GB/T 24159-2022Welded insulated cylinders (English PDF)

3.1 Lot/batch

A quantity of product (or inner vessel) composed according to the same rules.

3.2 Tare of cylinder

The mass of the empty cylinder (for horizontal gas cylinder, it includes frame or support) that meets the basic functions of filling, storage, transportation, use and safety.

3.3 Effective volume

The maximum volume of liquid that the cylinder is allowed to fill.

3.4 Heat transfer coefficient

The amount of heat that can be transferred between hot and cold fluids in unit area, unit temperature difference, unit time, representing the strength of the heat transfer process.

3.5 Free air

Air at an absolute pressure of 1.01325 x 10^5 Pa and a temperature of 15.6°C.

5.1 Model naming methods

Vertical type is represented by "DPL". Horizontal type is represented by "DPW". The rest are named according to the method specified in GB/T 15384. When the design is changed, Roman numerals I, II, III, etc. can be added at the end of the model as serial numbers.

5.2 Basic parameters

5.2.1 Nominal volume and inner diameter of inner vessel

The nominal volume and inner diameter of the inner vessel shall be selected according to Table 1. The nominal volume shall be an integer multiple of 5.

5.2.2 Pressure

5.2.2.1 The pressure used in the calculation of the internal pressure of the wall thickness of the inner vessel is the design pressure. The design pressure is the pressure test pressure of the inner vessel. The pressure of withstand voltage test of the inner vessel shall not be less than 2 times the nominal working pressure (Pd=Pt>=2P).

5.2.3 Effective volume

6.1 General requirements

6.1.1 The material of the main body (cylinder and head) of the inner vessel shall be austenitic stainless steel that meets the requirements of GB/T 24511 and the requirements of the design documents.

6.1.2 The components welded on the inner vessel shall be austenitic stainless steel specified in the corresponding material standards and in accordance with the requirements of the design documents.

6.1.3 The chemical composition and tensile properties of welding materials and their deposited metals shall comply with the requirements of NB/T 47018.1 and NB/T 47018.3 as well as the requirements of design documents.

6.1.5 The outer shell shall be of austenitic stainless steel.

6.2 Chemical composition

The chemical composition and allowable deviation of the main material of the inner vessel shall comply with the provisions of Table 2.

6.3 Mechanical properties

The mechanical properties of the main material of the inner vessel shall comply with the provisions of Table 3 and design documents.

7.1 General requirements

7.1.1 Composition

7.1.2 Connecting piece between inner vessel and outer shell

The stress value of the connecting piece between the inner vessel and the outer shell shall not be greater than 2/3 of the material's normal temperature yield strength (or specified plastic extension strength) under the following independent loads.

7.1.3 Performance indicators

The leakage rate of vacuum interspace and the leakage rate of vacuum interspace are as specified in Table 4. The static evaporation rate with the nominal working pressure not greater than 2.4MPa is in accordance with the provisions of Table 4.

7.1.4 Maximum filling volume and maximum filling mass

7.1.5 Design service life

The design service life shall not exceed 20 years. It shall be indicated in the design document and used as the content of the nameplate.

7.1.6 Accessories

7.1.6.1 The cleanliness of accessories that come into contact with oxygen, such as valves, pressure gauges, safety pressure relief devices and liquid level gauges, shall meet the requirements of 8.13.2.

7.4.3 Safety pressure relief device

7.4.3.1 The main safety pressure relief device and the auxiliary safety pressure relief device shall be arranged in parallel. The main safety pressure relief device shall use safety valves. The auxiliary safety pressure relief device of LNG is only allowed to use safety valves. The auxiliary safety pressure relief device for the rest of the medium shall be safety valve or bursting disc safety device.

7.4.3.2 The set pressure of the main safety relief device (safety valve) shall not be greater than 1.2 times the nominal working pressure (Pz<=1.2P). The discharge pressure shall meet the following requirements.

7.4.3.3 The auxiliary safety pressure relief device is only applicable to the situation of C.1.2. It shall meet the following requirements. […]

7.5 Pressure relief device of outer shell

The outer shell shall be provided with a pressure relief device to meet the following requirements. […]

8.1 Responsibilities of manufacturer

8.2 Batching

8.2.1 Manufacture according to inner vessel batches. The material batch number of the same batch of inner vessel shall not exceed two. Product batches are carried out on the basis of inner vessel batches. The same inner vessel batch shall be one product batch, or it can be composed of multiple product batches.

8.2.2 The quantity of a batch of inner vessels shall not be more than 200 (excluding destructive inspection bottles).

8.3 Material re-inspection

The main material of the inner vessel shall be re-inspected for chemical composition according to the furnace number. The mechanical properties shall be re-inspected according to the batch number. The mechanical property test specimens shall be taken along the direction perpendicular to the rolling direction of the steel plate.

