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Steam and Gas Hot Water Equipment for Industry
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Mead O'Brien 2019 Steam Seminar Registration is Now Open
Do the people who maintain your plant’s steam system really understand how to save you money?The Mead O’Brien Steam Seminar provides you a window into elements of the plant steam cycle as you observe live steam and condensate behavior in glass piping and glass-bodied steam traps under differing conditions. You will gain useful knowledge regarding:
- Steam generation
- Distribution
- Control & Heat transfer
- Heat Recovery opportunities
- Condensate removal & return
SAMPLE AGENDA
Steam System System-Wide Objective
- Basics of steam
- Steam energy facts
- Thermodynamic relationships
- Steam table uses
- Video: What is Steam?
- Steam system-wide components
Steam Traps
- What it is, where it fits, how it works
- Function and Operation of generic Steam Trap types How they operate against typical characteristics
- Testing techniques
- Troubleshooting and Video
- Functional problems associated with Steam traps
- Tools to maintain an efficient steam system
- Surveys and assessments
- Continuous monitoring
- SteamStar™
Distribution systems
- Functional problems associated with Distribution Systems Effects of not removing condensate formed in the system Water Hammer and Corrosion
- Differential Shock water hammer demonstration
- Piping for effectively removing the condensate
- PRVs: Use and effect on the steam distribution system Video: Guidelines for Steam System efficiency
Steam usage systems (heat transfer)
- Different heat transfer devices
- Functional problems associated with heat transfer systems Process control considerations & challenges
- Pressure zone and partial load example
- What the control people usually don’t consider
- Stall and how to overcome it
- Vacuum Breakers and TAVs (thermostatic air vents) Control modes and unintended consequences
- Leaving the pressure zone
Condensate return systems
- System efficiencies
- Electric condensate pumps: operation and advantages Mechanical condensate pumps; operation and advantages Open and closed systems: advantages & disadvantages Stall review and solutions
- Flash systems and heat recovery options
- Back to the boiler house: Deaerators and their function
For more information, or to sign up, visit this web site - https://events.meadobrien.com
US Power Grids, Oil and Gas Industries, and Risk of Hacking
A report released in June, from the security firm Dragos, describes a worrisome development by a hacker group named, “Xenotime” and at least two dangerous oil and gas intrusions and ongoing reconnaissance on United States power grids.
Multiple ICS (Industrial Control Sectors) sectors now face the XENOTIME threat; this means individual verticals – such as oil and gas, manufacturing, or electric – cannot ignore threats to other ICS entities because they are not specifically targeted.
The Dragos researchers have termed this threat proliferation as the world’s most dangerous cyberthreat since an event in 2017 where Xenotime had caused a serious operational outage at a crucial site in the Middle East.
The fact that concerns cybersecurity experts the most is that this hacking attack was a malware that chose to target the facility safety processes (SIS – safety instrumentation system).
For example, when temperatures in a reactor increase to an unsafe level, an SIS will automatically start a cooling process or immediately close a valve to prevent a safety accident. The SIS safety stems are both hardware and software that combine to protect facilities from life threatening accidents.
At this point, no one is sure who is behind Xenotime. Russia has been connected to one of the critical infrastructure attacks in the Ukraine. That attack was viewed to be the first hacker related power grid outage.
This is a “Cause for Concern” post that was published by Dragos on June 14, 2019.
“While none of the electric utility targeting events has resulted in a known, successful intrusion into victim organizations to date, the persistent attempts, and expansion in scope is cause for definite concern. XENOTIME has successfully compromised several oil and gas environments which demonstrates its ability to do so in other verticals. Specifically, XENOTIME remains one of only four threats (along with ELECTRUM, Sandworm, and the entities responsible for Stuxnet) to execute a deliberate disruptive or destructive attack.
XENOTIME is the only known entity to specifically target safety instrumented systems (SIS) for disruptive or destructive purposes. Electric utility environments are significantly different from oil and gas operations in several aspects, but electric operations still have safety and protection equipment that could be targeted with similar tradecraft. XENOTIME expressing consistent, direct interest in electric utility operations is a cause for deep concern given this adversary’s willingness to compromise process safety – and thus integrity – to fulfill its mission.
XENOTIME’s expansion to another industry vertical is emblematic of an increasingly hostile industrial threat landscape. Most observed XENOTIME activity focuses on initial information gathering and access operations necessary for follow-on ICS intrusion operations. As seen in long-running state-sponsored intrusions into US, UK, and other electric infrastructure, entities are increasingly interested in the fundamentals of ICS operations and displaying all the hallmarks associated with information and access acquisition necessary to conduct future attacks. While Dragos sees no evidence at this time indicating that XENOTIME (or any other activity group, such as ELECTRUM or ALLANITE) is capable of executing a prolonged disruptive or destructive event on electric utility operations, observed activity strongly signals adversary interest in meeting the prerequisites for doing so.”
Understanding Differential Pressure Measurement: Differential Pressure Gauge Example
This video (courtesy of Ashcroft) does an outstanding job illustrating the concepts of differential pressure and flow measurement using the differential pressure method.
