Large projects contain 1,000’s of valves, and on most occasions a lot of things are overlooked, such as large bore pipeline valves in gas lines. This article will explore further how the flow performance testing is conducted on specific applications on valves.
By Gobind Khiani – Consulting Fellow-Piping/Pipelines
An industry colleague was involved with a world renowned LNG project for pipeline valves, from the beach valve and the inlet facilities, including the pig receiver and slug catch. There were quite a few things that came up which are worth mentioning from a practical and project point of view:
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- Soft seated inserts vs. metal seats: While soft seats are better in terms of leakage, for the size of valves, they just did not survive the opening and closing tests under full pressure, and it ended up being necessary to use metal.
- Correct end for cavity venting and ensuring correct seat orientation: SR x DPE was used, and there was debate as to which side, SR or DPE, should face up and downstream.
- Whether there is any actual benefit of using DPE seats compared to the hassles: There is an argument to just go SR x SR and include vents between the two valves to ensure isolation.
- Proper drain line sizing: API 6D only specifies minimum DN25 (and this was the vendor standard) but for large (DN1100) valves it is better to go DN50.
- Whether one should have a cavity /drain vent on a buried valve such as the beach valve that will probably only be operated on once.
- Seat Injection (Flushing) Ports – Emergency sealant grease seat injection ports can also be used to flush the seats.
- Protection of the ball: For example, stainless steel weld overlay, vs. electroless nickel plating, vs. thermal spraying.
- Including a bleed valve arrangement on interconnecting pipe between two valves.
- Performing high gas pressure stroke testing on valves.
- Stem leak criteria and test method: Requirements for fugitive emissions and how a ppm limit relates to a leakage rate of ml/min. Additionally, changes to API 6D 23rd / 24th edition – Appendix H and now 25th Edition.
- Torque measurement method: Measuring electrical input to actuator vs. the torque sensor in the actuator.
- Backing rings and explosion decompression resistant seals: Asking for explosion decompression resistant seals limits their size.
- How to best manually operate the valve: For example, universal valve turning tools for the smaller torque arrestor brackets that some manufacturers can supply.
- Flow performance testing parameters.
Valve Testing
• Reduces or eliminates performance uncertainty.
• Removes and/or isolates the ‘what ifs’ when problem solving.
• Can be relatively inexpensive.
• Computational Fluid Dynamics as a possible evaluation method.
Emission Requirements
Measuring Methane
• Detection, localization, and quantification
• Overview of sensing principles
• Spatial and temporal scales of measurement
Available Technologies
Handheld methods (OGI, EPA Method 21), Continuous (laser, in-plume, imaging), Aircraft (LiDAR, etc), Vehicles (on pad, drive by etc), Drones (imaging, sniffing), Satellites.
Evaluating Measurement Systems
Technologies vs. methods vs. programs. Performance metrics, controlled release testing, modeling overview.
How To Choose The Correct Emission Technology?
While there is vendor diversity and a competitive landscape, many factors need to be considered to chose the correct emission control. There are also barriers to adoption for alternative solutions. It is important to discern hype from results, and companies must ask, is it worth the money? Measurement regulations in oil and gas include Conventional LDAR (Canada and the United States), or an Alternative LDAR and equivalence.
Implementation Challenges
• Understanding the current design of the valve and actuator with limited documentation.
• Understanding the seat design of the valve which was designed to Class V Shutoff Requirements. Class V Shutoff which is 0.0005 ml per minute of water per inch of orifice diameter per psi differential pressure in accordance with ANSI/FCI 70-2 and IEC 60534-4.
• Reconditioning the existing spare valve from warehouse inventory that had been on the shelf since 1989.
• Work with a valve actuation center to find a suitable replacement actuator which could be delivered in time for the outage.
• Redesigning existing instrumentation with limited documentation available.
• Modifications of structure steel supporting grating and rails due to the size & weight of a new actuator. Existing actuator weight approximately 500 lbs. v.s.1705 lbs. Existing overall actuator length 55 inches v.s.93 inches.
• Fabrication of the actuator/valve mounting assembly that could support the weight and torque output of the new actuator. This was coordinated by Engineering and Caltrol (Local Rep for Emerson).
Flow Testing in Progress:
• Test Coordinator conducting Cv Testing for every 10 degrees of valve travel.
• Down stream flow and back pressure manually coordinated with Test Coordinator.
• Test in progress showing downstream pipe with S-bend to keep pipe full during testing.
• Downstream control valve free discharging.
• Valve pressure tested at 60 and 250 psi and any leakage measured.
• Visual Inspection during pressure testing.
Image credit: https://www.sofisglobal.com/sofis-and-partners-install-more-than-1500-interlocks/
Utah Water Research Laboratory
Utah State University was established in 1888 as a Federal Land Grant University. Its early assignment was to study water, soil, plant, and animal life. The Utah Water Research Laboratory was completed in 1965 with 60,000 square feet of floor space and a flow capacity of over 100,000 gpm. This means it can divert the Logan River through the building. It tests large valves (largest 40,000 lbs), meters (78-inch), pipes, and more. It has done work for nuclear valve suppliers and utilities as well as the aerospace industry, including testing for flow, cavitation, torque, seating/unseating, leakage, and more!
Courtesy to industry colleagues and code committees that the author actively participates in.
ABOUT THE AUTHOR
Gobind N Khiani, a U Calgary alumnus of Masters in Mechanical Engineering is a seasoned change-maker. He has a proven track record in technical and value engineering and holds a Fellowship in Engineering and an MBA. He is the Chairman of the End User Group at API and Vice Chairman of the Standards Council of Canada. He has done peer review on Emissions Management regulatory documents for ECCA and participated in research and development initiatives. Further, his experience is in the energy sector in the improvement of standards, technical compliance, strategy, governance, digital innovation, engineering management, technology, sustainable development, and operations. He is also skilled in Asset Integrity and Maintenance Management. As a volunteer, he is involved in technical standards (energy, tech, public safety) and has been a mentor/judge at First Robotics Canada. He is also the past chair of the CBEC of APEGA.
