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This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization—Part 1: Rules for the structure and drafting of standardizing documents.
This document replaces NB/T 47012-2010 Pressure vessels for refrigerant equipment. The following main technical changes have been made with respect to NB/T 47012-2010:
a) Clause 1
——The pressure range and volume range applicable to the document have been modified;
——Provisions on the design by confirmatory test analysis method have been introduced.
b) Clause 3 "Terms and definitions" has been introduced;
c) Clause 4
——Provisions on the roles and responsibilities of the user/design employer have been introduced.
——Requirements for quality plan have been added to the roles and responsibilities of the manufacturer;
——The refrigerant has been adjusted according to the current situation and development needs of the industry;
——Category E welded joints have been added and relevant provisions have been made accordingly;
——Provisions on the welded joint coefficient on the secondary refrigerant side of heat exchanger have been introduced;
——The safety factor has been modified according to TSG 21-2016 Supervision Regulation on Safety Technology for Stationary Pressure Vessel.
d) Clause 5
——The provisions on the use of Q235 series and other materials have been modified;
——The provisions on the use and allowable stress of heat exchange tube materials have been modified;
——The provisions on the use and allowable stress of titanium heat exchange tube have been introduced;
——The provisions on the use of cast steel and cast iron have been introduced.
e) Clause 6
——The design calculation methods of internal pressure cylinder and external pressure cylinder have been modified, and the calculation of both are required to be performed in accordance with GB/T 150.3;
——Requirements for the center-to-center distance at the orifice of heat exchange tube with an outside diameter of ϕ6 mm have been introduced;
——The requirements for allowable deviation in the outside diameter of heat exchange tube and the tube orifice diameter of tubesheet have been modified, and provisions on allowable deviation in the outside diameter of small-diameter heat exchange tube and the tube orifice diameter of tubesheet have been introduced;
——The requirements for allowable deviation in tube orifice diameter of the baffle plate and the bearing plate have been modified, and provisions on allowable deviation in tube orifice diameter of the baffle plate and the bearing plate for small-diameter heat exchange tubes have been introduced;
——Provisions on external pressure design for integrally finned tubes made of copper and copper alloys, and titanium alloys by means of confirmatory external pressure test have been introduced.
f) Clause 7
——The presentation way of the clause has been modified with the same provisions as GB/T 150.1, GB/T 150.4, GB/T 151, JB/T 4734, JB/T 4745 and JB/T 4755 directly referenced instead of repeat.
——The dimensions concerning the width of tubesheet orifice bridge have been modified;
——Provisions on tube blockage for heat exchangers have been introduced.
g) Annexes
——Annex A “Design for external pressure of integrally finned heat exchange tubes made of copper and copper alloy and titanium alloy” has been added;
——The calculation method for safety valves has been modified so as to align with GB/T 9237-2017 Refrigerating systems and heat pumps—Safety and environmental requirements.
This standard was proposed by and is under the jurisdiction of the Stationary Pressure Vessel Subcommittee of the National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262).
The previous editions of this standard are as follows:
——JB/T 6917-1993, JB 6917-1998, JB/T 4750-2003 and NB/T 47012-2010.
Pressure vessels for refrigerant device
1 Scope
1.1 This document specifies design, manufacture, inspection and acceptance requirements of pressure vessels for refrigerant devices, including shell-and-tube heat exchangers (HEs) for refrigerant devices, , with liquefied gas as the refrigerant, the design pressure not higher than 5.0 MPa and design temperature not higher than 200 °C (hereinafter referred to as "vessels").
1.2 The working cycle of refrigerant device shall adopt vapor compression refrigeration cycle and heat pump and similar cycles.
1.3 This document is not applicable to the following pressure vessels:
a) Vessels with the inside diameter (the maximum geometric size of inner section boundary for vessels with non-circular section) less than 150 mm or volume capacity less than 0.03 m3;
b) Shell-free tube-in-tube HE, refrigerant tubular HE, plate HE;
c) The generator of direct-fired absorption refrigerant device.
