Why Mechanical Seal Support Material Matters for Northern Alberta Oil and Gas Operations

Centrifugal pumps at chemical plants and refineries rely on mechanical seals to prevent fluid from escaping. Every seal connection is a potential leak point, and leaks can lead to fugitive emissions, asset damage, unplanned downtime, environmental issues, and safety risks. Therefore, it’s important to pay attention to not only the mechanical seal itself but also the entire seal support system, including the mechanical seal support material components.

Most plants have historically used carbon steel piping with numerous threaded connections for their seal support systems. However, the fourth edition of API 682 recommends reducing threading and connection points wherever possible, leading the industry to shift to bendable tubing systems as the preferred choice for seal support systems. The 4th edition of API 682 recommends tubing as a mechanical seal support material to reduce potential leak points from connections. This article will explain the differences between tubing and piping and the advantages of tubing as a mechanical seal support material.

What Is the Difference between Piping and Tubing?

The words “pipe” and “tube” are sometimes used interchangeably, but there are significant differences between them.

Piping is round with its size designated by a schedule specifying the nominal pipe size (NPS) and wall thickness (WT), which roughly represents its capacity. The standard pipe schedules are covered by ASME B36.10 for wrought steel pipe and ASME B36.19 for stainless steel. Piping is usually welded in installation, and its most important mechanical parameters are its pressure rating, yield strength, and ductility. 

Tubing is measured by its outer diameter (OD) and wall thickness. Tubing is available in many more sizes than standard pipe schedules and is identified by the OD and WT dimensions. These dimensions are held to much tighter tolerances than pipe schedules. Unlike piping, tubing is extruded, which gives it much more consistent dimensions and surface finish. Tubing can also be bent to produce smooth directional changes, allowing for continuous, seamless tubing that needs minimal fittings for connections.

Advantages of Tubing as Mechanical Seal Support Material

Today’s fluid systems have much tougher demands than they had in the past. Modern processes have increasingly higher pressures, flow, and temperature requirements, but basic piping technology and methodology have not changed much. In addition, tougher regulatory requirements and industry standards have made leak detection and prevention higher priorities.

Replacing piping with tubing is an effective way to handle these more demanding process parameters and tougher regulations. Tubing has several advantages over piping:

Ease of installation. Tubing can usually be installed more quickly and cheaply than piping. While piping usually needs to be welded to seal effectively, tubing can be drawn into seamless shapes with minimal connections between components.

No elbows. Tube bending allows for compact systems with smooth directional changes, which results in smoother flow compared to piping, where flow becomes more turbulent as it passes through elbows.

Dimensional precision. As opposed to the standard pipe schedules, tubing is available in more options of diameters and wall thicknesses, and the tolerances are much tighter. Whereas piping dimensions are approximate and not very tightly controlled, tube wall thicknesses are much more uniform, allowing them to safely support higher pressures.

Better surface finish. The extrusion process gives tubing a smoother, more consistent internal surface finish than piping, producing better flow characteristics and better corrosion resistance when H₂S is present.

Fewer leak points. Tube fittings are designed not to leak because they have either a metal-to-metal seal or a mating component with an elastomeric seal. Piping, on the other hand, often requires threaded connections, pipe dope, and/or PTFE tape to minimize leakage. Pipes can be welded to prevent leaking, but this adds time and money to installation. Tubing systems can be installed easily with fewer connections—which means fewer potential leak points.

Lower costs. Tubing systems also tend to cost less overall than piping. Tubing is usually less expensive than piping, and although tube fittings cost more than pipe components, tubing systems as a whole save money in the long run because of the reduced downtime and simpler assembly and disassembly.

With its improved flow characteristics, improved sealing ability, ease of installation and maintenance, and reduced costs, tubing is usually the superior option for mechanical seal support material.

Mechanical Seal Support Materials: Pipe vs. Tube Summary

Look to Local Seal Support System Experts for Help

If you have questions about which mechanical seal support materials and components are best for your application, Edmonton Valve & Fitting can help. Our Field Advisors are experts in API 682 implementation for Northern Alberta refineries and will make sure you get the seal support solution you need. We can perform an onsite assessment to understand your process, then use that information to create the technical specifications for your seal support system.

In addition to determining the best seal support systems to use for your process, our Field Advisors can make specific recommendations regarding panel layout, instrumentation, and custom components to boost efficiency and reliability. Our goal is to ensure you have the best possible seal support system for your needs. All our products are backed by Swagelok’s industry-leading Limited Lifetime Warranty.