HG 20585-1998 Technical regulations for steel cryogenic pressure vessels
Some standard content:
Industry Standard of the People's Republic of China
HG20585-1998
Technical Specification for Steel Low Temperature Pressure Vessels1998—11-18
State Administration of Petroleum and Chemical Industry
1999—03-01
Industry Standard of the People's Republic of China
Technical Specification for Steel Low Temperature Pressure Vessels VesselsHG20585—1998
Editor: National Chemical Equipment Design Technology Center Approval Department: State Petroleum and Chemical Industry Bureau Implementation Date: March 1, 1999 National Chemical Engineering Construction Standard Editing Center (formerly the Engineering Construction Standard Editing Center of the Ministry of Chemical Industry) 1999 Beijing
This standard (HG20585-1998) is based on the original standard (HGJ19-89), based on the experience gained from many years of implementation, and based on the content of national standard GB150-19.98. and the standard specifications of domestic and foreign engineering companies in recent years. The newly revised standard has the following major changes compared with the original standard: 1. Modify the provisions of low temperature drop and low stress conditions with reference to ASMEVI-1 (95); 2. Modify the provisions of exempting small-size steel pipes from impact tests; 3. Clarify the assessment requirements for temperature-controlled hot processing materials; 4. Cancel the relevant contents of domestic and foreign low-temperature steel standards. Appendices A and B of this standard are appendices to this standard. This standard is proposed and managed by the National Chemical Equipment Design Technology Center. This standard is edited by the National Chemical Equipment Design Technology Center. The main drafter of this standard: Ying Daoyan
HG20585 "Technical Regulations for Steel Cryogenic Pressure Vessels" is a supplement and concretization of GB150 "Steel Pressure Vessels" in combination with the specific conditions of chemical vessel design, and stipulates the design, material selection, structure, manufacturing and inspection of steel cryogenic pressure vessels. The scope of application, referenced standards and definitions of this standard are the same as GB150 "Steel Pressure Vessels" (hereinafter referred to as GB150) unless otherwise specified.
1.0.1 This regulation applies to steel cryogenic pressure vessels for chemical use with a design pressure not exceeding 35.0MPa and a design temperature equal to or lower than -20℃ and not lower than -196℃.
1.0.2 Ferritic steel may cause low-stress brittle fracture when it is below a certain transformation temperature and has a considerable stress level and a sufficiently sharp notch (defect). In this regard, this regulation puts forward corresponding requirements in terms of materials, design, structure and manufacturing. 1.0.3 For low-temperature pressure vessels made of chromium-nickel austenitic steel, when the design temperature is not less than 196°C, only the following requirements need to be met, and the rest shall be considered as normal temperature pressure vessels. 1 The parent material shall be standard chromium-nickel austenitic steel with a carbon content of less than or equal to 0.10%, such as 0Cr18Ni9, 00Cr19Ni10, OCr18Ni10Ti, etc.
2 If casting materials are used, when the design temperature is less than -70°C, the austenitic cast steel shall also be subjected to a low-temperature Charpy impact test at the design temperature and meet the requirements of Table 4-2.
3 Welding materials and processes shall meet the following requirements: (1) The carbon content of the weld metal shall be less than or equal to 0.10%. (2) The chemical composition of the weld metal shall comply with the requirements of E308, E308L, E309 in GB983 "Stainless Steel Welding Rods" and H0Cr21Ni10, H00Cr21Ni10, H0Cr26Ni21 in GB4233, 4242 "Stainless Steel Wires for Welding". (3) When the design temperature is less than 70℃, the low temperature impact test of the weld metal shall be carried out and meet the requirements of Table 4-2.
4 The cold working deformation shall comply with the provisions of Article 6.2.2, Clause 3. 1.0.4 This regulation is only applicable to cryogenic pressure vessels, pressure components (including pipes, flanges and fasteners, etc.) and non-pressure components directly welded to cryogenic pressure components. Non-cryogenic pressure components and those that are exposed to low temperatures but are not pressure components and are not directly welded to pressure components do not need to comply with this regulation.
