To verify the strength and tightness of flange joints under service conditions, they must undergo type testing. The flanged pipe must exhibit no noticeable leakage under the combined effects of internal pressure and the corresponding bending moment. The test conditions are: The internal pressure is (1.5 PN+5) bar.
The relevant bending moment is calculated by adding the weight of the flanged pipe components and water in the test rig, as well as the external load, as a function of the length between the support points. The final bending moment values are shown in the following table:
Specific operations of flange joint type test:
The test assembly consists of two flanged pipes or fittings, assembled using standard bolts, nuts, and washers. Blind plates are installed at each end of the test assembly and tightened to the maximum PN specified by the bolt manufacturer for the test. Where not specified, the material grade of the bolts and nuts shall be EN ISO4016 grade 4.6.
The test assembly is mounted on two simple supports (as shown above), with the assembled flange joint located in the middle of the span. The support spacing is at least 6 times the DN or 4000 mm, whichever is less. This length is determined by the pipe or fitting mix, but only the test joint in the middle of the span is considered.
The test assembly is filled with water and easily vented. The pressure is continuously increased to the test pressure of (1.5 PN + 5) bar. An external load F is applied to the assembled flange joint via a flat plate, perpendicular to the axis of the test assembly. The combined force of the component and the weight of the water within produces the bending moment shown in the table above. All necessary safety precautions are taken during the pressure and bending moment tests.
Test conditions met:
The internal pressure and external load were maintained for 2 hours. During this time, the flange joints were thoroughly inspected and no leaks or damage was observed.
According to the EN545 standard, flanged connections for ductile iron pipes are rigid connections that maintain rigidity throughout the pipeline. Flanges, secured by bolts and nuts, are a standardized method for rigidly connecting pipes. They are suitable for applications such as valves, flowmeter accessories, and connecting dissimilar pipe materials, ensuring high strength and sealing. Choosing the appropriate ductile iron pipe fitting for your specific pipeline installation can achieve economical, reliable, and durable results. Contact us and we’ll provide you with professional and efficient water supply and drainage services!
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Post time: Oct-20-2025
