GB/T 18442.4-2019 PDF English (GB/T 18442.4-2011: Older version)
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Static vacuum insulated cryogenic pressure vessels -- Part 4: Fabrication
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Static vacuum insulated cryogenic pressure vessel -- Part 4: Fabrication
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GB/T 18442.4-2019: PDF in English (GBT 18442.4-2019) GB/T 18442.4-2019
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.020.40
J 76
Replacing GB/T 18442.4-2011
Static vacuum insulated cryogenic pressure vessels -
Part 4: Fabrication
ISSUED ON: DECEMBER 10, 2019
IMPLEMENTED ON: DECEMBER 10, 2019
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 7
3 Terms and definitions ... 8
4 General requirements ... 8
5 Material re-inspection, division and mark transplantation ... 9
6 Cold and hot forming and assembly ... 9
7 Welding ... 12
8 Nondestructive testing ... 16
9 Heat treatment ... 19
10 Cleaning requirements ... 19
11 Assembly requirements ... 20
12 Installation of adsorbent ... 21
13 Pipeline fabrication ... 21
14 Helium mass spectrometer leak detection ... 22
15 Tank coating ... 22
16 Mark and identification ... 23
17 Exit-factory data ... 23
18 Sealing and shipping ... 25
Static vacuum insulated cryogenic pressure vessels -
Part 4: Fabrication
1 Scope
This Part of GB/T 18442 specifies the basic requirements, such as material re-
inspection, machining and forming, welding, nondestructive testing, cleaning,
assembly, mark and identification, and exit-factory data, in the fabrication of
static vacuum insulated cryogenic pressure vessels (hereinafter referred to as
cryogenic vessels).
This Part applies to cryogenic vessels, which simultaneously meet the following
conditions:
a) The working pressure of the inner vessel is not less than 0.1 MPa;
b) The geometric volume is not less than 1 m3;
c) The insulation method is vacuum powder insulation, vacuum composite
insulation, or high vacuum multilayer insulation;
d) The storage medium is a refrigerated liquefied gas with a standard boiling
point of not lower than -196 °C.
This Part does not apply to cryogenic vessels in the following scope:
a) The material of inner vessel and outer jacket is non-ferrous metal or non-
metal;
b) HAVE a spherical structure;
c) Stacked insulation;
d) Mobile;
e) STORE refrigerated liquefied gas medium with standard boiling point
below -196 °C;
f) The storage medium is toxic gas according to GB 12268;
g) Those with special requirements such as national defense and military
equipment.
NB/T 47013.14 Nondestructive testing of pressure equipments - Part 14: X-
ray Computed radiographic testing
NB/T 47014 Welding procedure qualification for pressure equipment
NB/T 47016 Mechanical property tests of product welded test coupons for
pressure equipments
NB/T 47041 Vertical vessels supported by skirt
NB/T 47065.1 Vessel support - Part 1: Saddle support
NB/T 47065.2 Vessel support - Part 2: Leg Support
NB/T 47065.4 Vessel support - Part 4: Bracket support
TSG 21 Supervision Regulation on Safety Technology for Stationary
Pressure Vessel
3 Terms and definitions
The terms and definitions defined in GB/T 150, GB/T 18442.1, GB/T 18442.3
apply to this document.
4 General requirements
4.1 The fabrication of cryogenic vessels shall comply with the requirements of
TSG 21, GB/T 150.4, this Part, and the design documents approved by the
prescribed procedures.
4.2 When the pressure components (heads, forgings, etc.) and safety
accessories, instruments, handling accessories, etc. are purchased and
outsourced parts, the fabrication organization of the cryogenic vessel shall
ensure that, the quality of the purchased and outsourced parts meets the
requirements of the design documents and this Part, and can be used only after
passing the inspection.
4.3 The limit deviation of the linear dimension of the machined surface and non-
machined surface is in accordance with the requirements of grade m and grade
c in GB/T 1804-2000, respectively.
4.4 The connecting pipelines, parts, and accessories on the cryogenic vessel
shall be firmly and reliably installed. The outer surface shall be flat and beautiful,
without defects such as pressure injuries, cracks, welding slag, or paint peeling.
Valves and instruments, etc. shall be installed in a position convenient for
operation or observation.
polishing is 1 : 3. The depth of the polishing shall be no more than 5% of the
thickness of the steel at that location, and no more than 2 mm; otherwise repair-
welding shall be performed.
6.3 Groove
The surface quality of the groove shall comply with the provisions of GB/T 150.4.