8.5 Unspecified tolerance

The grades without linear and angular dimensional tolerances are in accordance with the provisions of GB/T 1804. The machined surface is medium grade m. Non-machined surfaces are rough grade c.

8.6 Cylinder body

8.7 Head

8.7.1 The steel plates used to make the head shall not be spliced. The wall stress value of the liner head shall not be greater than the wall stress value of the liner barrel.

8.7.2 After the head is formed, there shall be no mutations, cracks, peeling, wrinkles and other defects. The wall thickness shall meet the requirements of 7.2, 7.3 and design documents.

8.7.3 The shape and size tolerance of the head shall be inspected in accordance with the provisions of GB/T 25198. The results shall meet the requirements of Table 6.

8.8 Connection joints

8.9 Assembly

8.9.1 Components shall be checked before assembly. The pressure components are not allowed to be strongly aligned and leveled.

8.9.3 The components welded on the inner cylinder body shall avoid the longitudinal and circumferential welded joints of the inner cylinder body.

8.9.4 The connection between the base, frame and hoisting accessories and the cylinder body shall avoid the longitudinal and circumferential welds of the outer shell.

8.10 Welding

8.10.1 Welding preparation and welding environment

8.10.2 Groove requirements

There shall be no cracks, delamination, inclusions and other defects on the groove surface. Before welding, the groove and other harmful impurities such as oxides, oil stains and other harmful impurities shall be removed within at least 20mm of the surface of the base metal on both sides (calculated by the groove edge).

8.10.3 Qualification of inner vessel welding procedure

8.12 Withstand voltage test of inner vessel

8.12.1 The withstand voltage test of inner vessel shall be carried out one by one after the non-destructive testing is qualified.

8.12.2 The test shall have reliable safety protection measures. It is confirmed and approved by the technical person in charge of the manufacturer or the person in charge of safety production.

8.12.3 The test shall use two pressure test instruments with the same range and within the validity period of the verification. The range is 1.5 times to 3 times the test pressure (shall be 2 times the test pressure). The accuracy is not less than level 1.6. The diameter of the mechanical dial is not less than 100mm.

8.12.4 During the test, welded joints with leakage shall be repaired in accordance with the provisions of 8.10.4.5. After passing the test, perform the withstand voltage test again.

8.12.5 The pressure shall not drop during the pressure holding check. There shall be no leakage, visible macroscopic deformation and abnormal sound.

8.13 Surface quality and cleanliness

8.13.1 There shall be no defects on the surface of the sheet that will affect normal use.

For sharp scratches, grinding shall be carried out. The maximum grinding slope shall be 1.3. Grinding shall be smooth and clean. After grinding, the thickness of the inner vessel meets the requirements of 7.2. The thickness of the outer shell meets the requirements of 7.3.

8.13.2 Components forming (or in) a vacuum space shall be cleaned of hydrocarbons (oil, grease and so on), decontaminated. Good protection measures shall be taken after disposal. Residual hydrocarbons shall not exceed 125mg/m² after treatment of parts in direct contact with oxygen.

8.14 Air tightness test

9.1 Main materials of inner vessel

For re-inspection of chemical composition and mechanical properties of main material of inner vessel, when using domestic materials, the test methods and inspection requirements shall be carried out in accordance with the provisions of GB/T 24511.

9.2 Wall thickness determination

Wall thickness shall be measured with ultrasonic thickness gauge or vernier caliper and other tools according to the frequency specified in Table 7.

9.3 Welding specimens of inner vessel products

Tensile test method for welded specimens of inner vessel products is in accordance with the provisions of GB/T 228.1. The impact test method is in accordance with the provisions of GB/T 229 (impact temperature is not higher than -192°C). The bending test method is in accordance with the provisions of GB/T 2653.

9.4 Nondestructive testing

9.5 Withstand voltage test of inner vessel

9.6 Surface quality and cleanliness

The treatment method of surface quality and cleanliness shall be in accordance with the provisions of JB/T 6896. Choose appropriate method for components of vacuum space.

For the parts that are in direct contact with oxygen, it shall use the oil concentration measurement method. Use quality method to treat hydrocarbons.

9.7 Leakage rate of vacuum interspace

Before vacuuming, test according to the method specified in GB/T 18443.3.

9.8 Leakage and deflation rate of vacuum interspace

At the end of vacuuming, test according to the method specified in GB/T 18443.4.

9.9 Air tightness test

After the accessories such as valves, instruments and safety pressure relief devices are assembled, they shall be tested in accordance with the methods specified in GB/T 12137.

9.10 Low temperature vacuum

After filling with liquid nitrogen and reaching thermal equilibrium, measure according to the method specified in GB/T 18443.2. […]