1.0.5 In addition to complying with the relevant requirements of this regulation, the design of cryogenic pressure vessels shall also comply with the corresponding requirements of the following standards. GB150
HG20580
HG20581
HG20582
HG20583
HG20584
《Steel Pressure Vessels》
《Basic Regulations for Design of Steel Chemical Vessels》《Regulations for Material Selection of Steel Chemical Vessels》《Regulations for Strength Calculation of Steel Chemical Vessels》《Regulations for Structural Design of Steel Chemical Vessels》《Technical Requirements for Manufacturing of Steel Chemical Vessels》423
2 Definitions
2.0.1 Minimum operating temperature: refers to the lowest metal temperature that may occur during normal operation of the vessel. 2.0.2 Design temperature (minimum): refers to the lowest temperature that the metal of the pressure component may reach during normal operation of the vessel under the corresponding design pressure.
When different parts of the vessel may produce different temperatures during operation, the expected different temperatures can be taken as the design temperatures of the corresponding parts.
1When the container wall is in direct contact with the working medium and has external insulation, the design temperature shall be the lowest temperature of the medium or the normal working temperature of the medium minus the possible temperature fluctuation value. 2When there is heat transfer on both sides of the wall, the design temperature can be determined based on the wall temperature obtained by heat transfer calculation or the measured wall temperature, and the lowest temperature after considering the temperature fluctuation value. 3For pressure vessels affected by low ambient temperature, when its design temperature is controlled by the ambient temperature, its minimum design temperature shall be determined according to the following principles:
(1) For storage containers containing compressed gas and without insulation facilities, the design temperature shall be the lowest ambient temperature① minus 3℃. (2) For storage containers without insulation containing liquid that accounts for more than 1/4 of the container volume, the design temperature shall be the lowest ambient temperature. (3) For containers with insulation or materials that are often in a flowing state, the design temperature shall be determined by comprehensive consideration of the wall temperature based on the material temperature, flow rate, container size, heat dissipation, etc., and shall be determined through calculation analysis or reference examples. (4) Except for containers specially designed for emergency shutdown, the influence of ambient temperature on the wall temperature of the container should be considered based on normal operating conditions. Generally, the design temperature is not determined by accidental cooling in an accident state or natural cooling after shutdown. 2.0.3 Low temperature working pressure: refers to the working pressure of low temperature pressure vessels and their pressure components under the condition that the corresponding working temperature is lower than or equal to -20°C.
2.0.4 Low temperature and low stress conditions refer to the conditions where the overall membrane stress of the container shell or its pressure components drops to less than 75% of the product of the material allowable stress specified in GB150 [and the corresponding weld joint coefficient] under low temperature (≤-20°C) operating conditions. ① The lowest ambient temperature is the lowest value of the "monthly average minimum temperature" in each month over the years in the region. The "monthly average minimum temperature" is the sum of the lowest temperatures of each day of the month divided by the number of days in the month.
3 Pressure vessels for low temperature and low pressure conditions
3.0.1 Adjustment of design temperature
1 When the design temperature is not lower than -46℃, the design temperature of the pressure vessel for low temperature and low stress conditions shall be adjusted (increased) according to the requirements of Table 3-1. The adjusted design temperature is equal to the sum of the design temperature t and the temperature adjustment value △t. Table 3-1
Stress ratio. /（[]
Note: ①When the stress value is in the middle value, △t can be taken as the interpolated value; ②It can also be taken as the stress condition of Article 3.0.1, Clause 2. Design temperature adjustment value At.(C)
2When the design temperature is lower than -46℃ but not lower than -100℃, the design temperature adjustment value △t can be taken as 50℃ only when the primary overall membrane stress of the container shell or its pressure-bearing components drops to less than or equal to one-sixth of the standard normal temperature service point of the steel and is not greater than 50MPa.
