Both pipelines and piping systems play a pivotal role in the transportation of fluids, gases, and other materials across various industries. Even though the terms “piping” and “pipeline” are often used interchangeably, there are significant differences between the two. The major differences between piping and pipeline are already discussed here. Note that, there are distinctions between the materials used in piping and pipelines. In this article, we’ll learn some of the differences between piping and pipeline materials while exploring their characteristics, applications, and considerations.
What are Piping Materials?
Piping refers to a system of pipes used to convey fluids within a facility or plant. Piping materials are carefully selected based on factors such as the type of fluid being transported, temperature and pressure requirements, corrosion resistance, and cost considerations. Some of the materials used in Piping are:
Common metals used in piping systems are:
- Carbon steel,
- LTCS (low-temperature carbon steel)
- Stainless steel,
- Copper, aluminum, and various other alloys.
Carbon steel is a popular choice for its strength and affordability, while stainless steel is preferred for its corrosion resistance, making it suitable for corrosive environments.
Plastic materials are chosen for their corrosion resistance, flexibility, and ease of installation. Common plastic materials in piping are:
- Polyvinyl chloride (PVC),
- Polyethylene (PE)/HDPE, and
- Polypropylene (PP)
Fiberglass-reinforced plastic (FRP) and reinforced thermosetting resin (RTR) are composite materials increasingly utilized in piping. These materials offer a balance of strength, corrosion resistance, and lightweight characteristics.
What are Pipeline Materials?
Pipelines are long-distance transportation systems designed to carry large volumes of fluids or gases over extended distances. Pipeline materials must withstand the challenges posed by external environmental factors, such as soil conditions, temperature variations, and potential ground movement. Common materials used in pipelines are:
- Carbon Steel: Carbon steel remains a predominant material for pipelines, especially in the oil and gas industry. It provides a balance of strength, durability, and cost-effectiveness. Pipeline materials use API 5L code for the pipes and API 6D code for the valves.
- High-Strength Alloys: In high-pressure and extreme temperature applications, pipelines may incorporate high-strength alloys such as X65 or X70 to ensure structural integrity.
- Corrosion-Resistant Alloys: For corrosive environments, corrosion-resistant alloys like duplex stainless steel or nickel alloys are employed to prevent degradation over time.
- Non-metallic pipelines: Pipelines can also use PE/HDPE/PP materials or FRP/GRP/RTR/GRE materials for fluid transportation.
Differences between Piping Material and Pipeline Materials
The major differences between Piping and Pipeline Materials can be discussed considering various parameters as mentioned below:
Material Selection Criteria
Piping materials are decided considering the following parameters:
- The type of fluid that will be transported through the pipes
- The design and operating temperatures and pressures of the pipes
- The flow medium characteristics, such as viscosity, density, corrosiveness, abrasiveness, etc.
- The fracture tendencies of the pipes, such as fatigue, creep, thermal expansion, etc.
- The corrosion and erosion of the pipes, such as galvanic, pitting, stress corrosion cracking, etc.
- The environment where the pipes will be working, such as indoor, outdoor, underground, underwater, etc.
On the other hand, pipeline materials are selected considering the following factors:
- The fluid transportation efficiency (the ability of the pipeline to deliver the fluid with minimal losses, such as friction, leakage, etc.)
- Safety and reliability (the ability of the pipeline to prevent or withstand failures, such as rupture, explosion, fire, etc.)
- The environmental impact (the effect of the pipeline on the surrounding environment, such as soil, water, air, wildlife, etc.)
Piping materials have the capability of carrying fluids at very high temperatures and pressures. While the temperature capability of Pipelines is limited to 232 degrees C as per ASME B31.8 (120 degrees C as per ASME B31.4).
Design Allowable Stresses
Piping materials are limited by the design’s allowable stresses which is governed by the term Sc and Sh which are much lower than the material yield strength. On the other hand, the pipeline material’s design allowable stress is governed by SMYS (Specified minimum yield strength). So, pipeline materials have a very low safety factor than piping materials.
For the same pressure rating, pipeline materials usually have less material thickness as compared to piping materials. Hence, the weight of the piping materials is more than that of pipeline materials for the same pressure classes.
Piping materials are usually hydrostatically tested at 1.5 times the design pressure whereas pipeline materials are hydrotested at 1.25 times the design pressure.
In most cases, the piping materials have to resist the corrosion generated by the fluid it carries means internal corrosion. While pipeline materials need to withstand external corrosion from soil and environmental factors.
Temperature and Pressure Ratings
Piping materials must meet specific temperature and pressure requirements based on the application, while pipeline materials need to account for the varying conditions along their extensive routes.
Piping materials are often selected based on factors such as installation costs and ease of maintenance within a confined space. Pipeline materials, on the other hand, must balance upfront costs with the long-term durability required for extended transportation routes.
Pipelines traverse diverse landscapes, and materials must be chosen considering factors like soil conditions, seismic activity, and temperature fluctuations.
In a nutshell, Piping materials are often constructed with a wide range of materials and components, such as cast iron, carbon steel, low-temperature carbon steel, alloy steel, stainless steel, duplex stainless steel, nickel alloys, aluminum, titanium, etc. Piping materials also use different codes and standards for the pipes, fittings, and valves, such as ASTM, BS, API 5L, ASME B31, ANSI, DIN, ISO, etc. Pipeline materials have to mainly consider fluid transportation efficiency, safety and reliability, and environmental impact. Pipeline materials are typically constructed with a single type of material, such as steel, plastic, or composite. Pipeline materials use API 5L code for the pipes and API 6D code for the valves.