GB/T 20663-2017 Accumulators
1 Scope
1.1 This standard specifies materials, design, fabrication, performance and testing, inspection rules, marking, packaging, transportation and safe use and other requirements for accumulator pressure vessels (unless explicitly referred to a specific type of accumulator, hereinafter referred to as “the accumulators”).
1.2 The accumulators specified in this standard refer to containers in which the liquid at the liquid end is pressurized by utilizing the compressibility of gas in the gas chamber, and are divided into the product types as follows:
—bladder accumulators;
—diaphragm accumulators;
—piston accumulators.
1.3 The potential failure modes of the accumulators specified in this standard include:
—ductile yielding;
—brittle fracture;
—fatigue; and
—leakage.
1.4 This standard applies to the accumulators with parameters within the ranges specified in Table 1, petroleum-based hydraulic fluid or emulsion as the working medium at the liquid end, and nitrogen charged in the gas chamber.
Table 1 General parameters of the accumulators
Accumulator type Design pressure
MPa Design temperature
℃ Nominal capacity
L
Bladder accumulator ≤80 -40~+120 ≤350
Diaphragm accumulator ≤10
Piston accumulator ≤350
1.5 This standard does not apply to accumulators made of non-metallic materials.
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 150.1-2011 Pressure vessels - Part 1: General requirements
GB/T 150.2-2011 Pressure vessels - Part 2: Materials
GB/T 150.3-2011 Pressure vessels - Part 3: Design
GB/T 150.4-2011 Pressure vessels - Part 4: Fabrication, inspection and testing, and acceptance
GB/T 196 General purpose metric screw threads - Basic dimensions
GB/T 197 General purpose metric screw threads - Tolerances
GB/T 223
(all parts) Methods for chemical analysis of iron, steel and alloy
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 229 Metallic materials - Charpy pendulum impact test method
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method
GB/T 232 Metallic materials - Bend test
GB/T 246 Metal materials - Tube - Flattening test
GB/T 528 Rubber, vulcanized or thermoplastic - Determination of tensile stress-strain properties
GB/T 531.1 Rubber vulcanized or thermoplastic - Determination of indentation hardness - Part 1: Durometer method (Shore hardness)
GB/T 699 Quality carbon structure steels
GB/T 1220 Stainless steel bars
GB/T 1682 Rubber, vulcanized - Determination of low-temperature brittleness - Single test piece method
GB/T 1690 Rubber, vulcanized or thermoplastic - Determination of the effect of liquids
GB/T 3077 Alloy structure steels
GB/T 5777-2008 Seamless steel pipe and tubing methods for ultrasonic testing
GB/T 6479 Seamless steel tubes for high-pressure chemical fertilizer equipment
GB/T 7755 Rubber, vulcanized or thermoplastic - Determination of permeability to gases
GB/T 7759.1 Rubber, vulcanized or thermoplastic - Determination of compression set - Part 1: At ambient or elevated temperatures
GB/T 9251-2011 Methods for hydrostatic test of gas cylinders
GB/T 9252 Method for cycling test of gas cylinders
GB/T 11211 Rubber vulcanized or thermoplastic - Determination of adhesion to metal - Two-plate method
GB/T 13296 Seamless stainless steel tubes for boiler and heat exchanger
GB/T 13934 Rubber, vulcanized or thermoplastic - Determination of flex cracking and crack growth (De Mattia)
GB/T 14976 Seamless stainless steel pipes for fluid transport
GB/T 15385 Method for hydraulic burst test of gas cylinder
GB/T 18248 Seamless steel tubes for gas cylinder
GB/T 22085.1 Electron and laser beam welded joints - Guidance on quality levels for imperfections - Part 1: Steel
JB/T 4711 Coating and packing for pressure vessels transport
JB4732-1995 Steel pressure vessels - Design by analysis (as confirmed in 2005)
NB/T 47008 Carbon and alloy steel forgings for pressure equipment
NB/T 47009 Alloy steel forgings for low temperature pressure equipment
NB/T 47010 Stainless and heat-resisting steel forgings for pressure equipments
NB/T 47013.1 Nondestructive testing of pressure equipments - Part 1: General requirements
NB/T 47013.4 Nondestructive testing of pressure equipments - Part 4: Magnetic particle testing
NB/T 47013.5 Nondestructive testing of pressure equipments - Part 5: Penetrant testing
NB/T 47013.7 Nondestructive testing of pressure equipments - Part 7: Visual examination
NB/T 47013.8 Nondestructive testing of pressure equipments - Part 8: Leak testing
NB/T 47014 Welding procedure qualification for pressure equipment