3When the design temperature is lower than -100℃, the design temperature adjustment value is 0.3.0.2 The adjusted design temperature is equal to When the adjusted design temperature is higher than -20℃ but lower than 0℃, the material selection (including the impact test temperature of steel and welded joints), design, manufacturing and inspection requirements of pressure vessels shall be determined according to the adjusted design temperature. 3.0.3 When the adjusted design temperature is higher than -20℃ but lower than 0℃, the impact test temperature of the steel and welded joints of the pressure vessel shall be equal to or lower than the adjusted design temperature. Other design, manufacturing and inspection requirements do not need to follow the provisions of this standard. 3.0.4 When the adjusted design temperature is not lower than 0℃, the material selection, design, manufacturing and inspection requirements of pressure vessels do not need to follow the provisions of this standard.
3.0.5 According to the various working conditions that may occur in the container, the most demanding working temperature-stress combination should be selected as the basis for determining the low-temperature low-stress working condition.
3.0.6 The low-temperature low-stress working condition is not applicable to low-temperature containers with a lower limit of the standard tensile strength of steel greater than 540MPa. 425Www.bzxZ.net
4 Materials
4.0.1 The steel used in the pressure components of low-temperature pressure vessels shall comply with the requirements of this standard in addition to the provisions of the standards listed in Article 1.0.5.
4.0.2 The steel used in the pressure components of low-temperature pressure vessels must be killed steel. 4.0.3 The steel used in low-temperature pressure vessels and their pressure components must be subjected to Charpy (V-notch) low-temperature impact test in accordance with the requirements of Article 4.0.5, except when the cross-sectional dimensions of the material are too small to produce a small-sized specimen of 2.5mm×10mm×55mm (in this case, Article 4.0.6 should be followed).
4.0.4 The material standards, usage conditions and minimum test temperature of impact test for pressure components of cryogenic pressure vessels shall comply with the relevant steel standards and GB150.
For steels not listed in this standard (national standards or industry standards and grades), or for those using lower impact test temperatures, the following conditions shall be met at the same time.
1 It is considered through evaluation that the material properties and technical requirements are equivalent to or higher than those of the steels listed in this regulation, and meet the requirements of Article 4.0.5.
2 When using a lower impact test temperature than that specified in the steel standards and GB150 or changing the heat treatment state, the sampling rate of the impact test shall meet the following requirements:
Steel plates - one sheet at a time;
Steel pipes and steel bars - double the requirements of Article 4.0.5, Clause 4: Forgings - the inspection level shall not be lower than JB4726~4728 straight level, and the impact test sampling rate shall be increased by times. 3 With the consent of the equipment technical person in charge of the design unit. 4.0.5 Charpy (V-notch) low temperature impact test 1 The test temperature shall be determined according to the minimum design temperature of the vessel, and shall take into account factors such as the type and size of the bearing stress, the section thickness and the decrease in toughness of the welded joint. The determination principles are as follows: (1) The test temperature shall be equal to or lower than the design temperature (generally, it shall be equal to the design temperature). (2) When the design conditions meet the low temperature and low stress conditions, the impact test temperature may be adjusted according to 3.0.1 to 3.0.5. When the adjusted impact test temperature is higher than or equal to 0°C, it is not necessary to conduct a low temperature impact test. (3) For vessels with a shell thickness greater than 16 mm but unable to undergo post-weld stress relief heat treatment, the impact test temperature of the shell material and its welded joints shall be reduced according to the requirements of Table 4-1. (4) When the impact toughness of the heat affected zone of the parent material may decrease significantly due to welding, the material selection shall consider a larger toughness margin, or reduce the impact test temperature of the parent material to ensure that the low temperature toughness of each part of the welded joint (heat affected zone, fusion line, weld metal) can meet the requirements of this regulation.