Engineered restriction devices are often inserted into a closed pipe system to create a differential pressure for the purposes of measuring fluid flow rate. These restrictions can come in the form of an orifice plates, Venturi, wedge, and other designs.
To measure the differential pressure, taps must be installed on both sides of the plate. The upstream side will always produce the greater pressure, and is referred to as the high side. Conversely, the downstream pressure will always be the lesser value, due to the obstruction.
A differential pressure gauge's range is based on the maximum difference that can be expected as a result of the restriction. The gauge's dial will display the differential pressure in units of pressure measurement, like psi or bar. By applying the linear square root relationship between flow rate and pressure, the gauge style can be scaled in a specified rate of flow, such as gallons per minute. A dual scale dial can also be created to display both the flow rate and the differential pressure.
Another important consideration is the maximum line pressure, also referred to as the static pressure. The higher the static pressure, the more robust the gauge must be to contain it. That's why it's crucial to ensure that the gauge carries a static pressure rating that exceeds the highest pressure in the line.
For more information about differential pressure gauges, transmitters, and flow measurement, contact Mead O'Brien at (800) 892-2769 or visit their web site at https://meadobrien.com.
ValvTechnologies RiTech® Coating an Excellent Alternative for Applications Where Stellite Disbonding a Concern
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| Table of ValvTechnologies RiTech Coatings (Click for larger view) |
ValvTechnologies, a manufacturer of severe service valves, offers their RiTech® coatings and process as a better alternative to Stellite for these applications.
ValvTechnologies' RiTech® is a high-velocity oxygen fuel (HVOF), hot, high-velocity, gas jet coating process. RiTech® 31 is an alloy that maintains its hardness at high temperatures and is self-repairing in operation.
The article below, written by the editors of the Combined Cycle Journal and distributed by ValvTechnologies, explains the reported Stellite delamination problems as well as a RiTech® 31 user experience.
For more information about ValvTechnologies valves and RiTech® 31, contact Mead O'Brien by calling (800) 892-2769 or by visiting https://meadobrien.com.
Coating Critical Steam-valve Parts with Chrome Carbide Avoids Stellite Delamination Issue
Stellite liberation from large valves installed in main and hot reheat (HRH) steam systems serving F-class combined cycles, considered a major industry problem 10 years ago, has been eliminated by substituting chrome carbide as the hard-facing material for critical valve parts.
The editors first learned of stellite delamination at the 2009 7F Users Group Conference where the liberated material from a 20-in. HRH block valve was displayed. The industry had been made aware of stellite liberation by GE, which issued Technical Information Letter 1626 about three months ahead of the 7F meeting. It advised steam-turbine owners to check the condition of the stellite inlay sections used in fabricating seats for the OEM’s combined stop and control valves.
Revision 1 of that TIL, published at the end of 2010, recommended a “one-time seat stellite inlay UT inspection during valve installation or the next planned maintenance inspection”—this to identify any lack of bonding between the inlay and base metal on units with fewer than 50 starts.
Disbonding of stellite associated with combined-cycle plants has occurred primarily in parallel-slide gate valves and non-return globe valves. Hardfacing has been liberated from valve seats, guide rails, and discs. Tight shutoff of valves has been compromised in some cases.
Many incidents of stellite liberation were reported. To illustrate: CFM/VR-TESCO LLC (formerly Continental Field Machining), a leading valve services company said that in 2011 and 2012 it repaired 50 valves manufactured from F91 (forged body) or C12A (cast body) and ranging in size from 12 to 24 in. More than half of these jobs involved stellite liberation.
These repair projects were split roughly 50/50 between valves within the Code (ASME Boiler & Pressure Vessel Code) boundary and those that were part of the boiler external piping. Repairs on the former were performed according to guidelines presented in Section I of the Code and in the National Board Inspection Code; those outside the Code boundary were performed according to ASME B31.1.
There hasn’t been much discussion on stellite disbonding the last few years—at least at meetings attended by the editors, which include the Combined Cycle Users Group, Steam Turbine Users Group, and HRSG Forum with Bob Anderson.
However, mention was made by one owner/operator regarding the successful use of ValvTechnologies Inc.’s IsoTech® parallel-slide gate valves on his company’s HRSGs in eliminating the need for stellite. According to the manufacturer, critical parts for its severe-service valves, used where steam temperatures exceed 1000F, are provided with its RiTech® 31 coating.
This chrome carbide refractory coating is much harder than Stellite 6 (68-72 RC versus 34-38 RC). It is applied in state-of-the-art HVOF (high-velocity oxygen fuel) spray booths using a proprietary compressive spray technique to achieve high bond strength. Applications extend up to ASME/ANSI Class 4500 at 1800F for valves up to 36 in.
The chrome carbide hard-coated web guide ensures the discs are kept parallel through the entire valve stroke. As the valve is cycled under differential pressure, the hard surfaces reportedly burnish and polish each other, avoiding the scratching and galling cited by some others.