1.4 Vessels or pressure elements with the structural dimensions that cannot be determined in accordance with this standard are allowed to be designed by the following methods:
a) Stress analysis, calculation and assessment including finite element method, with the specific requirements complying with Annex E of GB/T 150.1-2011;
b) Comparative empirical design using comparable proven structures, with the specific requirements complying with Annex D of GB/T 150.1-2011;
c) Design by confirmatory test analysis method, with the specific requirements complying with Annex C of GB/T 150.1-2011 for design by confirmatory blasting test method, and complying with Annex A for external pressure design of integrally finned tubes made of copper and copper alloy and titanium alloy by confirmatory external pressure test.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions 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 150.1-2011 Pressure vessels--Part 1: General requirements
GB/T 150.2 Pressure vessels—Part 2: Materials
GB/T 150.3-2011 Pressure vessels—Part 3: Design
GB/T 150.4 Pressure vessels--Part 4: Fabrication, inspection and testing, and acceptance
GB/T 151 Heat exchangers
GB/T 536 Liquefied anhydrous ammonia
GB/T 1226-2017 General pressure gauge
GB/T 1348-2019 Spheroidal graphite iron castings
GB/T 1527 Drawn tube of copper and copper alloys
GB/T 3091 Welded steel pipes for low pressure liquid delivery
GB/T 3625 Titanium and titanium alloy tube for condensers and heat exchangers
GB/T 6893 Aluminum and aluminum alloys cold drawn(rolled) seamless tubes
GB/T 7778 Number designation and safety classification of refrigerants
GB/T 8163-2018 Seamless steel tubes for liquid service
GB/T 8890 Seamless copper alloy tube for condenser and heat-exchanger
GB/T 9439-2010 Grey iron castings
GB/T 9948 Seamless steel tubes for petroleum cracking
GB/T 17791 Seamless copper and copper alloys tube for air conditioner and refrigeration equipment
GB/T 20928 Seamless inner grooved copper tube
GB/T 25198 GB/T 25198Heads for pressure vessels
HG/T 20592 Steel pipe flanges (PN designated)
HG/T 20613 Bolting for use with steel pipe flanges (PN designated)
HG/T 20615 Steel pipe flanges (Class designated)
HG/T 20634 Bolting for use with steel pipe flanges (Class designated)
JB/T 4734 Aluminum welded vessels
JB/T 4745 Titanium welded vessels
JB/T 4755 Copper pressure vessels
JB/T 6918-2017 The sintered metal and glass visual lens and liquid meter for refrigeration
JB/T 10503 Specification for high performance tubes for air conditioning and refrigeration field service
NB/T 47013.8 Nondestructive testing of pressure equipments—Part 8: Leakage testing
NB/T 47014 Welding procedure qualification for pressure equipment
NB/T 47018
(All parts) Technical permission of welding materials for pressure equipment
NB/T 47020 Type and specification for pressure vessel flanges
NB/T 47021 A-type socket-weld flange
NB/T 47022 B-type socket-weld flange
NB/T 47023 Welding neck flange
NB/T 47024 Nonmetallic gaskets
NB/T 47025 Spiral wound gaskets
NB/T 47026 Double-jacketed gaskets
NB/T 47027 Stud blots & nuts for body flange
NB/T 47065.1-2018 Vessel support—Part 1: Saddle support
NB/T 47065.2-2018 Vessel support—Part 2: Leg support
NB/T 47065.3-2018 Vessel support—Part 3: Lug support
NB/T 47065.4-2018 Vessel support—Part 4: Bracket support
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 150.1 and GB/T 151 apply.
3.1
refrigerant
fluid used to transfer heat in a refrigeration system which absorbs heat in low temperature and low pressure environment and releases heat in high temperature and high pressure environment, usually accompanied by a phase change process
3.2
secondary refrigerant
fluid that transfers heat between the cooled medium and the evaporator of the refrigeration unit, which, for the purpose of this standard, refers to liquid, e.g. water and ethylene glycol, that does not change in phase during working process
4 General
4.1 Basic requirements
4.1.1 The design, manufacture, inspection and acceptance of the vessels shall not only comply with the provisions of this document, but also comply with the relevant national laws, regulations and technical codes for safety.
4.1.2 The designer and manufacturer of the vessels shall have and implement a sound and effective quality assurance system.
4.1.3 The design and manufacture of the vessels within the scope specified in TSG 21 shall be supervised by the special equipment safety supervision body.
4.2 Qualifications, roles and responsibilities
4.2.1 Qualifications
For pressure vessels within the scope specified in TSG 21, the designer shall obtain an appropriate pressure vessel design license; the manufacturer shall obtain an appropriate special equipment manufacturing license.