(5) Except for low-temperature containers, the test temperature of bolt materials installed outside the container can generally be 15 to 30°C higher than the shell design temperature. In the case of insulation, the design temperature of bolts for butt-welded or flat-welded flanges can be 15°C higher than the shell; the design temperature of bolts for slip-on flanges can be 30°C higher. The impact test temperature of nut materials is allowed to be 30°C higher than the test temperature of bolts. (6) For pressure-bearing components that do not require welding and are mainly subjected to bending stress, such as bolted flat covers, slip-on flanges, etc., the impact test temperature of the material is allowed to be 30°C higher than the design temperature of the container. 426
Table 4-1 Impact test temperature of shell materials and welded joints without post-weld heat treatment Design temperature
20~-40
Reduced temperature
Design temperature
-41～-60
Reduced temperature
Design temperature
61~-80
Reduced temperature
2 The heat treatment state of the specimen shall be consistent with the final use state of the material, including hot working and stress relief heat treatment during processing.
3 Requirements for specimen preparation
(1) The specimen shall be a 10mm×10mm×55mm Charpy impact specimen that meets the requirements of GB2106 "Metal Charpy (V-notch) Impact Test Method". Three specimens shall be tested in a group. (2) If the material cross-sectional dimensions limit the ability to produce standard-sized specimens, small specimens of 7.5 mm × 10 mm × 55 mm, 5 mm × 10 mm × 55 mm, and 2.5 mm × 10 mm × 55 mm should be produced for testing. When it is possible to produce standard-sized specimens, small specimens are not allowed to be used for testing. When standard-sized specimens cannot be produced, small specimens as large as possible should be used for testing. (3) The notch of the specimen should be cut along the thickness direction of the material (bars should be cut along the diameter direction). 4 Test method and sampling quantity
The test method should comply with the requirements of GB4159 "Metal Low-Temperature Charpy Impact Test Method". The sampling quantity should comply with the following requirements: (1) Steel plates
Each batch of steel plates consists of the same furnace number, the same thickness, and the same heat treatment furnace. Each batch of 6-16 mm steel plates should not exceed 15 tons, and each batch of steel plates larger than 16 mm should not exceed 25 tons. A group of three specimens should be taken from each batch of steel plates. The sampling position is at 1/4 of the plate width at the end of the steel plate, and the specimen is taken horizontally (the length direction of the specimen is perpendicular to the rolling direction). When the plate thickness is greater than or equal to 30mm, the center line of the specimen should be located at 1/4 of the plate thickness. The axis of the specimen notch is perpendicular to the plate surface. (2) Steel pipes
Each batch of steel pipes consists of the same furnace number, the same specification size, and the same heat treatment furnace. The number of each batch shall not exceed 200. Select any two steel pipes and take a group of three specimens at one end. The sampling direction depends on the diameter and wall thickness of the steel pipe. If possible, it is taken tangentially, otherwise it is taken longitudinally. The axis of the specimen notch is as perpendicular to the pipe wall as possible. For steel pipes used to manufacture container shells, a group (three) of specimens should be taken from each batch according to 10% of the number of steel pipes, and no less than two specimens should be taken for low-temperature impact test. When the number of steel pipes is not more than two, one specimen is taken from each batch. (3) Steel bars (including bolt materials)
Each batch of steel bars consists of the same furnace number, the same specification size, and the same heat treatment furnace. From each batch of steel bars that have completed the final heat treatment, select one and take a group of three samples.
The sampling direction is longitudinal, and the center of the sample is located at 1/2 of the radius of the steel bar as much as possible. (4) Forgings
Sampling shall be in accordance with the provisions of JB4726~4728.
