Lubrication plays a key role in maintaining the safety, integrity and performance of most machinery and equipment. But what is a lubricant? And what is the difference between an oil and a grease? Here we’ll discuss some basic principles in what is a much larger and complex subject.
By Dan Whiteley, Business Development Manager – Europe, Caspian & Africa
Many people say that lubrication is the lifeblood of machinery. It’s easy to see why. Friction occurs when two metal surfaces come into contact with one another. A lubricant helps to manage that friction by keeping the two metal surfaces apart.
To understand why this is important, imagine what would happen if the lubricant wasn’t there. As the parts came into contact with one another, vibration, noise, heat and material transfer could occur, leading to wear, damage and potential equipment failure.
This makes the selection and use of the correct lubricant essential for optimising equipment and extending its lifetime.
What is the difference between an oil and a grease?
When it comes to lubricants for industrial applications, there are two broad types: oils and greases. The key difference between the two is surprisingly simple.
- A grease is an oil with an added thickener
Which do you need for your application – a grease or an oil?
Grease and oil basically serve similar purposes. As a general rule, a grease is used if it has to stay in place, but there are other reasons why you may choose one over the other.
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People tend to choose an oil: · For high-speed applications · In closed/sealed systems · For continuous lubrication where the oil needs to flow freely · If the lubricant needs to penetrate into tight tolerances |
You will most likely want a grease: · For moderate/low-speed applications · In open/total loss systems · If improved sealing is required · If the lubricant needs to remain in place
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How to find the right lubricant for your equipment
There is much more to selecting a lubricant than ‘grease versus oil’. You need to consider many other factors, including the speed, load, temperature, and environment of the application.
If we focus on where grease selection is essential, then these considerations are particularly important when it comes to specialised applications such as gate valves used in the Oil and Gas industry.
What to look for in a gate valve lubricant in the Oil & Gas Industry
In this environment, the primary function of the valve lubricant is to protect the internal gate valve components during service, so the metal-to-metal seal remains true whenever the valve is closed. The valve lubricant also provides protection to the threaded stem of a manually operated gate valve and lubricates the stem-gate and gate-seat contacts to ensure smooth, low-torque valve functioning.
To provide long term protection, you should choose a valve lubricant with the following properties:
Adhesiveness, viscosity and density
It may seem obvious, but the most important requirement of any valve lubricant is that it remains inside the valve cavity. If the valve lubricant doesn’t have the required adhesiveness, viscosity and density, it may be displaced during operation through high pressures and flow, leaving the valve cavity & internal components unprotected.
Resilience to fluids and high temperatures
As liquids can displace a lubricant from the valve cavity, your valve lubricant must be resilient to all fluids, chemicals and any hydrocarbons that could circulate through your pressure control system. It should also be thermally stable across your system’s operating temperatures to ensure that it doesn’t melt, soften or harden during operation.
Sealing characteristics
If your gate-seat components’ seal faces are damaged, your valve lubricant can help the compromised valve gain a full pressure seal with zero LOR (Leak Off Test). This means your lubricant must have good sealing characteristics.
Proven long-term performance
If you need to repair or replace a gate valve, you will have to pause operations – which usually comes at a high cost. Therefore, gate valve lubricants must continue to perform for long periods. This makes long-term performance essential – so you should always choose a gate valve lubricant with a proven track record and significant testing behind it.
RS Clare has a 35-year global track record in providing high performance gate valve lubricants for the Oil & Gas industry, get in touch with us today.
Oil & Gas Lubricants & Lube Products | RS Clare
