Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GB/T 18442 consists of the following seven parts under the general title Static vacuum insulated cryogenic pressure vessels:
——Part 1: General requirements;
——Part 2: Materials;
——Part 3: Design;
——Part 4: Fabrication;
——Part 5: Inspection and testing;
——Part 6: Safety protection;
——Part 7: Rules of pressure strengthening for inner vessels.
This is Part 4 of GB/T 18442.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 18442.4-2011 Static vacuum insulated cryogenic pressure vessel - Part 4: Fabrication. In addition to editorial changes, the following main technical changes have been made with respect to GB/T 18442.4-2011:
——the general requirements are modified;
——the classification of welded joints is deleted and included in Part 1 of GB/T 18442.
——the material re-inspection is added;
——the calculation equation for the processing deformation rate of cold-formed steel plates is deleted and replaced by direct reference to GB/T 150.4;
——the measured ferrite content index of cold-formed austenitic stainless steel pipe is added;
——the technical requirements for fabrication, such as defect grinding, repair welding and seal head, are modified;
——the requirements for measured ferrite content in formed austenitic stainless steel seal head of inner vessel are added;
——the requirements for misalignment, corner angle and roundness of the jacket of Classes A and B welded joints are simplified, and replaced by direct reference to GB/T 150.4;
——the assembly requirements for tanks and supports are added;
——the fabrication requirements for welded joints between cylinder and tank are modified;
——the welding requirements are modified, and the requirements for weld reinforcement of Classes A and B welded joints are specified as directly referred from GB/T 150.4;
——the preparation requirements for welded test pieces of products are modified;
——the selection of non-destructive testing methods and testing methods such as CR, DR and TOFD are added; the technical requirements for non-destructive testing of inner vessel and outer jacket are improved, and the requirements for non-destructive testing record, data and report are added;
——the heat treatment requirements are added;
——the cleaning requirements and assembly requirements are detailed;
——the installation requirements for adsorbents are added;
——the design requirements such as welding structure of pipelines in pipeline fabrication are deleted and included in Part 3 of GB/T 18442;
——the requirements for non-destructive testing and pressure test for external pipelines are added;
——the installation requirements for safety accessories are deleted and included in Part 6 of GB/T 18442;
——the requirements for marking and identification, ex-factory documents, sealed storage and shipment are modified.
This part was proposed by and is under the jurisdiction of the National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262).
The previous editions of this part are as follows:
——GB/T 18442.4-2011;
——GB 18442-2001.
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, processing and forming, welding, non-destructive testing, cleaning, assembly, marking and identification and ex-factory documents in the fabrication of static vacuum insulated cryogenic pressure vessels (hereinafter referred to as “cryogenic vessels”).
This part is applicable to cryogenic vessels that simultaneously meet the following conditions:
a) cryogenic vessel with the working pressure of inner vessel not less than 0.1MPa;
b) cryogenic vessel with the geometric volume not less than 1m3;
c) cryogenic vessel with the insulation mode of vacuum powder insulation, vacuum composite insulation or high vacuum multilayer insulation;
d) cryogenic vessel storing refrigerated liquefied gas contents with standard boiling point not lower than -196℃.
This part is not applicable to cryogenic vessels that meet the following conditions:
a) cryogenic vessel with the inner vessel and outer jacket made of non-ferrous metal or non-metallic materials;
b) cryogenic vessel with spherical structure;
c) cryogenic vessel with stacked insulation;
d) transportable cryogenic vessel;
e) cryogenic vessel storing refrigerated liquefied gas contents with standard boiling point lower than -196℃;
f) cryogenic vessel storing toxic gas as specified in GB 12268;
g) cryogenic vessel with special requirements such as national defense military equipment.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 150-2011
(All parts) Pressure vessels
GB/T 1804-2000 General tolerances－Tolerances for linear and angular dimensions without individual tolerance indications
GB/T 9969 General principles for preparation of instructions for use of industrial products
GB/T 18442.1 Static vacuum insulated cryogenic pressure vessels - Part 1: General requirements
GB/T 18442.3 Static vacuum insulated cryogenic pressure vessels - Part 3: Design
GB/T 25198 Heads for pressure vessels
JB/T 4711 Coating and packing for pressure vessels transport
JB/T 6896 Surface cleanliness of air separation plants
NB/T 47013.1 Nondestructive testing of pressure equipment - Part 1: General requirements
NB/T 47013.2 Nondestructive testing of pressure equipment - Part 2: Radiographic testing
NB/T 47013.3 Nondestructive testing of pressure equipment - Part 3: Ultrasonic testing
NB/T 47013.4 Nondestructive testing of pressure equipment - Part 4: Magnetic particle testing
NB/T 47013.5 Nondestructive testing of pressure equipment - Part 5: Penetrant testing
NB/T 47013.10 Nondestructive testing of pressure equipment - Part 10: Ultrasonic time of flight diffraction technique
NB/T 47013.11 Nondestructive testing of pressure equipment - Part 11: Standard practice for X-ray digital radiography
NB/T 47013.14 Nondestructive testing of pressure equipment - 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 equipment
NB/T 47041 Vertical vessels supported by skirt
NB/T 47065.1 Vessel supports - Part 1: Saddle support
NB/T 47065.2 Vessel supports - Part 2: Leg support
NB/T 47065.4 Vessel supports - Part 4: Bracket support
TSG 21 Supervision regulation on safety technology for stationary pressure vessel
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 150, GB/T 18442.1 and GB/T 18442.3 apply.