5The impact energy shall meet the requirements listed in Table 4-2 according to the material strength grade. 427
Steel category
Ferritic steel
Welded joint
Austenitic steel
Material standard
Minimum
Tensile strength
>412~510
>510~570
Weld metal
Table 4-2 Low temperature impact energy requirements
Minimum impact energy standard》A(J)
10mm×10mmX55mm7.5mmX10mmX55mmStandard specimen
3 specimens
Small specimen
3 specimens
5mmX10mmX55mm
Small specimen
3 specimens
.5mm×10mm×55mm
Small specimen
3 specimens
Note: For high-strength steel (o>570MPa), the Axv of each specimen shall not be less than 27J. For other steel types, only one specimen among the three specimens is allowed to have an impact energy lower than the average value listed in the table, but it shall not be lower than 70% of the average value (see the single specimen value listed in the table). 6 If the impact test results do not meet the requirements, they shall be handled according to the following situations: (1) If the values of a group of three specimens are all lower than the specified average value, or the values of two specimens are lower than the specified single value, the inspected steel or welded joint shall be judged as unqualified. (2) For situations other than the above, three more specimens shall be made from the same specimen (or inspected steel) for re-testing. The average value of the six samples before and after shall not be less than the specified value, the number of samples below the specified average value shall not be more than two, and the failure of a single value shall not occur repeatedly, otherwise it is still considered unqualified.
(3) For steels that are impact tested in batches, when any of the inspected steels representing the batch fails, they should be tested piece by piece, or the batch of steel should be reprocessed and re-inspected as a new batch. (4) For steels that are impact tested piece by piece, if the test fails, it is allowed to be re-heat treated and re-tested. 4.0.6 For low-temperature steel pipes (listed in GB150), when it is impossible to prepare 2.5mm×10mm×10mm impact specimens due to steel pipe size limitations, impact testing can be exempted. For other low-carbon steel and carbon-manganese steel pipes, when it is impossible to prepare 2.5mm×10mm×10mm impact test specimens can be exempted from impact test, but the minimum design temperature shall be in accordance with the provisions of Table 4-3. Table 4-3 Minimum design temperature of steel pipes exempted from impact test Nominal thickness of steel pipe (mm)
Used in the state after welding
Minimum design temperature (℃)
Used in the state of heat treatment after welding
Note: Steel pipes exempted from impact test are no longer applicable to the design temperature adjustment in Chapter 3 of this standard. 4.0.7 When the thickness of steel plates used to manufacture the shell, convex head and spherical shell of low-temperature pressure vessels exceeds the following values, ultrasonic flaw detection shall be carried out in accordance with JB4730428
, and shall not be lower than Grade III. 1 For steel plates with a thickness greater than 16 to 20mm, 20% of each batch shall be sampled, with at least one sheet. 2 For steel plates with a thickness greater than 20mm, each sheet shall be inspected. 3 Seamless steel pipes used as the cylinder of low-temperature pressure vessels shall be ultrasonically inspected in accordance with JB4730. 4.0.8 Forgings for cryogenic pressure vessels shall comply with JB4726~4727 and shall not be lower than the grade requirements. When the design pressure is greater than or equal to 1.60MPa, it shall not be lower than the straight grade.
4.0.9 Welding materials for cryogenic pressure vessels (manual electric welding rods, gas shielded welding wires, submerged arc welding wires and fluxes, etc.) shall meet the following requirements.
1 Manual arc welding rods for welding pressure components of cryogenic pressure vessels or pressure components and non-pressure components shall use low-hydrogen alkaline welding rods of GB5117 "Carbon Steel Welding Rods" and GB5118 "Low Alloy Welding Rods". Submerged arc welding fluxes shall use alkaline or neutral fluxes. Specific welding rod grades available for selection are shown in Appendix B. 2 Ferritic welding materials (except 9% Ni steel) shall generally be used for welding between ferritic steels. The low-temperature impact test temperature of the welded joint and the requirements for low-temperature impact energy of the weld metal, fusion line (performed during process qualification), and heat-affected zone are the same as those of the parent metal, and meet the requirements of Table 4-2.
