1 Scope
This document specifies the design, manufacture, workmanship, surface treatment, nomenclature and marking of pressure measuring couplings with a connection end thread of M16 x 2 and a maximum working pressure of 63 MPa, which can be connected under pressure up to 40 MPa and are supplied with the corresponding stud end dimensions: GB/T 2878,2-M14 x 1.5, ISO 9974-2-M14 x 1.5, 1SO 1179-2-G 1/4,ISO 11926-2-7/16-20 UNF.
This document applies to pipe fittings for hydraulic systems with mineral oil as the working medium.
Note: For use with non-mineral oil working media, it is subject to negotiation between the supplier and the customer.
2 Normative references
The contents of the following documents constitute the essential provisions of this document through the normative references in the text. Among them, note the date of the reference documents, only the date of the corresponding version applicable to this document; do not note the date of the reference documents, the latest version (including all the revision of the list) applicable to this document.
GB/T 196 Basic Dimensions of General Purpose Screw Threads (GB/T 196-2003. ISO 724; 1993, MOD)
GB/T 197 General Purpose Screw Thread Tolerances (GB/T 197-2018, ISO 965-1: 2013, MOD)
GB/T 2878.2 Hydraulic Fluid Power Connections - Ports and Stud Ends with Metric Shank and O-ring Seals - Part 2: Heavy Stud Ends (S Series) (GB/T 2878.2-2011, ISO 6149-2: 2006, MOD)
GB/T 5576 Rubber and Latex Nomenclature (GB/T 5576 - 1997, idt ISO 1629:1995)
GB/T 10125 Corrosion Test in Artificial Atmospheres Salt Spray Test (GB/T 10125-2021. ISO 9227: 2017. MOD)
GB/T 17446 Fluid Power Systems and Components Vocabulary (GB/T 17446-2012, ISO 5598:2008, IDT)
GB/T 26143 Test Methods for Hydraulic Pipe Joints (GB/T 26143-2010, ISO 19879: 2010, IDT)
3 Terms and definitions
The terms and definitions defined in GB/T 17446 apply to this document.
4 Performance requirements
4.1 General rules
Products conforming to the dimensions in this document are not guaranteed to achieve the rated performance. The manufacturer shall carry out tests in accordance with the specifications contained in this document to ensure that the component meets the rated performance.
4.2 Working pressures and temperatures
The maximum working pressure of the pressure measuring coupling shall be 63 MPa and the working temperature range shall be -20 °C to 120 °C. Note: The operating temperature range of fittings with elastomeric seals is dependent on the seals.
4.3 Flow and pressure drop
4.3.1 At a flow rate of 6 L/min, the pressure drop in the pressure measuring coupling should not exceed 20 MPa.
4.3.2 The pressure drop value does not include the pressure drop in the pressure measuring hose necessary to achieve the test, which shall meet the requirements of ISO 18869 and the following provisions:
a) The pressure drop across the entire pressure measuring fitting assembly is tested;
b) the pressure drop after removal of the spool and spring;
c) The pressure drop measured in accordance with a) minus the pressure drop measured in accordance with b) is the result of the pressure drop in the pressure measuring joint.
Note: For the assessment of the pressure drop in the pressure measuring joint, it is not necessary to take into account the pressure drop in the ejector.
4.4 Connection of the pressure measuring joint and the matching joint
If a mating joint as described in chapter 5 is used, the mating joint should be sealed before the ejector opens the spool of the pressure measuring joint and the effective engagement length between the pressure measuring joint and the mating joint should be at least 2 times the pitch.
4.5 Burst pressure and cyclic endurance (pulse) pressure
When tested in accordance with 4.6, the pressure measuring joint shall be subjected to a burst pressure of at least 252 MPa and a cyclic endurance (impulse) pressure of 84 MPa.
4.6 Test requirements
4.6.1 The burst test and cyclic durability (impulse) test shall be in accordance with GB/T 26143.
4.6.2 The test specimen should be tightened in accordance with the torque requirements specified in the standards mentioned in 5.2 to 5.5.
5 Design
5.1 Basic structure, dimensions
5.1.1 The basic structure, dimensions of the pressure measuring joint shall conform to the provisions of Figure 1, and the stud end and seal shall conform to the corresponding standards mentioned in 5.2 to 5.5.
