How to Maintain Dry Gas Seal Pressure: What Northern California Refineries Need to Know
by Malik Durojaiye, on 10/1/21 9:00 AM
In many instances, dry gas seals are the preferred method for containing process fluids. When compared to wet seals, dry gas seals:
- have lower leakage rates;
- eliminate oil leakage that contaminates process gas;
- have lower power consumption;
- have a simpler design;
- and are more environmentally sustainable.
When leaks do occur in dry gas seals, process fluids are efficiently routed to a collection system. Often dry gas seals are the only option for heat-sensitive fluids and fluids that are corrosive to mechanical seals. However, dry gas seal pressure needs to be maintained to ensure mission-critical processing operations.
The loss in dry gas seal pressure can be varied but is frequently due to contaminants in the dry gas seal and deteriorating components. These issues can sometimes compound; deteriorating components result in additional contaminants in processes, resulting in extra wear and tear of parts. A loss of dry seal gas pressure could effectively shut down operations. As issues with that pressure may exacerbate other complications, it is imperative to understand potential solutions to problems causing low pressure in dry gas seals and seek expert guidance.
Determining the Causes of Low Pressure in Dry Gas Seals
Frequent causes of low dry gas seal pressure include damage to the seal faces that causes a gap between the grooves and contaminants getting inside seal components. Seal gas should be dry for effective operations to occur. However, when contaminants—such as dirt, liquid, and gas contaminated with outside particulates—get inside seal components, static faces are created, resulting in high seal gas flows. Though initially, this may result in increased pressure in dry gas seals, the long-term damage on components not being used at optimal conditions may result in leaks and a loss of pressure in dry gas seals.
Separating Grooves on Seal Faces
A notable characteristic of dry gas seals is the small grooves on the seal faces. Static pressure holds the seal faces together, but when pressure is greater than this static pressure, the faces separate, and a thin layer of gas forms between the seal faces. The small grooves in the seal faces increase the pressure between the stationary face and the rotating face and allow this thin layer of gas to form.
Contaminants can make these grooves ineffective at separating the seal faces. As a result, the grooves can become plugged with contaminants. In addition, the low pressure of the gas—from weakened grooves—creates a cascade of events such that the seal faces contact each other, and damage occurs to the seal faces.
Though contaminants may result in dry gas seals with low pressure, so too may deteriorating components. Deteriorating components may create low pressure in dry gas seals through leaks, the inability to create pressure in the buffer gas, and by allowing outside contaminants into processes.
Deteriorating components can cause issues with low pressure in dry gas seals in many ways. For example, an issue with a damaged filter may cause outside particulates to enter into the operating system. Or, if piping isn’t completely sealed, it may allow dirt to enter the supply line.
Deterioration can also occur if the gas delivery system—piping, valves, gas sources—accrued damage from typical operations or during maintenance of other components. This damage could lead to contaminants entering the system. This is especially true when aged carbon steel pipe begins to corrode. It’s important to replace these systems with quality stainless steel tubing.
In addition to the potential for pollutants to enter the system through damaged or deteriorating systems, dry gas seal low pressure can also be a result of ineffective control.
Ineffective Control of Pressure
The seal support system panel must be properly set for the pressure and flow based on the substances in operations. Improper settings or malfunctioning seal support systems may damage seal integrity. The material involved in operations should be selected based on the conditions and chemicals in operational processes. For instance, the type of elastomers used in O-rings must tolerate the pressure, temperature, and chemicals involved in successful operation.
Despite the many issues that can result in low pressure in dry gas seals, experts can help determine the problem and replace or refurbish components if needed.
Maintain Dry Gas Seal Pressure With Expert Guidance
Dry gas seal troubleshooting can be difficult without the proper training. When not properly assessed or tended to in time, issues that impact dry gas seal pressure can lead to costly and unplanned downtime. It’s best to identify the root cause as soon as possible.
At Swagelok, we understand the importance of designing and fabricating support systems that will maximize uptime for equipment using dry gas seals. For decades we’ve been helping process and manufacturing companies in Northern California and Western Nevada to improve the reliability of critical compressors and centrifugal pumps.
Our Field Engineers are available for consulting at your facility or online. We’ll work closely with you to understand your specific process requirements. With this understanding, we’ll design, fabricate, and thoroughly test your dry gas seal support systems following ISO 9001 standards. The result: maintained pressure in dry gas seal support systems that boost uptime and minimize any time you spend troubleshooting.
About Malik Durojaiye | Field Engineer, Assembly Services
Malik Durojaiye began his Swagelok career in 2019 as a Custom Solutions Engineer in our Assembly Services group. Prior to Swagelok, Malik developed as a design engineer as well as a manufacturing engineer for 6 years serving Kentucky and California with Altec Industries; a leading provider of products and services to the electric utility, telecommunications, tree care, lights and signs, and contractor markets.