available in 45 and 90-degree angles, they allow for turns in the pipeline to navigate obstacles or change gas flow direction.
- Tees: Feature three openings allowing gas to flow in three different directions allowing connecting pipelines or the addition of new lines.
- Reducers: Connect pipes of different sizes, allowing smooth transition useful in maintaining appropriate flow rate and pressure.
- Couplings: Used to join two pipes together in a straight line often during repairs or when extending pipeline length.
- Flanges: These are flat, circular fittings with bolt holes around the perimeter used to connect pipes, valves, or equipment by bolting them together.
Regulators
These control gas pressure as it flows through a pipeline. They lower the pressures of gas from the high-pressure transmission or distribution pipelines, conducive for a specific application.
This is because typically, gas is transported at high pressures to reduce the pipeline size and cost.
Regulators maintain safe gas pressure levels within the distribution system without which the system can leak or damage. There are various types of regulators depending on the application such as service regulators, intermediate regulators, high-pressure regulators, and industrial regulators.
In gas pipe systems, meters measure the flow rate and quantity of natural gas being transported. This s essential in determining gas consumption for billing purposes. Common types of gas meters used in gas pipe systems are:
- Rotary Meters: Utilize a rotating mechanism, usually multiple impellers, to measure gas flow common in industrial applications with higher flow rates.
- Diaphragm Meters: Common in residential and commercial applications operating by moving flexible diaphragms that expand and contract as gas flows.
- Ultrasonic Meters: Utilize sound waves in the measurement of gas flow.
- Turbine Meters: Accurately measure gas flow using a spinning turbine wheel finding use in both industrial and residential gas pipe systems.
- Orifice Meters: Consist a plate with a hole that restricts gas flow, with the resulting pressure drop used to determine flow rate.
Valves
These components are essential in the regulation, control and isolation of gas flow in natural gas pipelines. Valves can be opened or closed (partially or wholly) to adjust the gas flow rate essential for maintaining the desired system pressure.
When it comes to the safety of gas pipelines, valves are critical capable of being quickly closed in case of emergencies. When leaks or equipment failure occurs, valves can isolate the affected pipeline section to contain the problem.
Various types of valves are used in gas pipe systems including:
- Gate Valves: Used for on/off control especially for isolation purposes. They feature a gate-like disc raised and lowered to initiate valve opening and closing.
- Butterfly Valves: Here, a flat, rotating disc regulates gas flow in both on/off and throttling applications.
- Ball Valves: Have a bored spherical disc that control gas flow through quick, quarter-turn operation to initiate opening and closing.
- Check Valves: Allow for the flow of gas in only one direction preventing backflow.
- Pressure Relief Valves: These valves function to release excess pressure from the system preventing over-pressurization that can result in equipment damage.
Installing a Gas Pipe System
The process of installing a gas pipe system is a critical one requiring the utmost care and conformance to safety regulations. The following steps will generally guide you in conducting proper installation of gas line for residential:
i. Planning and Design: Consider factors like gas type, equipment, number of outlets, and route in developing a detailed design for your gas line. The design should also comply with local building codes and safety regulations accompanied by any necessary permits.
ii. Materials and Equipment: Obtain and organize the necessary materials and equipment you require for the installation process including components like valves, fittings, and regulators.
iii. Installation Process: Lay out the gas line as per the design using fittings to properly align and secure the pipes. Having valves and regulators at strategic points helps in the control of gas flow and pressure and later maintenance activities.
iv. Pressure Testing: This test is essential in ensuring there are no leaks before you start using the gas line. After pressurizing the system to a required level, keep a close eye for some time to identify any pressure drop or leakage.
v. Connecting Equipment: After confirming everything is in order, connect your appliances and equipment to the gas line. Perform more safety checks on the entire gas line system verifying the gas pressure for each equipment.
Factors Influencing Pipe Size in Gas Pipe Systems
Selecting the appropriate pipe size for a gas pipe system is a critical aspect of system design. The size of the pipe directly affects the system’s efficiency, safety, and functionality. The following lists some factors that influence the choice of pipe size:
i. Flow Rate: This is a primary factor typically measured in cubic feet/meter per hour. The higher the flow rate the larger the pipe diameter needed and the opposite is true.
ii. Pipe Material: This affects frictional resistance and as a result pressure drop. Materials like HDPE and PVC have smooth interiors which result in lower frictional resistance.
iii. Temperature: Gas temperature and that of the environment can affect the gas density and as a result flow characteristics. Where the temperatures are extremely high, this must be accommodated in the pipe design and size.
