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BSP pipe fittings dimension tolerance ISO 8434 6

Date:Jun 11, 2019

ISO 8434 6 standard specifies the dimensions across flats of elbow and tee connectors shall have a minus tolerance only. For sizes up to and including 24 mm, tolerances for across-flats dimensions for forgings shall be +0/-0,8 mm, and for sizes larger than 24 mm, they shall be +0/-1 mm. The basic forging size may be increased up to the maximum size shown for bar stock, but the size selected shall be a metric across-flat size with minus tolerance only.


Hex tolerances across flats shall be in accordance with ISO 4759-1, product grade C. Minimum across-corner hex dimensions are 1,092 times the nominal width across flats. The minimum side flat is 0,43 times the nominal width across flats. Unless otherwise specified or shown, hex corners shall be chamfered 15° to 30° to a

diameter equal to the width across flats, with a tolerance of +0/-0,4 mm.


Dimensions specified apply to finished parts, including any plating or other treatments. The tolerance value for all dimensions not otherwise limited shall be ±0,4 mm.


Where passages in straight connectors are machined from opposite ends, the offset at the meeting point shall not exceed 0,4 mm. No cross-sectional area at a junction of passages shall be less than that of the smallest passage.


Angular tolerances on axis of end on elbows, tees and crosses shall be ±2,5° for tube sizes up to and including 10 mm and ±1,5° for all larger sizes.


Details of contour shall be chosen by the manufacturer provided the dimensions given in Tables 5 to 22 are maintained. Wrench flats on elbows and tees shall conform to the dimensions in the relevant tables. Abrupt reduction of a section shall be avoided. Junctions of small external sections and adjoining sections that are

relatively heavy shall be blended by means of ample fillets.



60° cone connection ends,  the screw threads on the 60° cone connection ends shall be pipe threads in accordance with class A of ISO 228-1.


The screw threads for the stud ends of connectors shall be chosen from ISO 261 for ISO 6149-3 and ISO 228-1 (class A) for ISO 1179-2 and -3.



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