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Tank cars transport hazardous and non-hazardous materials across the country every day, and ensuring their safety is a top priority. One of the most important safeguards in place is the safety relief valve. These valves prevent dangerous overpressure situations, reducing the risk of leaks, spills, and costly damage.
Choosing the right safety relief valve isn’t just about compliance—it’s about protecting people, the environment, and your bottom line. Regular maintenance and adherence to industry standards help ensure that tank car systems operate safely and efficiently, no matter what they’re carrying.
What Are Safety Relief Valves?
Normal relief valves open and close gradually. Safety relief valves are designed to open quickly and stay open until pressure is reduced. They are triggered when a certain pressure limit is reached.
Without a safety relief valve, pressure can continue to build until the container explodes. This is called an overpressure incident and can result in a hazardous spill. Safety relief valves are entirely mechanical, making them extremely reliable.
A spring holds the valve closed, with an adjusting screw controlling the set pressure, and an outlet port that directs the relieved fluid away safely.
When system pressure rises above the limit, it overcomes the spring's tension and the valve opens, releasing the excess fluid or gas. As soon as the pressure returns to normal, the spring pushes the valve closed again. There's no need for any human intervention.
Alternatively, some valves use a small pilot valve that detects pressure changes and others detect pressure changes caused by heat, opening at much smaller increases.
Safety Relief Valves and Industrial Safety
The key role of safety relief valves is to prevent overpressure incidents, which can lead to dramatic explosions. These explosions can injure or kill nearby personnel and release large quantities of hazardous liquids or gases into the environment. Even if the container doesn't explode, an overpressure incident can cause a rupture and a significant leak.
These valves are the ultimate fail-safe when other systems for preventing overpressure fail, or when human error causes a problem. For example, a tank car may be loaded beyond its normal limits due to operator fatigue.
Preventing Equipment Damage
Safety relief valves reduce the stress put on the equipment by high pressure and prevent costly ruptures and explosions. In industrial operations, they also ensure the smooth flow of material, reducing overall wear and tear on machinery and pipelines. This can then prevent more damage in the future by extending the life of systems.
They can protect other valves from potentially blowing in the case of an incident while opening and closing safely without damage.
Minimizing Risk to Personnel
Explosions and leaks can cause injury and even death to personnel working nearby. Safety relief valves minimize this risk and allow workers to be safe and confident when working around hazardous materials. Combined with other measures such as proper use of PPE, they help keep your employees safe and avoid the human damage and cost of workplace injuries.
Protecting the Environment
While a small amount of hazardous material might leak when a safety relief valve opens, it will be much less than if the entire container is compromised. This reduces spills and emissions, protecting the environment, nearby residents, and wildlife from exposure to toxic chemicals.
Even non-hazardous materials such as food products can cause localized environmental damage when released.
Why Regulatory Requirements Matter With Safety Relief Valves
Regulatory requirements exist to ensure that minimum safety guidelines are met, creating a safe and efficient environment. They also help protect you from legal liability; if you use valves that are not up to code and something happens, you are much more likely to be sued...and lose.
The three most prominent standards are ISO, API, and ANSI.
International Organization for Standardization (ISO)
ISO standards are recognized in 173 countries, including the United States, Canada, and Mexico. Some smaller countries are not full members of ISO, but every country is in communication with the organization.
This means that ISO standards are usable in global trade and are internationally recognized. The standard outlines performance requirements and testing protocols, including extreme conditions. Adhering to ISO standards shows commitment to both high-quality products and internationally recognized norms and is particularly important if you trade across borders.
American Petroleum Institute (API)
If you are operating in the oil and gas industry, API provides standards for valve sizes, pressure ratings, and testing requirements. The energy sector has particularly demanding requirements, especially given the high stakes of a breach.
Using API standards helps you meet these requirements and demonstrates your commitment to safety. They are widely accepted in the oil and gas industry, including in foreign markets, due to their stringency.
American National Standards Institute (ANSI)
ANSI oversees most of the standards for manufacturing and operational safety in the U.S. Meeting ANSI standards is vital for both safety and compliance, and they cover design, construction, and inspection protocols. You can be fined or even shut down if you violate ANSI standards. They are the central clearing house for most standards in the U.S., so make sure any valves you purchase are marked as ANSI compliant.
Relief values that comply with these standards help keep personnel and the environment safe, and operations running smoothly. Your operational integrity...and your bottom line...will benefit.
What to Consider When Selecting a Safety Relief Valve
Choosing the right valve is key to both safety and performance. You need to choose a material that matches the material being transported and the environment you are working in, and which resists corrosion and extreme conditions.
Make sure your valve works with the pressure and temperature ranges normal for your system and that it is durable and easy to service. Valves require routine maintenance to operate properly, and valve seals or disks should be repaired or replaced as needed to make sure that the valve itself does not leak.
Best Practices for Selecting a Safety Relief Valve
When choosing your safety relief valves, you need to:
- Identify operating requirements including pressure levels, temperature demands, and media type. For example, take into account fluid vibration (often an issue with oil).
- Specifically tailor valves to each application and situation. This may mean a different type of valve in different places. Do not switch valves between locations unless they are genuinely identical.
- Check sizing. Under- or oversized valves compromise safety and efficiency and may also be more likely to release unnecessarily, resulting in leaks and impacting efficiency and costs.
- Perform routine inspections and maintenance to make sure your operations continue to run smoothly and correctly. Valves should be inspected every 6 to 12 months per manufacturers' recommendation.
Seeing professional advice can help avoid system issues. Professional installers can take measurements and make sure your valves are correctly sized and correctly installed for maximum safety and efficiency.
Stay Safe With the Right Relief Valve
Regardless of your industry or application, safety valve systems protect equipment, personnel, and the environment. Make sure that you adhere to all relevant standards and provide for consistent maintenance.
Selecting the right safety valve for your needs helps keep everyone safe and improves your bottom line. At McKenzie Valve, we have the expertise to help you choose the right safety relief valves...as well as other industrial parts for your needs.
Contact McKenzie Valve for safety relief valves that meet the highest standards and toughest demands.
FAQs
What is a safety relief valve, and why is it important?
A safety relief valve is a mechanical device that automatically opens when pressure reaches a certain level, often spring-operated. This releases excess pressure, protecting equipment, personnel, and the environment.
What industries rely on safety relief valves?
Many industries use safety relief valves, but the ones that rely on them the most are oil and gas, chemical processing, power generation, and food manufacturing (especially dairy).
How do I choose the right safety relief valve for my system?
You need to consider system pressure, temperature, fluid or media type, and compliance with industry standards. Don't forget to make sure the valves are the correct size.
What are the consequences of a malfunctioning safety relief valve?
A malfunctioning safety relief valve may either not release when needed, or release prematurely. The former results in significant safety risks including the potential risk of an explosion and large-scale spill. A valve that releases prematurely, on the other hand, can cause a leak resulting in costs. Faulty valves may also lead to regulatory fines and lawsuits if you are found liable for a spill.
How often should safety relief valves be inspected?
Safety relief valves should be inspected every 6 to 12 months to ensure they are functioning correctly. Check with the manufacturer for the best inspection period and take into account usage levels.
Why should I contact McKenzie Valve for safety relief valves?
With over 25 years of experience, McKenzie Valve provides the highest quality safety valves tailored to meet the stringent demands and regulatory requirements of multiple industries.