Test Procedure

The plugs were initially torqued to approximately 50% of the maximum torque values obtained from a previous test for aluminum and installed into three commercial grade aluminum manifolds that had port positions specially located for this test. Three manifolds were designed (6061 T6 Aluminum) with (3) ports on (3) sides and manifold # 3 had (2) ports on (2) sides. The manifolds allowed testing (3) samples of each SAE J1926 port sizes #2, #3, #4, #5, #6, #8, #10, and #12 on (3) manifolds. The rated working pressure of aluminum was 3000 psi. The manifolds were then plumbed into the impulse stand. The test setup used conventional petroleum base ISO VG 32 oil at a temperature of 100°F+/-10°F. A relief valve was plumbed in to control the pressure required to pass the NFPA standard T2.6.1R2-2000. The manifolds were installed so that the fluid flowed through the setup. This method ensures the most uniform fluid temperature and pressure waveform characteristics, as well as efficiently bleeding out any entrained air. The test was set up to meet the NFPA fatigue standard T2.6.1R2-2000.

The fatigue testing parameters outlined by the NFPA standards T2.6.1R2-2000 were as follows:

Test Duration^*........1,000,000 cycles
Cycle Rate............1.0Hz
Test Pressure.........3688 psi
Test Temperature......100° F ±10°F
Test Oil..............Benz Oil petroleum base ISO VG 32

  ^* Test continued for a total of 2,000,000 cycles.

The goal of this project at the Fluid Power Institute® was to establish torque values that successfully pass the 1,000,000 cycles Endurance Test specified in paragraph 8 of NFPA T2.6.1R2-2000. To determine torque values for EPCO anodized aluminum Zero-Leak Gold Plugs an iterative procedure was established. The plugs were anodized and dyed gold per MIL-A-8626 TYPE II Class 2 per Fort Wayne Anodizing.

Starting torque values for this evaluation were 50% of the values obtained from previous testing, test report titled “Zero Leak Gold Plug Testing” Project number 51579 dated 2/24/99, page 6 performed by the Fluid Power Institute at the Milwaukee School of Engineering (for torque values see Table 1).

Each plug size torque was increased by 20% in succession until successful completion of the NFPA 1,000,000-cycle Endurance Test.

Table 1: Starting Torque Values

For each test, the torque value was applied to the plugs and the manifold assemblies were plumbed into the impulse chamber and the Rated Fatigue Pressure Endurance Cycle Test started. The Cyclic Test Pressure (CTP) applied will be 3688 psi for Aluminum. Pressure waveforms for the 1,000,000 cycles Endurance Test will be in accordance with characteristics specified by paragraph 8 of T2.6.1R2-2000. The basic criteria for the wave shape is maximum rate of pressure rise must not exceed 80,000 psi/sec. The NFPA T2.6.1R2-2000, paragraph 8.4.4 states, “The Pulse Duration must be held to 100±10 milliseconds”.

When a failure occurs, a new Buna nitrile 70 durometer O-Ring will be installed on the plug size that failed and the torque will be increased to the next value for that size plug only. The port surface area and the plug will be cleaned to remove any fluid or residue prior to replacing the plug in the manifold to resume the testing. This process will be followed until all plugs pass the 1,000,000 cycles Endurance Test. A failure defined by NFPA T2.6.1R2-2000 states “ The inability to sustain a given load or to contain pressure in a pressure containing envelope”. By the stated definition a leak would cause a failure.

The final tests conducted on the plugs will be the Proof and Burst Tests. These tests require new aluminum Zero-Leak Gold Plugs with Buna nitrile 70 durometer O-Rings to be installed. The Proof and Burst Tests will be conducted in accordance with paragraphs 4.1 and 4.2 of SAE J1644 May93. Stated briefly “the Proof Pressure Test requires (3) samples to meet or exceed a ratio of 2:1 between proof and working pressure for 60 seconds minimum”. The Burst Test requirement states “ (3) samples be capable of withstanding the minimum of four times working pressure without failing”. During the test, O-Ring Ports will be labeled and scribed with a scratch across the Zero-Leak Gold aluminum plug leading into the manifold. From this mark it can be determined if any movement of the plug in relation to manifold has occurred. Torque values will be recorded after the test to determine if values had changed. The pressure fatigue test will then run until the plugs began to show signs of leakage or o-ring extrusion. If leakage or o-ring extrusion occurs on a plug, all three plugs of that size will be removed to examine the o-rings and plugs. If the o-ring or plug is damaged, they will be replaced. The plugs will then be torqued to a new torque value, approximately 20% greater then the previous value. This procedure will be repeated until the plugs achieve the minimum torque value needed to pass the million cycles without leaking. The impulse stand will run 24 hours a day, seven days a week for 1,000,000 cycles, except being shut down for maintenance or part failure.

After the fatigue testing is completed, the plugs will be torqued to their minimum values in high-pressure fittings. In the high-pressure fittings, the plugs will be subjected to a proof test (SAE J343 4.2 MAR 1999) and burst test (SAE J343 4.4 MAR 1999). The proof test consists of three of each size fitting passing a 2 to 1 working pressure of 3000 psi (6000 psi) for a duration of no less then 30 seconds nor more than 60 seconds. After passing the proof test the three fittings of each size will be subjected to a burst test. In the burst test the pressure will be increased at a constant rate to obtain the minimum burst pressure within a period of not less than 15 seconds nor more than 60 seconds. To pass the burst test the minimum burst pressure must equal to or greater than 4 times the working pressure of 3000 psi (12000 psi).

¹Test Report titled “Zero Leak Gold Plug Testing” Project number 51579 dated 2/24/99 page 6 performed by the Fluid Power Institute at the Milwaukee School of Engineering.