4.2.2 Roles and responsibilities
4.2.2.1 User/design employer
The user/design employer of the vessel shall submit the design conditions to the designer in due written form, at least incorporating
a) the main standards and specifications on which the vessel design is based;
b) operating parameters, including working pressure, working temperature range, liquid level and nozzle load;
c) place of use and natural conditions, including ambient temperature and seismic fortification intensity;
d) refrigerant reference number and safety grouping;
e) design service life;
f) geometric parameters and nozzle orientation; and
g) other necessary conditions for design.
4.2.2.2 Designer
a) The designer is held responsible for the accuracy and integrity of the design documents;
b) The design documents of the vessel shall at least include strength calculation sheets, design drawings, manufacturing technical conditions, risk assessment report if required by relevant regulations or the design employer, and the installation, operation and maintenance instructions if necessary;
c) The general design drawing of the pressure vessels within the scope specified in TSG 21 shall be stamped with the special seal for design of the special equipment designer;
d) The issued risk assessment report shall meet the requirements of Annex F in GB/T 150.1-2011;
e) The designer shall keep all the design documents for the design service life of the vessels.
4.2.2.3 Manufacturer
a) The manufacturer shall manufacture in accordance with the design drawing. To make a change in the original design, a written approval shall be obtained from the original designer, and the part to be changed shall be recorded in detail;
b) Before manufacturing the vessel, a sound quality plan shall be formulated, which at least includes manufacturing process control points, inspection items and acceptable criteria of the vessel or pressure element.
c) The inspection department of the manufacturer shall carry out all inspections and tests according to the requirements of this standard, the design drawings, design documents and quality plan during and after the manufacturing process, and shall accordingly issue a report and be held responsible for its accuracy and integrity.
d) For each vessel product manufactured, at least the following technical documents shall be kept for future reference for the designed service life of the vessel (for vessels manufactured according to TSG 21 and in batches, these documents may be kept by batch, with the serial numbers of all the vessels in the batch indicated):
——quality plan;
——manufacturing process drawing or manufacturing process card;
——product quality certificates;
——documents on welding process and heat treatment process of the vessel;
——records on the inspection and test items specified in the standard as voluntary for the manufacturer;
——records on the check, inspection and test performed during and after the manufacturing process; and
——original design drawings and as-built drawings of the vessel.
e) After obtaining the confirmation from the supervision and inspection organizations that the vessel quality meets the requirements of this document and the design documents, the product quality certificate shall be completed and delivered to the user.
4.3 Scope of the vessel
4.3.1 The refrigeration vessel specified in this standard covers the shell and its integrated the pressure and non-pressure elements, with the specific scope defined is in accordance with the requirements of 4.3.2 to 4.3.5.
4.3.2 Connection between the vessel and the external tube:
a) The groove end face of the first girth joint of welded connection;
b) The end face of the first threaded joint of threaded connection;
c) The first flange sealing surface of flanged connection;
d) The first sealing surface of connection by special connecting piece or pipe fittings.
4.3.3 Pressure-bearing covers, e.g. of nozzles and inspection holes, and their fasteners and seals.
4.3.4 Non-pressure elements and their connection welds with pressure elements
4.3.5 Safety accessories and instruments directly installed on the vessel (see Annex B).
4.4 Design parameters
4.4.1 Pressure (gauge pressure unless otherwise indicated)
4.4.1.1 Working pressure
It refers to the highest pressure that may occur at the top of the vessel when the refrigerant device is in normal operation or stops running. At the high pressure side, it shall be the highest pressure that may occur at the top of the vessel when the refrigerant device is in normal operation, while at the low pressure side, it shall be the highest pressure that may occur at the top of the vessel when the refrigerant device stops running.
4.4.1.2 Design pressure
It refers to the set maximum pressure at top of the vessel, which, together with the corresponding design temperature, taken as the design load condition, and shall not be lower than the working pressure. It is determined with the following considerations taken into account:
a) If the vessel consists of more than two pressure chambers and the pressures acting on each chamber are different, the design pressure shall be determined separately according to the pressure of each chamber.
b) In order to make the working pressure not exceed the design pressure of the vessel, the loaded amount of refrigerant is limited as follows:
1) For accumulator-type vessels, the loaded amount of refrigerant liquid shall not exceed 80% of the vessel volume capacity;
2) For cascade-type refrigerant devices, the loaded amount of refrigerant at the low temperature side is determined by calculation.