iv. Pressure Drop: Minimal pressure drop ensures the gas pressure is adequate during use. Pressure drop is a result of frictional resistance against the flowing gas prevalent in smaller pipes.
v. Gas Type: Different gas types have different densities which brings about different flow characteristics. Dense gases will require larger diameter pipes than less dense gases.
vi. Regulatory Requirements: There are regulatory standards and building codes that guide the minimum pipe size requirements. These are stipulated for different gas types to ensure safety and suitability in prevailing operational considerations.
vii. Pressure Conditions: Higher pressure systems require larger pipe sizes to safely accommodate and efficiently distribute gas.
viii. Length of Pipe Run: Larger pipe diameters on longer pipe runs ensure the gas pressure remains within acceptable limits at line end. This is because longer pipe runs increase frictional resistance.
Issues Common in Gas Pipe Systems
Sometimes gas pipe systems can experience various issues that require attention to maintain safety and efficiency. Some of the issues that can occur in gas pipe systems are mentioned below:
i. Leaks: This can occur due to pipe damaged or loose fittings or faulty connections. Gas leaks pose a great danger in gas pipe systems since gas is highly flammable posing a significant risk of fire or explosion.
ii. Corrosion: When corrosion occurs, it can weaken the metal gas pipes hampering their integrity and resulting in leaks.
iii. Pressure Issues: Gas pipe systems require just adequate pressure for effective end-use performance. Very low pressure can result in performance deficiency in appliances whereas high pressure can damage appliances.
iv. Blockages: When debris and other foreign matter get stuck in gas pipes they block the path of gas flow. This is dangerous since pressure buildup at the blockage can result in pipe damage.
v. Gas Odor: While natural gas is odorless, an odorant is added to aid in identifying leaks. When this odor is absent it can make leaks harder to detect posing great risk.
vi. Environmental Factors: Factors like soil erosion, flooding, and extremely high temperatures can affect gas pipe systems. Soil erosion and flooding can damage the piping while high temperatures can alter flow characteristics.
Uses of Gas Pipe Systems
Gas pipe systems serve a wide range of purposes in industrial, residential, and commercial settings. These systems are used in the distribution of gases like propane and natural gas safely to various points of use.
Some common uses of gas pipe systems are highlighted thus:
- Industrial and Manufacturing: Gas pipe systems are used to deliver gases like argon, nitrogen, and carbon (IV) oxide for industrial processes. For instance, CO2 is used for filling carbonated drinks whereas nitrogen is used in packaging food substances to retain freshness.
- Cooking: High-rise apartments and other planned estates utilize gas pipe systems to distribute LPG to each household for cooking. A similar system is also found in commercial kitchens, hotels, and restaurants.
- Hospitals: Oxygen used for life support, palliative care, and even surgery are delivered throughout the various hospital wards and sections via gas piping.
- Heating: In colder areas experiencing low-temperature winters, gas pipe systems are used for space heating through the floors and walls. Heat is generated by furnaces and boilers utilizing propane or natural gas before distribution via HVAC systems.
- Greenhouses: The heating system for greenhouses in colder areas is gas-based and built on the infrastructure of a gas pipe system.
- Laboratories: Gas pipe systems are used to supply gas for various applications in laboratories requiring equipment like Bunsen burners.
Why Use Gas Pipe Systems
Use of gas pipe systems has enabled the efficient distribution and delivery of gas to different points of use. Here are some key reasons why gas pipe systems are preferred and widely used:
i. Efficiency: Gas is a highly efficient energy source, especially for heating producing a high amount of heat per unit of fuel. Its use is thus enabled via gas pipe systems allowing wide distribution access.
ii. Clean Energy: Since natural gas and propane are considered clean fuels as opposed to other fossil fuels like coal and oil. Utilizing gas pipe systems in their distribution ensures fewer emissions of pollutants like nitrogen oxides.
iii. Versatility: Gas pipe systems find use across a wide range of applications not limited to industrial processes, heating, cooking, and power generation.
iv. Reliable: When correctly designed, installed, and maintained, gas pipe systems are highly reliable ensuring an efficient and consistent energy source supply.
v. Scalable: There are various gas pipe systems designed to meet specific application needs. Gas pipe systems can be as large and complex as natural gas pipelines to residential gas pipe systems.
Conclusion
Gas pipe systems are critical in the distribution of gas for commercial use such as natural gas and propane. While highly reliable, gas pipe systems require careful consideration throughout the design process, installation, and operation to avoid catastrophes.
