Steam Theory 1. Basics of Steam What is Steam? Principal Applications for Steam Types of Steam Flash Steam How to Read a Steam Table 2. Steam Control Problems With Temperature Control Steam Pressure Control Comparing Steam and Hot Water Heating Vacuum Steam Basics Vacuum Steam Heating Systems What is Vacuum Cooling? 3. Steam Heating Heating with Steam Steam Heating Mechanism Overall Heat Transfer Coefficient What is Vacuum Steam? Tracing the Causes of Heat Maintenance Issues 4. Basics of Steam Traps What is a Steam Trap? The History of Steam Traps #1 The History of Steam Traps #2 How Mechanical Traps Work: A Look at their Mechanism and Merits How Disc Traps Work: A Look at their Mechanism and Merits How Bimetal-Type Thermostatic Steam Traps Work: A Look at their Mechanisms and Merits 5. Steam Trap Selection Steam Trap Selection: How Application Affects Selection Steam Trap Selection: Understanding Specifications Steam Trap Selection: Safety Factor and Life Cycle Cost Traps and Orifices Part 1 Traps and Orifices Part 2 Casting vs. Forging Applications of Different Types of Steam Traps Don't Get Steamed : Selecting Steam Trap Design Understanding Steam Traps Compare Two Fixed Orifice Venturi Products to a Variable Orifice Free Float Steam Trap 6. Steam Trap Problems Is My Trap Leaking Live Steam? Temperature Control Trap Precautions Trap Installation Orientation Trap Back Pressure Double Trapping Group Trapping Steam Locking Air Binding My Steam Trap Is Good - Why Doesn't It Work? 7. Steam Trap Management Introduction to Steam Trap Management Steam Trap Losses - what it costs you A Guide to Steam Trap Testing Implement a Sustainable Steam Trap Management Program Impact Plant Performance by Improving the Steam System 8. Water Hammer Water Hammer: What is it? Water Hammer: The Mechanism Water Hammer: Cause and Location Water Hammer: In Steam Distribution Lines Water Hammer: In Equipment Water Hammer: In Condensate Transport Piping Identifying Water Hammer Using a Thermal Camera Mitigation of Water Hammer in Vertical Flashing Condensate Transport Piping Stop Knocking Your Condensate Return Steam Trap Management: Do Something; Anything. Please! 9. Risk Mitigation Steam System Optimization and Risk Mitigation Risk Based Methodology for Industrial Steam Systems Why Bad Things Happen to Good Steam Equipment Beware of the Dangers of Cold Traps Steam System Winterization: How to Protect Your Plant 10. Steam Quality Wet Steam vs. Dry Steam: The Importance of the Steam Dryness Fraction Separators and their Role in the Steam System Clean & Pure Steam Temperature Problems Caused by Air Removing Air from Steam Equipment Air Vents for Steam Steam Quality Considerations 11. Steam Distribution Best Practices for Condensate Removal on Steam Lines Installation Tips for Steam Traps on Steam Mains Erosion in Steam and Condensate Piping Corrosion in Steam and Condensate Piping Allocate New Plant Focus to Steam System Design—Part 1 12. Condensate Recovery Introduction to Condensate Recovery Returning Condensate and When to Use Condensate Pumps Condensate Recovery: Vented vs. Pressurized Systems Condensate Recovery Piping What is Stall? Methods of Preventing Stall Cavitation in Condensate Pumps Steam Heat Exchangers are Underworked and Over-Surfaced Allocate New Plant Focus to Steam System Design—Part 2 Optimize Reboiler Performance via Effective Condensate Drainage Vent Away Condensate Pump Frustrations in a Flash 13. Energy Efficiency Tips to improve steam plant efficiency Advice on Winter Preparation for Steam Systems Insulating Traps Steam Compressors Why Save Energy? Management Strategies for Conserving Energy Recovering Steam Clouds and Waste Heat Waste Heat Recovery Boiler Energy Saving Tips Steam Line Energy Saving Tips Steam-Using Equipment Energy Saving Tips Preventing Steam Leaks Handle Steam More Intelligently Optimize the Entire Steam System Use Available Data to Lower System Cost 14. Compressed Air / Gas Removing Condensate from Compressed Air Preventing Clogging of Air Traps Air Compressor Energy Saving Tips Improving Compressed Air Quality and Countermeasures Against Leaks 15. Other Valves Types of Manual Valves Bypass Valves Check Valve Installation and Benefits Pressure Reducing Valves for Steam Trap Back Pressure Contents: What is Back Pressure? The 'back pressure' is the pressure just downstream of the steam trap. In other words, back pressure is the outlet or secondary pressure of the trap. The difference between a trap's inlet (primary) pressure and back pressure is called the 'differential pressure'. What Influences Back Pressure? If the condensate is discharged to the atmosphere just after the trap, the back pressure is considered to be 0 MPaG [0 psig]. Even if the trap discharges to atmosphere, restrictions in the downstream piping such as elbows, tees and valves may add back pressure. Vertical lifts (risers) in the condensate piping add back pressure in the form of hydraulic head. If the condensate discharges into a flash tank and the flash tank pressure increases, the back pressure increases correspondingly. Back Pressure and Trap Discharge Capacity If the inlet (primary) pressure remains stable as the back pressure increases, the trap's differential pressure decreases, which reduces its discharge capacity. Conversely, as differential pressure increases, the trap's discharge capacity also increases. Maximum Allowable Back Pressure (MABP) Not only does back pressure influence trap condensate discharge capacity, it can also affect a trap's ability to operate properly. Accordingly, it is also important to consider the maximum allowable back pressure of a steam trap. A trap's maximum allowable back pressure is the maximum back pressure that the trap can be subjected to and still operate normally. It is usually expressed as a percentage of the trap inlet (primary) pressure. For thermodynamic disc traps, the back pressure plays a key role in how the trap cycles. As the back pressure increases, the disc valve closure time becomes shorter, and trap's cycle rate becomes faster and faster. At some point, the back pressure may become so high that the trap does not cycle at all and eventually remains open. Differences in Allowable Back Pressure The maximum allowable back pressure for disc traps is generally 50% to 80% of the inlet pressure, depending on the product design. So for example, given an inlet pressure of 1 MPaG [145 psig], the back pressure must be less than 0.5 MPaG [73 psig] (if MABP is 50%), or less than 0.8 MPaG [116 psig] (if MABP is 80%). Mechanical traps such as the Free Float® type, on the other hand, have a relatively high MABP of over 90%. Therefore, if the inlet pressure is 1 MPaG [145 psig], Free Float® traps can be used in applications with back pressures exceeding 0.9 MPaG [131 psig]. In summary, the maximum allowable back pressure differs depending on the type of trap. When making a trap selection, in addition to considering the condensate discharge capacity, it is also necessary to take into account the back pressure at the planned installation location. When modifying a system in order to recover condensate from steam traps currently discharging to atmosphere, it is important to determine the back pressure at these traps, and how it will affect both discharge capacity and trap operation. Trap Installation Orientation Double Trapping Also on TLV.com Free Float® Steam Traps for Process Use Free Float® Steam Traps for Steam Mains and Tracer Lines Steam and Condensate Training Seminars Engineering Calculator
