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 Heating Heating with Steam Steam Heating Mechanism Overall Heat Transfer Coefficient What is Vacuum Steam? Tracing the Causes of Heat Maintenance Issues 3. 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 4. 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 5. 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? 6. 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 7. 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! 8. 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 9. 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 10. 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 11. 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 12. 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 13. 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 14. Other Valves Types of Manual Valves Bypass Valves Check Valve Installation and Benefits Pressure Reducing Valves for Steam Erosion in Steam and Condensate Piping Contents: Erosion is a physical process that refers to the gradual wearing away of a solid through abrasion. This article will focus on erosion in steam and condensate piping, a common problem in steam plants wherein sections of piping are eroded away causing significant steam leakage. Steam Leak Caused by Pipe Erosion Erosion causes the thinning of the pipe wall that can eventually lead to holes in piping, causing live steam leaks that can be a serious safety hazard. What Causes Erosion? Water both entrained in steam flow and also as non-discharged condensate traveling at high speeds in piping is the source of most erosion. By repeatedly impacting piping at bends, the water can cause the gradual thinning of the pipe wall due to its mass and high velocity of impact, similar to what occurs in industrial water jet cutting. This type of erosion - caused by water droplets - is typically known as Liquid Droplet Impingement (LDI) Erosion. In many cases, but particularly with carbon steel piping, erosion can remove the protective inner piping surface treatment thereby speeding the electrochemical thinning of the pipe wall, a process know as corrosion. In fact, both erosion and corrosion typically work together to cause the thinning of the steam pipe inner wall. Piping Damage Caused by Erosion Resistance to erosion varies according to the material. For reasons related to cost and installation, carbon steel piping is typically used as standard practice in most steam distribution lines even though it isn't as resistant as stainless steel piping. Use of stainless steel piping is usually limited to pharmaceutical, biotech, clean steam, or other sterile applications. Erosion Occurring in Piping As liquid droplets hit the inner wall of the pipe, the wall slowly wears away. Some surface treatments can offer carbon steel piping protections against corrosion, but these aren't as resistant as those for stainless steel. The treatments can temporarily protect the steel to slow down erosion and corrosion. However, once thinning caused by erosion starts to occur, additional thinning of the pipe wall can occur even more rapidly. This is because the high velocity water not only physically breaks down the impacted region of the steel piping, but also accelerates corrosion by removing the surface treatments that protect the piping. Other Types of Erosion in Steam and Condensate Piping Erosion in steam and condensate piping is not limited to the above-mentioned erosion caused by liquid droplet impingement (LDI) or high velocity dis-entrained condensate. Condensate recovery piping in particular can be susceptible to erosion from improperly handled flash steam that occurs in the discharge stream. Indeed, even though condensate piping is designed for condensate transport, the process of flash re-vaporization can result in an environment very similar to steam distribution piping containing a large volume of high velocity wet steam. This type of LDI erosion is often called "flashing erosion". Flashing erosion can often be worsened by two related factors: Undersized condensate return lines that cause high flash steam velocity (water-cutting effect) Corrosive elements such as carbonic acid that can be associated with low temperature condensate Additionally, "cavitation erosion" can occur from the sudden shock wave impacts caused by the implosion of small liquid-free zones within condensate. Cavitation erosion occurs because flash steam can occupy a very large volume, but then suddenly and rapidly condense after a portion of its heat is lost, having been transferred to the adjacent fluid or piping. Due to specific volume differences between steam and condensate, the sudden condensation of flash steam can create a large void that is rapidly and often violently filled by adjacent condensate, thereby causing shock waves known as water hammer. The rapid collapse of the flash volume and associated shock caused by high velocity condensate filling the void can lead to significant piping erosion and damage. Erosion Countermeasures Countermeasures for Limiting Erosion in Condensate Recovery Piping Limiting erosion in condensate recovery piping requires multiple design considerations. One crucial element is to size the condensate return pipe large enough to accommodate steam and condensate two-phase flow, as discussed here: Condensate Recovery Piping Condensate recovery piping is typically designed using the average rate of condensate flow. However, if steam traps that operate intermittently are used, such as bucket, disc, piston, and thermostatic type traps, then the momentary discharge rate can be much greater than the calculated average. This can result in a much higher condensate flow velocity than anticipated, which may lead to greater erosion of the piping. Erosion at Trap Outlet Traps that operate intermittently may lead to greater erosion of piping at the trap outlet. In such cases, the options are to locate the trap further upstream and away from the direction change, eliminate direction changes where possible, over-size the discharge pipe if cost effective, or select a trap with a more continuous type discharge such as a Free Float® or float design. Countermeasures for Limiting Erosion in Steam Distribution Piping Preventing erosion in steam distribution piping is generally a more simple matter, and typically requires the removal of water droplets entrained within the steam. This involves the installation of a steam-condensate separator. Steam Separator Condensate entrained in steam is mechanically removed using a steam separator. Although steam supplied through the boiler can have a high percent of dryness, all boilers without super heater sections still contain certain amounts of condensate entrained in the steam that is created. Condensate also forms from radiation heat loss throughout the distribution piping. For these reasons, it is critically important to both install traps at regular intervals and install separators that mechanically remove water droplets from steam in required areas. Installation Tips for Steam Traps on Steam Mains Corrosion in Steam and Condensate Piping Also on TLV.com SF1 Separator Filter Engineering Calculator Steam Bulletin: Archive - Email Magazine