3 The welding consumables for welding dissimilar steels between ferritic steels are generally selected according to the parent metal with higher toughness requirements. The heat treatment state of the dissimilar steel welding process qualification and product welding test plate should be the same as the final use state of the container. The following requirements should be met during performance inspection: (1) The tensile strength of the welded joint shall not be lower than the smaller value of the lowest tensile strength of the parent metals on both sides. (2) The impact energy requirements of the weld metal, the fusion line on the lower strength side, and the heat-affected zone shall be based on the parent metal on the lower strength side, and meet the requirements of Table 4-2. The impact energy requirements of the fusion line and heat-affected zone on the higher strength side shall be based on the parent metal on the higher strength side, and meet the requirements of Table 4-2. (3) The bending test requirements of the joint shall be based on the lower requirement of the parent metal on both sides. 4 The selection of welding consumables between austenitic steels shall meet the requirements of Article 1.0.3, Clause 3. 5. For the welding of dissimilar steels between ferritic steel and austenitic steel, high chromium nickel or nickel-based welding materials of type Cr23Ni13 or Cr26Ni21 shall generally be used. In principle, no stress relief heat treatment shall be performed after welding. The welding process assessment and product welding test plate of such dissimilar steels shall meet the following requirements:
(1) The tensile strength of the welded joint shall not be lower than the smaller value of the lowest tensile strength of the parent materials on both sides. (2) The impact energy of the fusion line and heat-affected zone on the ferritic steel side shall meet the requirements of Table 4-2 according to the tensile strength of the ferritic steel, and the impact energy of the weld metal shall meet the requirements of Table 4-2. (3) The joint shall be subjected to a side bending test with a bending diameter of d=4a and 180°. After the bending test, there shall be no cracking defect exceeding 1.5mm in any direction measured on the tensile surface, and there shall be no cracking defect exceeding 3mm at the fusion line. 4.0.10 In addition to the required technical conditions specified in the material standards, the chemical composition, heat treatment state, performance index, inspection items or inspection rate must be specified in the design drawings or technical documents. 4.0.11 Design or construction using foreign steel for cryogenic pressure vessels must also comply with the corresponding requirements of this regulation for materials, and the allowable stress of the material shall be calculated according to the safety factor specified in GB150. 4.0.12 The low-temperature toughness and welded joint performance of non-pressure accessory materials directly welded to the pressure components of cryogenic pressure vessels must match the pressure components.
5 Strength calculation and structural design
5.0.1 The allowable stress of the pressure component material of the cryogenic pressure vessel shall be the value of 20C at room temperature. The strength calculation method shall be in accordance with the provisions of GB150 and HG20582.
5.0.2 The structural design of cryogenic pressure vessels and their components shall fully consider the following requirements: 1 The structure should be as simple as possible to reduce the degree of restraint of welded parts. 2 The structure should avoid excessive temperature gradients. 3 The structure should reduce local stress concentration and sharp changes in cross-section. 4 The connection welds of accessories should not be discontinuously welded or spot welded. 5 The saddle, ear seat, leg (except spherical tank) or skirt seat of the container should be equipped with a pad or connecting plate to avoid direct welding with the container shell as much as possible. The pad or connecting plate is considered as a low-temperature material. 6 When the container is welded with pipes and accessories with complex loads, stress relief is required after welding and heat treatment cannot be performed as a whole, the possibility of separate heat treatment of the components should be considered.
7 Pipe reinforcement should be used as a whole or thick-walled pipe reinforcement as much as possible. If a reinforcement plate is used, it should be a full penetration structure with a smooth transition of the weld.
5.0.3 The structural design of the weld should comply with the following provisions: 1 The welds of the pressure-bearing part of the pressure vessel are divided into four categories: AB, C, and D according to their location. The classification principle is the same as the relevant provisions of GB150.
In addition, the connecting welds of the base, lug, bracket, pad and other non-pressure accessories with the inner and outer shell walls of the pressure vessel are called Class E welds.