6.4 Head
6.4.1 The head shall meet the requirements of GB/T 25198 and design
drawings.
6.4.2 The head forming should adopt integral forming and meet the following
requirements:
a) The splicing welds of the first-spliced then-formed head are generally not
more than 3. The width of the spliced plate shall not be less than 300 mm.
The inner surface of the splicing weld, as well as the outer surface of the
splicing weld that affects the forming quality, before forming, shall be
polished to be flush with the base metal.
b) When using a full-size inner sample plate with gaps to check the shape
deviation of the inner surface of the head (see Figure 1), the indent size
is 3%Di~5%Di. The maximum shape deviation shall be no more than
1.25%Di for convexity and 0.625%Di for concavity. When checking, the
sample plate shall be perpendicular to the surface to be tested.
c) For the head of the inner vessel, it shall adopt proper forming process, to
avoid cracks in the transition section and straight side section of the head.
When using the warm forming process, it shall avoid the sensitization
temperature zone of austenitic stainless steel.
d) After the austenitic stainless steel head of inner vessel is formed, the
measured ferrite value of its transition section and straight side section
shall not be greater than 15%.
e) There shall be no longitudinal wrinkles on the straight side of the head.
f) The welding between the inner vessel accessories and the inner vessel
shall avoid type A and B welded joints on the inner vessel as far as
possible. The distance from the edge of the circumferential weld is not
less than 100 mm. When crossing the longitudinal weld, slot shall be made
to avoid.
6.5.5 After assembly welding of inner vessel and outer jacket is completed,
according to the requirements of 6.5.10 and 6.5.11 in GB/T 150.4-2011,
respectively, the diameter and roundness of the shell shall be checked.
6.6 Other assembly requirements
6.6.1 The main geometric dimensions and nozzle orientation of the tank shall
meet the requirements of the design drawings.
6.6.2 The fabrication and assembly requirements of leg supports are in
accordance with NB/T 47065.2.
6.6.3 The fabrication and assembly requirements of bracket supports are in
accordance with NB/T 47065.4.
6.6.4 The fabrication and assembly requirements of saddle supports are in
accordance with NB/T 47065.1.
6.6.5 The fabrication and assembly requirements of the skirt are in accordance
with NB/T 47041.
7 Welding
7.1 Preparation before welding and welding environment
The preparation before welding and welding environment shall comply with the
provisions in 7.1 of GB/T 150.4-2011.
7.2 Welding procedure
7.2.1 Cryogenic vessels shall, in accordance with NB/T 47014, be subjected to
welding procedure qualification; and, meet the requirements of TSG 21 and
GB/T 150.4.
7.2.2 When using materials of foreign designations (including filling materials)
for the pressure components of the welded structure, before the first use, the
fabrication organization shall conduct the welding procedure qualification
according to NB/T 47014.
7.2.3 The welding procedure qualification shall include the low-temperature
Charpy (V-notch) impact test of the weld and heat-affected zone. The sampling
c) For tanks designed according to fatigue analysis, the surplus height of
type A and B welds shall be removed, to make the weld surface flush with
the base metal surface;
d) Other surface quality shall meet the requirements of the design drawing.
7.3.3 The welding of temporary accessories shall meet the following
requirements:
a) For temporary lifting lugs and tie bar base plates welded on the tank, it
shall use materials with the same or similar mechanical properties and
welding performance as the tank; use the appropriate welding
consumables and welding procedure for welding.
b) After the temporary lifting lugs and tie bar base plates are cut off, the
welding scars left shall be polished and smooth. According to the
provisions of the drawing, it shall conduct penetrant testing or magnetic
particle testing. The surface shall be free of defects such as cracks. The
thickness after grinding shall not be less than the design thickness of the
location or the minimum forming thickness specified in the drawing.
7.4 Repair of welded joints and repair-welding of base metal defects
7.4.1 It shall analyze the causes of defects; propose the corresponding repair
or repair-welding plan.
7.4.2 Repair and repair-welding of welded joints shall be subjected to welding
procedure qualification or be supported by the welding procedure which passes
the qualification. When welding, there shall be detailed records of repair or
repair-welding.
7.4.3 The repair number of the same location of the weld should not exceed 2
times. If more than 2 times, before being repaired, it shall be approved by the
technical director of the fabrication organization. The number, location, and
status of the repair shall be recorded in the product quality certification
document.
7.4.4 The repaired locations shall, according to the previous requirements, pass
the testing.