c) Regarding the design pressure at the high pressure side, in the refrigeration cycle system, the part that bears condensation pressure due to the action of compressor belongs to the high pressure side. The design pressure at the high pressure side shall be higher than the saturated vapor pressure corresponding to the highest possible condensation temperature of refrigerant under normal operation conditions, and the relationship between the condensation temperature and saturated pressure may be determined according to Table 1 (this table lists the properties of commonly used refrigerants, and for the properties of other refrigerants, refer to relevant refrigerant user manuals).
d) Regarding the design pressure at the low pressure side, the part of refrigeration cycle system other than the high pressure side, the intermediate pressure part of the intercooler of two-stage compression refrigerant device and the condensing evaporator of cascade refrigerant device with the condensing temperature not higher than -15 °C belong to the low pressure side. The design pressure at the low pressure side shall be as follows:
1) The design pressure is generally determined according to the saturated vapor pressure of refrigerant at 38°C, as shown in Table 1;
2) When the ambient temperature exceeds 38°C, it is determined according to the highest pressure reached by the refrigerant.
4.4.2 Temperature
4.4.2.1 Design temperature
It refers to the set metal temperature of element, i.e. the average temperature along the element metal section, under normal operating conditions. The design temperature and design pressure are the conditions of design load. If the temperature of each working compartment of the vessel is different, the design temperature shall be determined separately. When the metal temperature of element is not lower than 0°C, the design temperature shall not be lower than the highest possible metal temperature of the element under normal operation; when the metal temperature of element is lower than 0°C, the design temperature shall not be higher than the lowest possible metal temperature of the element.
4.4.2.2 Design temperature at the high pressure side
It is selected according to the highest possible metal temperature of element at the high pressure side under normal operating conditions. For vessels that do not exchange heat, the maximum working temperature of refrigerant is generally taken as the design temperature. When the pressure element is exposed to two media with different temperatures, the higher temperature of the two media shall be generally selected. When the ambient temperature is lower than 0°C, the design temperature at the high pressure side is determined as above, but an assessment shall be made to confirm that the primary general membrane stress and bending stress of the vessel when the temperature is lower than 0°C during shutdown is less than or equal to 1/6 of the material's normal temperature yield strength and do not exceed 50 MPa. If not, it shall be designed according to the requirements of Annex E of GB/T 150.3-2011.
4.4.2.3 Design temperature at the low pressure side
When the service temperature is lower than 0°C, if the primary general membrane stress and bending stress at the service temperature is less than or equal to 1/6 of the normal temperature yield point of the material and do not exceed 50 MPa, the design temperature is the algebraic sum of the service temperature and 50°C (40°C for the vessel without post-weld heat treatment). When the design temperature obtained as above is not lower than -20°C, the design temperature shall be determined as the case not lower than 38°C. When the design temperature obtained as above method is lower than -20°C, the vessel shall be designed according to Annex E of GB/T 150.3-2011.
4.4.3 Thickness
4.4.3.1 The additional thickness of the vessel is the sum of the negative deviation of material thickness and corrosion allowance. The negative deviation of material thickness is determined according to the corresponding material standard; the corrosion allowance is determined as specified in 4.4.3.2.
4.4.3.2 Different corrosion allowance may be used when the corrosion degree varies with the elements of the vessel. The corrosion allowances for the elements of the vessel may be as follows:
a) When the outer surface of the vessel made of carbon steel or low alloy steel (with the inner side as the refrigerant side) is directly exposed to weather or exposed to air, water vapor and water, the corrosion allowance is not less than 1 mm;
b) With the same corrosion environment as mentioned in paragraph a), when the outer surface of the material has an effective corrosion-resistant protective film and is easy to maintain, the corrosion allowance is not less than 0.6 mm;
c) In indoors environment or with weatherproof measures, when the outer surface of the material has an effective corrosion-resistant protective film, and it is intended to be used in a slightly corrosive environment, the corrosion allowance is not less than 0.4 mm;
d) For the vessels and tube walls on the side exposed to the refrigerant, generally corrosion allowance is not considered;
e) The corrosion allowance is not less than 1 mm in the case of carbon steel vessels or low alloy steel vessels with water vapor or water as the medium;
f) Generally, corrosion allowance is not considered for heat exchange tubes as their thickness shall be able to meet the design service life requirements.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General
5 Materials
6 Design
7 Manufacturing, inspection and acceptance
Annex A (Normative) Design for external pressure of integrally finned heat exchange tubes made of copper and copper alloy and titanium alloy
Annex B (Normative) Safety accessories and instruments
Annex C (Normative) Requirements of pressure vessels for steel ammonia refrigerant devices for liquid ammonia and filling procedures