2 Class A welds shall be welded by double-sided butt welding, or by single-sided butt welding with the same quality as double-sided welding, which ensures full penetration and double-sided forming. For single-sided welding with pads, the pads must be removed after welding. 3 Class B welds shall also be welded by double-sided butt welding, which is the same as Class A welds, or by full penetration butt welding, which is equivalent to double-sided welding. If necessary, single-sided welding with pads without removing the pads is allowed. 4 Class C welds shall comply with the requirements of the following relevant clauses: (1) Butt welds between flat heads, tube sheets, flanges and similar components and shells shall comply with the requirements of Article 5.0.3, Clause 3. (2) The T-type or L-type connection weld between the flat head and the shell should comply with the following prescribed types equivalent to HG20583: a. Single-sided welding - J1, J2, J5, J7; b. Double-sided welding - J3, J4, J6.
Single-sided welding J1, J2, J7 should be a full-penetration structure. When using the J7 type welding structure with unloading groove, the head material should be forgings. If steel plates are used, they must meet the Z25 grade requirements of GB5313 "Thickness Direction Performance Steel Plate", or the steel plate must be ultrasonically inspected in accordance with JB4730 for 3 times the weld width of the welding area, and there must be no defects. (3) The T-type or L-type connection weld between the tube sheet (with flange) and the shell shall comply with the following structural types equivalent to HG20583:
a. Single-sided welding - R5.R7;
b. Single-sided welding with pad - R3R6, R8; c. Double-sided welding - R11, R9 (with short section). All connection welds, regardless of the type of joint, are full penetration structures. 430
(4) The flat welding structure between flange and cylinder and pipe is only applicable to the following working conditions: a. The design temperature is not less than -46℃, and the design pressure is not more than 4.0MPa (or 300 pounds); b. Use standard neck flat welding flange or JB4700 type B equipment flange. (5) The connection weld between the inner head and the cylinder can adopt the structure shown in Figure 5-1, but the design pressure should not be greater than 1.0MPa or the design temperature should not be lower than -30℃, and the minimum tensile strength at room temperature specified in the material standard should not be greater than 540MPa. Take ≥S and must be ≥15
Take 2S but need not exceed 25
Figure 5-1 Connection structure between the inner head and the cylinder
5D-type welds shall comply with the requirements of the following relevant clauses: (1) The butt weld between the pipe and the vessel wall shall comply with the requirements of Class A welds. (2) Except for the provisions of 5.0.3, Item 5 (4) to 5.0.3, Item 5 (6), the fillet weld between the pipe and the vessel wall shall adopt a fully penetrated structure.
The fillet weld of double-sided welding shall comply with the requirements equivalent to G4~G18, G24, and G25 in HG20583. The fillet welds of single-sided welding shall comply with the structural types equivalent to G2, G3, G34, G37, and G41 in HG20583 to ensure the penetration requirements.
(3) The connection welds between the pipe with reinforcement plate and the container wall shall comply with the requirements equivalent to G28, G29, G30, and G33 in HG20583. The material requirements for the pipe, container wall and reinforcement plate are the same as those of Article 5.0.3, Clause 4 (5). The difference in the average linear expansion coefficient between the reinforcement plate and the wall material shall be within 15%, and the same material as the wall shall be used as much as possible. The structure with reinforcement plate shall not be used in occasions where the container wall thickness is greater than 30mm, nor in occasions where the design temperature is lower than -46°C. (4) The welding connection between the flange and the container wall shall adopt the structural type shown in Figure 5-2 and shall meet the following requirements: a.The maximum gap between the flange and the wall should not be greater than 3mm; b. The material requirements for the flange and the wall are the same as those in 5.0.3, Clause 4 (5). c. When the external load or thermal stress is large, the structure shown in Figure 5-2 (b) and (c) should be used. d. The structure in Figure 5-2 (d), (e) and (f) is only used in situations where the design temperature is not less than -46°C. 431
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