7.4.5 For the repairs carried out after the pressure-tight test, if the repair depth
is greater than 1/2 wall thickness, the pressure-tight test shall be repeated.
7.4.6 If it is necessary to repair after helium mass spectrometer leak detection,
the repaired locations shall be tested as qualified by appropriate inspection
methods; the helium mass spectrometer leak detection shall be carried out
again.
requirements, the product represented by the test coupon shall be judged
as unqualified.
8 Nondestructive testing
8.1 Nondestructive testing methods
8.1.1 Nondestructive testing methods include radiographic testing, ultrasonic
testing, magnetic particle testing, and penetrant testing. Radiographic testing
shall meet the requirements of NB/T 47013.2, NB/T 47013.11, or NB/T
47013.14. Ultrasonic testing shall meet the requirements of NB/T 47013.3 or
NB/T 47013.10. Magnetic particle testing shall meet the requirements of NB/T
47013.4. Penetrant testing shall be in accordance with NB/T 47013.5.
8.1.2 The fabrication organization or nondestructive testing organization shall,
in accordance with the requirements of the design drawings and the provisions
of NB/T 47013.1, formulate the nondestructive testing process.
8.1.3 The selection of nondestructive testing methods shall meet the provisions
of the corresponding nondestructive testing standards.
8.2 Selection of nondestructive testing methods
8.2.1 Type A and B welded joints of inner vessel and outer jacket (except for
closed type B welded joints of craft manhole cylinder of inner vessel and of craft
manhole head with the convex surface compressed, closed type B welded
joints of outer jacket), pipeline butt joints shall be subjected to radiographic
testing or ultrasonic testing. Ultrasonic testing includes time-of-flight diffraction
ultrasonic testing (TOFD), recordable pulse reflection ultrasonic testing, and
non-recordable pulse reflection ultrasonic testing.
8.2.2 When the non-recordable pulse reflection ultrasonic testing is used, the
radiographic testing or the time-of-flight diffraction ultrasonic testing shall be
used as additional local testing.
8.2.3 For the nondestructive testing of the surface of the stainless steel welded
joint of the tank, it shall adopt penetrant testing. For the nondestructive testing
of the surface of carbon steel or low-alloy steel welded joints, it shall adopt
magnetic particle testing or penetrant testing.
8.2.4 For the nondestructive testing of the surface of welded joints of the tank
made of ferromagnetic materials, magnetic particle testing shall be used
preferably.
8.3 Nondestructive testing ratio and technical requirements of inner
vessel
b) All welded joints covered by reinforcing rings, pads, supports, internals,
etc.;
c) For the tube socket that meets 6.1.3 in GB/T 150.3-2011 without additional
reinforcement, welded joints in the range with a length along the surface
of the outer jacket from the center of the opening equal to 1.5 times the
diameter of the opening.
8.4.3 All the spliced joints on the convex heads, which are first spliced and then
formed, shall be subjected to 100% radiographic testing and 100% surface
testing. The technical grade of radiographic testing shall not be lower than
grade AB. The conformity level shall not be lower than level III. The conformity
level of surface testing shall not be lower than level I.
8.4.4 Welding scars left after cutting and grinding the temporary lifting lugs and
tie bar base plates on the outer jacket shall be surface-tested. The conformity
level of surface testing shall not be lower than level I.
8.5 Nondestructive testing ratio and technical requirements of pipeline
8.5.1 For the pipelines inside and outside the vacuum annular space, according
to NB/T 47013.2, the type B welded joints shall be 100% radiographically tested.
The technical grade of radiographic testing shall not be lower than grade AB.
The conformity level shall not be lower than level II.
8.5.2 For the pipelines inside and outside the vacuum annular space, in
accordance with NB/T 47013.5, the type C and D welded joints shall be
subjected to 100% penetrant testing. The conformity level shall be level I.
8.6 Duplicate testing
8.6.1 If an unacceptable defect is found in a welded joint that has undergone
nondestructive testing, after the defect is removed, repair-welding shall be
carried out. The previous nondestructive testing method and conformity level
shall be used for re-testing and assessment of the location.
8.6.2 For welded joints subjected to local nondestructive testing, when
unacceptable defects are found, the testing length shall be increased at the
extensions of the two ends of the defect. The increased length is 10% of the
length of the welded joint; both sides are not less than 250 mm. If there are still
unacceptable defects, 100% nondestructive testing is performed on the welded
joint.
