Ultra Cryogenic Valve Introduction
Ultra Cryogenic Valve Design Standard
Lots of Valve are used below 100 environment.
In this condition, valve design manufacture and
inspection have its own special requirement.
According to these requirement to process design
manufacture and inspection we called as cryogenic
valve.
Ultra Cryogenic Valve Design Standard
BS 6364 Cryogenic Valve
MESC SPE 77/200 Cryogenic and Ultra Cryogenic ValveShell
JB/T 7749 Cryogenic Valve Technical Condition
MSS SP-134 Requirements of cryogenic valve and its body/ Bonnet extension body
Ultra Cryogenic Valve Design Instruction
1Valve Material use Austenitic stainless steel
Well low temperature
tolerance property
Well welding property
Thermal Conductivity
Well corrosion resistance
Austenitic Stainless Steel minimum used temperature
Austenitic Stainless Steel Charpy notch impact value ( Energy unit J)
Steel No. 27 196 218 254
304 208.8 118 121.6 122
304L 160 90.9 90.9 90.9
310 192.6 120.7 116.7 116.6
317 162.7 89.5 77.5 77.3
ASTM JIS Minimum temperature ()
A351 G5121 JIS B8243 ANSI B31.3
CF8 SCS13A -196 -254
CF8M SCS14A -196 -254
CF3 SCS19A -196 -254
CF3M SCS16A -196 -254
CF8C SCS21 -196 -198
Nominal Diameter
Minimum Design
Temperature
DN15
-
DN25
DN40
-
DN50
DN80
-
DN100
DN150-
DN200
DN250-
DN300
DN350-
DN400
DN450-
DN600
DN700-
DN800
DN900
-
DN1200
-196~-101
250 250 300 350 400 450 500 550 600
-100~-50
100 125 150 175 200 250 300 350 400
Ultra Cryogenic Valve Design Instruction
2Bonnet Extension Design
Extend bonnet to ensure the bottom of packing
boxs temperature is maintain above 0
If extend bonnet is made by welding, then it must
pass RT inspection (level 2 as qualified) and
process solid solution or stabilization treatment
Ultra Cryogenic Valve Design Instruction
3Deep cryogenic treatment
Deep cryogenic treatment can make material process martensite
transformation, to ensure the texture stabilization when use.
All fittings must process deep cryogenic treatment before assemble
or precision polish, at least process two cycle.
4Stem
Stem is forming by solid forging.
Process nitrogen treatment on stem and filler contact
part, to raise stem surface hardness.
Polish stem and filler contact part, surface roughness
should above Ra 0.8 micrometer.
Ultra Cryogenic Valve Design Instruction
Ultra Cryogenic Valve Design Instruction
5Valve seal surface
Plasma spray welding STL Seal surface polishing
GateGlobeCheck seal surface welding alloy STL, hardness bigger than HRC30.
Seal surface polish treatment, let surface roughness reach Ra 0.4 micrometer.
Paint WC or Ni-Cr alloy on ball body and seat seal surface, then surface hardness
reach between HRC 68~72.
Ultra Cryogenic Valve Design Instruction
6Seal sub-structure design
Austenite Stainless steel will happen phase transformation
during low temperature, and produce phase transformation stress
and change form, in the mean time, temperature change will
produce temperature transformation stress and change form.
Therefore ultra cryogenic valve fittings need to process deep
cryogenic treatment, lower the temperature effect to valves seal
property. When design seal structure, should consider correspond
measurement, to ensure seals effective and reliable.
Ultra Cryogenic Valve Design Instruction
6.1Seal sub structure design-Gate Globe
Cone seal
surface
Flexible wedge gate
Globe Valve Gate Valve
Valve bodyvalve seat seal surface surfacing cemented carbide
Ultra Cryogenic Valve Design Instruction
6.2 Seal sub structure design-Ball
Valve seat structure enlarge view
Floating ball structure
Fixed ball structure
Valve seat seal surface
adopted PCTFE or paint
WC or Ni-Cr alloy on ball
body and seat seal
surface
Ultra Cryogenic Valve Design Instruction
Flexible seal ring
Multi-layer seal
ring
6.3 Seal sub structure design-Butterfly
Ultra Cryogenic Valve Design Instruction
6.4 Seal sub structure design
Seal surface change forming because of low temperature,
may cause well valve seat in normal temperature leakage
during low temperature condition. When calculate seal
pretightening force, in a satisfy specific pressure foundation,
we increase cryogenic valve seat pretightening force properly,
about 30%.
