By Scott Moreland, Vice President of Sales – Quadax
A quadruple (four) offset design valve allowing for a circular sealing surface, along with very low friction on the seals, will comply with the desired effect of allowing for zero leakage at low temperatures. This is true especially after a high number of cycles at very low temperatures, while most other TOVs have begun a process of increasingly leaking beyond acceptable levels. A four offset construction and state of the art manufacturing technology has resulted in a design which offers 100% compliance even with the highest tightness and extreme temperature requirements.
Now take those extreme applications and add the requirement to the reliability of functioning time and again sporadically in the unique application of refueling a rocket with LNG/liquid hydrogen in less-than-ideal weather conditions, i.e. coastal locations. The frequency of the loading at very low temperatures, the rough handling of the equipment given the surroundings and circumstances of quickly turning the process on and off, along with the outside temperatures and corrosive atmosphere of the coastal locations for launching pads, all give rise to very extreme conditions in which a valve has to operate without failing while high cycling. Leading aerospace companies in the U.S. have found strong business partners for their valve requirements and therefore the solution to maintaining zero leakage on/off operation.
Space Travel
To meet the constantly growing demand for the economic transportation of medium and heavier satellites for civilian purposes, the launching stations for orbital missiles are continuously expanded. The fueling systems are upgraded continually and have to be ready for processing at any given time. During the fueling process, temperature swings are extreme, which must be addressed with a valving solution which requires complete and safe shut-off every time.
When it comes to refueling that utilizes LNG at less than -259˚F, aerospace companies have very well-defined specifications including special testing, special cleaning, and very durable material requirements. To assure zero leakage in these extreme temperatures in the refueling process, a valve manufactured with a completely round seat and sealing geometry is required, along with other features which will provide positive sealing, even if the materials are shrinking or expanding given the unique temperature differences throughout the process and environment. The quadruple offset valve is designed to work in these very low temperatures, as well as in extremely high temperatures (up to 1472˚F).
Besides the negative environmental effect, excessive fugitive emissions could also have an impact on the security and safety of personnel. The operating companies of these launch sites are therefore paying particular attention to this fact and request an individual performance testing for the approval of cryogenic valves which shall be installed in their refueling systems. QUADAX most recently performed a special test combining the cryogenic test according to BS 6364 with an endurance test according to EN 12567. A four offset butterfly valve DN 500 mm, ANSI class 150, was tested at the ITIS BV test laboratory in the Netherlands, specifying 10 thermal cycles with a fugitive emission test at 20˚C/68˚F and at -196˚C/-320˚F alternating. In addition, the requirement called for an endurance test, with 500 mechanical movements at -196˚C measuring the internal and external leakage after determined cycles. The benchmark in terms of the seat leakage was less than 3000 ml/min. for a valve of DN 500 mm based on BS 6364 and a maximum allowable fugitive emission of ≤1.0•10-3 mbar•1•s-1 at any time of the cycles. The valve was tested with helium at 19 bar test pressure whereas the seat leakage and fugitive emission was measured after 20/40/80/150/300 and 500 cycles.
The four offset design and a high precision in manufacturing has resulted in remarkable performance in cryogenic applications. The test institute, ITIS BV, certified that the seat leakage never exceeded a low value of 590 ml/min., and after 500 cycles zero leakage at all could be detected. Moreover, the fugitive emission at the bonnet and trunnion gaskets of the top entry valve never exceeded a value of ≤1.0•10-5 mbar•1•s-1. The round seat and sealing geometry is a totally friction-free metal to metal design. Due to this round geometry, after several hundred cycles the seat and sealing ring is looped in and can provide the highest tightness, even if the material is shrinking and expanding due to extreme temperature differences.
Valve Offerings
The successful testing undertaken on the valves, along with a broad range of size and configurations, provide the user in extreme temperatures with a go-to partner for reliable valves. The five configurations – lugged style, double flanged to ISO 5752, long patterned double flanged to replace gate valve face to face per ANSI 16.10, buttweld end design for welded into lines, and top entry design – allow for complete repairability when a valve is welded into place. These choices, along with piping size ranges from 2 in. (50 mm) to 72 in. (1800 mm) and pressure ranges from ANSI classes 150 – 1500, allow the user to pick the very best fit for their piping systems.
