Verification of Leak-Tightness in Ductile Iron Pipe Joints According to EN545

Ductile iron pipe has become one of the preferred materials for water pipeline systems due to its high strength, toughness, and excellent corrosion resistance. The reliability of a pipeline system depends not only on the pipe itself, but more critically on its connection points—the joints. The EN545 standard specifies a series of joint performance tests, the following four of which are core components for verifying sealing reliability:
1. Positive Internal Hydrostatic Pressure Test

• Test Purpose: Under conditions of dimensional deviation between the ductile iron pipe socket and the spigot, the test assembly is subjected to a shear force of up to 50 times the DN value, while meeting the deflection angle specified in the EN545 standard. This verifies whether the joint will leak when subjected to sustained internal water pressure. This is the most basic and critical sealing performance test. Test Pressure: (1.5 PFA + 5) bar
• Test Duration: 2 hours
• Test Requirement: No visible leakage

2. Internal Negative Hydrostatic Test

• Test Purpose: With the ductile iron pipe socket and spigot dimensions deviated upward, the test assembly withstands a shear force of up to 50 times the DN value and meets the deflection angle specified in EN545. This simulates the vacuum created by draining the pipe, a sudden pump shutdown, or a sudden change in water level. This verifies that the joint can withstand atmospheric pressure and prevent external air from being drawn into the pipe.
• Test Pressure: -0.9 bar
• Test Duration: 2 hours
• Test Requirement: Maximum pressure change during the test: 0.09 bar

3. External Positive Hydrostatic Test

• Test Purpose: With the ductile iron pipe socket and spigot dimensions deviated upward, the test assembly withstands a shear force of up to 50 times the DN value. This verifies that the joint can effectively prevent external water from infiltrating the pipe when the pipe is unpressurized and the outside is flooded by groundwater or flooding. Test Pressure: 2 bar
• Test Duration: 2 hours
• Test Requirement: No visible leakage

4. Cyclic Internal Hydraulic Test

• Test Purpose: To evaluate the durability and fatigue resistance of ductile iron pipe fittings under long-term pressure fluctuations, given the dimensional deviations of the socket and spigot. In actual operation, pipeline pressure fluctuates frequently due to pump starts and stops, valve openings, and other factors. This test simulates these dynamic conditions.
• Test Pressure: Alternating between PMA and (PMA-5) bar pressures.
• Test Cycle: 24,000 cycles.
• Test Requirement: No visible leakage

It is through these rigorous tests that ductile iron pipe fittings that meet the EN545 standard are guaranteed to possess exceptional sealing reliability, environmental adaptability, and long service life. Whether operating in complex environments with high-pressure water transfer, vacuum conditions, external flooding, or frequent pressure fluctuations, they provide a solid and reliable guarantee for the entire piping system, ensuring a truly leak-proof performance. Choosing EN545-certified ductile iron pipe products means choosing long-term safety and peace of mind.

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