Ultra Cryogenic Valve Design Instruction
7Abnormal prevent pressure-rise structure
For parts of ball valvegate valve and globe valve etc, in close mode still exist sealing lumen, with the temperature raise slowly,
low temperature liquid natural gas in lumen will gasify with the
temperature is higher, volume will enlarge 600 time, pressure will
increase swiftly, if pressure cannot exhaust it will be serious
accident.
Therefore when design the valve should consider when lumens pressure rise, valve can exhaust high pressure medium
automatically.
Gas form Liquid form Danger
Ultra Cryogenic Valve Design Instruction
7.1 Abnormal prevent pressure-rise structure
Internal Venting--- To pass through venting hole and connect lumen and pipeline intake end, to balance the lumen pressure with
pipeline intake end.
Intake endVenting hole
Ultra Cryogenic Valve Design Instruction
7.1 Abnormal prevent pressure-rise structure
Danger
Danger
Venting
Venting
Ultra Cryogenic Valve Design Instruction
8Bonnet and stem clearance
Long neck bonnet and stem clearance
has effect to packing box temperature
field distribution.
Through flow field analysis, clearance
value should less than 5mm range,
maximum gas flow speed cause by
temperature difference in dissection is
very small, convection heat transfer can
be ignore.
Stem
Bonnet
Stembonnet clearance less
than 5mm
Ultra Cryogenic Valve Design Instruction
9Upper seal
Upper
seal
Filler
Upper seal is the place nearest the filler.
To prevent accident when upper seal
is shutting down, bonnet lumen is full
of liquid and cause the pressure rise
between upper seal and filler.
Bush
Ultra Cryogenic Valve Design Instruction
10Antistatic design
Based on LNG medium is flammable and
explosive, when designing ultra cryogenic valve,
must consider antistatic measure. Especially for
those non-metal high molecular material valve
seats, have gather static danger, static may
cause burning and explosion by spark.
When designing, should consider set a
connective device between stem and bodystem and shutting part, measure the resistance
value after assembling, the value should less
than 10 design standard.
Ultra Cryogenic Valve Design Instruction
11Auto compensate filler
Ultra cryogenic valves stem normally adopt packing seal type. Because of packing usually
use non-metal material, its linear expansion coefficient is bigger than metal packing box and
stem, therefore filler assemble in common
temperature, lowering to specific temperature, its shrinkage bigger than filler hole and stem, will
cause pretightening stress reduce then leakage.
When design filler capping compacting
structure, adopt butterfly type spring washer to
process pretightening, to let filler pretightening
during low temperature gain continuous
compensation, to ensure filler seal property is
effective long enough.
Butterfly
type
spring
Ultra Cryogenic Valve Classic structure
1Gate Valve
Extension
stem
Rising stemOS&Y)
Wedge flexible gate
Upper seal
structure
Intake set relief
hole
Auto
Compensate
filler
Small stem
clearance
Reasonable
extension thickness
Ultra Cryogenic Valve Classic structure
2Globe valve
Auto
Compensate
filler
Rising stemOS&Y)
Extension
stem
Upper seal
structure
Cone shape disc
Small stem
clearance
Reasonable
extension
thickness
Ultra Cryogenic Valve Classic structure
3Check valve
Full flow design
Swing check
valve
Inside hanger type structure
Ultra Cryogenic Valve Classic structure
4Ball valve
Extension bonnet design
FireproofAntistatic
Stem spray proof
Auto compensate filler
Ultra Cryogenic Valve Classic structure
5Butterfly valve
Extension bonnet design
Triple eccentric butterfly valve
Stem spray proof
Auto compensate filler
Ultra Cryogenic Valve Classic structure
Fittings name Material
BodyBonnet CF8 CF8M CF3 CF3M
GateDisc CF8 CF8M CF3 CF3M
BallDisc F304 F316 F304L F316L
Stem F304 F316 F304L F316L Ni-Cr alloy
Seal surface STL WC / PCTFE
Screw/Nuts B8/8 B8M/8M
Filler Flexible graphite PTFE
Gasket 316+Flexible graphite 316+PTFE
Casting Solid solution treatment
Processing
Deep cryogenic
treatment
2 cycle
Precision processing
Seal surface polish
AssemblePressure test
Type testPacking
Shipment
Chemical component
Mechanical
property
Microstructure
Cryogenic impact
Surfacingprocessing
PT
Hardness
RT
Ultra Cryogenic Valve Craftsmanship procedure
Ultra Cryogenic Valve Inspection
10M3 Liquid Nitrogen Tank
4 cryogenic freezingInspection flume
MinimumL 800*W 600*D600
MaximumL 2800*W 2000*D 2000
Ultra Cryogenic Valve Inspection equipment
Helium Inspection
machine
Helium detector
Data acquisition
computer
Ultra Cryogenic Valve Inspection equipment
Ultra Cryogenic Valve Inspection equipment
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