67479813

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


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


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.



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.


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.


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


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


Flexible seal ring

Multi-layer seal

ring

6.3 Seal sub structure design-Butterfly


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%.


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


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


7.1 Abnormal prevent pressure-rise structure

Danger

Danger

Venting

Venting


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


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


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.


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


2Globe valve

Auto

Compensate

filler

Rising stemOS&Y)

Extension

stem

Upper seal

structure

Cone shape disc

Small stem

clearance

Reasonable

extension

thickness


3Check valve

Full flow design

Swing check

valve

Inside hanger type structure


4Ball valve

Extension bonnet design

FireproofAntistatic

Stem spray proof

Auto compensate filler


5Butterfly valve

Extension bonnet design

Triple eccentric butterfly valve

Stem spray proof

Auto compensate filler


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


Documents

67479813