4 General requirements
4.1 Cryogenic vessels shall be fabricated in accordance with TSG 21, GB/T 150.4, this part and the design documents approved by the established procedures.
4.2 Where pressure elements (seal heads, forgings, etc.) and safety accessories, instruments, handling accessories, etc. are purchased or outsourced, the cryogenic vessel fabrication unit shall ensure that the quality of these elements meets the requirements of the design documents and this part, and may not be used before passing the inspection.
4.3 The limit deviation of linear dimension for machined and non-machined surfaces shall respectively meet the requirements of Grade m and Grade c in GB/T 1804-2000.
4.4 The installation of all connecting pipelines, parts, components and accessories on cryogenic vessels shall be firm and reliable, and the outer surfaces thereof shall be smooth and beautiful, free from defects such as crushing, cracking, welding slag or paint layer peeling off. Valves and instruments shall be installed at positions convenient for operation or observation.
5 Material re-inspection, cutting and mark transplantation
5.1 The material re-inspection shall meet the requirements of TSG 21, GB/T 150.4 and design documents.
5.2 Materials for fabricating pressure elements shall be provided with traceable marks. In the fabrication process, if the original mark is cut off or the material is cut, the fabrication unit shall transplant the logo before material cutting.
5.3 Cold cutting, thermal cutting or other appropriate method may be adopted for material cutting. Where thermal cutting is adopted, the surface slag and surface layer affecting the fabrication quality shall be removed.
5.4 The hard printing shall not be used for transplanted marks, welder marks and other marks for pressure elements of inner vessels.
6 Cold/thermal forming and assembly
6.1 Forming
6.1.1 The cylinder and seal head may be processed into required shapes by cold/thermal forming.
6.1.2 Where the deformation rate of cold formed austenitic stainless steel cylinder and seal head exceeds the control index specified in GB/T 150.4, solution treatment shall be carried out according to the corresponding material standards.
6.1.3 For cold-formed austenitic stainless steel pipes exposed to cryogenic contents, the measured ferrite content after forming shall not be greater than 15%.
6.1.4 The fabrication unit shall determine the machining allowance according to the fabrication process, and the thickness of formed pressure elements shall not be less than the minimum forming thickness indicated in design drawings.
6.2 Surface grinding
Mechanical damage on the steel plate surface shall be avoided during fabrication. Defects such as sharp scars as well as local scars and notches on the stainless steel surface shall be ground with the maximum inclination of 1:3. The grinding depth shall not be greater than 5% the thickness of steel at this position, and not be greater than 2mm, otherwise repair welding shall be carried out.
6.3 Groove
The groove surface quality shall meet the requirements of GB/T 150.4.
6.4 Seal head
6.4.1 The seal head shall meet the requirements of GB/T 25198 and the design drawings.
6.4.2 The seal head should be integrally formed and meet the following requirements:
a) for the seal head which is formed after plate splicing, the number of splicing welds is generally not greater than three, and the width of the splicing plate shall not be less than 300mm. The internal surface of splicing weld and the external surface of splicing weld that affects the forming quality shall be polished until they are flush with the base metal before forming.
b) when checking the shape deviation of the internal surface of the seal head with a full-size internal template with clearance (see Figure 1), the indent dimension is 3％Di~5％Di, the maximum shape deviation for convex shall not be greater than 1.25%Di, and that for concave shall not be greater than 0.625%Di. During the check, the template shall be perpendicular to the surface to be tested.
c) proper forming process shall be adopted for the seal head of inner vessel to avoid cracks in the transition section and straight section of the seal head. Where warm forming process is adopted, the sensitive temperature zone of austenitic stainless steel shall be bypassed.
d) for the formed austenitic stainless steel seal heads of inner vessels, the measured ferrite content of transition section and straight section shall not be greater than 15%.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 Material re-inspection, cutting and mark transplantation
6 Cold/thermal forming and assembly
7 Welding
8 Non-destructive testing
9 Heat treatment
10 Cleaning requirements
11 Assembling requirements
12 Adsorbent installation
13 Pipeline fabrication
14 Helium mass spectrometer leak detection
15 Tank coating
16 Marking and identification
17 Ex-factory documents
18 Sealed storage and shipment
