BS ISO 6164:2018 pdf downlaod – Hydraulic fluid power — Four-screw, one- piece square flange connections for use at pressures of 42 MPa, DN 25 to 80
5 Selection criteria
The following specifications supplement the dimensional data contained in Tables 1 to 4 with respect to all unspecified details:
a) The nominal matching flange size clamp shall be selected for the matching port size from Figures 3 and Table 3.
b) The flanged head size, shown in Figure 4 and Table 4, shall be selected in accordance with the size selected for the flange clamps and ports.
c) O-rings shall be selected conforming to the dimensions given in ISO 3601-1 and corresponding to the size code in Annex B, Table B.1.
d) Metric screws shall be selected corresponding to the sizes and lengths indicated in Table 1.
e) Screw type shall be designated according to 4.3 as well as thread size and length of screws.
f) Designate square flange connector sizes by the nominal flange size that corresponds to the maximum diameter of the bore through the flanged head.
6 Tolerances
6.1 Unless otherwise specified, tolerances shall be in accordance with ISO 2768-m (medium).
6.2 Dimensions and tolerances given in the tables apply to the finished parts, plated or otherwise processed, as specified by agreement between purchaser and manufacturer.
7 Corrosion protection
7.1 The external surface of all carbon steel flange clamps and all carbon steel flanged heads, except weld-on flanged heads, shall be protected with an appropriate coating to pass a minimum 72 h salt spray test in accordance with ISO 9227, unless otherwise agreed upon by the supplier and purchaser. Weld-on flanged heads shall be protected from corrosion by an oil film, phosphate coating or by other means that do not negatively affect weldability. This protection shall meet or exceed a 16 h neutral salt spray test in accordance with ISO 9227, unless otherwise agreed upon by the supplier and purchaser.
7.2 Screws shall be protected from corrosion by an oil film, phosphate coating, or other means that do not encourage hydrogen embrittlement, to meet or exceed the requirements of a 16 h neutral salt spray test in accordance with ISO 9227. 7.3 Appearance of red rust during the above salt spray tests shall be considered failure, except for in the following locations:
— all internal passages;
— edges; — areas where the parts are suspended or affixed in the test chamber and condensate can accumulate.
7.4 Parts conforming to this document shall not be cadmium plated. Hexavalent chromate coatings are not preferred for commercial and industrial usage for environmental reasons. Changes in plating can affect assembly torques and require requalification. 7.5 Internal fluid passages shall be protected from corrosion during storage and shipping.
7.6 All connection components shall be free from all hanging burrs, loose scale and slivers that might become dislodged in use, and from all other defects that might affect their serviceability.
All machined surfaces shall have a surface roiughness value of ISO 1302-MRR Ra 6,3, except where otherwise specified.
7.7 A smooth sealing surface shall be provided. Annular tool marks up to a surface roughness value of ISO 1302-MRR Ra 3,2 are permitted (see Figure 4 Footnote a for additional information).
7.8 For more specific finish requirements, see Figures 1 to 4.
8 Pressure/temperature requirements 8.1 Surges of pressure higher than the nominal ratings will reduce the ability of the flange connections to retain the hydraulic fluid. This should be taken into account in the design of the hydraulic system. Flange connections conforming to this document shall be subjected to the burst and cyclic endurance tests specified in ISO 19879 (test assembly type 1 with 2 straight connections or type 4) to verify that they meet the specified pressure/temperature requirements.
8.2 Flange connections conforming to this document and made of carbon steel shall be suitable for use at the working pressures given in Table 1 when used at temperatures between –40 °C and +120 °C. Flange connections conforming to this document shall not be assembled at temperatures lower than –20 °C. 8.3 Flange connections conforming to this document and made of stainless steel shall be suitable for use at the working pressures given in Tables 1 or 2 when used at temperatures between –60 °C and +100 °C. Higher temperatures require reduction of the pressure ratings in agreement with the manufacturer. Flange connections conforming to this document shall not be assembled at temperatures lower than –20 °C.