The four offset valves are designed to offer four key principles to the company’s customer base:
Extreme temperature ranges.
– Homogenous materials allowing for same expanding/shrinkage.
– Temperatures from -454˚F (-270˚C) to 1472˚F (800˚C).
– Large temperature swings are easy
Superior tightness.
– Meet or exceed the most stringent tightness requirements.
– Bubble-tight even in cryogenic applications.
– Innovated and patented sealing design.
Increased operational safety.
– Totally friction-free in sealing areas.
– Reduced risk of failures.
– No wear in sealing areas.
– Longer service life.
Reduced operating costs.
– Higher Cv/Kv values against other TOVs.
– Lower nominal pipe diameters.
– Lower torque requirements.
– Reduced maintenance costs (lower cost of overall ownership)
As a recent LNG customer found by switching to the four offset design, they now have valves in an older facility that are operating better and more efficiently than when the system was new. By switching from a side entry design TOV manufactured by a major valve manufacturer to the four offset design top entry, the customer’s people are experiencing less service issues and maintenance on the system; a safer environment with bubbletight closing and lower fugitive emissions; and lower overall costs to the maintenance budget. This created a success story that has since been replicated at several subsequent user sites and has given a strong referral point for other LNG users to look to whenever they have valving decisions to make for safer, more efficient piping designs.
Designed for Beyond Earth
Partners in the aerospace industry who, after years of struggling with less effective designs, now specify a four offset valve into their system knowing that they are installing a more reliable and safer option. In the U.S. where the aerospace programs are now run by private companies in close cooperation with the federal space program, the need for reliable and safe is at the forefront of all when installing systems for fueling. Every major aerospace company has moved to using the four offset design in their most critical systems. These companies have found a willing partner that can provide them with peace of mind whenever they design and then install piping systems requiring proven dependability and top-most safe operation for their people and the coastal environments where launch pads are found.
The use of LNG/hydrogen in rocket fueling systems require increased storage and processing of LNG, which has led to a need to have reliable valves in the piping systems. After years of experimenting and use of inferior products, the aerospace customers now require positive testing sometimes beyond what is referenced in BS 6364 where most triple offset valves can comply, although with much effort and for a short period – primarily during FATs. As provided by the ITIS BV testing, the design more than exceeds the requirements of refueling systems.
Reportedly, the aerospace groups agree that the valves have been tested beyond the requirements set forth by BS 6364 and provide the best results when utilized in the fueling systems, with a strong history of performance over years of practical applications.
At a spaceport there is a high technological infrastructure on which spacecrafts are launched. The fuel combination of hydrogen and oxygen, along with LNG temperatures, are mostly used in liquid fuel rockets today. Both in the production and storage of liquid rocket propellants as well as during the refueling of the rocket, with such cryogenic fuel components having a temperature colder than -364˚F/-220˚C. Reliability and, of course, personnel safety are top priorities. Even the smallest leakage can have disastrous consequences, which is why customers appreciate the high quality, four offset design.
Scott Moreland has over 40 years in the valve industry serving mostly in a manufacturing capacity with experience with global companies: Watts Industries/KF, Zy-Tech Global (PBV ball valves), Cornerstone Valve, Mogas Industries & PetrolValve, LLC. While working primarily in sales management and marketing roles, he has experience in product management, distribution cooperation and end user AVL approvals. During his career, Scott has been working in capacities which allowed for global travel where he has key contacts and experience in all valve markets introducing or partnering with key valve providers. His experience in valve designs include ball valves, check valves, severe service & critical applications types valves and innovative designs, i.e., four-offset designs with QVI. Scott has also worked closely with API and Valve World throughout the years.
Scott currently holds the title of Vice President of Sales for Quadax Valves.