SPECIAL TOPIC : Hydrogen & Renewable Energy
be designed with adequate strength and toughness . In addition to service fluids pressure , valves need to withstand the ground load . In frigid and frozen zones , the low-temperature impact toughness of material should be considered to avoid brittle fractures ; these are typically caused by axial tension and pressure led by temperature fluctuations , external loads caused by landslides , ground subsidence , and flooding . For fully welded ball valves , welding line and heat-affected zone ( HAZ ), and crack tip opening displacement ( CTOD ) should be taken into consideration .
Figure 4 : External load safety assessment ( anti-bending , tensile , compression ). Figure 5 : Full welded trunnion mounted ball valve .
It is important to note that the failure location is not in the ball valve but the pipeline . The best way to validate the location is by using software simulation analysis .
Figure 7 : Strength analysis and cryogenic designed products .
A further detailed evaluation of existing coatings and approaches for assessing coating performance is therefore required .
Further , the testing should be carried out to evaluate :
• The hydrogen permeation results of several small-scale plates with different coating types and thicknesses . It should also be evaluated at different gas pressures in a 100 % hydrogen environment .
• Hydrogen permeation data for all coatings .
• A comparison of small-scale plate permeation testing to full-scale pipe hydrogen permeation under different test pressures . Review of test results of different thicknesses .
• An assessment of the effect of coating type and thickness on pipe performance because of hydrogen diffusion .
• Recommendations for additional work .
Hydrogen Gas Service Characteristics
• Gas phase or mixed phases , small atom ,
• High temp . and pressure ,
• H 2 / H 2S environment ( hydrogen embrittlement & corrosion ),
• Flammable and explosive ,
• Hydrogen bubbling and cracking .
Valve Solutions for Hydrogen Services
There are several solutions currently offered by manufacturers for valves in hydrogen services . These include :
• Fugitive emission design ,
• Pressure seal bonnet for high-pressure class ,
• Live load nut of packing seal ,
• All internal passage sharp edges rounded ,
• Avoid threaded structure for internal parts ,
• Special control of material composition and forming technology .
For general gas service , such as shrinkage holes , use casting material to avoid cracks and other defects of pressurebearing parts . For high-temperature or high-pressure gas service , use raw material with AOD / VOD . The preferred forging type is the type with grain size 5 ( CS , AS ) or 7 ( SS ) size ASTM E112 .
A ball valve used in the refining industry is typically a forged bolted metal seated ball valve . They are ideal for hydrocracking units which contain H 2 gas along with HT & HP . These valves require good sealing performance and reliable operation .
For long-distance pipeline transportation of mixed H 2 gas service , fully welded ball valves are also common and should
External Load Safety Assessments ( Anti-Bending , Tensile , Compression )
When the valves are closed , two seats can block the fluids from both sides . Fluid pressure relief can be accessible through a relief valve whose relief hole functions for in-line seal service . Meanwhile , a blow-out valve is equipped at the bottom of the body for regularly exhausting debris and contaminant . Precautions should be taken to avoid the adverse influence of debris on the sealing . If leakage occurs , emergency sealing solutions should be offered .
Liquid hydrogen is formed by cooling hydrogen to - 253 ℃ for liquefaction , the density of which can reach 780 times that of ordinary hydrogen , and the storage capacity of the same volume is 8-10 times that of gaseous hydrogen ( under different pressures ). The main pressure range of cryogenic liquid hydrogen valve is low pressure , generally less than 4MPa . Hydrogen storage has therefore become a challenge to be solved .
Founded in 1979 , ValtekSul is a company focused on the design and manufacture of control valves , instruments and equipments for industrial fluids control .
Our mission is continuous long-term technological investment that allows us to meet and respond to the changing needs of our customers around the world .
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Figure 6 : Strength analysis and cryogenic designed products . www . valve-world-americas . net • March 2023 | Valve World Americas 19