The user sharing his experience with the ValvTechnologies product said their parallel slide gate valves have been operating on four or five of his company’s HRSGs for three years or so and the only hiccup was a stem-packing leak on one valve which was quickly corrected. This testifies to the vendor’s claim that RiTech 31 hard-coating technology is impervious to the effects of high-temperature cycling typically experienced today in combined-cycle main-steam isolation and HRH applications. The company guarantees coating integrity for 10 years or 10,000 cycles—whichever comes first.
Finally, the user mentioned that a representative of the manufacturer annually visits each plant where ValvTechnologies valves are installed to verify that they continue to meet expectations.
Courtesy of Combined Cycle Journal. Combined Cycle Journal is the independent voice of the gas-turbine-based generation sector of America’s electricity industry.
Pneumatic Valve Actuators
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| Actuated valve with pneumatic scotch yoke actuator (Metso Neles) |
Pneumatic valve actuators are used in extreme conditions in many industries such as oil and gas, chemical, water and wastewater, bulk storage, pulp & paper, and power generation. These devices are used in a multitude of valve control processes for regulation (or cessation) of flow, and / or controlling pressure and level. Due to their reliability and simplicity, pneumatic actuators are one of the most popular types of actuators used in industry today.
Pneumatic valve actuators work by conversion of air pressure into motion. The device applies a force of air to a diaphragm, rotary vane, or piston that is attached to the actuator shaft, which is then mechanically connected to the stem of the valve or damper. Depending on the type, pneumatic actuators produce either linear or rotary motion.
ACTUATOR ACTION - SPRING RETURN OR DOUBLE ACTING
Spring Return — Pneumatic actuators with spring return design have air supplied from one side. The spring on the opposite side is responsible for the motion. With this design, air compression moves the opens or shuts the valves while the spring is responsible for the opposite motion.
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| Diaphragm actuator (Metso Neles) |
Double Acting — Double acting actuators have air fed on both sides of a piston. The pressure on one side is higher as compared to the other that results in the required in movement. Air is used to open and close the valves.
PNEUMATIC ACTUATOR DESIGNS
Diaphragm Actuators — Diaphragm actuators work by applying pressure to a thin membrane or diaphragm.
Piston Actuators — Piston actuators apply compress air to a piston that is within a cylinder. Air is fed into a chamber that moves the piston in one direction. The piston moves in the opposite direction when air pressure is removed (spring assisted) or directed to the other side (double acting).
Rack and Pinion — Rack and pinion actuators produce rotation by applying pressure to pistons with gears that turn a pinion gear. Rack and pinion actuators can be spring return or double acting. They are valued because of their compact size and versatility.
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| Rack and pinion actuator (Metso Jamesbury) |
Scotch Yoke — A scotch-yoke actuator contains a piston, yoke, connecting shaft, and rotary pin. They can be direct acting or spring return. They are capable of providing very high torque outputs and are generally used on larger valves. Scotch yoke actuators can be powered by air or process gas.
Rotary Vane —Vane actuators use a mechanical vane, connected to a shaft, that separates a circular shaped body in two "clamshell" halves. The vane moves in response to the differential pressure inside the actuator body, turning the shaft clockwise or counter-clockwise in response to the pressure differential. External springs units are available for spring return models.
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| Scotch yoke actuator (Metso Neles) |
BENEFITS OF PNEUMATIC ACTUATORS
The use of compressed air (typically found in all industrial facilities) as the power source is the prime advantage for the use of pneumatic actuators. Additionally, pneumatic actuators have an advantage in suitability for different environments and can be used in extremes temperatures. They are preferred over electrical actuators in explosive, flammable and other hazardous areas because they do not require electricity (a possible ignition source) to operate. They do not create electrical fields or electrical noise since there is no electrical motor. Pneumatic valve actuators are faster opening and closing compared to their electric counterparts. Finally, they are low cost, lightweight, durable, require little maintenance (depending on quality) and there are a myriad of positioning controls, speed controls, and communications devices available for tailoring the actuator to the application.
DRAWBACKS OF PNEUMATIC ACTUATORS
While compressed air is the main reason for using pneumatic actuators, it can also be considered a drawback. For instance, pneumatic actuators can perform poorly when the air supply source is located at a distance, resulting in lag and slow response. Another drawback of pneumatic actuators is the additional cost for the compressed air system due to the requirement of dust filters and moisture removing dryers. These are required to ensure clean air is fed into the system.
APPLYING PNEUMATIC ACTUATORS
There are many aspects to the proper, safe, and efficient application of pneumatic actuators to valves and dampers. The sizing the power (torque) output being paramount. All valves and dampers have unique torque requirements. You must consider a threshold force for opening (breakaway), as the valve continues to move to its open or closed position, and then for seating. Matching the actuators to the valve type, and operating conditions is critical. Published torque curves must be reviewed and understood. Too little torque and the valve will not respond. Too much torque increases cost and can damage the valve. Spring return adds to this complexity. Considering all this, it is strongly suggested you always discuss any valve actuation requirement with an experience applications expert. They will ensure the proper, safe, and cost effective mating of pneumatic actuator to valve or damper.
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