5.1.2 The dimensions of the matching coupling are shown in Figure 2.
5.1.3 M16×2 thread shall conform to GB/T 196. 6g tolerance class for male threads and 6H tolerance class for female threads shall conform to GB/T 197.
5.2FM 14×1.5 pressure measuring connector
5.2.1 With GB/T 2878.2 stud end thread for M14×1.5 pressure measurement joint size see Figure 3, code for FM 14×1.5.
5.2.2 The delivery of the pressure measuring coupling shall include the seal and protective cap at the stud end, unless otherwise agreed between the manufacturer and the user.
5.3 EM 14 x 1.5 pressure measuring couplings
5.3.1 Pressure measuring couplings with thread M1471 on the stud end in accordance with ISO 9974-2 are shown in Figure 4 and are designated EM 14 x 1.5.
5.3.2 The pressure measuring couplings shall be delivered with seals and protective caps on the stud end, unless otherwise agreed between the manufacturer and the user.
5.4 EG 1/4 pressure measuring couplings
5.4.1 The dimensions of a pressure measuring fitting with a thread of G1/4 at the stud end in accordance with ISO 1179-2 are shown in Figure 5 and are designated EG 1/4.
5.4.2 The pressure measuring couplings shall be delivered with seals and protective caps on the stud end, unless otherwise agreed between the manufacturer and the user.
5.5FU 7/16-20 pressure measuring couplings
5.5.1 The dimensions of the pressure measuring coupling with a stud end thread of 7/16-20 UNF according to ISO 11926-2 are shown in Figure 6 and are designated FU7/16-20.
5.5.2 The pressure measuring couplings shall be delivered with seals and protective caps on the stud end, unless otherwise agreed between the manufacturer and the user.
6 Manufacture
6.1 Method of manufacture
The parts of the pressure measuring coupling can be made by forging or cold forming, or by machining from bar stock.
6.2 Workmanship
The process shall be in accordance with best commercial practice in order to produce high quality parts. Pressure measuring joints shall be free from visible dirt, burrs, particles or lumps that may be dislodged in use and any other defects that may affect the function of the component. Unless otherwise specified, the roughness of the remaining machined surfaces shall meet Ra ≤ 6.3 p.m.
6.3 Surface finish
Unless otherwise agreed between the manufacturer and the user, all external surfaces and threads of the pressure measuring couplings shall be plated or coated and shall pass a 72 h neutral salt spray test in accordance with GB/T 10125. During the salt spray test, the presence of red rust spots on any part shall be considered a failure, except for the following specified parts:
--All internal runners;
--edges and corners, such as the tips of hexagons, serrations and the tops of threaded teeth (where mechanical damage to the plating or coating has been caused by the effects of mass production or transport);
--Areas of mechanical deformation of coatings or coatings due to buckling, flaring, bending and other columnar, sheet metal forming;
--hanging or fixed parts in the test chamber (where condensate may collect).
Internal fluid passages should be protected from corrosion during storage.
For environmental reasons, parts manufactured in accordance with this document should not be cadmium plated and hexavalent chromate coatings are not preferred. Changes in the plating may affect the assembly torque and should be revalidated if necessary.
7 Naming of joints
The following nomenclature should be used for pressure measuring joints conforming to the provisions of this document: "Pressure measuring joint" followed by the standard number in one blank space, followed by "-", followed by the code for the type of pressure measuring joint given in Chapter 5, followed by "-". ", followed by the seal material code for the stud end in accordance with GBT5576.
Example:
Pressure measuring coupling GB/T 41981.2-FM 14×1.5-NBR
8 Marking
Pressure fittings should be permanently marked with the name of the manufacturer or with a positive mark.
9 Marking instructions (cf. this document)
When choosing to comply with this document, it is appropriate to use the following statement in test reports, catalogues and sales documents;
"Pressure measuring couplings conform to GB/T 41981.2-2022K Hydraulic drive connection pressure measuring couplings Part 2: Pressure connectable type".
1 Scope
2 Normative references
3 Terms and definitions
4 Performance requirements
5 Design
6 Manufacture
7 Naming of joints
8 Marking
9 Marking instructions (cf. this document)