8.6.3 When the unacceptable defects are found by penetrant and magnetic
particle testing, polishing and necessary repair-welding shall be carried out.
Moreover, the previous nondestructive testing method shall be used to re-test
this location.
11 Assembly requirements
11.1 After passing the pressure-tight test, the inner vessel can be assembled
with the outer jacket and shall meet the following requirements:
a) After the insulation material is wrapped, the inner vessel of high vacuum
multilayer insulation shall be set with the outer jacket as soon as possible,
to prevent the insulation material from moisture and pollution;
b) When fitting, the annular space shall be clean. It shall prevent damage to
the outer surface of the multilayer insulation material, annular space
pipeline, and inner vessel;
c) When fitting, the coaxiality deviation between the inner vessel and the
outer jacket shall be reduced as much as possible.
11.2 Before the inner vessel and outer jacket are assembled, the high vacuum
multilayer insulation layer shall be installed and shall meet the following
requirements:
a) Multilayer insulation material shall be dried;
b) The number of layers and layer density shall meet the requirements of the
design drawings;
c) The reflective screen and the spacer material shall be closed to each other;
d) Try to avoid the phenomenon of direct contact (short-circuit) between the
reflective screens and local absence of reflective screens;
e) The outermost layer shall have corresponding measures to prevent the
insulation layer from loosening and falling off.
11.3 After the assembly of the inner vessel and the outer jacket is completed,
the filling of vacuum powder insulation material shall be carried out and shall
meet the following requirements:
a) Powder insulation material shall be dried;
b) When filling, it shall control the filling density of powder insulation material;
c) Take measures as far as possible, to prevent the settlement of powder
insulation material;
d) When filling powder insulation material under pressure, there shall be
corresponding measures preventing the inner vessel from destabilizing;
13.5 When the pipeline assembly is intermittently constructed, the open nozzle
shall be closed in time.
13.6 For the valve, the installation direction shall be determined according to
the design flow chart. The screw-type globe valve shall be closed when turning
clockwise.
13.7 On the pipeline, it shall clearly mark the purpose of each interface and
accessory. The pipeline valve shall be indicated with the flow direction of the
medium. The globe valve shall be indicated with the opening and closing
directions.
13.8 Safety valves and pressure gauges can only be installed and used after
they pass the verification.
13.9 The pipeline should be fixed with pipe clamps. The fixation of pipe clamps
shall not limit the thermal expansion and cold contraction of the pipeline.
13.10 For the equipment with static conductive grounding requirements, the
sections of pipes shall be electrically conductive. When the resistance value
between each pair of flanges or threaded joints exceeds 0.03 Ω, wire jumpers
shall be provided.
13.11 The external pipeline shall be subjected to pressure-tight test and
airtightness test.
14 Helium mass spectrometer leak detection
14.1 After the inner vessel and the outer jacket are assembled, the vacuum
annular space shall be subjected to helium mass spectrometer leak detection.
The leak rate index shall comply with the provisions of GB/T 18442.3 and the
design drawings.
14.2 Leakage location shall be repaired according to the welding repair process.
After it is tested as qualified according to the previous nondestructive testing
requirements, the helium mass spectrometer leak detection shall be repeated.
15 Tank coating
The coating of the tank shall meet the requirements of JB/T 4711 and design
documents.
c) Special equipment manufacturing supervision and inspection certificate;
d) Risk assessment report;
e) Strength calculation sheets;
f) Stress analysis report (when required);
g) Calculation sheets of safety discharge quantity of tank, flow capacity of
safety valve, discharge area of bursting disc, and discharge area of the
explosion-proof device of outer jacket;
h) Installation, use and maintenance instructions;
i) List of spare parts and accessories and corresponding quality qualification
certificates;
j) Electrical and instrument explosion-proof certificates (when required).
17.2 The product quality certification document shall have at least the following
contents:
a) Bill of materials;
b) Material quality certificate of main pressure components;
c) Quality plan;
d) Product quality certification documents when pressure components
(heads, forgings, etc.) are purchased or outsourced parts;
e) Inspection report of tank appearance and geometric dimensions;
f) Welding records;
g) Nondestructive testing report;
h) Heat treatment report and automatic recording curve (when required);
i) Pressure-tight test report;
j) Airtightness test or other leak test report;
k) Rubbing or copy of product nameplate;
l) Vacuum performance testing report (including testing of sealed-off vacuum
degree, testing of vacuum annular space leak rate, testing of vacuum
annular space leak-degassing rate);
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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