TSG21 Supervision regulation on safety technology for stationary pressure vessel
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
bladder accumulator
accumulator mainly consisting of a shell and a bladder, in which liquid and gas are separated by a flexible bladder
3.2
diaphragm accumulator
accumulator in which the upper and lower shell portions are connected by welding, self-threading or applied annular lock nut, and liquid and gas are separated by a flexible rubber diaphragm
3.3
piston accumulator
accumulator consisting of a cylindrical body, piston and end cap, in which liquid and gas are separated by a piston seal assembly
3.4
operating pressure
maximum pressure that may be reached by the accumulator under normal operating conditions
3.5
charging gas pressure
gas pressure in the accumulator when there is no pressure at the liquid end
3.6
nominal capacity
volume of the gas chamber of the accumulator in the charged state
3.7
design pressure
set maximum pressure of the accumulator, which, together with the corresponding design temperature, is used as the design load condition and has a value not lower than the operating pressure
3.8
design temperature
metal temperature of the element (average of the temperatures along the metal cross-section of the element) which is set for the accumulator under normal operating conditions, and, together with the design pressure, is used as the design load condition
3.9
discharge volume
value of hydraulic fluid volume in the accumulator changed as the pressure in the pressurized accumulator changes between the highest and lowest actuating pressures of the circuit
3.10
discharge flow
amount of hydraulic fluid discharged per unit of time
3.11
batch
defined number of accumulator shells with the same vessel type, the same design conditions, the same nominal diameter and wall thickness, material from the same heat number, by the same manufacturing process, and heat treatment according to the same heat treatment specification
3.12
standard products
products in series which have undergone material selection, design, fabrication and acceptance as specified in this standard and passed type tests, and been approved for series production
4 Structure types and designations, ratings
4.1 Structure types and designations
4.1.1 The structure types of bladder accumulators are divided into Type A, Type AB, and Type B, the structure types, part names, and product designations of which are provided in Annex A.
4.1.2 The structure types of threaded diaphragm accumulators are divided into Type A, Type B and Type C, the structure types, part names, and product designations of which are provided in Annex B. The structure types of welded diaphragm accumulators are divided into Type A and Type B, the structure types, part names, and product designations of which are provided in Annex C.
4.1.3 The structure types of piston accumulators are divided into Type A and Type B, the structure types, part names, and product designations of which are provided in Annex D.
4.2 Ratings
4.2.1 Ten design pressure rating of the accumulators is divided into 10 classes (Mpa)—6.3, 10, 16, 20, 25, 31.5, 40, 50, 63, and 80. When the design pressure is between two adjacent pressure classes, it shall be determined by agreement between the seller and the buyer.
4.2.2 The nominal capacity of the accumulators is divided into 24 classes (L)—0.25, 0.40, 0.63, 1.0, 1.6, 2.5, 4.0, 6.3, 10, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, and 350. When the required capacity is between two adjacent capacity classes, it shall be determined by agreement between the seller and the buyer.
5 Materials
5.1 General
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Structure types and designations, ratings
5 Materials
6 Design
7 Fabrication
8 Performance and testing
9 Inspection rules
10 Marking, packaging and transportation
11 Accompanying documents
12 Safe use of accumulators
Annex A (Informative) Structure types and marking methods of bladder accumulators
Annex B (Informative) Structure types and marking methods of diaphragm accumulators with threaded connection
Annex C (Normative) Specifications for welded diaphragm accumulators
Annex D (Informative) Structure types and marking methods of piston accumulators
Annex E (Informative) Technical specifications for bladder and diaphragm
Annex F (Normative) Requirements for fatigue tests of accumulators
Annex G (Normative) Design fatigue curve
Annex H (Informative) Accumulator discharge flow test set-up
